1、SpringMVC的返回JSON数据
到目前为止咱们编写的所有Controller的办法的返回值都是String类型，然而大家应该都晓得，咱们有时候数据传递特地是在ajax中，咱们返回的数据常常须要应用json，那么如何来保障返回的数据的是json格局呢？应用@ResponseBody注解
pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.mashibing</groupId> <artifactId>springmv_ajax</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <!-- https://mvnrepository.com/artifact/org.springframework/spring-context --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>5.2.3.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework/spring-web --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>5.2.3.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.2.3.RELEASE</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jsp-api</artifactId> <version>2.0</version> <scope>provided</scope> </dependency> <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.10.3</version> </dependency> <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.10.3</version> </dependency> <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.10.3</version> </dependency> </dependencies></project>springmvc.xml
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd"> <context:component-scan base-package="com.mashibing"></context:component-scan> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/page/"></property> <property name="suffix" value=".jsp"></property> </bean> <mvc:default-servlet-handler></mvc:default-servlet-handler> <mvc:annotation-driven></mvc:annotation-driven></beans>JsonController.java
package com.mashibing.controller;import com.mashibing.bean.User;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import java.util.ArrayList;import java.util.Date;import java.util.List;@Controllerpublic class JsonController { @ResponseBody @RequestMapping("/json") public List<User> json(){ List<User> list = new ArrayList<User>(); list.add(new User(1,"zhangsan",12,"男",new Date(),"1234@qq.com")); list.add(new User(2,"zhangsan2",12,"男",new Date(),"1234@qq.com")); list.add(new User(3,"zhangsan3",12,"男",new Date(),"1234@qq.com")); return list; }}User.java
package com.mashibing.bean;import com.fasterxml.jackson.annotation.JsonFormat;import com.fasterxml.jackson.annotation.JsonIgnore;import java.util.Date;public class User { private Integer id; private String name; private Integer age; private String gender; @JsonFormat( pattern = "yyyy-MM-dd") private Date birth; @JsonIgnore private String email; public User() { } public User(Integer id, String name, Integer age, String gender, Date birth, String email) { this.id = id; this.name = name; this.age = age; this.gender = gender; this.birth = birth; this.email = email; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public Date getBirth() { return birth; } public void setBirth(Date birth) { this.birth = birth; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } @Override public String toString() { return "User{" + "id=" + id + ", name='" + name + '\'' + ", age=" + age + ", gender='" + gender + '\'' + ", birth=" + birth + ", email='" + email + '\'' + '}'; }}同时@ResponseBody能够间接将返回的字符串数据作为响应内容
package com.mashibing.controller;import com.mashibing.bean.User;import org.springframework.http.HttpEntity;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;@Controllerpublic class OtherController { @ResponseBody @RequestMapping("/testResponseBody") public String testResponseBody(){ return "<h1>success</h1>"; }}2、发送ajax申请获取json数据
ajax.jsp
<%@ page import="java.util.Date" %><%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title> <script type="text/javascript" src="script/jquery-1.9.1.min.js"></script></head><% pageContext.setAttribute("ctp",request.getContextPath());%><body><%=new Date()%><a href="${ctp}/json">获取用户信息</a><div></div><script type="text/javascript"> $("a:first").click(function () { $.ajax({ url:"${ctp}/json", type:"GET", success:function (data) { console.log(data) $.each(data,function() { var user = this.id+"--"+this.name+"--"+this.age+"--"+this.gender+"--"+this.birth+"--"+this.email; $("div").append(user+'<br/>'); }) } }); return false; });</script></body></html>3、应用@RequestBody获取申请体信息
testOther.jsp
<%-- Created by IntelliJ IDEA. User: root Date: 2020/3/13 Time: 15:04 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html><% pageContext.setAttribute("ctp",request.getContextPath());%><head> <title>Title</title></head><body><form action="${ctp}/testRequestBody" method="post" enctype="multipart/form-data"> <input name="username" value="zhangsan"><br> <input name="password" value="123456"><br> <input type="file" name="file" ><br> <input type="submit"><br></form></body></html>OtherController.java
package com.mashibing.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;@Controllerpublic class OtherController { @RequestMapping("/testRequestBody") public String testRequestBody(@RequestBody String body){ System.out.println("申请体："+body); return "success"; }}同时@RequestBody可能承受json格局的申请数据：
testOther.jsp
<%-- Created by IntelliJ IDEA. User: root Date: 2020/3/13 Time: 15:04 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><script type="text/javascript" src="script/jquery-1.9.1.min.js"></script><html><% pageContext.setAttribute("ctp",request.getContextPath());%><head> <title>Title</title></head><body><form action="${ctp}/testRequestBody" method="post" enctype="multipart/form-data"> <input name="username" value="zhangsan"><br> <input name="password" value="123456"><br> <input type="file" name="file" ><br> <input type="submit"><br></form><hr/><a href="${ctp}/testRequestJson">发送json数据</a><script type="text/javascript"> $("a:first").click(function () { var user = {id:"1",name:"zhangsan",age:"12",gender:"男",birth:"2020-3-13",email:"123@qq.com"}; var userJson = JSON.stringify(user); $.ajax({ url:"${ctp}/testRequestJson", type:"POST", data:userJson, contentType:"application/json", success:function (data) { alert(data); } }); return false; });</script></body></html>OtherController.java
package com.mashibing.controller;import com.mashibing.bean.User;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;@Controllerpublic class OtherController { @RequestMapping("/testRequestBody") public String testRequestBody(@RequestBody String body){ System.out.println("申请体："+body); return "success"; } @RequestMapping("/testRequestJson") public String testRequestBody(@RequestBody User user){ System.out.println("对象："+user); return "success"; }}在承受申请的时候还能够应用HttpEntity对象，用来承受参数，能够获取申请头信息。
package com.mashibing.controller;import com.mashibing.bean.User;import org.springframework.http.HttpEntity;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;@Controllerpublic class OtherController { @RequestMapping("/testHttpEntity") public String testRequestBody(HttpEntity<String> httpEntity){ System.out.println(httpEntity); return "success"; }}4、应用RespsonseEntity能够用来定制响应内容
package com.mashibing.controller;import com.mashibing.bean.User;import org.springframework.http.HttpEntity;import org.springframework.http.HttpHeaders;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.stereotype.Controller;import org.springframework.util.MultiValueMap;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;@Controllerpublic class OtherController { @RequestMapping("/testResponseEntity") public ResponseEntity<String> testResponseEntity(){ String body = "<h1>hello</h1>"; MultiValueMap<String,String> header = new HttpHeaders(); header.add("Set-Cookie","name=zhangsan"); return new ResponseEntity<String>(body,header, HttpStatus.OK); }}5、文件下载
package com.mashibing.controller;import com.mashibing.bean.User;import org.springframework.http.HttpEntity;import org.springframework.http.HttpHeaders;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.stereotype.Controller;import org.springframework.util.MultiValueMap;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import javax.servlet.ServletContext;import javax.servlet.http.HttpServletRequest;import java.io.FileInputStream;import java.io.FileNotFoundException;@Controllerpublic class OtherController { @RequestMapping("/download") public ResponseEntity<byte[]> download(HttpServletRequest request) throws Exception { //获取要下载文件的门路及输出流对象 ServletContext servletContext = request.getServletContext(); String realPath = servletContext.getRealPath("/script/jquery-1.9.1.min.js"); FileInputStream fileInputStream = new FileInputStream(realPath); byte[] bytes = new byte[fileInputStream.available()]; fileInputStream.read(bytes); fileInputStream.close(); //将要下载文件内容返回 HttpHeaders httpHeaders = new HttpHeaders(); httpHeaders.set("Content-Disposition","attachment;filename=jquery-1.9.1.min.js"); return new ResponseEntity<byte[]>(bytes,httpHeaders,HttpStatus.OK); }}6、文件上传
Spring MVC 为文件上传提供了间接的反对，这种反对是通过即插即用的 MultipartResolver 实现的。Spring 用 Jakarta Commons FileUpload 技术实现了一个 MultipartResolver 实现类：CommonsMultipartResovler
Spring MVC 上下文中默认没有拆卸 MultipartResovler，因而默认状况下不能解决文件的上传工作，如果想应用 Spring 的文件上传性能，需当初上下文中配置 MultipartResolver。
pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.mashibing</groupId> <artifactId>springmvc_upload</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <!-- https://mvnrepository.com/artifact/org.springframework/spring-context --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>5.2.3.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework/spring-web --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>5.2.3.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.2.3.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jsp-api</artifactId> <version>2.0</version> <scope>provided</scope> </dependency> <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.10.3</version> </dependency> <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.10.3</version> </dependency> <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.10.3</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-io/commons-io --> <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.6</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload --> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.4</version> </dependency> </dependencies></project>web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> <servlet> <servlet-name>springmvc</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:springmvc.xml</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>springmvc</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <filter> <filter-name>encoding</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>encoding</filter-name> <url-pattern>/*</url-pattern> </filter-mapping></web-app>springmvc.xml
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd"> <mvc:default-servlet-handler></mvc:default-servlet-handler> <mvc:annotation-driven></mvc:annotation-driven> <context:component-scan base-package="com.mashibing"></context:component-scan> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/page/"></property> <property name="suffix" value=".jsp"></property> </bean> <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> <property name="defaultEncoding" value="UTF-8"></property> <property name="maxUploadSize" value="1024000"></property> </bean></beans>index.jsp
<%-- Created by IntelliJ IDEA. User: root Date: 2020/3/13 Time: 17:00 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html> <head> <title>$Title$</title> </head> <body> <form action="testUpload" method="post" enctype="multipart/form-data"> 文件: <input type="file" name="file"/><br><br> 形容: <input type="text" name="desc"/><br><br> <input type="submit" value="提交"/> </form> </body></html>UploadHandler.java
package com.mashibing.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.multipart.MultipartFile;import java.io.File;import java.io.IOException;import java.io.InputStream;@Controllerpublic class UploadHandler { @RequestMapping(value = "/testUpload", method = RequestMethod.POST) public String testUpload(@RequestParam(value = "desc", required = false) String desc, @RequestParam("file") MultipartFile multipartFile) throws IOException { System.out.println("desc : " + desc); System.out.println("OriginalFilename : " + multipartFile.getOriginalFilename()); multipartFile.transferTo(new File("D:\\file\\"+multipartFile.getOriginalFilename())); return "success"; //减少胜利页面: /views/success.jsp }}success.jsp
<%-- Created by IntelliJ IDEA. User: root Date: 2020/3/13 Time: 17:03 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title></head><body>success</body></html>如果是多文件上传，那么又改如何解决呢？
index.jsp
<%-- Created by IntelliJ IDEA. User: root Date: 2020/3/13 Time: 17:00 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html> <head> <title>$Title$</title> </head> <body> <form action="testUpload" method="post" enctype="multipart/form-data"> 文件: <input type="file" name="file"/><br><br> 文件: <input type="file" name="file"/><br><br> 文件: <input type="file" name="file"/><br><br> 形容: <input type="text" name="desc"/><br><br> <input type="submit" value="提交"/> </form> </body></html>UploadHandler.java
package com.mashibing.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.multipart.MultipartFile;import java.io.File;import java.io.IOException;import java.io.InputStream;@Controllerpublic class UploadHandler { @RequestMapping(value = "/testUpload", method = RequestMethod.POST) public String testUpload(@RequestParam(value = "desc", required = false) String desc, @RequestParam("file") MultipartFile[] multipartFile) throws IOException { System.out.println("desc : " + desc); for (MultipartFile file : multipartFile) { if (!file.isEmpty()) { System.out.println("OriginalFilename : " + file.getOriginalFilename()); file.transferTo(new File("D:\\file\\" + file.getOriginalFilename())); } } return "success"; //减少胜利页面: /views/success.jsp }}7、Springmvc拦截器
SpringMVC提供了拦截器机制，容许运行指标办法之前进行一些拦挡工作或者指标办法运行之后进行一下其余相干的解决。自定义的拦截器必须实现HandlerInterceptor接口。
preHandle()：这个办法在业务处理器解决申请之前被调用，在该办法中对用户申请 request 进行解决。如果程序员决定该拦截器对申请进行拦挡解决后还要调用其余的拦截器，或者是业务处理器去进行解决，则返回true；如果程序员决定不须要再调用其余的组件去解决申请，则返回false
postHandle()：这个办法在业务处理器解决完申请后，然而DispatcherServlet 向客户端返回响应前被调用，在该办法中对用户申请request进行解决。
afterCompletion()：这个办法在DispatcherServlet齐全解决完申请后被调用，能够在该办法中进行一些资源清理的操作。
1、自定义第一个拦截器
MyFirstInterceptor.java
package com.mashibing.interceptor;import org.springframework.web.servlet.HandlerInterceptor;import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class MyFirstInterceptor implements HandlerInterceptor { public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println(this.getClass().getName()+"------->preHandle"); return true; } public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println(this.getClass().getName()+"------->postHandle"); } public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { System.out.println(this.getClass().getName()+"------->afterCompletion"); }}TestInterceptorController.java
package com.mashibing.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;@Controllerpublic class TestInterceptorController { @RequestMapping("test01") public String test01(){ System.out.println("test01"); return "success"; }}springmvc.xml
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd"> <mvc:default-servlet-handler></mvc:default-servlet-handler> <mvc:annotation-driven></mvc:annotation-driven> <context:component-scan base-package="com.mashibing"></context:component-scan> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/page/"></property> <property name="suffix" value=".jsp"></property> </bean> <mvc:interceptors> <bean class="com.mashibing.interceptor.MyFirstInterceptor"></bean> </mvc:interceptors></beans>success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title></head><body><% System.out.println("success.jsp");%>success</body></html>通过运行后果可能发现拦截器的执行程序如下：
能够看到先执行拦截器的preHandle办法----》执行指标办法----》执行拦截器的postHandle办法----》执行页面跳转----》执行拦截器的afterCompletion办法
在配置拦截器的时候有两个须要留神的点：
1、如果prehandle办法返回值 为false，那么意味着不放行，那么就会造成后续的所有操作都中断
2、如果执行到办法中出现异常，那么后续流程不会解决然而afterCompletion办法会执行
2、定义多个拦截器
再增加另外一个拦截器
MySecondInterceptor.java
package com.mashibing.interceptor;import org.springframework.web.servlet.HandlerInterceptor;import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class MySecondInterceptor implements HandlerInterceptor { public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println(this.getClass().getName()+"------->preHandle"); return true; } public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println(this.getClass().getName()+"------->postHandle"); } public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { System.out.println(this.getClass().getName()+"------->afterCompletion"); }}看到如下执行程序：
调整两个拦截器的配置程序：
大家能够看到对应的成果，谁先执行取决于配置的程序。
拦截器的preHandle是依照程序执行的
拦截器的postHandle是依照逆序执行的
拦截器的afterCompletion是依照逆序执行的
如果执行的时候外围的业务代码出问题了，那么曾经通过的拦截器的afterCompletion会接着执行。
8、拦截器跟过滤器的区别
1、过滤器是基于函数回调的，而拦截器是基于java反射的
2、过滤器依赖于servlet容器，而拦截器不依赖与Servlet容器
3、过滤器简直对所有的申请都起作用，而拦截器只能对action申请起作用
4、拦截器能够拜访action的上下文，而过滤器不能够
5、在controller的生命周期中，拦截器能够屡次调用，而过滤器只能在web容器初始化的时候初始化一次，后续匹配的所有申请都会通过过滤器来进行过滤
9、SpringMVC的国际化操作
在日常工作中，如果你的网站须要给不同语言地区的人进行查看，此时就须要应用国际化的基本操作，springmvc的国际化操作比拟容易。
index.jsp
<%-- Created by IntelliJ IDEA. User: root Date: 2020/3/13 Time: 17:00 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html> <head> <title>$Title$</title> </head> <body> <a href="i18n">国际化页面登录</a> </body></html>login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt"%><html><head> <title>Title</title></head><body><h1><fmt:message key="welcomeinfo"/></h1><form action="login" method="post" > <fmt:message key="username"/>: <input type="text" name="username"/><br><br> <fmt:message key="password"/>: <input type="password" name="password"/><br><br> <input type="submit" value="<fmt:message key="loginBtn"/>"/></form></body></html>I18nController.java
package com.mashibing.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;@Controllerpublic class I18nController { @RequestMapping("i18n") public String i18n(){ return "login"; }}login_en_US.properties
welcomeinfo=welcome to mashibing.comusername=USERNAMEpassword=PASSWORDloginBtn=LOGINlogin_zh_CN.properties
welcomeinfo=欢送进入马士兵教育username=用户名password=明码loginBtn=登录springmvc.xml
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd"> <mvc:default-servlet-handler></mvc:default-servlet-handler> <mvc:annotation-driven></mvc:annotation-driven> <context:component-scan base-package="com.mashibing"></context:component-scan> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/page/"></property> <property name="suffix" value=".jsp"></property> </bean> <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource"> <property name="basename" value="login"></property> </bean></beans>其实SpringMVC中国际化的解决非常简单，就是依照浏览器所带来的语言信息决定的。
Locale locale = request.getLocale();//获取浏览器的区域信息在DispatcherServlet中会蕴含一个组件，用来专门获取区域信息
通过图片可能发现，默认调用的是org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver类
在程序中能够获取Locale的相干信息：
package com.mashibing.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.MessageSource;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import java.util.Locale;@Controllerpublic class I18nController { @Autowired private MessageSource messageSource; @RequestMapping("i18n") public String i18n(Locale locale){ System.out.println(locale); String username = messageSource.getMessage("username", null, locale); System.out.println(username); return "login"; }}10、通过超链接来切换国际化
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt"%><html><head> <title>Title</title></head><body><h1><fmt:message key="welcomeinfo"/></h1><form action="login" method="post" > <fmt:message key="username"/>: <input type="text" name="username"/><br><br> <fmt:message key="password"/>: <input type="password" name="password"/><br><br> <input type="submit" value="<fmt:message key="loginBtn"/>"/> <a href="i18n?locale=zh_CN">中文</a><a href="i18n?locale=en_US">英文</a></form></body></html>MyLocaleResolver.java
package com.mashibing;import org.springframework.web.servlet.LocaleResolver;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.util.Locale;public class MyLocaleResolver implements LocaleResolver { /** * 解析并返回locale * @param request * @return */ @Override public Locale resolveLocale(HttpServletRequest request) { Locale locale = null; String localeStr = request.getParameter("locale"); if(localeStr!=null && ! "".equals(localeStr)){ locale = new Locale(localeStr.split("_")[0],localeStr.split("_")[1]); }else{ locale = request.getLocale(); } return locale; } /** * 不反对设置locale的信息 * @param request * @param response * @param locale */ @Override public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) { throw new UnsupportedOperationException( "Cannot change HTTP accept header - use a different locale resolution strategy"); }}springmvc.xml
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd"><mvc:default-servlet-handler></mvc:default-servlet-handler><mvc:annotation-driven></mvc:annotation-driven><context:component-scan base-package="com.mashibing"></context:component-scan><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/page/"></property> <property name="suffix" value=".jsp"></property></bean><bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource"> <property name="basename" value="login"></property></bean> <!--配置区域信息解析器--> <bean id="localeResolver" class="com.mashibing.MyLocaleResolver"></bean></beans>除了能够自定义区域信息解析器之外，咱们还能够应用SpringMVC中自带的SessionLocaleResolver:
I18nController.java
package com.mashibing.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.MessageSource;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.servlet.i18n.SessionLocaleResolver;import javax.servlet.http.HttpSession;import java.util.Locale;@Controllerpublic class I18nController { @Autowired private MessageSource messageSource; @RequestMapping("i18n") public String i18n(@RequestParam(value = "locale",defaultValue = "zh_CN") String localeStr,Locale locale, HttpSession session){ Locale l = null; if(localeStr!=null && ! "".equals(localeStr)){ l = new Locale(localeStr.split("_")[0],localeStr.split("_")[1]); }else{ l = locale; } session.setAttribute(SessionLocaleResolver.class.getName() + ".LOCALE",l); return "login"; }}springmvc.xml
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd"><mvc:default-servlet-handler></mvc:default-servlet-handler><mvc:annotation-driven></mvc:annotation-driven><context:component-scan base-package="com.mashibing"></context:component-scan><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/page/"></property> <property name="suffix" value=".jsp"></property></bean><bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource"> <property name="basename" value="login"></property></bean> <!--配置区域信息解析器--><!-- <bean id="localeResolver" class="com.mashibing.MyLocaleResolver"></bean>--> <bean id="localeResolver" class="org.springframework.web.servlet.i18n.SessionLocaleResolver"></bean></beans>应用LocaleChangeInterceptor来实现国际化：
springmvc.xml
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd"><mvc:default-servlet-handler></mvc:default-servlet-handler><mvc:annotation-driven></mvc:annotation-driven><context:component-scan base-package="com.mashibing"></context:component-scan><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/page/"></property> <property name="suffix" value=".jsp"></property></bean><!-- <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">--><!-- <property name="defaultEncoding" value="UTF-8"></property>--><!-- <property name="maxUploadSize" value="1024000"></property>--><!-- </bean>--><!-- <mvc:interceptors>--><!-- <bean class="com.mashibing.interceptor.MySecondInterceptor"></bean>--><!-- <bean class="com.mashibing.interceptor.MyFirstInterceptor"></bean>--><!-- </mvc:interceptors>--><bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource"> <property name="basename" value="login"></property></bean><!--配置区域信息解析器--><!-- <bean id="localeResolver" class="com.mashibing.MyLocaleResolver"></bean>--><bean id="localeResolver" class="org.springframework.web.servlet.i18n.SessionLocaleResolver"></bean> <mvc:interceptors> <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor"></bean> </mvc:interceptors></beans>I18nController.java
package com.mashibing.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.MessageSource;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.servlet.i18n.SessionLocaleResolver;import javax.servlet.http.HttpSession;import java.util.Locale;@Controllerpublic class I18nController { @Autowired private MessageSource messageSource; @RequestMapping("i18n") public String i18n(@RequestParam(value = "locale",defaultValue = "zh_CN") String localeStr,Locale locale, HttpSession session){// Locale l = null;// if(localeStr!=null && ! "".equals(localeStr)){// l = new Locale(localeStr.split("_")[0],localeStr.split("_")[1]);// }else{// l = locale;// }// session.setAttribute(SessionLocaleResolver.class.getName() + ".LOCALE",l); return "login"; }}11、SpringMVC异样解决机制
在SpringMVC中领有一套十分弱小的异样解决机制，SpringMVC通过HandlerExceptionResolver处理程序的异样，包含申请映射，数据绑定以及指标办法的执行时产生的异样。
在容器启动好，进入DispatcherServlet之后，会对HandlerExceptionResolver进行初始化操作：
会默认的从DispatcherServlet.properties中找到对应的异样解决类：
#默认的解决类org.springframework.web.servlet.HandlerExceptionResolver=#解决@ExceptionHandlerorg.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver,\#解决@ResponseStatus，给自定义异样应用org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver,\#判断是否是SpringMVC自带异样org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver本人定义异样解决形式：
index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html> <head> <title>$Title$</title> </head> <body><a href="exception1">本人解决异样</a> </body></html>ExceptionController.java
package com.mashibing.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.servlet.ModelAndView;import javax.jws.WebParam;@Controllerpublic class ExceptionController { @RequestMapping("exception1") public String exception(){ System.out.println("exception......."); System.out.println(10/0); return "success"; } @ExceptionHandler(value = {ArithmeticException.class}) public ModelAndView handlerException(Exception exception){ ModelAndView mv = new ModelAndView(); mv.setViewName("error"); mv.addObject("ex",exception); return mv; }}error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title></head><body>我的出错页面：错误信息：${ex}</body></html>在一个类中可能会蕴含多个异样的解决办法，在不同的办法上能够应用不同范畴的异样，在查找的时候会优先调用范畴小的异样解决；
package com.mashibing.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.servlet.ModelAndView;import javax.jws.WebParam;@Controllerpublic class ExceptionController { @RequestMapping("exception1") public String exception(){ System.out.println("exception......."); System.out.println(10/0); return "success"; } @ExceptionHandler(value = {ArithmeticException.class}) public ModelAndView handlerException1(Exception exception){ System.out.println("handlerException1........"); ModelAndView mv = new ModelAndView(); mv.setViewName("error"); mv.addObject("ex",exception); return mv; } @ExceptionHandler(value = {Exception.class}) public ModelAndView handlerException2(Exception exception){ System.out.println("handlerException2........"); ModelAndView mv = new ModelAndView(); mv.setViewName("error"); mv.addObject("ex",exception); return mv; }}在不同的类中可能会蕴含不同的异样解决，因而咱们须要定义一个全局的异样控制器,应用@ControllerAdvice注解标注，如果本类跟全局都有相干异样的解决，那么会优先应用本类的。
package com.mashibing.controller;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.servlet.ModelAndView;@ControllerAdvicepublic class MyGlobalExceptionHandler { @ExceptionHandler(value = {ArithmeticException.class}) public ModelAndView handlerException1(Exception exception){ System.out.println("handlerException1........"); ModelAndView mv = new ModelAndView(); mv.setViewName("error"); mv.addObject("ex",exception); return mv; }}@ResponseStatus的应用：
@ResponseStatus能够标注到办法上，然而标注在办法之后可能导致该办法无奈被拜访，因而更多的是在自定义类上
package com.mashibing.controller;import org.springframework.http.HttpStatus;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseStatus;import org.springframework.web.servlet.ModelAndView;import javax.jws.WebParam;@Controllerpublic class ExceptionController { @ResponseStatus(reason = "不晓得什么起因，反正谬误",value = HttpStatus.NOT_ACCEPTABLE) @RequestMapping("exception1") public String exception(){ System.out.println("exception......."); return "success"; }}@ResponseStatus作用在类上
UserNameException.java
package com.mashibing.controller;import org.springframework.http.HttpStatus;import org.springframework.web.bind.annotation.ResponseStatus;@ResponseStatus(reason = "名字不是admin",value = HttpStatus.NOT_ACCEPTABLE)public class UserNameException extends RuntimeException {}ExceptionController.java
package com.mashibing.controller;import org.springframework.http.HttpStatus;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseStatus;import org.springframework.web.servlet.ModelAndView;import javax.jws.WebParam;@Controllerpublic class ExceptionController { @RequestMapping("exception1") public String exception(){ System.out.println("exception......."); return "success"; } @RequestMapping("exception2") public String exception2(String username){ System.out.println("exception2222......."); if ("admin".equals(username)){ return "success"; }else{ throw new UserNameException(); } }}springmvc自定义的异样：
index.jsp
<%-- Created by IntelliJ IDEA. User: root Date: 2020/3/13 Time: 17:00 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html> <head> <title>$Title$</title> </head> <body><a href="exception1">本人解决异样</a><a href="exception2?username=zhangsan">自定义异样解决</a><a href="exception3">Springmvc本人异样解决</a> </body></html>ExceptionController.java
package com.mashibing.controller;import org.springframework.http.HttpStatus;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.ResponseStatus;import org.springframework.web.servlet.ModelAndView;import javax.jws.WebParam;@Controllerpublic class ExceptionController { @RequestMapping("exception1") public String exception(){ System.out.println("exception......."); return "success"; } @RequestMapping("exception2") public String exception2(String username){ System.out.println("exception2222......."); if ("admin".equals(username)){ return "success"; }else{ throw new UserNameException(); } } @RequestMapping(value = "exception3",method = RequestMethod.POST) public String exception3(String username){ System.out.println("exception3......."); return "success"; }}