关于springboot:Spring-Boot快速入门之十三-拦截器

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【注】本文译自：https://www.tutorialspoint.com/spring_boot/spring_boot_interceptor.htm

在以下两种状况下，能够在 Spring Boot 中应用拦截器来执行操作：

  • 发送申请到控制器之前
  • 发送响应到客户端之前

    譬如，能够应用拦截器在发送申请到控制器之前增加申请头，并在发送响应到客户端之前增加响应头。

    要用拦截器，你须要创立 @Component 类，并且要实现 HandlerInterceptor 接口。

    上面是应用拦截器要晓得的三个办法：

  • preHandle() 办法：用于在发送申请到控制器之前执行操作。这个办法该当返回 true 以响应客户端。
  • postHandle() 办法：用于在发送响应到客户端之前执行操作。
  • afterCompletion() 办法：用于在申请和响应实现之后执行操作。

    察看以下代码以加深了解：

@Component

public class ProductServiceInterceptor implements HandlerInterceptor {

 @Override

 public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {return true;}

 @Override

 public void postHandle(

 HttpServletRequest request, HttpServletResponse response, Object handler,

 ModelAndView modelAndView) throws Exception {}

 @Override

 public void afterCompletion(HttpServletRequest request, HttpServletResponse response,

 Object handler, Exception exception) throws Exception {}}

还要通过 WebMvcConfigurerAdapter 用 InterceptorRegistry 注册这个拦截器：

@Component

public class ProductServiceInterceptorAppConfig extends WebMvcConfigurerAdapter {

 @Autowired

 ProductServiceInterceptor productServiceInterceptor;

  

 @Override

 public void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(productServiceInterceptor);

 }

}

在上面给出的示例中，咱们将要应用前面给出的 GET products API：

Interceptor 类文件 ProductServiceInterceptor.java 如下所示：

package com.tutorialspoint.demo.interceptor;

  

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

  

import [org.springframework.stereotype.Component;](http://org.springframework.stereotype.component%3b/)

import org.springframework.web.servlet.HandlerInterceptor;

import org.springframework.web.servlet.ModelAndView;

  

@Component

public class ProductServiceInterceptor implements HandlerInterceptor {

 @Override

 public boolean preHandle

 (HttpServletRequest request, HttpServletResponse response, Object handler)

 throws Exception {System.out.println("Pre Handle method is Calling");

 return true;

 }

 @Override

 public void postHandle(HttpServletRequest request, HttpServletResponse response,

 Object handler, ModelAndView modelAndView) throws Exception {System.out.println("Post Handle method is Calling");

 }

 @Override

 public void afterCompletion

 (HttpServletRequest request, HttpServletResponse response, Object

 handler, Exception exception) throws Exception {System.out.println("Request and Response is completed");

 }

}

Application Configuration 类文件把拦截器注册到 Interceptor Registry 中，ProductServiceInterceptorAppConfig.java 文件如下：

package com.tutorialspoint.demo.interceptor;

  

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Component;

import org.springframework.web.servlet.config.annotation.InterceptorRegistry;

import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

  

@Component

public class ProductServiceInterceptorAppConfig extends WebMvcConfigurerAdapter {

 @Autowired

 ProductServiceInterceptor productServiceInterceptor;

  

 @Override

 public void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(productServiceInterceptor);

 }

}

Controller 类文件 ProductServiceController.java 如下：

package com.tutorialspoint.demo.controller;

  

import java.util.HashMap;

import java.util.Map;

  

import org.springframework.http.HttpStatus;

import org.springframework.http.ResponseEntity;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestBody;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

import com.tutorialspoint.demo.exception.ProductNotfoundException;

import com.tutorialspoint.demo.model.Product;

  

@RestController

public class ProductServiceController {private static Map<String, Product> productRepo = new HashMap<>(); 

 static {Product honey = new Product();

 honey.setId("1");

 honey.setName("Honey");

 productRepo.put(honey.getId(), honey); 

 Product almond = new Product();

 almond.setId("2");

 almond.setName("Almond");

 productRepo.put(almond.getId(), almond); 

 }

 @RequestMapping(value = "/products")

 public ResponseEntity<Object> getProduct() {return new ResponseEntity<>(productRepo.values(), HttpStatus.OK);

 }

}

POJO 类文件 Product.java 如下：

package com.tutorialspoint.demo.model;

  

public class Product {

 private String id;

 private String name;

  

 public String getId() {return id;}

 public void setId(String id) {this.id = id;}

 public String getName() {return name;}

 public void setName(String name) {this.name = name;}

}

主 Spring Boot 利用类文件 DemoApplication.java 如下所示：

package com.tutorialspoint.demo;

  

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

  

@SpringBootApplication

public class DemoApplication {public static void main(String\[\] args) {SpringApplication.run(DemoApplication.class, args); 

 }

}

Maven build – pom.xml 文件在此：

<?xml version = "1.0" encoding = "UTF-8"?>

<project xmlns = "[http://maven.apache.org/POM/4.0.0](http://maven.apache.org/POM/4.0.0)" xmlns:xsi = "[http://www.w3.org/2001/XMLSchema-instance](http://www.w3.org/2001/XMLSchema-instance)"

 xsi:schemaLocation = "[http://maven.apache.org/POM/4.0.0](http://maven.apache.org/POM/4.0.0)

 [http://maven.apache.org/xsd/maven-4.0.0.xsd](http://maven.apache.org/xsd/maven-4.0.0.xsd)">

 <modelVersion>4.0.0</modelVersion>

 <groupId>com.tutorialspoint</groupId>

 <artifactId>demo</artifactId>

 <version>0.0.1-SNAPSHOT</version>

 <packaging>jar</packaging>

 <name>demo</name>

 <description>Demo project for Spring Boot</description>

  

 <parent>

 <groupId>org.springframework.boot</groupId>

 <artifactId>spring-boot-starter-parent</artifactId>

 <version>1.5.8.RELEASE</version>

 <relativePath/>

 </parent>

  

 <properties>

 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

 <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

 <java.version>1.8</java.version>

 </properties>

  

 <dependencies>

 <dependency>

 <groupId>org.springframework.boot</groupId>

 <artifactId>spring-boot-starter-web</artifactId>

 </dependency>

  

 <dependency>

 <groupId>org.springframework.boot</groupId>

 <artifactId>spring-boot-starter-test</artifactId>

 <scope>test</scope>

 </dependency>

 </dependencies>

  

 <build>

 <plugins>

 <plugin>

 <groupId>org.springframework.boot</groupId>

 <artifactId>spring-boot-maven-plugin</artifactId>

 </plugin>

 </plugins>

 </build>

</project>

Gradle Build build.gradle 文件在此：

buildscript {

 ext {springBootVersion = '1.5.8.RELEASE'}

 repositories {mavenCentral()

 }

 dependencies {classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")

 }

}

apply plugin: 'java'

apply plugin: 'eclipse'

apply plugin: 'org.springframework.boot'

group = 'com.tutorialspoint'

version = '0.0.1-SNAPSHOT'

sourceCompatibility = 1.8

  

repositories {mavenCentral()

}

dependencies {compile('org.springframework.boot:spring-boot-starter-web')

 testCompile('org.springframework.boot:spring-boot-starter-test')

}

你能够应用上面的 Maven 或 Gradle 命令创立可执行的 JAR 文件，运行 Spring Boot 利用：

对于 Maven，应用以下命令：

mvn clean install

在“BUILD SUCCESS”之后，你能够在 target 目录下找到 JAR 文件：

对于 Gradle，应用以下命令：

gradle clean build

在“BUILD SUCCESSFUL”之后，你能够在 build/libs 目录下找到 JAR 文件：

能够应用以下命令运行 JAR 文件：

java –jar <JARFILE>

此刻，利用曾经在 Tomcat 8080 端口启动了，如下所示：

在 POSTMAN 利用中单击以下 URL，你能够看到上面的后果：

GET API: http://localhost:8080/products

在控制台窗口，你能够看到加在拦截器中的 System.out.println 打印进去的后果，截屏如下：

正文完
springboot
发表至： springboot
2020-08-31
 0
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