关于springboot:Spring-Boot快速入门之十四Servlet-过滤器

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【注】本文译自：https://www.tutorialspoint.co…_boot/spring_boot_servlet_filter.htm

过滤器是一种拦挡利用中 HTTP 申请和响应的对象，应用过滤器，你能够执行以下两种情景下的两种操作：

在发送申请到到控制器之前
在发送响应到客户端之前

上面的示例代码是以 @Component 注解的类来实现 Servlet 过滤器：

public class SimpleFilter implements Filter {

 @Override

 public void destroy() {}

  

 @Override

 public void doFilter

 (ServletRequest request, ServletResponse response, FilterChain filterchain) 

 throws IOException, ServletException {}

  

 @Override

 public void init(FilterConfig filterconfig) throws ServletException {}}

上面的示例代码展现了在发送申请到控制器之前，从 ServletRequest 对象读取近程主机和地址：

在 doFilter() 办法中，咱们加了 System.out.println 语句打印近程主机和地址：

package com.tutorialspoint.demo;

  

import java.io.IOException;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

  

import org.springframework.stereotype.Component;

  

@Component

public class SimpleFilter implements Filter {

 @Override

 public void destroy() {}

  

 @Override

 public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterchain) 

 throws IOException, ServletException {System.out.println("Remote Host:"+request.getRemoteHost());

 System.out.println("Remote Address:"+request.getRemoteAddr());

 filterchain.doFilter(request, response);

 }

  

 @Override

 public void init(FilterConfig filterconfig) throws ServletException {}}

在 Spring Boot 主利用类文件中，咱们加了简略 REST 端点返回“Hello World”字串：

package com.tutorialspoint.demo;

  

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

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

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

  

@SpringBootApplication

@RestController

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

 }

 @RequestMapping(value = "/")

 public String hello() {return "Hello World";}

}

Maven build – pom.xml 代码如下：

<?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 代码如下：

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')

}

你能够应用以下 Maven 或 Gradle 命令来创立可执行 JAR 文件，运行 Spring Boot 利用：

Maven 命令如下：