Spring Boot过滤器

过滤器是用于截获应用程序的 HTTP 请求和响应的对象。通过使用 filter，我们可以在两个实例上执行两个操作 -

在将请求发送到控制器之前
在向客户端发送响应之前。

下面的代码显示了带有@Component注释的 Servlet Filter 实现类的示例代码。

@Component
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 {}
}

下面的示例演示在将请求发送到控制器之前从 ServletRequest 对象读取远程主机和远程地址的代码。在 doFilter() 方法中，我们添加了 System.out.println 语句来打印远程主机和远程地址。

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 主应用程序类文件中，我们添加了返回“Hello World”字符串的简单 REST 端点。

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 的代码 – pom.xml 如下：

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

   
   4.0.0
   com.tutorialspoint
   demo
   0.0.1-SNAPSHOT
   jar
   demo
   Demo project for Spring Boot

   
      org.springframework.boot
      spring-boot-starter-parent
      1.5.8.RELEASE
       
   

   
      UTF-8
      UTF-8
      1.8
   

   
      
         org.springframework.boot
         spring-boot-starter-web
      

      
         org.springframework.boot
         spring-boot-starter-test
         test
      
   

   
      
         
            org.springframework.boot
            spring-boot-maven-plugin

Gradle Build – build.gradle 的代码如下

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')
}

您可以创建一个可执行的JAR文件，并使用如下所示的Maven或Gradle命令运行Spring Boot应用程序

对于 Maven，请使用如下所示的命令