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Filter功能
它使用户可以改变一个 request和修改一个response. Filter 不是一个servlet,它不能产生一个response,它能够在一个request到达servlet之前预处理request,也可以在离开 servlet时处理response.换种说法,filter其实是一个 “servlet chaining” (servlet 链).
一个Filter包括:
1)、在servlet被调用之前截获;
2)、在servlet被调用之前检查servlet request;
3)、根据需要修改request头和request数据;
4)、根据需要修改response头和response数据;
5)、在servlet被调用之后截获.
自定义Filter
一、第一种方法(稍麻烦)
1、实现Filter 方法,如下所示
public class GlobalFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
String requestURI = request.getRequestURI();
System.out.println(requestURI);
filterChain.doFilter(request, servletResponse);
}
@Override
public void destroy() {
}
}
2、加载Filter 配置
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean filterRegistration(){
// 新建过滤器注册类
FilterRegistrationBean registration = new FilterRegistrationBean();
// 添加自定义 过滤器
registration.setFilter(globalFilter());
// 设置过滤器的URL模式
registration.addUrlPatterns("/*");
//设置过滤器顺序
registration.setOrder(1);
return registration;
}
@Bean
public GlobalFilter globalFilter(){
return new GlobalFilter();
}
}
3、测试
由于我们在过滤器的地方打印了请求的URI ,所以我们可以随意发送一些请求,看控制台打印 URI 的情况,如下所示, 表明我们自定义的Filter 已经生效了:
二、第二种方 法(简洁,推荐使用这种)
1、自定义MyFilter, 如果请求URI 包含 my
, 则进行下一步处理
注:添加 @WebFilter
package com.fxbin.demo.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
/**
* created with IntelliJ IDEA.
* author: fxbin
* date: 2018/9/9
* time: 14:22
* description:
*/
@WebFilter(filterName = "myFilter", urlPatterns = "/*")
public class MyFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
System.out.println("init...");
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
String requestURI = request.getRequestURI();
if(requestURI.contains("my")){
System.out.println("成功啦。。。, 请求URI是:" + requestURI);
}
filterChain.doFilter(request, servletResponse);
}
@Override
public void destroy() {
System.out.println("destroy...");
}
}
2、在Application 启动类 添加 @ServletComponentScan
注解
注: @ServletComponentScan
package com.fxbin.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@ServletComponentScan
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
3、测试
发送一个 包含 my
的请求 ,http://localhost:8181/my/test, 控制台打印如下内容,表名成功了
源码地址:
https://gitee.com/fxbin123/SpringBoot2Example/tree/master/SpringBoot-Filter