Spring boot下添加filter

https://www.cnblogs.com/OnlyCT/p/7133639.html

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前言

传统的javaEE增加Filter是在web.xml中配置，如以下代码：

<filter>
   <filter-name>TestFilter</filter-name>
    <filter-class>com.cppba.filter.TestFilter</filter-class>
</filter>
<filter-mapping>
  <filter-name>TestFilter</filter-name>
  <url-pattern>/*</url-pattern>
  <init-param>
    <param-name>paramName</param-name>
    <param-value>paramValue</param-value>
  </init-param>
</filter-mapping>

然而spring-boot中很明显不能这样实现，那怎么办呢？看完下面的教程，答案自然知道了。

老方法（新方法请直接下拉）

1.创建自定义Filter

package com.cppba.filter;

import javax.servlet.*;
import java.io.IOException;

public class TestFilter implements Filter {
  @Override
  public void init(FilterConfig filterConfig) throws ServletException {

  }

  @Override
  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
      throws IOException, ServletException {
    System.out.println("TestFilter");
  }

  @Override
  public void destroy() {

  }
}

2.在ApplicationConfiguration.java中增加一个@bean

@Bean
 public FilterRegistrationBean testFilterRegistration() {

   FilterRegistrationBean registration = new FilterRegistrationBean();
   registration.setFilter(new TestFilter());
   registration.addUrlPatterns("/*");
   registration.addInitParameter("paramName", "paramValue");
   registration.setName("testFilter");
   registration.setOrder(1);
   return registration;
 }

3.启动项目

你会看到控制台打印如下代码：

4.访问项目

最后我们访问以下http://127.0.0.1:8080/test

如果你看到控制台打印出:TestFilter

恭喜你，配置成功！

2017-04-20 最新spring-boot增加Filter方法

首先定义一个Filter

@Order(1)
//重点
@WebFilter(filterName = "testFilter1", urlPatterns = "/*")
public class TestFilterFirst implements Filter {
  @Override
  public void init(FilterConfig filterConfig) throws ServletException {

  }

  @Override
  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
      throws IOException, ServletException {
    System.out.println("TestFilter1");
    filterChain.doFilter(servletRequest,servletResponse);
  }

  @Override
  public void destroy() {

  }
}

比较核心的代码是自定义类上面加上@WebFilter，其中@Order注解表示执行过滤顺序，值越小，越先执行

我们在spring-boot的入口处加上如下注解@ServletComponentScan：

@SpringBootApplication(scanBasePackages = "com.cppba")
//重点
@ServletComponentScan
public class Application {
  public static void main(String[] args) throws UnknownHostException {
    SpringApplication app = new SpringApplication(Application.class);
    Environment environment = app.run(args).getEnvironment();
  }
}

这种方法效果和上面版本一样，但是用起来更加方便！