A solution to the problem of invalid Filter filter based on tomcat8

When colleagues encounter coding problems, they want to make a character coding filter to solve the whole station. The class and configuration of the filter are as follows:

Filter class:

<span style="font-size:12px;">package com.chaoxing.newspaper.web.filter;
import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
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 javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CharacterEncodingFilter implements Filter {
	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
		System.out.println(" Filter execution ");
		 final HttpServletRequest request = (HttpServletRequest) req; 
	    HttpServletResponse response = (HttpServletResponse) res; 
	     
	    // To solve post The Chinese character of the request is confused  
	    request.setCharacterEncoding("UTF-8"); 
	    response.setCharacterEncoding("UTF-8"); 
	    response.setContentType("text/html;charset=UTF-8");
		
		chain.doFilter((ServletRequest) Proxy.newProxyInstance(this.getClass().getClassLoader(), request.getClass().getInterfaces(), new InvocationHandler(){
			@Override
			public Object invoke(Object proxy, Method method, Object[] args)
					throws Throwable {
				String methodname = method.getName(); // Get the current method  
	      if(methodname.equals("getParameter")){ 
	        // perform request.getparameter To get the results  
	        String value = (String) method.invoke(request, args); 
	        if(value==null){ 
	          return null; 
	        } 
	        if(!request.getMethod().equalsIgnoreCase("get")){ // Judgment is for get request  
	          return value; 
	        } 
	        System.out.println(value+"|||||");
	        // Conversion code return  
	        value = new String(value.getBytes("UTF-8"),"UTF-8"); 
	        System.out.println(value+"=======");
	        return value; 
	      } 
	      // to request Perform the requested  
	      return method.invoke(request, args); 
	      } 
			
		} ), res);
	}
	public void init(FilterConfig fConfig) throws ServletException {
		System.out.println(" Filter initialization ");
	}
	@Override
	public void destroy() {
		System.out.println(" Filter completion ");
	}
}</span>

Filter configuration:

<span style="font-size:12px;"> <!-- Solve the whole station disorderly code filter  --> 
 <filter> 
  <filter-name>CharacterEncoding</filter-name> 
  <filter-class>com.XXX.web.filter.CharacterEncodingFilter</filter-class> 
 </filter> 
 <filter-mapping> 
  <filter-name>CharacterEncoding</filter-name> 
  <url-pattern>/*</url-pattern> 
 </filter-mapping></span> 

However, in the case that the front-end form is submitted as get, the result is still messy.

At the beginning, 1 was obsessed with whether the filter was wrong and the code set was wrong. However, after testing, there was no mistake. The filter worked normally.

Finally, change value.getByte (" ES17en-8859-1 "," utf-8 ") to ES19en.getByte (" ES21en-8 "," utf-8 ") to get the value. And then at the end of the day,

The default code set of tomcat8 is utf-8, and the default code set before tomcat8 is iso-8859-1.

Summary: The default encoding set before tomcat7 and its version is iso-8859-1, and the default character set of tomcat8 is es34EN-8, so transcoding for the results of ES35en.getParameter () is no longer required, and the encoding filter class is no longer required