filter get乱码 全站编码解决 包装模式

包装模式简介：

package com.itheima.test;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;

public class MyBufferedReader extends BufferedReader {//似你   BufferedReader包装类
    //针对父类已经是一个包装类的情况下，包装模式可以进一步简化 

    /*private BufferedReader br;//还有你
    private int i=0;
    public MyBufferedReader(Reader in) {
        super(in);
        this.br =(BufferedReader) in;//拜托你
    }
    @Override
        public String readLine() throws IOException {
            String str = br.readLine();
            if(str==null)
                return null;
            i++;
            return i+" "+str;
        }*/

    //改下后的
    //private BufferedReader br;//还有你
    private int i=0;
    public MyBufferedReader(Reader in) {
        super(in);
        //this.br =(BufferedReader) in;//拜托你
    }
    @Override
        public String readLine() throws IOException {
            String str = super.readLine();
            if(str==null)
                return null;
            i++;
            return i+" "+str;
        }
}

先继承同样的接口，然后将接口传进来，通过构造方法

测试

package com.itheima.test;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;

public class WrapperTest {

    public static void main(String[] args) {
        try {
            FileReader fr = new FileReader("src/com/itheima/test/MyBufferedReader.java");
            BufferedReader br=new BufferedReader(fr);
            MyBufferedReader mbr = new MyBufferedReader(br);
            String line=null;
            while((line=mbr.readLine())!=null){
                System.out.println(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

tomcat 的高版本已经解决了get请求的乱码问题，如果要包装的类实现的接口已经有一个包装类了，可以直接继承那个包装类，进行简单的包装，简单包装后直接写需要包装的方法就可以了。

package com.itheima.web.filter;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

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.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet Filter implementation class CharacterEncodingFilter
 */
public class CharacterEncodingFilter implements Filter {

    public void destroy() {

    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        request.setCharacterEncoding("UTF-8");//post乱码
        response.setCharacterEncoding("UTF-8");//添加，有经验
        response.setContentType("text/html;charset=UTF-8");//响应时没有乱码

        //对于get提交，也要解决？？？   （Tomcat高版本下对get提交已解决）

        //调包
        MyHttpServletRequest myrequest = new MyHttpServletRequest(request);
        chain.doFilter(myrequest, response);
    }

    class MyHttpServletRequest extends HttpServletRequestWrapper{

        public MyHttpServletRequest(HttpServletRequest request) {
            super(request);
        }

        @Override//改写你
        public String getParameter(String name) {
            String paramValue =  super.getParameter(name);//取参数值
            if(paramValue==null)
                return null;
            //要判断请求类型？？？  get   就要做乱码处理
            String type = super.getMethod();//post   get获取提交方式
            if(type.equalsIgnoreCase("get")){
                //说明要进行乱码处理
                try {
                    paramValue = new String(paramValue.getBytes("iso-8859-1"),"UTF-8");//getBytes(“iso-8859-1”)是使用iso-8859-1编码表进行转换。
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            }

            return paramValue;
        }
    }

    public void init(FilterConfig fConfig) throws ServletException {

    }

}