黑馬day14 過濾器之解決所有亂碼

時間 2019-11-19

標籤黑馬 day14 day 過濾器解決所有亂碼简体版

原文原文鏈接

關於亂碼的產生以及怎樣解決亂碼請看個人博客字節亂碼, 字符亂碼,表單提交get&post亂碼html

這裏主要使用一個過濾器可以解決上述的所有亂碼：java

1.過濾亂碼的過濾器：web

package cn.itheima.filter;
import java.io.IOException;
import java.util.Map;
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;

public class EncodingFilter implements Filter {
	private FilterConfig config = null;
	private String encode = null;
	public void destroy() {
		
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		response.setContentType("text/html;charset="+encode); //--解決響應亂碼
		chain.doFilter(new MyHttpServletRequest((HttpServletRequest) request), response);//--包裝改造request中和獲取請求參數相關的方法解決請求參數亂碼
	}
	
	public void init(FilterConfig filterConfig) throws ServletException {
		this.config = filterConfig;
		encode = config.getInitParameter("encode") == null
							?"utf-8"
									:config.getInitParameter("encode");
	}
	class MyHttpServletRequest extends HttpServletRequestWrapper{
		private HttpServletRequest request = null;
		private boolean isNotEncode = true;
		public MyHttpServletRequest(HttpServletRequest request) {
			super(request);
			this.request = request;
		}
		
		@Override
		public Map getParameterMap() {
			try{
				if(request.getMethod().equalsIgnoreCase("POST")){//--假設是post提交,一行代碼解決post提交請求參數亂碼
					request.setCharacterEncoding(encode);
					return request.getParameterMap();
				}else if(request.getMethod().equalsIgnoreCase("GET")){//--假設是get提交,則應該手動編解碼解決亂碼
					Map<String,String[]> map = request.getParameterMap();//獲取有亂碼的map
					if(isNotEncode){//僅僅能在第一次解決亂碼
						for(Map.Entry<String, String[]> entry : map.entrySet()){//遍歷map,解決所有值的亂碼
							String [] vs = entry.getValue();
							for(int i=0;i<vs.length;i++){
								vs[i] = new String(vs[i].getBytes("iso8859-1"),encode);
							}
						}
						isNotEncode = false;//設置爲false,第二次就不會再進這個代碼塊了
					}
					return map;
				}else{
					return request.getParameterMap();
				}
			}catch (Exception e) {
				e.printStackTrace();
				throw new RuntimeException(e);
			}
		}
		
		@Override
		public String[] getParameterValues(String name) {
			return (String[]) getParameterMap().get(name);
		}
		
		@Override
		public String getParameter(String name) {
			return getParameterValues(name) == null ? null : getParameterValues(name)[0];
		}
		
		
	}
}

2.web.xml的配置：

<filter>
  	<filter-name>EncodingFilter</filter-name>
  	<filter-class>cn.itheima.filter.EncodingFilter</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>EncodingFilter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>

3.jsp測試亂碼：分別包含get和post提交

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title></title>
	<meta http-equiv=" pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
  </head>
  <body>
  <h1>post提交</h1>
    <form action="${pageContext.request.contextPath }/servlet/FilterDemo1" method="post">
    	姓名：<input type="text"  name="name"/><br>
    	地址：<input type="text"  name="addr"/><br>
    	<input type="submit" value="提交"/><br>
    </form>
    <h1>get提交</h1>
    <form action="${pageContext.request.contextPath }/servlet/FilterDemo1" method="get">
    	姓名：<input type="text"  name="name"/><br>
    	地址：<input type="text"  name="addr"/><br>
    	<input type="submit" value="提交"/><br>
    </form>
  </body>
</html>

4.jsp提交後轉向的頁面：

package cn.itheima.servlet;

import java.io.IOException;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FilterDemo1 extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.getWriter().write("你好！過濾器！
我沒有亂碼！app
");
		String name = request.getParameter("name");
		String addr = request.getParameter("addr");
		System.out.println(name);
		System.out.println(addr);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}
jsp

結果分析：