2，POST方式我们看下javax.servlet.http.HttpUtils的parsePostData方法，下面贴出源码。
public static Hashtable parsePostData(int len, ServletInputStream in)
{
if (len <= 0)
{
return new Hashtable();
}
if (in == null)
{
throw new IllegalArgumentException();
}
byte[] postedBytes = new byte[len];
try
{
int offset = 0;
do
{
int inputLen = in.read(postedBytes, offset, len - offset);
if (inputLen <= 0)
{
String msg = lStrings.getString("err.io.short_read");
throw new IllegalArgumentException(msg);
}
offset += inputLen;
}
while (len - offset > 0);
}
catch (IOException e)
{
throw new IllegalArgumentException(e.getMessage());
}
try
{
String postedBody = new String(postedBytes, 0, len, "8859_1");
return parseQueryString(postedBody);
}
catch (UnsupportedEncodingException e)
{
}
throw new IllegalArgumentException(e.getMessage());
}
其实研究这个tomcat的编码源码没啥意义，也就不用管了，记住就好，不管是GET还是POST，tomcat都是用8859_1来编码的。req.setCharacterEncoding("UTF-8");GET方式，上面的操作不生效，因为get方式提交参数丫的不是在header里面是在url后面跟着的，只能自己用String来转换了。String userName = new String(req.getParameter("userName").getBytes("ISO-8859-1"),"UTF-8");<a href="/linkin/LinkinServlet?userName=林肯公园">GET方式传参</a>这2种情况和上面的用GET方式提交表单一样，处理方式也一样，这里不做赘述了。
<Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" URIEncoding="UTF-8" />如果是POST方式，就只能增加编码过滤器。没使用框架的话用自己写一个过滤器，建议将过滤的编码写成配置的，比如写在<init-param>标签中。如果使用了spring，则直接配置就OK。
<filter> <filter-name>encodingFilter</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <!-- 编码格式 --> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <!-- 控制是否强制设置编码，如果是true，不管request中有没有指定编码，这个过滤器设置编码都会被触发，如果是false，只是在request中没有设置编码的时候被触发设置上这里的编码 --> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <!-- 这里是jsp中的编码格式 都被设置为统一的了 --> <filter-mapping> <filter-name>encodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
下面贴出这个类的源码：核心就是doFilterInternal()方法。
package org.springframework.web.filter;
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CharacterEncodingFilter extends OncePerRequestFilter
{
/**
* @param request
* @param response
* @param filterChain
* @throws ServletException
* @throws IOException
* 个人不喜欢forceEncoding这种控制和别的控制一起写的写法，单独拎出来写成旗标多好
* 一般情况下，为了不冲掉自己的request中原有的编码，建议forceEncoding配置成false
*/
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException
{
//1，如果配置的encoding为空，不设置编码
//2，如果配置的encoding不为空，forceEncoding为true，不管request中有没有自己的编码都会设置编码
//3，如果配置的encoding不为空，forceEncoding为false，只有在request没有自己的编码的时候才会设置编码
if (this.encoding != null && (this.forceEncoding || request.getCharacterEncoding() == null))
{
request.setCharacterEncoding(this.encoding);
if (this.forceEncoding)
{
response.setCharacterEncoding(this.encoding);
}
}
filterChain.doFilter(request, response);
}
}
另外这里也稍微花点时间来说明一下，OncePerRequestFilter这个抽象过滤器很好的实现了对每个request只执行一次过滤操作，如果有类似的需求可以继承该类并实现doFilterInternal方法来完成，上面的CharacterEncodingFilter就是继承这个抽象类的，下面贴出这个抽象类的源码，后面整理框架的时候我会做详细的整理的。
package org.springframework.web.filter;
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public abstract class OncePerRequestFilter extends GenericFilterBean {
public static final String ALREADY_FILTERED_SUFFIX = ".FILTERED";
//开始过滤，有点小技巧，实现了只过滤一次的功能
public final void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
if (!(request instanceof HttpServletRequest) || !(response instanceof HttpServletResponse)) {
throw new ServletException("OncePerRequestFilter just supports HTTP requests");
}
HttpServletRequest httpRequest = (HttpServletRequest) request;
HttpServletResponse httpResponse = (HttpServletResponse) response;
String alreadyFilteredAttributeName = getAlreadyFilteredAttributeName();
if (request.getAttribute(alreadyFilteredAttributeName) != null || shouldNotFilter(httpRequest)) {//第2次进来
// Proceed without invoking this filter...
filterChain.doFilter(request, response);
}
else {//第一次进来
// Do invoke this filter...
request.setAttribute(alreadyFilteredAttributeName, Boolean.TRUE);
try {
doFilterInternal(httpRequest, httpResponse, filterChain);
}
finally {//最后清空alreadyFilteredAttributeName属性
// Remove the "already filtered" request attribute for this request.
request.removeAttribute(alreadyFilteredAttributeName);
}
}
}
protected String getAlreadyFilteredAttributeName() {
String name = getFilterName();
if (name == null) {
name = getClass().getName();
}
return name + ALREADY_FILTERED_SUFFIX;
}
protected boolean shouldNotFilter(HttpServletRequest request) throws ServletException {
return false;
}
//推迟到子类实现，真正的过滤的方法
protected abstract void doFilterInternal(
HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException;
}
resp.getWriter().write(req.getParameter("userName"));在返回响应之前添加response.setCharacterEncoding("UTF-8");其实用上面那个设置编码格式的方式不怎么好，最好用下面这种的。response.setContentType("text/html;charset=UTF-8");
response.setContentType("application/json;charset=gbk");
java.net.URLEncoder.encode("林肯公园","UTF-8");在后台不需要转码，Servlet引擎已经帮我做好了。某些情况下比如搜索引擎的搜索时，如果发送请求的是GET方式，浏览器上面的中文就会变成application/x-www-form-urlencoded MIME字符串，比如“%E6%E6”这种，Servlet引擎来解析这段字符串的时候自动会给我们转会成汉字的。转码的代码如下：URLDecoder.decode(req.getParameter("userName"), "UTF-8");
第二点，BASE64Encoder，BASE64Decoder编码和解码，这种编码和解码还会涉及算法的，了解下好了。这2个类在API中查不到，因为JDK已经不推荐使用了，不过我个人觉得还是挺好使的。
String name = new sun.misc.BASE64Encoder().encode("林肯公园".getBytes());// name:wda/z7mr1LA=
System.out.println(new String((new sun.misc.BASE64Decoder()).decodeBuffer(name)));//林肯公园
OK，最后贴出自己写的Servlet和jsp：
package linkin;
import java.io.IOException;
import java.net.URLDecoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* @author LinkinPark
* @author 2015-7-10
* @Descri 解决j2e中文乱码问题
*/
public class LinkinServlet extends HttpServlet
{
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
{
//req.setCharacterEncoding("UTF-8");//解决POST方式
//String userName = new String(req.getParameter("userName").getBytes("ISO-8859-1"),"UTF-8");//解决GET方式
System.out.println(req.getParameter("userName"));
System.out.println(URLDecoder.decode(req.getParameter("userName"), "UTF-8"));
req.setAttribute("userName", "林肯公园");
//resp.setCharacterEncoding("UTF-8");//解决向页面传参乱码问题，建议使用下面这种
resp.setContentType("text/html;charset=UTF-8");//解决向页面传参乱码问题，建议使用这种
resp.getWriter().write(req.getParameter("userName"));
//req.getRequestDispatcher("/jsp/Linkin1.jsp").forward(req, resp);
//resp.sendRedirect("/linkin/jsp/Linkin1.jsp");
//下面使用base64来编码和解码
String name = new sun.misc.BASE64Encoder().encode("林肯公园".getBytes());// name:wda/z7mr1LA=
System.out.println(new String((new sun.misc.BASE64Decoder()).decodeBuffer(name)));//林肯公园
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
{
this.doGet(req, resp);
}
public static void main(String[] args) throws Exception
{
}
}
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>Servlet中文乱码</title>
<script type="text/javascript" src="/linkin/jsp/jquery-1.8.0.js"></script>
<script type="text/javascript">
var huhu = function(){
var userName = $("#userName").val();
$.ajax({
url : "/linkin/LinkinServlet",
type : "GET",
async : true,
data:{userName:userName},
dataType : "json",
success : function(a) {
}
});
}
</script>
</head>
<body>
<form action="/linkin/LinkinServlet" method="GET">
姓名：<input type="text" name="userName" id="userName" />
<input type="button" value="提交" name="tijiao" onclick="huhu();"/>
<a href="/linkin/LinkinServlet?userName=<%=java.net.URLEncoder.encode("林肯公园","UTF-8") %>林肯公园">GET方式传参</a>
</form>
</body>
</html>
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原文地址：http://blog.csdn.net/u011794238/article/details/46831009
