Question

从servlet中传值回JSP页面，数字和英文字母都显示，如果是汉字就会显示一串问号？

运行的时候显示出一串问号？如果是中文乱码的问题，那该如何解决呀！
servlet代码：
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("This ok!");
response.setContentType("text/html");
PrintWriter out = response.getWriter();
response.setHeader("Cache-Control", "no-cache");
String username = request.getParameter("username");
StringBuffer sb=new StringBuffer();
// sb.append("<?xml version=\"1.0\" encoding=\"GB2312\"?>");
sb.append("username has exist");
System.out.println("username:"+username);
out.write(sb.toString());
out.close();
}

Jsp页面：
<script language="JavaScript">
var httpRequest;

function createHttpRequest(){
if(window.XMLHttpRequest){

httpRequest=new XMLHttpRequest();
}}
function check()
{
createHttpRequest();
var username=document.getElementById("username").value;
var url="servlet/TestServlet?username="+username;
httpRequest.open("get",url,true);
httpRequest.onreadystatechange=showResult;
httpRequest.send();}
function showResult(){
if(httpRequest.readyState==4){
if(httpRequest.status==200){
var result=httpRequest.responseText;
alert(result);
var checkResult=document.getElementById("checkResult").innerHTML="<B>"+result+"</B>";
}}}
</script>
<form name="myForm">
<table>
<tr><td>"用户名</td>
<td><input type="text" name="username" id="username" onblur="check()"></td>
</tr>
<tr><td>
<input type="text" name="password" name="password" ></td></tr>
</table>
</form>
<span id="checkResult"></span>

Answer 1

乱码方法有很多种，jsp和servlet中处理乱码的方法都不一样
jsp中：①在程序最顶端加上语句<%@ page contentType="text/html;charset=gbk"%>
②在你接收参数的上面加上request.setCharacterEncoding ("gbk");
③在你的页面中加上response.setContentType ("text/html;charset=gbk");
servlet中：①写入response.setContentType ("text/html;charset=gbk");
②request.setCharacterEncoding ("gbk");
一般这样做，你的程序就不会有乱码了，补充一下，request是处理提交参数的乱码，response是处理页面乱码

Answer 2

接收的时候要写成String userName=new String(request.getParameter("userName").getBytes("GB2312"));