或许很多人会出现??这种令人头痛的mysql的中文乱码问题：解决如下：
1.先对于新建的数据库要设置默认的字符集为UTF-8
create database mydb default character set utf8 collate utf8_general_ci;
2.然后对于想对应的表进行设置默认字符集
CREATE TABLE IF NOT EXISTS `mydb` (
`username` varchar(64) NOT NULL,
`userid` int(11) NOT NULL,
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
3.最重要的一步在jdbc中的uri的地址中添加如下语句?characterEncoding=UTF-8设置字符集为UTF-8
jdbc:mysql://localhost:3306/db_name?characterEncoding=UTF-8
如下是一个例子：
regServlet.java
package cn.lonecloud.demo; import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet; import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession; public class RegServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { response.setContentType("text/html");
PrintWriter out = response.getWriter();
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
Connection conn=null;
PreparedStatement prst=null;
ResultSet rs=null;
String db_driver="com.mysql.jdbc.Driver";
String db_url="jdbc:mysql://localhost:3306/db_friend?characterEncoding=UTF-8";
String db_user="root";
String db_password="";
String sql1="select * from userinfo where username=?";
String sql2="insert into userinfo values(?,?)";
try {
String username=request.getParameter("userName");
String userpass=request.getParameter("password");
Class.forName(db_driver);
conn=DriverManager.getConnection(db_url,db_user,db_password);
prst=conn.prepareStatement(sql1);
prst.setString(1, username);
rs=prst.executeQuery();
if (!rs.next()) {
prst=conn.prepareStatement(sql2);
prst.setString(1, username);
prst.setString(2, userpass);
int count=prst.executeUpdate();
if (count!=0) {
HttpSession session=request.getSession();
session.setAttribute("username", username);
request.setAttribute("msg", "注册成功！");
request.getRequestDispatcher("index.jsp").forward(request, response); }else{
request.setAttribute("msg", "登录失败，密码错误！");
request.getRequestDispatcher("error.jsp").forward(request, response); }
}else {
request.setAttribute("msg", "用户不存在！");
request.getRequestDispatcher("error.jsp").forward(request, response); }
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
if (rs!=null) {
try {
rs.close();
} catch (Exception e2) {
// TODO: handle exception
e2.printStackTrace();
}
}
if (prst!=null) {
try {
prst.close();
} catch (Exception e2) {
// TODO: handle exception
e2.printStackTrace();
}
}
if (conn!=null) {
try {
conn.close();
} catch (Exception e2) {
// TODO: handle exception
e2.printStackTrace();
}
}
out.close();
}
} }
reg.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>新用户注册</h1>
<form action="RegServlet" method="post">
<input type="text" name="userName"></br>
<input type="password" name="password"></br>
<input type="submit" id="btn_load">
</form>
</body>
</html>
LoginFilter.java
package cn.lonecloud.demo; import java.io.IOException; 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;
import javax.servlet.http.HttpSession; public class LoginFilter implements Filter {
@Override
public void destroy() {
// TODO Auto-generated method stub } @Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
//在过滤器中必须加入下面这两句话，不然会不能这样调用下面的方法
HttpServletRequest req=(HttpServletRequest) request;
HttpServletResponse resp=(HttpServletResponse)response;
request.setCharacterEncoding("UTF-8");
String path=req.getServletPath();
HttpSession session=req.getSession();
String username=(String)session.getAttribute("username");
System.out.println(path);
boolean b1=path.endsWith("login.jsp");
boolean b2=path.endsWith("error.jsp");
boolean b3=path.endsWith("LoginServlet");
boolean b4=path.endsWith("RegServlet");
boolean b5=path.endsWith("reg.jsp");
boolean b6=(username!=null);
if (b1||b2||b3||b4||b5||b6) {
chain.doFilter(request, response);
}else {
resp.sendRedirect("error.jsp");
} } @Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub } }