myeclispe中向mysql中插入中文数据出现??问题解决办法

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
        
    }
    
}