我的sql連接有問題嗎？用的是Dwr！看下面代碼以及出的問題，請大神們幫我呀！

我的DBManager！用於連接數據庫！
package com.qhit.util;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

public class DBManager {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
PreparedStatement ps = null;
DataSource ds = null;
String jndiName = "java:comp/env/jdbc/bk";
private static DBManager db;

private DBManager() throws NamingException {

    Context context = new InitialContext();
    ds = (DataSource) context.lookup(jndiName);

}

public static DBManager getDBManager() throws NamingException {
    if (db != null) {
        return db;
    } else {
        db = new DBManager();
    }
    return db;
}

public int executeUpdate(String sql) throws SQLException {
    conn = ds.getConnection();
    st = conn.createStatement();

    return st.executeUpdate(sql);
}

public ResultSet executeQuery(String sql) throws SQLException {
    conn = ds.getConnection();
    st = conn.createStatement();
    return st.executeQuery(sql);
}

public int excuteUpdateByPrepareStatement(String sql, Object[] objs)
        throws SQLException {
    ps = conn.prepareStatement(sql);
    for (int i = 1; i <= objs.length; i++) {
        ps.setObject(i, objs[i - 1]);

    }
    return ps.executeUpdate();
}

public void close() {
    try {
        if (rs != null) {
            if (!rs.isClosed()) {
                rs.close();
            }
        }
        if (st != null) {
            if (!st.isClosed()) {
                st.close();
            }
        }
        if (ps != null) {
            if (!ps.isClosed()) {
                ps.close();
            }

        }
        if (conn != null) {
            if (!conn.isClosed()) {
                conn.close();
            }
        }
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}

}

我的dao===========

package com.qhit.dao;

import java.sql.SQLException;

import javax.naming.NamingException;

import com.qhit.entity.UserInfo;
import com.qhit.util.DBManager;

public class userDao {
public boolean userNameExist(String uname) {
boolean result = false;
try {
DBManager db = DBManager.getDBManager();
String sql = "select uid from userInfo where uname='" + uname + "'";
result = db.executeQuery(sql).next();
db.close();
} catch (NamingException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return result;
}

public void saveUserInfo(UserInfo ui){
    try {
        DBManager dbManager=DBManager.getDBManager();
        String sql="insert into userInfo(uname, trueName, upass, usex, uphone,uoicq, uphoto, usignName, uemail, uaddress) values(?,?,?,?,?,?,?,?,?,?)";
        Object[] objs = new Object[10];
            objs[0]=ui.getUname();
            objs[1]=ui.getTrueName();
            objs[2]=ui.getUpass();
            objs[3]=ui.isUsex();
            objs[4]=ui.getUphone();
            objs[5]=ui.getUoicq();
            objs[6]=ui.getUphoto();
            objs[7]=ui.getUsignName();
            objs[8]=ui.getUemail();
            objs[9]=ui.getUaddress();
        dbManager.excuteUpdateByPrepareStatement(sql, objs);
        dbManager.close();
    } catch (NamingException e) {
        e.printStackTrace();
    } catch (SQLException e) {
        e.printStackTrace();
    }
}

}

我的Dwr

package com.qhit.dwr;

import com.qhit.dao.userDao;
import com.qhit.entity.UserInfo;

public class userInfoDwr {
userDao udao = new userDao();
public String saveUserInfo(UserInfo ui){
String name=ui.getUname();
if(name=="" || name.length()>20 || ui.getUname().length()<5){
return "您的用戶名不是5-20位";
}
if (udao.userNameExist(name)) {

return "用戶名已存在,不可用！";
}else{
udao.saveUserInfo(ui);
}
return ui.getUname()+"用戶名可用";
}

}

我的js

function checkUp(){
var userinfo={

uname:DWRUtil.getValue('txtname')
};
UserInfoDWR.saveUserInfo(userinfo,function(data){
alert(data);
});

}

Myeclipse報的錯誤是說我的Connection 已經關閉！

java.sql.SQLException: Connection is closed.

但是如果我將我的dao裡面的第一個連接不關閉的時候，在頁面輸入英文和漢字都好著！可一旦輸入漢字的時候，就會拋出一個Error錯誤！

所以請大神們幫我看下我的DBManager哪裡有錯誤！因為我的DBManager是作為工具類寫的，之前用的時候也報過錯！報錯也是和這次類似！也是同樣的位置的問題！

再次謝謝大神的幫助！

最佳回答：

這個你單步調試一下看看具體信息吧