Question

java怎么连接mysql啊,标准的连接代码

Answer 1

package edu.fzu.hotelsys.utils;

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

/**
 * @author Administrator
 *
 */
public class DBUtilsOld {
	
	//数据库连接信息
	private static final String CONN_URL="jdbc:mysql://localhost:3306/hotel_db";
	private static final String USERNAME="hotelmgr";
	private static final String PASSWD="abc123";
	
	//单例实现
	private static final DBUtilsOld ME=new DBUtilsOld();
	
	public static DBUtilsOld getInstance(){
		return ME;
	}
	
	private DBUtilsOld(){
		
	}
	
	/**
	 * 获得连接
	 * @return
	 */
	public Connection getConn(){
		
		Connection conn=null;
		
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn=DriverManager.getConnection(CONN_URL, USERNAME, PASSWD);
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return conn;
		
	}
	
	/**
	 * 释放资源
	 * @param conn
	 * @param pstmt
	 * @param rset
	 */
	public void releaseRes(Connection conn, PreparedStatement pstmt, ResultSet rset){
	   

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

}

追问

驱动jar包怎么弄呢，大神

Answer 2

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

public class DBUtil {

private static final String DRIVER = "com.mysql.jdbc.Driver";
private static String IP = "127.0.0.1";
private static String PORT = "3306";
private static final String USER_NAME = "root";
private static final String PASSWORD = "root";
private static final String DATABASE_NAME = "test_2015";

private static final String URL = new StringBuffer().append("jdbc:mysql://").append(IP).append(":").append(PORT).append("/").append(DATABASE_NAME).append("?useUnicode=true&characterEncoding=UTF-8").toString();
// private static final String URL = "jdbc:mysql://127.0.0.1:3306/test_2015?useUnicode=true&characterEncoding=UTF-8";

private static final ThreadLocal<Connection> t = new ThreadLocal<Connection>();

static {
try {
Class.forName(DRIVER);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}

public static Connection getConnection() {
Connection conn = t.get();
if (conn == null) {
conn = createConnection();
t.set(conn);
}
return conn;
}

public static void close() {
Connection conn = t.get();
if (conn != null) {
try {
conn.close();
t.set(null);
} catch (SQLException e) {
e.printStackTrace();
}
}
}

private static Connection createConnection() {
Connection conn = null;
try {
conn = DriverManager.getConnection(URL, USER_NAME, PASSWORD);
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}

public static void main(String[] args) throws SQLException {
Connection conn = DBUtil.getConnection();
String sql = "SELECT user_name AS userName, password FROM t_user WHERE user_id = ?";
PreparedStatement p = conn.prepareStatement(sql);
int userId = 1;
p.setObject(1, userId);
ResultSet r = p.executeQuery();
String userName = "";
String password = "";
if (r.next()) {
userName = r.getString("userName");
password = r.getString("password");
}
DBUtil.close();
System.out.println("用户名：" + userName);
System.out.println("密码：" + password);
}

}