jdbc

package com.haole.tools;





import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;


public class DBConnection {

private static DBConnection db = null ;
private static Connection conn = null ;

private static Properties properties = null ;

/**
* 单例模式 得到同一个DB实例
* @return DB 的一个实例
*/
public static synchronized DBConnection getDBInstance(){
if(null != db){
return db ;
}else{
db = new DBConnection() ;
return db ;
}
}

static{
properties = new Properties() ;
try{
//得到一个输入流到db.properties
properties.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("DBConfig.property")) ;
}catch(IOException e){
System.out.println("读取属性文件 db.properties失败；属性文件不存在" + e.getMessage()) ;
}
}

/**
* 通过访问属性文件加载驱动文件
* @return Connection 的一个实例
* @throws ClassNotFoundException
* @throws SQLException
*/
public static Connection getConnection() throws ClassNotFoundException, SQLException{
//得到数据库驱动文件
String driver = properties.getProperty("SQLDriver") ;
//数据库连接的url
String url = properties.getProperty("SQLURL") ;
//数据库连接用户名
String username = properties.getProperty("user") ;
//数据库连接密码
String password = properties.getProperty("password") ;
//加载驱动文件
Class.forName(driver) ;
//与数据库建立连接
conn = DriverManager.getConnection(url,username , password) ;
return conn ;
}
public static void getClose(Connection conn){
   if(conn!=null){
   try {
conn.close();

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
   }
}

public static int executeSQL(String sql, String[] param) {
Connection conn = null;
PreparedStatement pst = null;
int num = 0;
try {
conn =getConnection() ;
conn.setAutoCommit(false);
if (conn == null) {
System.out.println("连接为空");
} else {
pst = conn.prepareStatement(sql);
if (param != null) {
for (int i = 0; i < param.length; i++) {
pst.setString(i + 1, param[i]);
}
}
num = pst.executeUpdate();
conn.commit();
conn.setAutoCommit(true);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
DBConnection.getClose(conn);
}
return num;
}
   
public static ResultSet executeQuery(String sql, String[] param) {
ResultSet rs = null;
PreparedStatement pst = null;
Connection conn = null;

try {
conn = getConnection();
pst = conn.prepareStatement(sql);
if (param != null) {
for (int i = 0; i < param.length; i++) {
pst.setString(i + 1, param[i]);
}
}
rs = pst.executeQuery();
} catch (Exception e) {
e.printStackTrace();
}
return rs;
}
// public static void main(String[] args){
// try {
// DBConnection.getConnection();
// String sql ="select * from t_gtype t1,t_gtype t2 where t1.gtparId=t2.gtid and t2.gtid=42";
//
// ResultSet rs = DBConnection.executeQuery(sql, null);
// boolean flag = false;
// while(rs.next()){
// flag = true;
// System.out.print("flag======"+flag);
// }
// flag = false ;
// } catch (ClassNotFoundException e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// } catch (SQLException e) {
// // TODO Auto-generated catch block
// e.getMessage();
// }
// }
}