import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import org.omg.CORBA.PRIVATE_MEMBER;
/**
* @author 郑水洪
* SQL SERVER 2005连接
* 端口默认是：1433 这里是1434
*
* 在内存中，只需要加载一次数据库驱动即可，所以应该放到static代码快中 (优化性能)
*/
public class JdbcUtil {
private static String url = "jdbc:mysql://localhost:3306/test";
private static String userName = "root";
private static String password ="root";
private static String driverName = "com.mysql.jdbc.Driver";
//1.加载数据库驱动
static{
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
// TODO: handle exception
e.printStackTrace();
System.out.println("数据库加载驱动失败!");
}
}
//2.建立连接
public static Connection getConnection(){
Connection connection = null;
try {
connection = DriverManager.getConnection(url, userName, password);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return connection;
}
//3.申明sql执行器
//4.执行SQL 操作数据
// 5、关闭资源
public static void free(ResultSet resultSet,Statement statement,PreparedStatement preparedStatement,Connection connection){
try{
if (resultSet!=null) {
resultSet.close();
}
}catch (SQLException e) {
e.printStackTrace();
}finally{
try {
if(statement!=null){
statement.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
if (preparedStatement!=null) {
preparedStatement.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
if (connection!=null) {
connection.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
}
//query
// public static ArrayList<Object> query(String sql,String colum){//应该用反射
//
// Connection connection = null;
// ResultSet resultSet = null;
// PreparedStatement preparedStatement =null;
//
// try{
// connection = getConnection();
// //SQL执行器
// preparedStatement = connection.prepareStatement(sql);
// resultSet =preparedStatement.executeQuery();
// while (resultSet.next()) {
// resultSet.getString(colum);
// }
// }catch(Exception e){
// e.printStackTrace();
// }finally{
//
// }
// return null;
// }
//query 字段
public static String query(String sql,String colum){//应该用反射
Connection connection = null;
ResultSet resultSet = null;
PreparedStatement preparedStatement =null;
String str ="";
try{
connection = getConnection();
//SQL执行器
preparedStatement = connection.prepareStatement(sql);
resultSet =preparedStatement.executeQuery();
while (resultSet.next()) {
str = resultSet.getString(colum);
}
}catch(Exception e){
e.printStackTrace();
}finally{
}
return str;
}
public static void main(String[] args) {
String sql =" select * from demo r where r.id=1";
String colum = "name";
System.out.println(query(sql,colum));
}
}