y-y/DbUtil.java

package org.atm.dao;

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

public class DbUtil {

	protected static PreparedStatement ps = null;
	protected static ResultSet rs = null;
	protected static Connection conn = null;

	public static synchronized Connection getConn() {
		try {
			Class.forName("org.postgresql.Driver");
			conn = DriverManager.getConnection("jdbc:postgresql://localhost:5432/cstatm-mte", "postgres", "gitops123");
		} catch (Exception e) {
			System.err.println("Load org.postgresql.Driver Failed，Check pgJDBC jar is not Exist!");
			return null;
		}
		return conn;
	}

	public static void close() {
		try {
			if (rs != null)
				rs.close();
			if (ps != null)
				ps.close();
			if (conn != null)
				conn.close();

		} catch (SQLException e) {
			System.err.println("Close DB link Failed!");
			return;
		}
	}

	public static PreparedStatement executePreparedStatement(String sql) {
		try {
			ps = getConn().prepareStatement(sql);
		} catch (Exception e) {
			System.err.println("Create PreparedStatement Failed!");
			return null;
		}
		return ps;
	}

	public static ResultSet executeQuery(String sql) {

		try {
			ps = executePreparedStatement(sql);
			rs = ps.executeQuery();
		} catch (SQLException e) {
			System.err.println("Execute Query Failed!");
			return null;
		}
		return rs;
	}

	public static void executeUpdate(String sql) {
		try {
			ps = executePreparedStatement(sql);
			ps.executeUpdate();
		} catch (SQLException e) {
			System.err.println("Execute Update Failed!");
		} finally {
			try {
				if (ps != null)
					ps.close();
			} catch (SQLException e) {
				System.err.println("Close Resources Failed!");
				return;
			}
		}
	}

}// end DbUtil