util.java

简单的用户管理

/**
 * 
 */
package com.howeisoft.ums.util;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Properties;

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

/**
 * @author howei
 * 
 */
public class Util {
	private static Properties cfg = new Properties();

	static {
		try {
			InputStream in = Util.class.getClassLoader().getResourceAsStream(
					"driver_data.properties");
			cfg.load(in);
			in.close();
		} catch (Exception e) {
			e.printStackTrace();
			throw new ExceptionInInitializerError();
		}
	}

	public static Connection getConnection() {
		if (cfg.getProperty("jdbc/MY_DS") == null) {
			return getConnection_DM();
		}

		return getConnection_JNDI();
	}

	private static Connection getConnection_JNDI() {
		try {
			Context ctx = new InitialContext();
			DataSource ds = (DataSource) ctx.lookup("java:comp/env/"
					+ cfg.getProperty("jdbc/MY_DS"));
			return ds.getConnection();
		} catch (Exception e) {
			e.printStackTrace();
			throw new RuntimeException("无法连接到 " + cfg.getProperty("jdbc/MY_DS"));
		}
	}

	private static Connection getConnection_DM() {

		try {
			Class.forName(cfg.getProperty("driver")).newInstance();
			return DriverManager.getConnection(cfg.getProperty("url"), cfg
					.getProperty("user"), cfg.getProperty("password"));
		} catch (Exception e) {
			e.printStackTrace();
			throw new RuntimeException("参数配置不正确 ");
		}
	}

	public static void close(Connection con, Statement st, ResultSet rs) {
		try {
			rs.close();
		} catch (Exception e) {
			e.printStackTrace();
		}

		close(con, st);
	}

	public static void close(Connection con, Statement st) {
		try {
			st.close();
		} catch (Exception e) {
			e.printStackTrace();
		}

		try {
			con.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}