【JDBC】工具类的抽取

jdbc.properties属性文件

driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql:///jdbctest
username=root
password=1234

JDBCUtils.java工具类

package com.imooc.jdbc.utils;

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

/**
 * JDBC的工具类
 * @author jt
 *
 */
public class JDBCUtils {
	private static final String driverClass;
	private static final String url;
	private static final String username;
	private static final String password;
	
	static{
		// 加载属性文件并解析：
		Properties props = new Properties();
		// 如何获得属性文件的输入流？
		// 通常情况下使用类的加载器的方式进行获取：
		InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("jdbc.properties");
		try {
			props.load(is);
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		driverClass = props.getProperty("driverClass");
		url = props.getProperty("url");
		username = props.getProperty("username");
		password = props.getProperty("password");
	}

	/**
	 * 注册驱动的方法
	 * @throws ClassNotFoundException 
	 */
	public static void loadDriver() throws ClassNotFoundException{
		Class.forName(driverClass);
	}
	
	/**
	 * 获得连接的方法:
	 * @throws SQLException 
	 */
	public static Connection getConnection() throws Exception{
		loadDriver();
		Connection conn = DriverManager.getConnection(url, username, password);
		return conn;
	}
	
	/**
	 * 资源释放
	 */
	public static void release(Statement stmt,Connection conn){
		if(stmt != null){
			try {
				stmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			stmt = null;
		}
		if(conn != null){
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			conn = null;
		}
	}
	
	public static void release(ResultSet rs,Statement stmt,Connection conn){
		if(rs!= null){
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			rs = null;
		}
		if(stmt != null){
			try {
				stmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			stmt = null;
		}
		if(conn != null){
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			conn = null;
		}
	}
}

JDBCDemo3.java测试

package com.imooc.jdbc.demo1;

import java.sql.Connection;
import java.sql.Statement;

import org.junit.Test;

import com.imooc.jdbc.utils.JDBCUtils;

public class JDBCDemo3 {

	@Test
	// 保存记录
	public void demo1(){
		Connection conn = null;
		Statement stmt  = null;
		try{
			// 获得连接:
			conn = JDBCUtils.getConnection();
			// 创建执行SQL语句的对象
			stmt = conn.createStatement();
			// 编写SQL:
			String sql = "insert into user values (null,'ggg','123','小六')";
			// 执行SQL:
			int num = stmt.executeUpdate(sql);
			if(num > 0){
				System.out.println("保存成功!");
			}
		}catch(Exception e){
			e.printStackTrace();
		}finally{
			// 释放资源:
			JDBCUtils.release(stmt, conn);
		}
	}
}