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  • 数据库连接池Demo

    c3p0连接池Demo

    		/**
    		 * c3p0连接池demo
    		 * 依赖包:
    		 * 		c3p0-0.9.5.2.jar
    		 * 		mcchange-commons-java.jar
    		 */
    		// 创建连接池
    		ComboPooledDataSource combo = new ComboPooledDataSource();
    		// 从连接池获取连接对象
    		Connection conn = combo.getConnection();
    		PreparedStatement stmt = conn.prepareStatement("select * from emp");
    
    

    druid连接池Demo

    /**
    		 * 依赖包:druid.jar
    		 */
    		// 类加载器获取配置文件输入流对象
    		InputStream is= DruidTest.class.getClassLoader().getResourceAsStream("druid.properties");		
    		Properties ps = new Properties();
    		ps.load(is);
    		// 创建连接池对象
    		DataSource ds = DruidDataSourceFactory.createDataSource(ps);
    		// 从连接池获取连接对象
    		Connection conn = ds.getConnection();
    		
    		PreparedStatement stmt = conn.prepareStatement("select * from emp");
    

    c3p0加dbUtils

    // 依赖包:commons.dbutils.jar
    public class DbUtils {
    	static ComboPooledDataSource pool = new ComboPooledDataSource();
    	static QueryRunner qr = new QueryRunner(pool);
    	
    	@Test
    	public void add() throws SQLException {
    		String sql = "insert into `job` values (null,'清洁工','扫地')";
    		qr.update(sql);
    	}
    	
    	@Test
    	public void delete() throws SQLException {
    		String sql = "delete from job where `jname`=?";
    		qr.update(sql,"清洁工");
    	}
    	
    	// 得到查询结果的首个对象的数组形式
    	@Test 
    	public void query1() throws SQLException {
    		String sql = "select * from job";
    		Object[] obj = qr.query(sql, new ArrayHandler());
    		System.out.println(Arrays.toString(obj)); // [1, 董事长, 管理整个公司,接单]
    	}
    	
    	// 得到查询结果的所有对象的数组形式
    	@Test 
    	public void query2() throws SQLException {
    		String sql = "select * from job";
    		List<Object[]> obj = qr.query(sql, new ArrayListHandler());
    		for (Object[] objects : obj) {
    			System.out.println(Arrays.toString(objects));
    		}
    		/*
    		 * [1, 董事长, 管理整个公司,接单] 
    		 * [2, 经理, 管理部门员工] 
    		 * [3, 销售员, 向客人推销产品] 
    		 * [4, 文员, 使用办公软件] 
    		 * [5,总经理, 打扫卫生]
    		 */
    	}
    	
    	// 得到查询的首个对象的Job对象形式
    	@Test
    	public void query3() throws SQLException {
    		String sql = "select * from job";
    		Job j = qr.query(sql, new BeanHandler<>(Job.class));
    		System.out.println(j);
    	}
    	
    
    	// 得到查询结果集的所有对象的Job对象形式
    	@Test
    	public void query4() throws SQLException {
    		String sql = "select * from job";
    		List<Job> j = qr.query(sql, new BeanListHandler<>(Job.class));
    		System.out.println(j);
    	}
    	
    	// 得到单个查询结果
    	@Test
    	public void query5() throws SQLException {
    		String sql = "select `jname` from job where `id`=1";
    		Object obj = qr.query(sql, new ScalarHandler());
    		System.out.println(obj);
    	}
    
    
    }
    
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  • 原文地址:https://www.cnblogs.com/zhz-8919/p/10919894.html
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