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);
    }


}