JdbcBaseReview 系列之JdbcDBUtils(四)-----jbdc的jar包

public class Jdbc4DBUtils {

    //DbUtils是APache提供的一个开源的方便我们操作jdbc的jar包
    //QuerRunner类, 是该jar包的核心类 所有的操作数据库的方法都被封装在这个类中
    // 更新,查询都是使用QuerRunner类

    @Test
    public void t1() throws SQLException {
        //获得连接对象
        Connection conn = JdbcUtil.getConnection();
        //建立一个QueryRunner对象,用来执行sql 语句
        QueryRunner qr = new QueryRunner();

        String sql = "insert into stu values(null,'妲己',12)";

        //调用update方法,可以执行 增 删 改 等sql语句
        qr.update(conn, sql);

        conn.close();

    }

    @Test
    public void t2() throws SQLException {
        Connection conn = JdbcUtil.getConnection();
        QueryRunner qr = new QueryRunner();
        String queryOne = "select * from stu where id=8 ";
        Stu query = qr.query(conn, queryOne, new BeanHandler<Stu>(Stu.class));

        System.out.println(query);

    }

    //演示BeanListHandler的使用
    //使用BeanListHandler可以得到一个装载指定类型对象的集合数组
    //@throws SQLException
    @Test
    public void t3() throws SQLException {
        Connection conn = JdbcUtil.getConnection();
        QueryRunner qr = new QueryRunner();
        String queryAll = "select name, age from stu";

        List<Stu> stus = qr.query(conn, queryAll, new BeanListHandler<Stu>(Stu.class));
        //手敲四个字母iter + tab键
        for (Stu stu : stus) {
            System.out.println(stu.toString());
        }

    }

    @Test
    public void t4() throws SQLException {
        Connection conn = JdbcUtil.getConnection();
        QueryRunner qr = new QueryRunner();
        String queryAll = "select name, age from stu";
        List<Map<String, Object>> query = qr.query(conn, queryAll, new MapListHandler());
        System.out.println(query);

        //手敲四个字母iter + tab键
        for (Map<String, Object> stringObjectMap : query) {
            for (String s : stringObjectMap.keySet()) {
                System.out.println(s);
            }
        }

    }

    @Test
    public void t5() throws SQLException {
        Connection conn = JdbcUtil.getConnection();
        QueryRunner qr = new QueryRunner();
        String queryAll = "select *from stu";
        List<Object[]> query = qr.query(conn, queryAll, new ArrayListHandler());

//        System.out.println(query);
        for (Object[] objects : query) {
            for (Object object : objects) {
                System.out.printf(object + "-");
            }
            System.out.println();
        }
    }

    /*
     ResultSetHandler是接口
     BeanListHandler, BeanHandler等类都实现了ResultSetHandler接口
     @throws SQLException
     */
    @Test
    public void t6() throws SQLException {
        Connection conn = JdbcUtil.getConnection();
        QueryRunner qr = new QueryRunner();
        String queryAll = "select *from stu where id=8";
        qr.query(conn, queryAll, new ResultSetHandler<Stu>() {
            @Override
            public Stu handle(ResultSet resultSet) throws SQLException {
                while (resultSet.next()) {
                    Stu stu = new Stu();
                    stu.setName(resultSet.getString(2));
                    stu.setAge(resultSet.getInt(3));
                    stu.setId(resultSet.getInt(1));
                    System.out.println(stu);
                    return stu;
                }
                return null;
            }
        });
    }
}