1. 程式人生 > 實用技巧 >第9周LeetCode記錄

第9周LeetCode記錄

1.匯入jar包

2.建立JdbcTemplate物件,依賴於資料來源DataSource

       JdbcTemplate jt = new JdbcTemplate(new ComboPooledDataSource()); //依賴於資料來源DataSource

3.呼叫JdbcTemplate方法來完成CRUD操作

  update();

    String sql = "update t_user set password = ? where id=?";
       jt.update(sql,"111","1");
@Test
    public void
test01(){ String sql = "insert into t_user values(null,?,?)"; int i = jt.update(sql, "校長", "123"); System.out.println(i); }

  queryForMap();會把查詢出來的單個記錄封裝為map集合

@Test
    public void test03(){
        String sql = "select * from t_user where id=?";
        Map<String, Object> map = jt.queryForMap(sql, 1);
        System.out.println(map);
    }

  queryForList();查詢所有記錄封裝到list集合中

@Test
    public void test02(){
        String sql = "select * from t_user";
        List<Map<String, Object>> maps = jt.queryForList(sql);
        for (Map<String, Object> map : maps) {
            System.out.println(map);
        }
    }

  query(); 查詢出來的單個物件封裝為一個javabean

@Test
    public void test04(){
        String sql ="SELECT * FROM t_user";
        List<User> userList = jt.query(sql, new RowMapper<User>() {
            @Override
            public User mapRow(ResultSet rst, int i) throws SQLException {
                User u = new User();
                int id = rst.getInt(1);
                String username = rst.getString(2);
                String password = rst.getString(3);
                u.setId(id);
                u.setUsername(username);
                u.setPassword(password);
                return u;
            }
        });
        for (User user : userList) {
            System.out.println(user);
        }
    }

//使用RowMapper的實現類BeanPropertyRowMapper
//注意該方法中必須保證bean中各個屬性的資料名於資料庫中欄位名一致。資料型別也需要注意
@Test
public void test05(){ String sql ="SELECT * FROM t_user"; List<User> userList = jt.query(sql,new BeanPropertyRowMapper<User>(User.class)); for (User user : userList) { System.out.println(user); } }

  queryForObject(); 用於聚合函式的執行

@Test
    public void test06(){
        String sql = "select count(id) from t_user";
        Long aLong = jt.queryForObject(sql, Long.class);
        System.out.println(aLong);
    }

4. 不用close(),因為模板會自動處理