今天我学习了jdbcTemplate 以前没有听说过

DAO层接口：

public interface UserDao {

    List<User> USER_LIST();

    void addUser(User user);

    void deleteUser(int id);

    User getUser(int id);

    void updateUser(User user);
}

DAO层实现类：

public List<User> USER_LIST() {
    String sql = "select * from user";
    return this.getJdbcTemplate().query(sql,new UserRowMapper());
}

public void addUser(User user) {
    String sql = "insert into user values(?,?,?,?)";
    this.getJdbcTemplate().update(sql,null,user.getUserName(),user.getPassword(),user.getAge());
}

public void deleteUser(int id) {
    String sql = "delete from user where id=?";
    this.getJdbcTemplate().update(sql,id);
}

public User getUser(int id) {
    String sql = "select * from user where id=?";
    return this.getJdbcTemplate().queryForObject(sql,new UserRowMapper(),id);
}

public void updateUser(User user) {
    String sql = "update user set userName = ?,password = ?,age = ? where id=?";
    this.getJdbcTemplate().update(sql,user.getUserName(),user.getPassword(),user.getAge(),user.getId());
}

class UserRowMapper implements RowMapper<User> {
    public User mapRow(ResultSet resultSet, int i) throws SQLException {
        User user = new User();
        user.setId(resultSet.getInt("id"));
        user.setUserName(resultSet.getString("userName"));
        user.setPassword(resultSet.getString("password"));
        user.setAge(resultSet.getInt("age"));
        return user;
    }
}

mybatis：DAO层写接口，然后映射到xml文件

JDBCTemplate和mybatis的区别：

mybatis写起来更加简单 JDBCTemplate需要先继承JdbcDaoSupport，然后再用getJdbcTemplate方法进行增删改查的操作，还要有一个工具类实现RowMapper来封装数据，而mybatis的DAO接口可以通过配置文件

<property name="mapperLocations" value="classpath*:/sqlmap/*.xml"/>

直接映射到xml文件，简化很多步骤

junit单元测试

@Test
public void testUserList(){
    ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
    UserDao dao = (UserDao) ctx.getBean("userDao");
    List<User> users = dao.USER_LIST();
    for (User user:users) {
        System.out.println(user.toString());
    }

}
@Test
public void testDeleteUser(){
    ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
    UserDao dao = (UserDao) ctx.getBean("userDao");
    dao.deleteUser(1);
}

@Test
public void testAddUser(){
    ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
    UserDao dao = (UserDao) ctx.getBean("userDao");
    User user = new User();
    user.setId(1);
    user.setUserName("fffad");
    user.setPassword("fwe");
    user.setAge(32);
    dao.addUser(user);
}

@Test
public void testGetUser(){
    ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
    UserDao dao = (UserDao) ctx.getBean("userDao");
    User user = dao.getUser(2);
    System.out.println(user.toString());
}

@Test
public void testUpdateUser(){
    ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
    UserDao dao = (UserDao) ctx.getBean("userDao");
    User user = new User();
    user.setId(5);
    user.setUserName("fff");
    user.setPassword("ttt");
    user.setAge(666);
    dao.updateUser(user);
}

创建容器，把配置文件放里面，再去配置文件中找到需要的bean进行操作