1. Cloning first article code, and then proceed as follows:
① add saved in the user interface method dao
/**
* 用户的持久层接口 IUserDao.java
*/
public interface IUserDao {
//查询所有操作
List<User> findAll();
// 一：在dao接口中添加保存用户的方法
//保存用户
void saveUser(User user);
}
② mapping configuration corresponding to the configuration in the IUserDao.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace表示方法findAll在哪个dao实现接口-->
<mapper namespace="com.itheima.dao.IUserDao">
<!--配置查询所有-->
<!--resultType表示要封装到哪里去-->
<select id="findAll" resultType="com.itheima.domain.User">
select * from user
</select>
<!-- 二：配置对应的映射配置-->
<!--配置保存用户-->
<!--parameterType表示参数的类型，我们是通过接口从User中引入参数的值，所以是User类型-->
<!--这里按mybatis的要求取出User里的username,address,sex,birthday的值 #{username},#{address},#{sex},#{birthday}-->
<insert id="saveUser" parameterType="com.itheima.domain.User">
insert into user(username,address,sex,birthday) values (#{username},#{address},#{sex},#{birthday});
</insert>
</mapper>
③ Test save operation in the test class MybatisTest
public class MybatisTest {
//测试查询所有
@Test
public void testFindAll() throws IOException {
//1.读取配置文件
InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
//2.创建SqlSessionFactory工厂
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
//3.使用工厂生产SqlSession对象
SqlSession session = factory.openSession();
//4.创建Dao接口的代理对象（动态代理）
IUserDao userDao = session.getMapper(IUserDao.class);
//5.使用代理对象执行方法
List<User> users = userDao.findAll();
for (User user : users) {
System.out.println(user);
}
//6.释放资源
session.close();
in.close();
}
// 三：测试保存操作
@Test
public void testSave() throws IOException {
User user = new User();
user.setUsername("mybatis saveUser");
user.setAddress("北京市");
user.setSex("男");
user.setBirthday(new Date());
//1.读取配置文件
InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
//2.创建SqlSessionFactory工厂
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
//3.使用工厂生产SqlSession对象
SqlSession session = factory.openSession();
//4.创建Dao接口的代理对象（动态代理）
IUserDao userDao = session.getMapper(IUserDao.class);
//5.使用代理对象执行保存方法
userDao.saveUser(user);
//6.释放资源
session.close();
in.close();
//提交事务
session.commit();
}
}
③ ④ can be seen that there are many duplicate code, need to be optimized to extract the common portions thereof
public class MybatisTest {
private InputStream in;
private SqlSession session;
private IUserDao userDao;
@Before //用于测试方法执行之前执行
public void init() throws IOException {
//1.读取配置文件
in = Resources.getResourceAsStream("SqlMapConfig.xml");
//2.创建SqlSessionFactory工厂
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
//3.使用工厂生产SqlSession对象
session = factory.openSession();
//4.创建Dao接口的代理对象（动态代理）
userDao = session.getMapper(IUserDao.class);
}
@After //用于测试方法执行之后执行
public void destroy() throws IOException {
//提交事务
session.commit();
//6.释放资源
session.close();
in.close();
}
//测试查询所有
@Test
public void testFindAll() throws IOException {
//5.使用代理对象执行查询方法
List<User> users = userDao.findAll();
for (User user : users) {
System.out.println(user);
}
}
//测试保存操作
@Test
public void testSave() throws IOException {
User user = new User();
user.setUsername("mybatis saveUser");
user.setAddress("北京市");
user.setSex("男");
user.setBirthday(new Date());
//5.使用代理对象执行保存方法
userDao.saveUser(user);
}
}
⑤ run saveUser, see mysql in the user table, you will find the data successfully saved
⑥ add update operation (with exactly the same steps above)
- Adding updated user interface method of IUserDao
//更新用户
void updateUser(User user);
- IUserDao.xml mapper configured to map the corresponding file
<!--配置更新用户-->
<update id="updateUser" parameterType="com.itheima.domain.User">
update user set username=#{username},address=#{address},sex=#{sex},birthday=#{birthday} where id=#{id}
</update>
- MybatisTest adding a test update
//测试更新操作
@Test
public void testUpdate() {
User user = new User();
user.setUsername("mybatis Update user");
user.setAddress("北京市");
user.setSex("女");
user.setBirthday(new Date());
user.setId(49);
userDao.updateUser(user);
}
- See mysql after running in user table, see id = 49 data is updated at
⑦ again added to the above steps as delete, query based on user id, fuzzy query, the total number of users query operation
IUserDao Interface:
//根据id删除用户
void deleteUser(Integer userId);
//根据id查询用户信息
User findById(Integer userId);
//根据名称模糊查询用户信息
List<User> findByName(String username);
//查询总用户数
int findTotal();
IUserDao.xml:
<!--配置删除用户-->
<delete id="deleteUser" parameterType="Integer">
delete from user where id=#{uid}
</delete>
<!--根据id查询用户-->
<select id="findById" parameterType="INT" resultType="com.itheima.domain.User">
select * from user where id=#{uid}
</select>
<!--根据名称模糊查询-->
<select id="findByName" parameterType="String" resultType="com.itheima.domain.User">
<!--select * from user where username like #{name}-->
select * from user where username like '%${value}%'
</select>
<!--获取用户的总记录条数-->
<select id="findTotal" resultType="int">
select count(id) from user
</select>
MybatisTest.java ：
//测试删除操作
@Test
public void testDelete() {
//执行删除方法
userDao.deleteUser(49);
}
//测试根据id查询的操作
@Test
public void testFindById() {
//执行根据id查询的方法
User user = userDao.findById(45);
System.out.println(user);
}
//测试模糊查询的操作
@Test
public void testFindByName() {
//执行根据名称模糊查询用户的方法
//List<User> users = userDao.findByName("%王%");
List<User> users = userDao.findByName("王");
for (User user : users) {
System.out.println(user);
}
}
//测试查询总记录条数
@Test
public void testFindTotal() {
//执行根据名称模糊查询用户的方法
int count = userDao.findTotal();
System.out.println(count);
}
Note Fuzzy query point ⑧ place:
two methods, with select * from user where username like ' % $ {value}%' better.
⑨ objects passing pojo
Mybatis ognl expression analysis target using the value field, or $ # {} {} is the attribute names in parentheses in pojo
ognl: object graphic nanavigation language: language object graph Navigation
- Get the user's name
① class writing: user.getUsername ()
written expression OGNL ②: user.username
③ the mybatis write directly username, because parameterType provides class property belongs to, there is no need to write the object name
User:
//根据queryVo中的条件查询用户
List<User> findUserByVo(QueryVo vo);
IUserDao.xml
<!--根据queryVo的条件查询用户-->
<select id="findUserByVo" parameterType="com.itheima.domain.QueryVo" resultType="com.itheima.domain.User">
select * from user where username like #{user.username}
</select>
QueryVo
public class QueryVo {
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}
MybatisTest
//测试使用QueryVo作为查询条件
@Test
public void testFindByVo() {
QueryVo vo = new QueryVo();
User user = new User();
user.setUsername("%王%");
vo.setUser(user);
List<User> users = userDao.findUserByVo(vo);
for (User u : users) {
System.out.println(u);
}
}