整合MyBatis

• pom.xml添加依賴

<dependencies>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.1.1</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.11</version>
    </dependency>
</dependencies>

注：此處不引入spring-boot-starter-jdbc依賴是由于mybatis-spring-boot-starter中已經(jīng)包含了此依賴。MySQL版本不對可能會報錯。

• application.properties配置mysql連接

spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

使用MyBatis

• 創(chuàng)建映射對象User

public class User {

    private Long id;
    private String name;
    private Integer age;

    public User() {}

    public User(Long id, String name, Integer age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public User(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public Long getId() { return id; }

    public void setId(Long id) { this.id = id; }

    public String getName() { return name; }

    public void setName(String name) { this.name = name; }

    public Integer getAge() { return age; }

    public void setAge(Integer age) { this.age = age; }

}

• 創(chuàng)建User映射的操作UserMapper，實現(xiàn)插入和查詢操作

@Mapper
public interface UserMapper {

    @Select("SELECT * FROM USER WHERE NAME = #{name}")
    User findByName(@Param("name") String name);

    @Insert("INSERT INTO USER(NAME, AGE) VALUES(#{name}, #{age})")
    int insert(@Param("name") String name, @Param("age") Integer age);
}

• 單元測試：測試結(jié)束回滾數(shù)據(jù)，保證測試單元每次運行的數(shù)據(jù)環(huán)境獨立

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = Application.class)
public class ApplicationTests {

    @Autowired
    private UserMapper userMapper;

    @Test
    @Rollback
    public void findByName() throws Exception {
        userMapper.insert("AAA", 20);
        User u = userMapper.findByName("AAA");
        Assert.assertEquals(20, u.getAge().intValue());
    }
}

MyBatis注解配置詳解

• 使用@Param傳參數(shù)

@Insert("INSERT INTO USER(NAME, AGE) VALUES(#{name}, #{age})")
int insert(@Param("name") String name, @Param("age") Integer age);

@Param中定義的name對應(yīng)了SQL中的#{name}，age對應(yīng)了SQL中的#{age}。

• 通過Map對象來昨晚傳遞參數(shù)的容器

@Insert("INSERT INTO USER(NAME, AGE) VALUES(#{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER})")
int insertByMap(Map<String, Object> map);

示例：

Map<String, Object> map = new HashMap<>();
map.put("name", "CCC");
map.put("age", 40);
userMapper.insertByMap(map);

• 使用普通的Java對象來作為查詢條件的傳參

@Insert("INSERT INTO USER(NAME, AGE) VALUES(#{name}, #{age})")
int insertByUser(User user);

#{name}、#{age}分別對應(yīng)User對象中的name和age屬性。

增刪改查

public interface UserMapper {

    @Select("SELECT * FROM user WHERE name = #{name}")
    User findByName(@Param("name") String name);

    @Insert("INSERT INTO user(name, age) VALUES(#{name}, #{age})")
    int insert(@Param("name") String name, @Param("age") Integer age);

    @Update("UPDATE user SET age=#{age} WHERE name=#{name}")
    void update(User user);

    @Delete("DELETE FROM user WHERE id =#{id}")
    void delete(Long id);
}

• 測試：

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = Application.class)
@Transactional
public class ApplicationTests {

    @Autowired
    private UserMapper userMapper;

    @Test
    @Rollback
    public void testUserMapper() throws Exception {
        // insert一條數(shù)據(jù)，并select出來驗證
        userMapper.insert("AAA", 20);
        User u = userMapper.findByName("AAA");
        Assert.assertEquals(20, u.getAge().intValue());
        // update一條數(shù)據(jù)，并select出來驗證
        u.setAge(30);
        userMapper.update(u);
        u = userMapper.findByName("AAA");
        Assert.assertEquals(30, u.getAge().intValue());
        // 刪除這條數(shù)據(jù)，并select驗證
        userMapper.delete(u.getId());
        u = userMapper.findByName("AAA");
        Assert.assertEquals(null, u);
    }
}

• 查，返回結(jié)果的綁定，使用@Results和@Result注解來進行綁定

@Results({
    @Result(property = "name", column = "name"),
    @Result(property = "age", column = "age")
})
@Select("SELECT name, age FROM user")
List<User> findAll();

注：@Result中的property屬性對應(yīng)User對象中的成員名，column對應(yīng)SELECT出的字段名。
在該配置中故意沒有查出id屬性，只對User對應(yīng)中的name和age對象做了映射配置，這樣可以通過下面的單元測試來驗證查出的id為null，而其他屬性不為null：

@Test
@Rollback
public void testUserMapper() throws Exception {
    List<User> userList = userMapper.findAll();
    for(User user : userList) {
        Assert.assertEquals(null, user.getId());
        Assert.assertNotEquals(null, user.getName());
    }
}