1.导入 Spring 整合 Junit 所需的依赖

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <!--        Spring 整合 Junit-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>

2.编写测试类

//设置类运行器
@RunWith(SpringJUnit4ClassRunner.class)
//设置Spring环境对应的配置类，并加载配置类
@ContextConfiguration(classes = SpringCong.class)
public class UserServiceTest {
}

3.测试示例

1.配置类

1. JDBC 配置类

public class JdbcConfig {
    @Value("${jdbc.driver}")
    private String driver;

    @Value("${jdbc.url}")
    private String url;

    @Value("${jdbc.username}")
    private String username;

    @Value("${jdbc.password}")
    private String password;

    @Bean
    public DataSource dataSource(){
        DruidDataSource ds=new DruidDataSource();

        ds.setDriverClassName(driver);
        ds.setUrl(url);
        ds.setUsername(username);
        ds.setPassword(password);
        return ds;
    }
}

2. Mybatis 配置类

public class MybatisConfig {
    //定义bean，SqlSessionFactoryBean，用于创建SqlSessionFactory对象
    @Bean
    public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource dataSource){
        SqlSessionFactoryBean ssfb=new SqlSessionFactoryBean();
        //设置模型类的别名
        ssfb.setTypeAliasesPackage("com.my.domain");
        //设置数据源
        ssfb.setDataSource(dataSource);
        return ssfb;
    }
    //返回 MapperScannerConfigurer 对象
    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer(){
        MapperScannerConfigurer msc=new MapperScannerConfigurer();
        //包扫描
        msc.setBasePackage("com.my.dao");
        return msc;
    }
}

3. Spring 配置类

@Configuration
@ComponentScan("com.my")
@PropertySource("classpath:jdbc.properties")
@Import({JdbcConfig.class,MybatisConfig.class})
public class SpringCong {
}

2.配置文件

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/spring_db?useServerPrepStmts=true
jdbc.username=root
jdbc.password=root

3.实体类

public class User {
    private Integer id;
    private String username;
    private String password;

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

4.数据层接口（使用注解方式实现）

public interface UserDao {
    @Insert("insert into user_tb(username, password) VALUES (#{username},#{password})")
    void save(User user);

    @Delete("delete from user_tb where id=#{id}")
    void delete(Integer id);

    @Update("update user_tb set username=#{username},password=#{password}")
    void update(User user);

    @Select("select * from user_tb")
    List<User> selectAll();
}

5.业务层实现类（业务层接口略）

@Service("userService")
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDao userDao;

    @Override
    public void save(User user) {
        userDao.save(user);
    }

    @Override
    public void delete(Integer id) {
        userDao.delete(id);
    }

    @Override
    public void update(User user) {
        userDao.update(user);
    }

    @Override
    public List<User> selectAll() {
        return userDao.selectAll();
    }
}

6.测试类

//设置类运行器
@RunWith(SpringJUnit4ClassRunner.class)
//设置Spring环境对应的配置类，并加载配置类
@ContextConfiguration(classes = SpringCong.class)
public class UserServiceTest {

    @Autowired
    private UserService userService;

    @Test
    public void testSelectAll(){
        System.out.println(userService.selectAll());
        //输出结果为：
        // [User{id=1, username='张嘉圣杰', password='123456'}, User{id=2, username='张飘飘', password='456789'}]
    }
}