上一篇：（十六）Spring对事务的支持

环境

spring6里程碑版本的仓库
依赖：spring context依赖、spring对junit的支持相关依赖、junit4依赖、junit5依赖

  <!--配置多个仓库-->
  <repositories>
    <!--spring6里程碑版本的仓库-->
    <repository>
      <id>repository.spring.milestone</id>
      <name>Spring Milestone Repository</name>
      <url>https://repo.spring.io/milestone</url>
    </repository>
  </repositories>

  <dependencies>
    <!--spring context依赖-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>6.0.0-M2</version>
    </dependency>
    <!--spring对junit的支持-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <!--这个版本即支持junit4又支持junit5-->
      <version>6.0.0-M2</version>
    </dependency>
    <!--junit4依赖-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.13.2</version>
      <scope>test</scope>
    </dependency>
    <!--junit5依赖-->
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter</artifactId>
      <version>5.9.0</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

声明bean：

@Component("user")
public class User {
    @Value("张三")
    private String name;

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                '}';
    }

    public String getName() {
        return name;
    }

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

spring配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    <context:component-scan base-package="com.junit.bean"/>
</beans>

Spring对JUnit4的支持

传统的单元测试：

@Test
    public void testUser(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
        User user = applicationContext.getBean("user", User.class);
        System.out.println(user);
    }

    @Test
    public void testUser2(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
        User user = applicationContext.getBean("user", User.class);
        System.out.println(user);
    }
    @Test
    public void testUser3(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
        User user = applicationContext.getBean("user", User.class);
        System.out.println(user);
    }

我们发现每次单元测试都要new一个ApplicationContext，并且根据getBean获取bean，这显然代码重复，没有得到复用。
Spring提供的方便主要是这几个注解：
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(配置文件名)
一般是从类的根路径加载所以写成：
@ContextConfiguration(“classpath:spring.xml”)
在单元测试类上使用这两个注解之后，在单元测试类中的属性上可以使用@Autowired。比较方便。
所以单元测试就变成这样：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:spring.xml")
public class SpringJunit4Test {

    @Autowired
    private User user;

    @Test
    public void testUser(){
        /*ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
        User user = applicationContext.getBean("user", User.class);*/
        System.out.println(user);
    }

    @Test
    public void testUser2(){
        /*ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
        User user = applicationContext.getBean("user", User.class);*/
        System.out.println(user);
    }
    @Test
    public void testUser3(){
        /*ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
        User user = applicationContext.getBean("user", User.class);*/
        System.out.println(user);
    }
}

Spring对JUnit5的支持

在JUnit5当中，可以使用Spring提供的以下两个注解，标注到单元测试类上，这样在类当中就可以使用@Autowired注解了。
@ExtendWith(SpringExtension.class)
@ContextConfiguration(“classpath:spring.xml”)

@ExtendWith(SpringExtension.class)
@ContextConfiguration("classpath:spring.xml")
public class SpringJunit5Test {
    @Autowired
    private User user;
    @Test
    public void testUser(){
        System.out.println(user);
    }
}