Spring 基于注解装配Bean

傷城~ 2022-02-09 12:21 482阅读 0赞

文章目录

    • Spring 基于注解的配置
      • 创建Bean
      • 依赖注入
        • 普通值注入
        • 引用值注入
        • 生命周期
        • 作用域

Spring 基于注解的配置

从 Spring 2.5 开始就可以使用注解来配置依赖注入。而不是采用 XML 来描述一个 bean 连线，你可以使用相关类，方法或字段声明的注解，将 bean 配置移动到组件类本身。

  • 注解：就是一个类，使用@注解名称
  • 开发中：使用注解 取代 xml配置文件。

创建Bean

@Component取代<bean class="">
@Component(“id”) 取代 <bean id="" class="">

web开发，提供3个@Component注解衍生注解（功能一样）取代<bean class="">

  • @Repository ：dao层
  • @Service：service层
  • @Controller：web层

注解使用前提，添加命名空间，让spring扫描含有注解类

  • 配置

    1. <!-- 组件扫描，扫描含有注解的类 -->
    2. <context:component-scan base-package="com.cc.study.annotation"></context:component-scan>
  1. </beans>
  • schema命名空间
    在这里插入图片描述

  • User

    @Component(“userId”)
    public class User {

    1. private String username;
    2. private Address address;
    4. public String getUsername() {
    5.     return username;
    6. }
    8. public void setUsername(String username) {
    9.     this.username = username;
    10. }
    12. public Address getAddress() {
    13.     return address;
    14. }
    16. public void setAddress(Address address) {
    17.     this.address = address;
    18. }

    }

  • 测试

    @Test

    1. public void demo01(){
    2.     String xmlPath = "annotation.xml";
    3.     ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    4.     User user = (User) applicationContext.getBean("userId");
    5.     System.out.println(user);
    6. }

结果发现报错了，报错如下：

  1. java.lang.IllegalArgumentException
  2.     at org.springframework.asm.ClassReader.<init>(Unknown Source)
  3.     at org.springframework.asm.ClassReader.<init>(Unknown Source)
  4.     at org.springframework.asm.ClassReader.<init>(Unknown Source)
  5.     at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:52)
  6.     at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80)
  7.     at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101)
  8.     at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:76)
  9.     at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:298)
  10.     at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300)
  11.     at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300)
  12.     at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:230)
  13.     at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:153)
  14.     at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:130)
  15.     at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:285)
  16.     at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:223)
  17.     at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:630)
  18.     at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461)
  19.     at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
  20.     at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
  21.     at com.cc.study.annotation.TestAnnotation.demo01(TestAnnotation.java:16)
  22.     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  23.     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  24.     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  25.     at java.lang.reflect.Method.invoke(Method.java:498)
  26.     at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
  27.     at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
  28.     at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
  29.     at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
  30.     at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
  31.     at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
  32.     at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
  33.     at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
  34.     at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
  35.     at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
  36.     at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
  37.     at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
  38.     at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
  39.     at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117)
  40.     at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
  41.     at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:262)
  42.     at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:84)
  43.     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  44.     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  45.     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  46.     at java.lang.reflect.Method.invoke(Method.java:498)
  47.     at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

然后我试了一下把Spring的版本改成4.0，把JDK改为1.8即可

  1. <dependencies>
  2.         <!-- 4个核心（beans、core、context、expression） -->
  3.         <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
  4.         <dependency>
  5.             <groupId>org.springframework</groupId>
  6.             <artifactId>spring-context</artifactId>
  7.             <version>4.2.0.RELEASE</version>
  8.         </dependency>
  9.         <!-- https://mvnrepository.com/artifact/org.springframework/spring-beans -->
  10.         <dependency>
  11.             <groupId>org.springframework</groupId>
  12.             <artifactId>spring-beans</artifactId>
  13.             <version>4.2.0.RELEASE</version>
  14.         </dependency>
  15.         <!-- https://mvnrepository.com/artifact/org.springframework/spring-core -->
  16.         <dependency>
  17.             <groupId>org.springframework</groupId>
  18.             <artifactId>spring-core</artifactId>
  19.             <version>4.2.0.RELEASE</version>
  20.         </dependency>
  21.         <!-- https://mvnrepository.com/artifact/org.springframework/spring-expression -->
  22.         <dependency>
  23.             <groupId>org.springframework</groupId>
  24.             <artifactId>spring-expression</artifactId>
  25.             <version>4.2.0.RELEASE</version>
  26.         </dependency>
  27.         <dependency>
  28.             <groupId>junit</groupId>
  29.             <artifactId>junit</artifactId>
  30.             <version>4.7</version>
  31.         </dependency>
  32.     </dependencies>
  33.     <build>
  34.         <plugins>
  35.             <plugin>
  36.                 <groupId>org.apache.maven.plugins</groupId>
  37.                 <artifactId>maven-compiler-plugin</artifactId>
  38.                 <configuration>
  39.                     <source>1.8</source>
  40.                     <target>1.8</target>
  41.                 </configuration>
  42.             </plugin>
  43.         </plugins>
  44.     </build>

测试结果：
在这里插入图片描述

依赖注入

依赖注入，给私有字段设置，也可以给setter方法设置

普通值注入

使用@Value

  • User

    @Component(“userId”)
    public class User {

    1. @Value("Kevin")
    2. private String username;
    3. private Address address;
    5. public String getUsername() {
    6.     return username;
    7. }
    9. public void setUsername(String username) {
    10.     this.username = username;
    11. }
    13. public Address getAddress() {
    14.     return address;
    15. }
    17. public void setAddress(Address address) {
    18.     this.address = address;
    19. }

    }

  • 测试

    @Test

    1. public void demo02(){
    2.     String xmlPath = "annotation.xml";
    3.     ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    4.     User user = (User) applicationContext.getBean("userId");
    5.     System.out.println(user.getUsername());
    6. }

在这里插入图片描述

引用值注入

方式1：按照【类型】注入
@Autowired

  • Address

    @Component
    public class Address {

    1. @Value("北京")
    2. private String addr;
    3. @Value("112")
    4. private String tel;
    6. public String getAddr() {
    7.     return addr;
    8. }
    10. public void setAddr(String addr) {
    11.     this.addr = addr;
    12. }
    14. public String getTel() {
    15.     return tel;
    16. }
    18. public void setTel(String tel) {
    19.     this.tel = tel;
    20. }

    }

  • User

    @Component(“userId”)
    public class User {

    1. @Value("Kevin")
    2. private String username;
    3. @Autowired
    4. private Address address;
    6. public String getUsername() {
    7.     return username;
    8. }
    10. public void setUsername(String username) {
    11.     this.username = username;
    12. }
    14. public Address getAddress() {
    15.     return address;
    16. }
    18. public void setAddress(Address address) {
    19.     this.address = address;
    20. }

    }

  • 测试

    @Test

    1. public void demo03(){
    2.     String xmlPath = "annotation.xml";
    3.     ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    4.     User user = (User) applicationContext.getBean("userId");
    5.     System.out.println(user.getUsername());
    6.     System.out.println(user.getAddress().getAddr());
    7.     System.out.println(user.getAddress().getTel());
    8. }

在这里插入图片描述

方式2：按照【名称】注入1
@Autowired
@Qualifier(“名称”)

  • Address

    @Component(“addressId”)
    public class Address {

    1. @Value("北京")
    2. private String addr;
    3. @Value("112")
    4. private String tel;
    6. public String getAddr() {
    7.     return addr;
    8. }
    10. public void setAddr(String addr) {
    11.     this.addr = addr;
    12. }
    14. public String getTel() {
    15.     return tel;
    16. }
    18. public void setTel(String tel) {
    19.     this.tel = tel;
    20. }

    }

  • User

    @Component(“userId”)
    public class User {

    1. @Value("Kevin")
    2. private String username;
    3. @Autowired
    4. @Qualifier("addressId")
    5. private Address address;
    7. public String getUsername() {
    8.     return username;
    9. }
    11. public void setUsername(String username) {
    12.     this.username = username;
    13. }
    15. public Address getAddress() {
    16.     return address;
    17. }
    19. public void setAddress(Address address) {
    20.     this.address = address;
    21. }

    }

  • 测试

    @Test

    1. public void demo03(){
    2.     String xmlPath = "annotation.xml";
    3.     ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    4.     User user = (User) applicationContext.getBean("userId");
    5.     System.out.println(user.getUsername());
    6.     System.out.println(user.getAddress().getAddr());
    7.     System.out.println(user.getAddress().getTel());
    8. }

在这里插入图片描述

方式3：按照【名称】注入2
@Resource(name=“名称”)

  • User

    @Component(“userId”)
    public class User {

    1. @Value("Kevin")
    2. private String username;
    4. @Resource(name = "addressId")
    5. private Address address;
    7. public String getUsername() {
    8.     return username;
    9. }
    11. public void setUsername(String username) {
    12.     this.username = username;
    13. }
    15. public Address getAddress() {
    16.     return address;
    17. }
    19. public void setAddress(Address address) {
    20.     this.address = address;
    21. }

    }

  • 测试

    @Test

    1. public void demo03(){
    2.     String xmlPath = "annotation.xml";
    3.     ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    4.     User user = (User) applicationContext.getBean("userId");
    5.     System.out.println(user.getUsername());
    6.     System.out.println(user.getAddress().getAddr());
    7.     System.out.println(user.getAddress().getTel());
    8. }

在这里插入图片描述

生命周期

初始化：@PostConstruct
销毁：@PreDestroy

  • User

    @Component(“userId”)
    public class User {

    1. @Value("Kevin")
    2. private String username;
    4. @Resource(name = "addressId")
    5. private Address address;
    7. public String getUsername() {
    8.     return username;
    9. }
    11. public void setUsername(String username) {
    12.     this.username = username;
    13. }
    15. public Address getAddress() {
    16.     return address;
    17. }
    19. public void setAddress(Address address) {
    20.     this.address = address;
    21. }
    23. @PostConstruct
    24. public void init(){
    25.     System.out.println("初始化");
    26. }
    27. @PreDestroy
    28. public void destroy(){
    29.     System.out.println("销毁");
    30. }

    }

  • 测试

    @Test

    1. public void demo04(){
    2.     String xmlPath = "annotation.xml";
    3.     AbstractApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    4.     User user = (User) applicationContext.getBean("userId");
    5.     System.out.println(user.getUsername());
    6.     System.out.println(user.getAddress().getAddr());
    7.     System.out.println(user.getAddress().getTel());
    8.     applicationContext.close();
    9. }

在这里插入图片描述

作用域

@Scope(“prototype”) 多例

  • User

    @Component(“userId”)
    @Scope(“prototype”)
    public class User {

    1. @Value("Kevin")
    2. private String username;
    4. @Resource(name = "addressId")
    5. private Address address;
    7. public String getUsername() {
    8.     return username;
    9. }
    11. public void setUsername(String username) {
    12.     this.username = username;
    13. }
    15. public Address getAddress() {
    16.     return address;
    17. }
    19. public void setAddress(Address address) {
    20.     this.address = address;
    21. }
    23. @PostConstruct
    24. public void init(){
    25.     System.out.println("初始化");
    26. }
    27. @PreDestroy
    28. public void destroy(){
    29.     System.out.println("销毁");
    30. }

    }

  • 测试

    @Test

    1. public void demo05(){
    2.     String xmlPath = "annotation.xml";
    3.     AbstractApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    4.     User user1 = (User) applicationContext.getBean("userId");
    5.     User user2 = (User) applicationContext.getBean("userId");
    6.     System.out.println(user1);
    7.     System.out.println(user2);
    8. }

在这里插入图片描述

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