Spring 基于注解装配Bean

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
@Component(“id”) 取代

web开发，提供3个@Component注解衍生注解（功能一样）取代

• @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

• schema命名空间
  
• User

@Component("userId")
public class User {
    private String username;
    private Address address;

    public String getUsername() {
        return username;
    }

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

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}

• 测试

 @Test
    public void demo01(){
        String xmlPath = "annotation.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        User user = (User) applicationContext.getBean("userId");
        System.out.println(user);
    }

结果发现报错了，报错如下：

java.lang.IllegalArgumentException
	at org.springframework.asm.ClassReader.(Unknown Source)
	at org.springframework.asm.ClassReader.(Unknown Source)
	at org.springframework.asm.ClassReader.(Unknown Source)
	at org.springframework.core.type.classreading.SimpleMetadataReader.(SimpleMetadataReader.java:52)
	at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80)
	at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101)
	at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:76)
	at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:298)
	at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300)
	at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300)
	at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:230)
	at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:153)
	at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:130)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:285)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:223)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:630)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461)
	at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139)
	at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:83)
	at com.cc.study.annotation.TestAnnotation.demo01(TestAnnotation.java:16)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:262)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:84)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	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

        
        
        
            org.springframework
            spring-context
            4.2.0.RELEASE
        
        
        
            org.springframework
            spring-beans
            4.2.0.RELEASE
        
        
        
            org.springframework
            spring-core
            4.2.0.RELEASE
        
        
        
            org.springframework
            spring-expression
            4.2.0.RELEASE
        
        
            junit
            junit
            4.7
        
    
    
        
            
                org.apache.maven.plugins
                maven-compiler-plugin
                
                    1.8
                    1.8
                
            
        
    

测试结果：

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 {
    @Value("Kevin")
    private String username;
    private Address address;

    public String getUsername() {
        return username;
    }

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

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}

• 测试

  @Test
    public void demo02(){
        String xmlPath = "annotation.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        User user = (User) applicationContext.getBean("userId");
        System.out.println(user.getUsername());
    }

引用值注入

方式1：按照【类型】注入
@Autowired

• Address

@Component
public class Address {
    @Value("北京")
    private String addr;
    @Value("112")
    private String tel;

    public String getAddr() {
        return addr;
    }

    public void setAddr(String addr) {
        this.addr = addr;
    }

    public String getTel() {
        return tel;
    }

    public void setTel(String tel) {
        this.tel = tel;
    }
}

• User

@Component("userId")
public class User {
    @Value("Kevin")
    private String username;
    @Autowired
    private Address address;

    public String getUsername() {
        return username;
    }

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

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}

• 测试

 @Test
    public void demo03(){
        String xmlPath = "annotation.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        User user = (User) applicationContext.getBean("userId");
        System.out.println(user.getUsername());
        System.out.println(user.getAddress().getAddr());
        System.out.println(user.getAddress().getTel());
    }

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

• Address

@Component("addressId")
public class Address {
    @Value("北京")
    private String addr;
    @Value("112")
    private String tel;

    public String getAddr() {
        return addr;
    }

    public void setAddr(String addr) {
        this.addr = addr;
    }

    public String getTel() {
        return tel;
    }

    public void setTel(String tel) {
        this.tel = tel;
    }
}

• User

@Component("userId")
public class User {
    @Value("Kevin")
    private String username;
    @Autowired
    @Qualifier("addressId")
    private Address address;

    public String getUsername() {
        return username;
    }

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

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}

• 测试

 @Test
    public void demo03(){
        String xmlPath = "annotation.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        User user = (User) applicationContext.getBean("userId");
        System.out.println(user.getUsername());
        System.out.println(user.getAddress().getAddr());
        System.out.println(user.getAddress().getTel());
    }

方式3：按照【名称】注入2
@Resource(name=“名称”)

• User

@Component("userId")
public class User {
    @Value("Kevin")
    private String username;

    @Resource(name = "addressId")
    private Address address;

    public String getUsername() {
        return username;
    }

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

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}

• 测试

 @Test
    public void demo03(){
        String xmlPath = "annotation.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        User user = (User) applicationContext.getBean("userId");
        System.out.println(user.getUsername());
        System.out.println(user.getAddress().getAddr());
        System.out.println(user.getAddress().getTel());
    }

生命周期

初始化：@PostConstruct
销毁：@PreDestroy

• User

@Component("userId")
public class User {
    @Value("Kevin")
    private String username;

    @Resource(name = "addressId")
    private Address address;

    public String getUsername() {
        return username;
    }

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

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    @PostConstruct
    public void init(){
        System.out.println("初始化");
    }
    @PreDestroy
    public void destroy(){
        System.out.println("销毁");
    }
}

• 测试

 @Test
    public void demo04(){
        String xmlPath = "annotation.xml";
        AbstractApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        User user = (User) applicationContext.getBean("userId");
        System.out.println(user.getUsername());
        System.out.println(user.getAddress().getAddr());
        System.out.println(user.getAddress().getTel());
        applicationContext.close();
    }

作用域

@Scope(“prototype”) 多例

• User

@Component("userId")
@Scope("prototype")
public class User {
    @Value("Kevin")
    private String username;

    @Resource(name = "addressId")
    private Address address;

    public String getUsername() {
        return username;
    }

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

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    @PostConstruct
    public void init(){
        System.out.println("初始化");
    }
    @PreDestroy
    public void destroy(){
        System.out.println("销毁");
    }
}

• 测试

 @Test
    public void demo05(){
        String xmlPath = "annotation.xml";
        AbstractApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
        User user1 = (User) applicationContext.getBean("userId");
        User user2 = (User) applicationContext.getBean("userId");
        System.out.println(user1);
        System.out.println(user2);
    }