Spring入门第十六课

接上一次讲课

先看代码：

package logan.spring.study.annotation.repository;

public interface UserRepository {

    void save();

}

package logan.spring.study.annotation.repository;

import org.springframework.stereotype.Repository;

@Repository("userRepository")

public class UserRepositoryImpl implements UserRepository {

    @Override

    public void save() {

        // TODO Auto-generated method stub

        System.out.println("UserRepository Save...");

    }

}

package logan.spring.study.annotation.service;

import org.springframework.stereotype.Service;

import logan.spring.study.annotation.repository.UserRepository;

@Service

public class UserService {

    private UserRepository userRepository;

    public void add(){

        System.out.println("UserService add...");

        userRepository.save();

    }

}

package logan.spring.study.annotation.controller;

import org.springframework.stereotype.Controller;

import logan.spring.study.annotation.service.UserService;

@Controller

public class UserController {

    UserService userService;

    public void execute(){

        System.out.println("UserController execute...");

        userService.add();

    }

}

<?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-4.3.xsd">

    <context:component-scan

    base-package="logan.spring.study.annotation">

    </context:component-scan>

</beans>

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;

import logan.spring.study.annotation.repository.UserRepository;

import logan.spring.study.annotation.service.UserService;

public class Main {

    public static void main(String[] args) {

        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");

//        TestObject to = (TestObject) ctx.getBean("testObject");

//        System.out.println(to);

        UserController userController = (UserController) ctx.getBean("userController");

        System.out.println(userController);

        userController.execute();

//        UserService userService = (UserService) ctx.getBean("userService");

//        System.out.println(userService);

//        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");

//        System.out.println(userRepository);

    }

}

输出结果：

五月 27, 2017 11:15:37 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 11:15:37 CST 2017]; root of context hierarchy

五月 27, 2017 11:15:37 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

Exception in thread "main" logan.spring.study.annotation.controller.UserController@78ac1102

UserController execute...

java.lang.NullPointerException

    at logan.spring.study.annotation.controller.UserController.execute(UserController.java:13)

    at logan.spring.study.annotation.Main.main(Main.java:18)

可以看到空指针异常，因为没有办法调用userController.execute();

组件装配

<context:component-scan>元素还会自动注册AutowiredAnnotationBeanPostProcessor实例，该实例可以自动装配具有@Autowired和@Resource，@Inject注解的属性。

使用@Autowired自动装配Bean

@Autowired注解自动装配具有兼容类型的单个Bean属性：

-构造器，普通字段（即使是非public），一切具有参数的方法都可以应用@Autowired注解

-默认情况下，所有使用@Autowired注解的属性都要被设置，当Spring找不到匹配度Bean装配属性时，会抛出异常，若某一属性允许不被设置，可以设置@Autowired注解的required属性为false.

-默认情况下，当IOC容器里存在多个类型兼容的Bean时，通过类型的自动装配将无法工作，此时可以在@Qualifiter注解里面提供Bean的名称，Spring允许对方法的入参标注@Qualifiter已指定注入Bean的名称。

-@Autowired注解也可以应用在数组类型的属性上，此时Spring将会把所有匹配的Bean警醒自动装配。

-@Autowired注解也可以应用在集合属性上，此时Spring读取该集合的类型信息，然后自动装配所有与之兼容的Bean。

-@Autowired注解用在java.util.map上时，若该Map的键值为String，那么Spring将自动装配与之Map值类型兼容的Bean，此时Bean的名称作为键值。

看如下代码：

package logan.spring.study.annotation.repository;

public interface UserRepository {

    void save();

}

package logan.spring.study.annotation.repository;

import org.springframework.stereotype.Repository;

@Repository("userRepository")

public class UserRepositoryImpl implements UserRepository {

    @Override

    public void save() {

        // TODO Auto-generated method stub

        System.out.println("UserRepository Save...");

    }

}

package logan.spring.study.annotation.service;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import logan.spring.study.annotation.repository.UserRepository;

@Service

public class UserService {

    @Autowired

    private UserRepository userRepository;

    public void add(){

        System.out.println("UserService add...");

        userRepository.save();

    }

}

package logan.spring.study.annotation.controller;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Controller;

import logan.spring.study.annotation.service.UserService;

@Controller

public class UserController {

    @Autowired

    UserService userService;

    public void execute(){

        System.out.println("UserController execute...");

        userService.add();

    }

}

<?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-4.3.xsd">

    <context:component-scan

    base-package="logan.spring.study.annotation">

    </context:component-scan>

</beans>

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;

import logan.spring.study.annotation.repository.UserRepository;

import logan.spring.study.annotation.service.UserService;

public class Main {

    public static void main(String[] args) {

        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");

//        TestObject to = (TestObject) ctx.getBean("testObject");

//        System.out.println(to);

        UserController userController = (UserController) ctx.getBean("userController");

        System.out.println(userController);

        userController.execute();

//        UserService userService = (UserService) ctx.getBean("userService");

//        System.out.println(userService);

//        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");

//        System.out.println(userRepository);

    }

}

输出结果：

五月 27, 2017 12:16:53 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 12:16:53 CST 2017]; root of context hierarchy

五月 27, 2017 12:16:53 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

logan.spring.study.annotation.controller.UserController@704d6e83

UserController execute...

UserService add...

UserRepository Save...

在看如下代码：

package logan.spring.study.annotation;

import org.springframework.stereotype.Component;

@Component

public class TestObject {

}

package logan.spring.study.annotation.repository;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Repository;

import logan.spring.study.annotation.TestObject;

@Repository("userRepository")

public class UserRepositoryImpl implements UserRepository {

    @Autowired

    private TestObject testObject;

    @Override

    public void save() {

        // TODO Auto-generated method stub

        System.out.println("UserRepository Save...");

        System.out.println(testObject);

    }

}

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;

import logan.spring.study.annotation.repository.UserRepository;

import logan.spring.study.annotation.service.UserService;

public class Main {

    public static void main(String[] args) {

        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");

//        TestObject to = (TestObject) ctx.getBean("testObject");

//        System.out.println(to);

        UserController userController = (UserController) ctx.getBean("userController");

        System.out.println(userController);

        userController.execute();

//        UserService userService = (UserService) ctx.getBean("userService");

//        System.out.println(userService);

//        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");

//        System.out.println(userRepository);

    }

}

输出结果为：

五月 27, 2017 1:22:00 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 13:21:59 CST 2017]; root of context hierarchy

五月 27, 2017 1:22:00 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

logan.spring.study.annotation.controller.UserController@43a0cee9

UserController execute...

UserService add...

UserRepository Save...

logan.spring.study.annotation.TestObject@eb21112

如果没有TestObject就会出错，如下：

package logan.spring.study.annotation;

public class TestObject {

}

输出结果为：

五月 27, 2017 1:25:00 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 13:25:00 CST 2017]; root of context hierarchy

五月 27, 2017 1:25:00 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

五月 27, 2017 1:25:00 下午 org.springframework.context.support.ClassPathXmlApplicationContext refresh

警告: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'userService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userRepository': Unsatisfied dependency expressed through field 'testObject'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.TestObject' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'userService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userRepository': Unsatisfied dependency expressed through field 'testObject'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.TestObject' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)

    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)

    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)

    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)

    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)

    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)

    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866)

    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542)

    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)

    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)

    at logan.spring.study.annotation.Main.main(Main.java:12)

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userRepository': Unsatisfied dependency expressed through field 'testObject'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.TestObject' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)

    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)

    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)

    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)

    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)

    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)

    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)

    ... 15 more

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userRepository': Unsatisfied dependency expressed through field 'testObject'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.TestObject' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)

    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)

    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)

    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)

    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)

    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)

    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)

    ... 28 more

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.TestObject' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1486)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)

    ... 41 more

如果没有TestObject，还想让编译成功，如下：

package logan.spring.study.annotation.repository;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Repository;

import logan.spring.study.annotation.TestObject;

@Repository("userRepository")

public class UserRepositoryImpl implements UserRepository {

    @Autowired(required=false)

    private TestObject testObject;

    @Override

    public void save() {

        // TODO Auto-generated method stub

        System.out.println("UserRepository Save...");

        System.out.println(testObject);

    }

}

输出结果为：

五月 27, 2017 1:29:07 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 13:29:07 CST 2017]; root of context hierarchy

五月 27, 2017 1:29:07 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

logan.spring.study.annotation.controller.UserController@704d6e83

UserController execute...

UserService add...

UserRepository Save...

null

如果有好几个类型相同的Bean，会出错吗？

看如下代码：

package logan.spring.study.annotation.repository;

import org.springframework.stereotype.Repository;

@Repository

public class UserJdbcRepository implements UserRepository{

    @Override

    public void save() {

        // TODO Auto-generated method stub

        System.out.println("UserJdbcRepository save....");

    }

}

package logan.spring.study.annotation.repository;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Repository;

import logan.spring.study.annotation.TestObject;

@Repository

public class UserRepositoryImpl implements UserRepository {

    @Autowired(required=false)

    private TestObject testObject;

    @Override

    public void save() {

        // TODO Auto-generated method stub

        System.out.println("UserRepository Save...");

        System.out.println(testObject);

    }

}

这样会运行出错：

五月 27, 2017 1:33:57 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 13:33:57 CST 2017]; root of context hierarchy

五月 27, 2017 1:33:57 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

五月 27, 2017 1:33:58 下午 org.springframework.context.support.ClassPathXmlApplicationContext refresh

警告: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'userService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.repository.UserRepository' available: expected single matching bean but found 2: userJdbcRepository,userRepositoryImpl

Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'userService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.repository.UserRepository' available: expected single matching bean but found 2: userJdbcRepository,userRepositoryImpl

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)

    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)

    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)

    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)

    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)

    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)

    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866)

    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542)

    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)

    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)

    at logan.spring.study.annotation.Main.main(Main.java:12)

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.repository.UserRepository' available: expected single matching bean but found 2: userJdbcRepository,userRepositoryImpl

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)

    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)

    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)

    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)

    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)

    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)

    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)

    ... 15 more

Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'logan.spring.study.annotation.repository.UserRepository' available: expected single matching bean but found 2: userJdbcRepository,userRepositoryImpl

    at org.springframework.beans.factory.config.DependencyDescriptor.resolveNotUnique(DependencyDescriptor.java:173)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1116)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)

    ... 28 more

解决方法就是指定userRepository

package logan.spring.study.annotation.repository;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Repository;

import logan.spring.study.annotation.TestObject;

@Repository("userRepository")

public class UserRepositoryImpl implements UserRepository {

    @Autowired(required=false)

    private TestObject testObject;

    @Override

    public void save() {

        // TODO Auto-generated method stub

        System.out.println("UserRepository Save...");

        System.out.println(testObject);

    }

}

输出结果为：

五月 27, 2017 1:37:26 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 13:37:26 CST 2017]; root of context hierarchy

五月 27, 2017 1:37:26 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

logan.spring.study.annotation.controller.UserController@4d1b0d2a

UserController execute...

UserService add...

UserRepository Save...

null

还可以在UserService里面指定：

package logan.spring.study.annotation.service;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.stereotype.Service;

import logan.spring.study.annotation.repository.UserRepository;

@Service

public class UserService {

    @Autowired

    @Qualifier("userRepositoryImpl")

    private UserRepository userRepository;

    public void add(){

        System.out.println("UserService add...");

        userRepository.save();

    }

}

package logan.spring.study.annotation.repository;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Repository;

import logan.spring.study.annotation.TestObject;

@Repository

public class UserRepositoryImpl implements UserRepository {

    @Autowired(required=false)

    private TestObject testObject;

    @Override

    public void save() {

        // TODO Auto-generated method stub

        System.out.println("UserRepository Save...");

        System.out.println(testObject);

    }

}

输出结果为：

五月 27, 2017 1:41:07 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 13:41:07 CST 2017]; root of context hierarchy

五月 27, 2017 1:41:07 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

logan.spring.study.annotation.controller.UserController@67b467e9

UserController execute...

UserService add...

UserRepository Save...

null

对于set方法也是可以的，如下看代码：

package logan.spring.study.annotation.service;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.stereotype.Service;

import logan.spring.study.annotation.repository.UserRepository;

@Service

public class UserService {

    private UserRepository userRepository;

    @Autowired

    @Qualifier("userRepositoryImpl")

    public void setUserRepository(UserRepository userRepository) {

        this.userRepository = userRepository;

    }

    public void add(){

        System.out.println("UserService add...");

        userRepository.save();

    }

}

输出结果为：

五月 27, 2017 1:42:58 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 13:42:58 CST 2017]; root of context hierarchy

五月 27, 2017 1:42:58 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [beans-annotation.xml]

logan.spring.study.annotation.controller.UserController@545997b1

UserController execute...

UserService add...

UserRepository Save...

null

还可以放在入参的里面：

package logan.spring.study.annotation.service;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.stereotype.Service;

import logan.spring.study.annotation.repository.UserRepository;

@Service

public class UserService {

    private UserRepository userRepository;

    @Autowired

    public void setUserRepository(@Qualifier("userRepositoryImpl") UserRepository userRepository) {

        this.userRepository = userRepository;

    }

    public void add(){

        System.out.println("UserService add...");

        userRepository.save();

    }

}

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