@Resource 
javax.annotation 
JSR250 (Common Annotations for Java) 
@Inject 
javax.inject 
JSR330 (Dependency Injection for Java) 
@Autowired 
org.springframework.bean.factory 
Spring 

@Autowired和@Inject 
- 默认 autowired by type 
- 可以 通过@Qualifier 显式指定 autowired by qualifier name。 
- 如果 autowired by type 失败（找不到或者找到多个实现），则退化为autowired by field name 
@Resource 
- 默认 autowired by field name 
- 如果 autowired by field name失败，会退化为 autowired by type 
- 可以 通过@Qualifier 显式指定 autowired by qualifier name 
- 如果 autowired by qualifier name失败，会退化为 autowired by field name。但是这时候如果 autowired by field name失败，就不会再退化为autowired by type了。 

<bean id="lamborghini" class="me.arganzheng.study.spring.autowired.Lamborghini"> 
<qualifier value="luxury"/> 
<!-- inject any dependencies required by this bean --> 
</bean>

@Component("lamborghini") 
@Qualifier("luxury") 
public class Lamborghini implements Car { 
} 

@Component 
@Named("lamborghini") 
@Qualifier("luxury") 
public class Lamborghini implements Car { 
} 

<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:aop="http://www.springframework.org/schema/aop" 
xmlns:context="http://www.springframework.org/schema/context" 
xmlns:util="http://www.springframework.org/schema/util" 
xsi:schemaLocation=" 
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd 
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd 
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd"> 
<context:annotation-config /> 
<context:component-scan base-package="me.arganzheng.study" /> 
<util:constant id="en" 
static-field="me.arganzheng.study.spring.autowired.Constants.Language.EN" /> 
<util:constant id="ja" 
static-field="me.arganzheng.study.spring.autowired.Constants.Language.JP" /> 
<util:constant id="ind" 
static-field="me.arganzheng.study.spring.autowired.Constants.Language.IND" /> 
<util:constant id="pt" 
static-field="me.arganzheng.study.spring.autowired.Constants.Language.PT" /> 
<util:constant id="th" 
static-field="me.arganzheng.study.spring.autowired.Constants.Language.TH" /> 
<util:constant id="ar" 
static-field="me.arganzheng.study.spring.autowired.Constants.Language.AR" /> 
<util:constant id="en-rIn" 
static-field="me.arganzheng.study.spring.autowired.Constants.Language.EN_RIN" /> 
<util:map id="languageChangesMap" key-type="java.lang.String" 
value-type="java.lang.String"> 
<entry key="pt" value="pt" /> 
<entry key="br" value="pt" /> 
<entry key="jp" value="ja" /> 
<entry key="ja" value="ja" /> 
<entry key="ind" value="ind" /> 
<entry key="id" value="ind" /> 
<entry key="en-rin" value="en-rIn" /> 
<entry key="in" value="en-rIn" /> 
<entry key="en" value="en" /> 
<entry key="gb" value="en" /> 
<entry key="th" value="th" /> 
<entry key="ar" value="ar" /> 
<entry key="eg" value="ar" /> 
</util:map> 
</beans> 

package me.arganzheng.study.spring.autowired; 
public interface Constants { 
public interface Language { 
public static final String EN = "CommonConstants.LANG_ENGLISH"; 
public static final String JP = "CommonConstants.LANG_JAPANESE"; 
public static final String IND = "CommonConstants.LANG_INDONESIAN"; 
public static final String PT = "CommonConstants.LANG_PORTUGUESE"; 
public static final String TH = "CommonConstants.LANG_THAI"; 
public static final String EN_RIN = "CommonConstants.LANG_ENGLISH_INDIA"; 
public static final String AR = "CommonConstants.LANG_Arabic"; 
} 
} 

public class AutowiredTest extends BaseSpringTestCase { 
@Autowired 
private Map<String, String> languageChangesMap; 
@Test 
public void testAutowired() { 
notNull(languageChangesMap); 
System.out.println(languageChangesMap.getClass().getSimpleName()); 
System.out.println(languageChangesMap); 
} 
} 

LinkedHashMap 
{en=CommonConstants.LANG_ENGLISH, ja=CommonConstants.LANG_JAPANESE, ind=CommonConstants.LANG_INDONESIAN, pt=CommonConstants.LANG_PORTUGUESE, th=CommonConstants.LANG_THAI, ar=CommonConstants.LANG_Arabic, en-rIn=CommonConstants.LANG_ENGLISH_INDIA} 

[org.springframework.test.context.support.DependencyInjectionTestExecutionListener@5c51ee0a] to prepare test instance [me.arganzheng.study.spring.autowired.AutowiredTest@6e301e0] 
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'me.arganzheng.study.spring.autowired.AutowiredTest': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.util.Map me.arganzheng.study.spring.autowired.AutowiredTest.languageChangesMap; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [java.lang.String] found for dependency [map with value type java.lang.String]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} 
... 
ed by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [java.lang.String] found for dependency [map with value type java.lang.String]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:986) 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:843) 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:768) 
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486) 
... 28 more 

protected Object doResolveDependency(DependencyDescriptor descriptor, Class<?> type, String beanName, 
Set<String> autowiredBeanNames, TypeConverter typeConverter) throws BeansException { 
... 
else if (Map.class.isAssignableFrom(type) && type.isInterface()) { 
Class<?> keyType = descriptor.getMapKeyType(); 
if (keyType == null || !String.class.isAssignableFrom(keyType)) { 
if (descriptor.isRequired()) { 
throw new FatalBeanException("Key type [" + keyType + "] of map [" + type.getName() + 
"] must be assignable to [java.lang.String]"); 
} 
return null; 
} 
Class<?> valueType = descriptor.getMapValueType(); 
if (valueType == null) { 
if (descriptor.isRequired()) { 
throw new FatalBeanException("No value type declared for map [" + type.getName() + "]"); 
} 
return null; 
} 
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, valueType, descriptor); 
if (matchingBeans.isEmpty()) { 
if (descriptor.isRequired()) { 
raiseNoSuchBeanDefinitionException(valueType, "map with value type " + valueType.getName(), descriptor); 
} 
return null; 
} 
if (autowiredBeanNames != null) { 
autowiredBeanNames.addAll(matchingBeans.keySet()); 
} 
return matchingBeans; 
} 
... 
}

[org.springframework.test.context.support.DependencyInjectionTestExecutionListener@9476189] to prepare test instance [me.arganzheng.study.spring.autowired.AutowiredTest@2d546e21] 
... 
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [java.lang.String] found for dependency [map with value type java.lang.String]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=languageChangesMap)} 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:986) 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:843) 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:768) 
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486) 
... 28 more 

protected Object doResolveDependency(DependencyDescriptor descriptor, Class<?> type, String beanName, 
Set<String> autowiredBeanNames, TypeConverter typeConverter) throws BeansException { 
Object value = getAutowireCandidateResolver().getSuggestedValue(descriptor); 
if (value != null) { 
if (value instanceof String) { 
String strVal = resolveEmbeddedValue((String) value); 
BeanDefinition bd = (beanName != null && containsBean(beanName) ? getMergedBeanDefinition(beanName) : null); 
value = evaluateBeanDefinitionString(strVal, bd); 
} 
TypeConverter converter = (typeConverter != null ? typeConverter : getTypeConverter()); 
return (descriptor.getField() != null ? 
converter.convertIfNecessary(value, type, descriptor.getField()) : 
converter.convertIfNecessary(value, type, descriptor.getMethodParameter())); 
} 
if (type.isArray()) { 
Class<?> componentType = type.getComponentType(); 
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, componentType, descriptor); 
if (matchingBeans.isEmpty()) { 
if (descriptor.isRequired()) { 
raiseNoSuchBeanDefinitionException(componentType, "array of " + componentType.getName(), descriptor); 
} 
return null; 
} 
if (autowiredBeanNames != null) { 
autowiredBeanNames.addAll(matchingBeans.keySet()); 
} 
TypeConverter converter = (typeConverter != null ? typeConverter : getTypeConverter()); 
return converter.convertIfNecessary(matchingBeans.values(), type); 
} 
else if (Collection.class.isAssignableFrom(type) && type.isInterface()) { 
Class<?> elementType = descriptor.getCollectionType(); 
if (elementType == null) { 
if (descriptor.isRequired()) { 
throw new FatalBeanException("No element type declared for collection [" + type.getName() + "]"); 
} 
return null; 
} 
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, elementType, descriptor); 
if (matchingBeans.isEmpty()) { 
if (descriptor.isRequired()) { 
raiseNoSuchBeanDefinitionException(elementType, "collection of " + elementType.getName(), descriptor); 
} 
return null; 
} 
if (autowiredBeanNames != null) { 
autowiredBeanNames.addAll(matchingBeans.keySet()); 
} 
TypeConverter converter = (typeConverter != null ? typeConverter : getTypeConverter()); 
return converter.convertIfNecessary(matchingBeans.values(), type); 
} 
else if (Map.class.isAssignableFrom(type) && type.isInterface()) { 
Class<?> keyType = descriptor.getMapKeyType(); 
if (keyType == null || !String.class.isAssignableFrom(keyType)) { 
if (descriptor.isRequired()) { 
throw new FatalBeanException("Key type [" + keyType + "] of map [" + type.getName() + 
"] must be assignable to [java.lang.String]"); 
} 
return null; 
} 
Class<?> valueType = descriptor.getMapValueType(); 
if (valueType == null) { 
if (descriptor.isRequired()) { 
throw new FatalBeanException("No value type declared for map [" + type.getName() + "]"); 
} 
return null; 
} 
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, valueType, descriptor); 
if (matchingBeans.isEmpty()) { 
if (descriptor.isRequired()) { 
raiseNoSuchBeanDefinitionException(valueType, "map with value type " + valueType.getName(), descriptor); 
} 
return null; 
} 
if (autowiredBeanNames != null) { 
autowiredBeanNames.addAll(matchingBeans.keySet()); 
} 
return matchingBeans; 
} 
else { 
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, type, descriptor); 
if (matchingBeans.isEmpty()) { 
if (descriptor.isRequired()) { 
raiseNoSuchBeanDefinitionException(type, "", descriptor); 
} 
return null; 
} 
if (matchingBeans.size() > 1) { 
String primaryBeanName = determinePrimaryCandidate(matchingBeans, descriptor); 
if (primaryBeanName == null) { 
throw new NoUniqueBeanDefinitionException(type, matchingBeans.keySet()); 
} 
if (autowiredBeanNames != null) { 
autowiredBeanNames.add(primaryBeanName); 
} 
return matchingBeans.get(primaryBeanName); 
} 
// We have exactly one match. 
Map.Entry<String, Object> entry = matchingBeans.entrySet().iterator().next(); 
if (autowiredBeanNames != null) { 
autowiredBeanNames.add(entry.getKey()); 
} 
return entry.getValue(); 
} 
} 

org.springframework.beans.factory.NoSuchBeanDefinitionException: 
No unique bean of type [me.arganzheng.study.spring.autowired.Car] is defined: 
expected single matching bean but found 2: [audi, toyota]. 

public class AutowiredTest extends BaseSpringTestCase { 
@Resource 
@Qualifier("languageChangesMap") 
private Map<String, String> languageChangesMap; 
@Test 
public void testAutowired() { 
assertNotNull(languageChangesMap); 
System.out.println(languageChangesMap.getClass().getSimpleName()); 
System.out.println(languageChangesMap); 
} 
}

LinkedHashMap 
{pt=pt, br=pt, jp=ja, ja=ja, ind=ind, id=ind, en-rin=en-rIn, in=en-rIn, en=en, gb=en, th=th, ar=ar, eg=ar} 

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [java.lang.String] found for dependency [map with value type java.lang.String]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@javax.annotation.Resource(shareable=true, mappedName=, description=, name=, type=class java.lang.Object, authenticationType=CONTAINER, lookup=)} 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:986) 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:843) 
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:768) 
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:438) 
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:416) 
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:550) 
at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:150) 
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) 
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:303) 
... 26 more 

public class AutowiredTest extends BaseSpringTestCase { 
@Resource 
@Qualifier("languageChangesMap") 
private Map<String, String> languageChangesMap; 
@Resource 
private List<Car> cars; 
@Test 
public void testAutowired() { 
assertNotNull(languageChangesMap); 
System.out.println(languageChangesMap.getClass().getSimpleName()); 
System.out.println(languageChangesMap); 
assertNotNull(cars); 
System.out.println(cars.getClass().getSimpleName()); 
System.out.println(cars); 
} 
}

LinkedHashMap 
{pt=pt, br=pt, jp=ja, ja=ja, ind=ind, id=ind, en-rin=en-rIn, in=en-rIn, en=en, gb=en, th=th, ar=ar, eg=ar} 
ArrayList 

package me.arganzheng.study.spring.autowired; 
import org.springframework.beans.factory.annotation.Qualifier; 
import org.springframework.stereotype.Component; 
@Component 
@Qualifier("luxury") 
public class Lamborghini implements Car { 
} 

package me.arganzheng.study.spring.autowired; 
import javax.inject.Named; 
import org.springframework.stereotype.Component; 
@Component 
@Named("luxury") 
public class RollsRoyce implements Car { 
} 

package me.arganzheng.study.spring.autowired; 
import static junit.framework.Assert.assertNotNull; 
import java.util.List; 
import me.arganzheng.study.BaseSpringTestCase; 
import org.junit.Test; 
import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.beans.factory.annotation.Qualifier; 
/** 
* 
* @author zhengzhibin 
* 
*/ 
public class AutowiredTest extends BaseSpringTestCase { 
@Autowired 
@Qualifier("luxury") 
private List<Car> luxuryCars; 
@Test 
public void testAutowired() { 
assertNotNull(luxuryCars); 
System.out.println(luxuryCars.getClass().getSimpleName()); 
System.out.println(luxuryCars); 
} 
}

ArrayList 
[me.arganzheng.study.spring.autowired.Lamborghini@66b875e1, me.arganzheng.study.spring.autowired.RollsRoyce@58433b76] 

no. (Default) No autowiring. Bean references must be defined via a ref element. Changing the default setting is not recommended for larger deployments, because specifying collaborators explicitly gives greater control and clarity. To some extent, it documents the structure of a system. 
byName. Autowiring by property name. Spring looks for a bean with the same name as the property that needs to be autowired. For example, if a bean definition is set to autowire by name, and it contains a master property (that is, it has a setMaster(..) method), Spring looks for a bean definition named master, and uses it to set the property. 
byType. Allows a property to be autowired if exactly one bean of the property type exists in the container. If more than one exists, a fatal exception is thrown, which indicates that you may not use byType autowiring for that bean. If there are no matching beans, nothing happens; the property is not set. 
constructor. Analogous to byType, but applies to constructor arguments. If there is not exactly one bean of the constructor argument type in the container, a fatal error is raised.