1 package com.spring.model; 2 3 public class Tiger { 4 5 private String tigerName="TigerKing"; 6 7 public String toString(){ 8 return "TigerName:"+tigerName; 9 } 10 }
1 package com.spring.model; 2 3 public class Monkey { 4 5 private String monkeyName = "MonkeyKing"; 6 7 public String toString(){ 8 return "MonkeyName:" + monkeyName; 9 } 10 11 }
1 package com.spring.model; 2 3 public class Zoo { 4 private Tiger tiger; 5 private Monkey monkey; 6 7 public Tiger getTiger() { 8 return tiger; 9 } 10 public void setTiger(Tiger tiger) { 11 this.tiger = tiger; 12 } 13 public Monkey getMonkey() { 14 return monkey; 15 } 16 public void setMonkey(Monkey monkey) { 17 this.monkey = monkey; 18 } 19 20 public String toString(){ 21 return tiger + "\n" + monkey; 22 } 23 24 }
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans 3 xmlns="http://www.springframework.org/schema/beans" 4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 5 xmlns:p="http://www.springframework.org/schema/p" 6 xmlns:context="http://www.springframework.org/schema/context" 7 xsi:schemaLocation="http://www.springframework.org/schema/beans 8 http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 9 http://www.springframework.org/schema/context 10 http://www.springframework.org/schema/context/spring-context-3.0.xsd 11 "> 12 13 <bean id="zoo" class="com.spring.model.Zoo" > 14 <property name="tiger" ref="tiger" /> 15 <property name="monkey" ref="monkey" /> 16 </bean> 17 18 <bean id="tiger" class="com.spring.model.Tiger" /> 19 <bean id="monkey" class="com.spring.model.Monkey" /> 20 21 </beans>
1 public class TestAnnotation { 2 /** 3 * 不使用注解 4 */ 5 @Test 6 public void test(){ 7 //读取配置文件 8 ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext2.xml"); 9 Zoo zoo=(Zoo) ctx.getBean("zoo"); 10 System.out.println(zoo.toString()); 11 } 12 }
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans 3 xmlns="http://www.springframework.org/schema/beans" 4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 5 xmlns:p="http://www.springframework.org/schema/p" 6 xmlns:context="http://www.springframework.org/schema/context" 7 xsi:schemaLocation="http://www.springframework.org/schema/beans 8 http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 9 http://www.springframework.org/schema/context 10 http://www.springframework.org/schema/context/spring-context-3.0.xsd 11 "> 12 13 <context:component-scan base-package="com.spring" /> 14 15 <bean id="zoo" class="com.spring.model.Zoo" /> 16 <bean id="tiger" class="com.spring.model.Tiger" /> 17 <bean id="monkey" class="com.spring.model.Monkey" /> 18 19 </beans>
1 package com.spring.model; 2 3 import org.springframework.beans.factory.annotation.Autowired; 4 5 public class Zoo { 6 7 @Autowired 8 private Tiger tiger; 9 10 @Autowired 11 private Monkey monkey; 12 13 public String toString(){ 14 return tiger + "\n" + monkey; 15 } 16 17 }
1 package com.spring.model; 2 3 import org.springframework.beans.factory.annotation.Autowired; 4 5 public class Zoo { 6 7 @Autowired(required=false) 8 private Tiger tiger; 9 10 @Autowired(required=false) 11 private Monkey monkey; 12 13 public String toString(){ 14 return tiger + "\n" + monkey; 15 } 16 17 }
1 package com.spring.service; 2 3 public interface ICar { 4 5 public String getCarName(); 6 }
1 package com.spring.service.impl; 2 3 import com.spring.service.ICar; 4 5 public class BMWCar implements ICar{ 6 7 public String getCarName(){ 8 return "BMW car"; 9 } 10 }
1 package com.spring.service.impl; 2 3 import com.spring.service.ICar; 4 5 public class BenzCar implements ICar{ 6 7 public String getCarName(){ 8 return "Benz car"; 9 } 10 }
1 package com.spring.model; 2 3 import org.springframework.beans.factory.annotation.Autowired; 4 5 import com.spring.service.ICar; 6 7 public class CarFactory { 8 9 @Autowired 10 private ICar car; 11 12 public String toString(){ 13 return car.getCarName(); 14 } 15 16 }
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans 3 xmlns="http://www.springframework.org/schema/beans" 4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 5 xmlns:p="http://www.springframework.org/schema/p" 6 xmlns:context="http://www.springframework.org/schema/context" 7 xsi:schemaLocation="http://www.springframework.org/schema/beans 8 http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 9 http://www.springframework.org/schema/context 10 http://www.springframework.org/schema/context/spring-context-3.0.xsd 11 "> 12 13 <context:component-scan base-package="com.spring" /> 14 15 <!-- Autowired注解配合Qualifier注解 --> 16 <bean id="carFactory" class="com.spring.model.CarFactory" /> 17 <bean id="bmwCar" class="com.spring.service.impl.BMWCar" /> 18 <bean id="benz" class="com.spring.service.impl.BenzCar" /> 19 20 </beans>
1 /** 2 * Autowired注解配合Qualifier注解 3 */ 4 @Test 5 public void test1(){ 6 //读取配置文件 7 ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext2.xml"); 8 CarFactory carFactory=(CarFactory) ctx.getBean("carFactory"); 9 System.out.println(carFactory.toString()); 10 }
1 package com.spring.model; 2 3 import org.springframework.beans.factory.annotation.Autowired; 4 import org.springframework.beans.factory.annotation.Qualifier; 5 6 import com.spring.service.ICar; 7 8 public class CarFactory { 9 10 @Autowired 11 @Qualifier("bmwCar") 12 private ICar car; 13 14 public String toString(){ 15 return car.getCarName(); 16 } 17 18 }
1 package com.spring.model; 2 3 import javax.annotation.Resource; 4 5 public class Zoo1 { 6 7 @Resource(name="tiger") 8 private Tiger tiger; 9 10 @Resource(type=Monkey.class) 11 private Monkey monkey; 12 13 public String toString(){ 14 return tiger + "\n" + monkey; 15 } 16 }
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans 3 xmlns="http://www.springframework.org/schema/beans" 4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 5 xmlns:p="http://www.springframework.org/schema/p" 6 xmlns:context="http://www.springframework.org/schema/context" 7 xsi:schemaLocation="http://www.springframework.org/schema/beans 8 http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 9 http://www.springframework.org/schema/context 10 http://www.springframework.org/schema/context/spring-context-3.0.xsd 11 "> 12 13 <context:component-scan base-package="com.spring" /> 14 15 </beans>
1 package com.spring.model; 2 3 import org.springframework.beans.factory.annotation.Autowired; 4 import org.springframework.stereotype.Service; 5 6 @Service 7 public class Zoo { 8 9 @Autowired 10 private Tiger tiger; 11 12 @Autowired 13 private Monkey monkey; 14 15 public String toString(){ 16 return tiger + "\n" + monkey; 17 } 18 19 }
1 package com.spring.model; 2 3 import org.springframework.beans.factory.annotation.Autowired; 4 import org.springframework.context.annotation.Scope; 5 import org.springframework.stereotype.Service; 6 7 @Service("Zoo") 8 @Scope("prototype") 9 public class Zoo { 10 11 @Autowired 12 private Tiger tiger; 13 14 @Autowired 15 private Monkey monkey; 16 17 public String toString(){ 18 return tiger + "\n" + monkey; 19 } 20 21 }
1 <context:component-scan base-package="cn.gacl.java"/>
1 <context:component-scan base-package="cn.gacl.dao.impl,cn.gacl.service.impl,cn.gacl.action"/>
1 @Controller 2 @Scope("prototype") 3 public class UserAction extends BaseAction<User>{ 4 …… 5 }
使用@Controller注解标识UserAction之后,就表示要把UserAction交给Spring容器管理,在Spring容器中会存在一个名字为"userAction"的action,这个名字是根据UserAction类名来取的。注意:如果@Controller不指定其value【@Controller】,则默认的bean名字为这个类的类名首字母小写,如果指定value【@Controller(value="UserAction")】或者【@Controller("UserAction")】,则使用value作为bean的名字。
这里的UserAction还使用了@Scope注解,@Scope("prototype")表示将Action的范围声明为原型,可以利用容器的scope="prototype"来保证每一个请求有一个单独的Action来处理,避免struts中Action的线程安全问题。spring 默认scope 是单例模式(scope="singleton"),这样只会创建一个Action对象,每次访问都是同一Action对象,数据不安全,struts2 是要求每次次访问都对应不同的Action,scope="prototype" 可以保证当有请求的时候都创建一个Action对象
1 @Service("userService") 2 public class UserServiceImpl implements UserService { 3 ……… 4 }
@Service("userService")注解是告诉Spring,当Spring要创建UserServiceImpl的的实例时,bean的名字必须叫做"userService",这样当Action需要使用UserServiceImpl的的实例时,就可以由Spring创建好的"userService",然后注入给Action:在Action只需要声明一个名字叫“userService”的变量来接收由Spring注入的"userService"即可,具体代码如下:
1 // 注入userService 2 @Resource(name = "userService") 3 private UserService userService;
注意:在Action声明的“userService”变量的类型必须是“UserServiceImpl”或者是其父类“UserService”,否则由于类型不一致而无法注入,由于Action中的声明的“userService”变量使用了@Resource注解去标注,并且指明了其name = "userService",这就等于告诉Spring,说我Action要实例化一个“userService”,你Spring快点帮我实例化好,然后给我,当Spring看到userService变量上的@Resource的注解时,根据其指明的name属性可以知道,Action中需要用到一个UserServiceImpl的实例,此时Spring就会把自己创建好的名字叫做"userService"的UserServiceImpl的实例注入给Action中的“userService”变量,帮助Action完成userService的实例化,这样在Action中就不用通过“UserService userService = new UserServiceImpl();”这种最原始的方式去实例化userService了。如果没有Spring,那么当Action需要使用UserServiceImpl时,必须通过“UserService userService = new UserServiceImpl();”主动去创建实例对象,但使用了Spring之后,Action要使用UserServiceImpl时,就不用主动去创建UserServiceImpl的实例了,创建UserServiceImpl实例已经交给Spring来做了,Spring把创建好的UserServiceImpl实例给Action,Action拿到就可以直接用了。Action由原来的主动创建UserServiceImpl实例后就可以马上使用,变成了被动等待由Spring创建好UserServiceImpl实例之后再注入给Action,Action才能够使用。这说明Action对“UserServiceImpl”类的“控制权”已经被“反转”了,原来主动权在自己手上,自己要使用“UserServiceImpl”类的实例,自己主动去new一个出来马上就可以使用了,但现在自己不能主动去new“UserServiceImpl”类的实例,new“UserServiceImpl”类的实例的权力已经被Spring拿走了,只有Spring才能够new“UserServiceImpl”类的实例,而Action只能等Spring创建好“UserServiceImpl”类的实例后,再“恳求”Spring把创建好的“UserServiceImpl”类的实例给他,这样他才能够使用“UserServiceImpl”,这就是Spring核心思想“控制反转”,也叫“依赖注入”,“依赖注入”也很好理解,Action需要使用UserServiceImpl干活,那么就是对UserServiceImpl产生了依赖,Spring把Acion需要依赖的UserServiceImpl注入(也就是“给”)给Action,这就是所谓的“依赖注入”。对Action而言,Action依赖什么东西,就请求Spring注入给他,对Spring而言,Action需要什么,Spring就主动注入给他。
1 @Repository(value="userDao") 2 public class UserDaoImpl extends BaseDaoImpl<User> { 3 ……… 4 }
@Repository(value="userDao")注解是告诉Spring,让Spring创建一个名字叫“userDao”的UserDaoImpl实例。
当Service需要使用Spring创建的名字叫“userDao”的UserDaoImpl实例时,就可以使用@Resource(name = "userDao")注解告诉Spring,Spring把创建好的userDao注入给Service即可。1 // 注入userDao,从数据库中根据用户Id取出指定用户时需要用到 2 @Resource(name = "userDao") 3 private BaseDao<User> userDao;
<context:component-scan base-package="cn.test"/>