(2)Spring的三种实例 bean 的方式 以及 Spring中bean的作用域。 以及 bean的生命周期

第一种：

1.使用类构造器实例化

<bean id="personService" class="cn.itm.service.impl.PersonServiceBean"></bean>

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1. import cn.itm.service.PersonService; 
2.  
3. public class PersonServiceBeanimplements PersonService{ 
4.  
5.     public void save(){ 
6.         System.out.println("我是 save() 方法"); 
7.     } 
8. } 

import cn.itm.service.PersonService;public class PersonServiceBean implements PersonService{public void save(){System.out.println("我是 save() 方法");}}

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1. public class SpringTest { 
2.  
3.     @BeforeClass 
4.     public staticvoid setUpBeforeClass() throws Exception { 
5.     } 
6.  
7.     // 专门用来实例化  Spring 容器的。 
8.     @Test publicvoid instanceSpring(){ 
9.         // 在类路径下，寻找配置文件来实例化容器。 
10.         ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); 
11.          
12.         // 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过   接口  引用。 
13.         PersonService personService = (PersonService) ctx.getBean("personService"); 
14.         //调用  业务方法： 
15.         personService.save(); 
16.     } 
17. } 

public class SpringTest {@BeforeClasspublic static void setUpBeforeClass() throws Exception {}// 专门用来实例化 Spring 容器的。@Test public void instanceSpring(){// 在类路径下，寻找配置文件来实例化容器。ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");// 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过 接口 引用。PersonService personService = (PersonService) ctx.getBean("personService");//调用 业务方法：personService.save();}}

第二种：

2.使用静态工厂方法实例化

<bean id="personService2" class="cn.itm.service.impl.PersonServiceBeanFactory"
                    factory-method="createPersonServiceBean"></bean>

-----------------------------------------------------------------------------------------------------------------------------

    public staticPersonServiceBean createPersonServiceBean(){
        return new PersonServiceBean();
    }

[java] view plaincopyprint?

1. package cn.itm.service.impl; 
2.  
3. public class PersonServiceBeanFactory { 
4.  
5.     // 新建一个工厂方法，这个工厂方法用来创建一个bean对象。 
6.     /**
7.      *  PersonServiceBean 使用 PersonServiceBeanFactory的createPersonServiceBean()创建的。
8.      *
9.      */ 
10.     public static PersonServiceBean createPersonServiceBean(){ 
11.         return new PersonServiceBean(); 
12.     } 
13. } 

package cn.itm.service.impl;public class PersonServiceBeanFactory {// 新建一个工厂方法，这个工厂方法用来创建一个bean对象。/** * PersonServiceBean 使用 PersonServiceBeanFactory的createPersonServiceBean()创建的。 * */public static PersonServiceBean createPersonServiceBean(){return new PersonServiceBean();}}

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1. public class SpringTest { 
2.  
3.     @BeforeClass 
4.     public staticvoid setUpBeforeClass() throws Exception { 
5.     } 
6.  
7.     // 专门用来实例化  Spring 容器的。 
8.     @Test publicvoid instanceSpring(){ 
9.         // 在类路径下，寻找配置文件来实例化容器。 
10.         ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); 
11.          
12.         // 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过   接口  引用。 
13.         PersonService personService = (PersonService) ctx.getBean("personService2"); 
14.         //调用  业务方法： 
15.         personService.save(); 
16.     } 
17. } 

public class SpringTest {@BeforeClasspublic static void setUpBeforeClass() throws Exception {}// 专门用来实例化 Spring 容器的。@Test public void instanceSpring(){// 在类路径下，寻找配置文件来实例化容器。ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");// 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过 接口 引用。PersonService personService = (PersonService) ctx.getBean("personService2");//调用 业务方法：personService.save();}}

第三种：使用实例工厂方法实例化:

           <bean id="personServiceFactory" class="cn.itm.service.impl.PersonServiceBeanFactory" ></bean>
           <bean id="personService3" factory-bean="personServiceFactory"
                           factory-method="createPersonServiceBean"></bean>

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1. <?xml version="1.0" encoding="UTF-8"?> 
2. <beans xmlns="http://www.springframework.org/schema/beans" 
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
4.        xsi:schemaLocation="http://www.springframework.org/schema/beans 
5.            http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> 
6.             
7.             
8.             
9.            <bean id="personServiceFactory"class="cn.itm.service.impl.PersonServiceBeanFactory" ></bean> 
10.            <bean id="personService3" factory-bean="personServiceFactory"  
11.                         factory-method="createPersonServiceBean"></bean> 
12.             
13. </beans> 

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> <bean id="personServiceFactory" class="cn.itm.service.impl.PersonServiceBeanFactory" ></bean> <bean id="personService3" factory-bean="personServiceFactory" factory-method="createPersonServiceBean"></bean> </beans>

相比第二种：把 static 关键字去掉了。

[java] view plaincopyprint?

1. package cn.itm.service.impl; 
2.  
3. public class PersonServiceBeanFactory { 
4.      
5.     public PersonServiceBean createPersonServiceBean(){ 
6.         return new PersonServiceBean(); 
7.     } 
8.      
9.      
10. } 

package cn.itm.service.impl;public class PersonServiceBeanFactory {public PersonServiceBean createPersonServiceBean(){return new PersonServiceBean();}}

[java] view plaincopyprint?

1. public class SpringTest { 
2.  
3.     @BeforeClass 
4.     public staticvoid setUpBeforeClass() throws Exception { 
5.     } 
6.  
7.     // 专门用来实例化  Spring 容器的。 
8.     @Test publicvoid instanceSpring(){ 
9.         // 在类路径下，寻找配置文件来实例化容器。 
10.         ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); 
11.          
12.         // 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过   接口  引用。 
13.         PersonService personService = (PersonService) ctx.getBean("personService3"); 
14.         //调用  业务方法： 
15.         personService.save(); 
16.     } 
17. } 

public class SpringTest {@BeforeClasspublic static void setUpBeforeClass() throws Exception {}// 专门用来实例化 Spring 容器的。@Test public void instanceSpring(){// 在类路径下，寻找配置文件来实例化容器。ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");// 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过 接口 引用。PersonService personService = (PersonService) ctx.getBean("personService3");//调用 业务方法：personService.save();}}

Spring中  bean的作用域：

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1. <?xmlversion="1.0"encoding="UTF-8"?> 
2. <beans xmlns="http://www.springframework.org/schema/beans" 
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
4.        xsi:schemaLocation="http://www.springframework.org/schema/beans 
5.            http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> 
6.             
7.             
8.             
9.            <beanid="personServiceFactory"class="cn.itm.service.impl.PersonServiceBeanFactory"></bean> 
10.            <beanid="personService3"factory-bean="personServiceFactory"  
11.                         factory-method="createPersonServiceBean"></bean> 
12.             
13. </beans> 

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> <bean id="personServiceFactory" class="cn.itm.service.impl.PersonServiceBeanFactory" ></bean> <bean id="personService3" factory-bean="personServiceFactory" factory-method="createPersonServiceBean" ></bean> </beans>

[java] view plaincopyprint?

1. public class SpringTest { 
2.  
3.     @BeforeClass 
4.     public staticvoid setUpBeforeClass() throws Exception { 
5.     } 
6.  
7.     // 专门用来实例化  Spring 容器的。 
8.     @Test publicvoid instanceSpring(){ 
9.         // 在类路径下，寻找配置文件来实例化容器。 
10.         ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); 
11.          
12.         // 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过   接口  引用。 
13.         PersonService personService1 = (PersonService) ctx.getBean("personService3"); 
14.         PersonService personService2 = (PersonService) ctx.getBean("personService3"); 
15.          
16.         System.out.println( personService1 == personService2); 
17.     } 
18. } 

public class SpringTest {@BeforeClasspublic static void setUpBeforeClass() throws Exception {}// 专门用来实例化 Spring 容器的。@Test public void instanceSpring(){// 在类路径下，寻找配置文件来实例化容器。ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");// 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过 接口 引用。PersonService personService1 = (PersonService) ctx.getBean("personService3");PersonService personService2 = (PersonService) ctx.getBean("personService3");System.out.println( personService1 == personService2);}}
打印结果：true。

<bean id="personServiceFactory" class="cn.itm.service.impl.PersonServiceBeanFactory" ></bean>
           <bean id="personService3" factory-bean="personServiceFactory"
                           factory-method="createPersonServiceBean" scope="prototype"></bean>

[java] view plaincopyprint?

1. public class SpringTest { 
2.  
3.     @BeforeClass 
4.     public staticvoid setUpBeforeClass() throws Exception { 
5.     } 
6.  
7.     // 专门用来实例化  Spring 容器的。 
8.     @Test publicvoid instanceSpring(){ 
9.         // 在类路径下，寻找配置文件来实例化容器。 
10.         ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); 
11.          
12.         // 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过   接口  引用。 
13.         PersonService personService1 = (PersonService) ctx.getBean("personService3"); 
14.         PersonService personService2 = (PersonService) ctx.getBean("personService3"); 
15.          
16.         System.out.println( personService1 == personService2); 
17.     } 
18. } 

public class SpringTest {@BeforeClasspublic static void setUpBeforeClass() throws Exception {}// 专门用来实例化 Spring 容器的。@Test public void instanceSpring(){// 在类路径下，寻找配置文件来实例化容器。ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");// 填写 bean的名称，也就是 id属性的值：personService。获取后，就可以通过 接口 引用。PersonService personService1 = (PersonService) ctx.getBean("personService3");PersonService personService2 = (PersonService) ctx.getBean("personService3");System.out.println( personService1 == personService2);}}
打印结果：false。

【1】singleton

在每个Spring IoC容器中一个bean定义只有一个对象实例。

默认情况下会在容器启动时初始化bean，但我们可以指定Bean节点的lazy-init=“true”来延迟初始化bean，这时候，只有第一次获取bean会才初始化bean。如：
<bean id="xxx" class="cn.itcast.OrderServiceBean" lazy-init="true"/>
如果想对所有bean都应用延迟初始化，可以在根节点beans设置default-lazy-init=“true“，如下：
<beans default-lazy-init="true“ ...>

【2】prototype
每次从容器获取bean都是新的对象。

生命周期的测试：

[html] view plaincopyprint?

1. <?xmlversion="1.0"encoding="UTF-8"?> 
2. <beans xmlns="http://www.springframework.org/schema/beans" 
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
4.        xsi:schemaLocation="http://www.springframework.org/schema/beans 
5.            http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> 
6.             
7.            <!-- 在容器实例化的时候，就会对bean进行实例化。。而加入  scope="prototype" 时，是在调用getBean方法的时候，实例化的 --> 
8.            <beanid="personService"class="cn.itm.service.impl.PersonServiceBean"></bean> 
9.             
10.      
11. </beans> 

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> <!-- 在容器实例化的时候，就会对bean进行实例化。。而加入 scope="prototype" 时，是在调用getBean方法的时候，实例化的 --> <bean id="personService" class="cn.itm.service.impl.PersonServiceBean"></bean> </beans>

[java] view plaincopyprint?

1. import cn.itm.service.PersonService; 
2.  
3. public class PersonServiceBeanimplements PersonService{ 
4.  
5.     public PersonServiceBean(){ 
6.         System.out.println("我被实例化了"); 
7.     } 
8.     public void save(){ 
9.         System.out.println("我是 save() 方法"); 
10.     } 
11. } 

import cn.itm.service.PersonService;public class PersonServiceBean implements PersonService{public PersonServiceBean(){System.out.println("我被实例化了");}public void save(){System.out.println("我是 save() 方法");}}
测试类：

[java] view plaincopyprint?

1. public class SpringTest { 
2.  
3.     @BeforeClass 
4.     public staticvoid setUpBeforeClass() throws Exception { 
5.     } 
6.  
7.     // 专门用来实例化  Spring 容器的。 
8.     @Test publicvoid instanceSpring(){ 
9.         // 在类路径下，寻找配置文件来实例化容器。 
10.         ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); 
11.          
12. //      PersonService personService1 = (PersonService) ctx.getBean("personService3"); 
13.          
14.     } 
15. } 

public class SpringTest {@BeforeClasspublic static void setUpBeforeClass() throws Exception {}// 专门用来实例化 Spring 容器的。@Test public void instanceSpring(){// 在类路径下，寻找配置文件来实例化容器。ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");//PersonService personService1 = (PersonService) ctx.getBean("personService3");}}
打印结果：我被实例化了。

在每个Spring IoC容器中一个bean定义只有一个对象实例。

       默认情况下会在容器启动时初始化bean，但我们可以指定Bean节点的lazy-init=“true”来延迟初始化bean，这时候，只有第一次获取bean会才初始化bean。如：
<bean id="xxx" class="cn.itcast.OrderServiceBean" lazy-init="true"/>

        如果想对所有bean都应用延迟初始化，可以在根节点beans设置default-lazy-init=“true“，如下：
<beans default-lazy-init="true“ ...>

指定Bean的初始化方法和销毁方法
    <bean id="xxx" class="cn.itcast.OrderServiceBean" init-method="init"

             destroy-method="close"/>

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1. <?xmlversion="1.0"encoding="UTF-8"?> 
2. <beans xmlns="http://www.springframework.org/schema/beans" 
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
4.        xsi:schemaLocation="http://www.springframework.org/schema/beans 
5.            http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> 
6.             
7.            <beanid="personService"class="cn.itm.service.impl.PersonServiceBean"  
8.            lazy-init="false"destroy-method="destory"></bean> 
9.             
10.      
11. </beans> 

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> <bean id="personService" class="cn.itm.service.impl.PersonServiceBean" lazy-init="false" destroy-method="destory"></bean> </beans>

[java] view plaincopyprint?

1. package cn.itm.service.impl; 
2.  
3. import cn.itm.service.PersonService; 
4.  
5. public class PersonServiceBeanimplements PersonService{ 
6.  
7.     public PersonServiceBean(){ 
8.         System.out.println("我被实例化了"); 
9.     } 
10.     public void save(){ 
11.         System.out.println("我是 save() 方法"); 
12.     } 
13.      
14.     public void destory(){ 
15.         System.out.println("关闭"); 
16.     } 
17. } 

package cn.itm.service.impl;import cn.itm.service.PersonService;public class PersonServiceBean implements PersonService{public PersonServiceBean(){System.out.println("我被实例化了");}public void save(){System.out.println("我是 save() 方法");}public void destory(){System.out.println("关闭");}}

AbstractApplicationContext

[java] view plaincopyprint?

1. public class SpringTest { 
2.  
3.     @BeforeClass 
4.     public staticvoid setUpBeforeClass() throws Exception { 
5.     } 
6.  
7.     // 专门用来实例化  Spring 容器的。 
8.     @Test publicvoid instanceSpring(){ 
9.          
10.         AbstractApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); 
11.         ctx.close(); 
12.     } 
13. } 

public class SpringTest {@BeforeClasspublic static void setUpBeforeClass() throws Exception {}// 专门用来实例化 Spring 容器的。@Test public void instanceSpring(){AbstractApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");ctx.close();}}