Spring 管理bean的生命周期

于 2011-11-14 11:59:00 发布
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文章标签： java runtime
两个生命周期时间与bean关系尤为重要：
postinitialization（初始化后）和predestruction（销毁前）。

（Spring并不管理那些被配置成非单例bean的生命周期）



指定初始化方法：
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  1. packagecn.partner4java.init;
  3. /**
  4. * 指定初始化方法
  5. * @author partner4java
  6. *
  7. */
  8. publicclassSimpleBean {
  9. privateString name;
  10. privateintage =0;
  12. publicvoidinit(){
  13. if(name ==null){
  14. System.out.println("name为空");
  15. }
  16. if(age ==0){
  17. System.out.println("age为0");
  18. }
  19. }
  21. publicString getName() {
  22. returnname;
  23. }
  24. publicvoidsetName(String name) {
  25. this.name = name;
  26. }
  27. publicintgetAge() {
  28. returnage;
  29. }
  30. publicvoidsetAge(intage) {
  31. this.age = age;
  32. }
  34. }
view plain copy to clipboard print ?
  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="
  5. http://www.springframework.org/schema/beans
  6. http://www.springframework.org/schema/beans/spring-beans.xsd">
  8. <bean id="simple1"class="cn.partner4java.init.SimpleBean"
  9. init-method="init">
  10. <property name="age"value="29"/>
  11. <property name="name"value="Dr. Jekyll"/>
  12. </bean>
  13. <bean id="simple2"class="cn.partner4java.init.SimpleBean"
  14. init-method="init">
  15. <property name="age"value="29"/>
  16. </bean>
  17. <bean id="simple3"class="cn.partner4java.init.SimpleBean"
  18. init-method="init">
  19. <property name="name"value="Mr. Hyde"/>
  20. </bean>
  22. </beans>

调用：
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  1. //在调用获取的时候就会调用init，在调用init之前，已经使用控制反转设置方法依赖注入设置进数据
  2. BeanFactory beanFactory = getBeanFactory();
  3. System.out.println("simple1");
  4. beanFactory.getBean("simple1");
  5. System.out.println("simple2");
  6. beanFactory.getBean("simple2");
  7. System.out.println("simple3");
  8. beanFactory.getBean("simple3");
  10. //后台打印：
  11. //simple1
  12. //simple2
  13. //name为空
  14. //simple3
  15. //age为0




实现InitializingBean接口：
Spring中InitializingBean接口允许你在bean的代码中这样定义：你希望bean能接收到Spring已经完成对其配置的通知。就像使用初始化方法时一样，你可以借机检查bean的配置以确保其有效，若要必要，还可以给出默认值。
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  1. publicclassSimpleBeanIBimplementsInitializingBean {
  2. privatestaticfinalString DEFAULT_NAME ="Jan Machacek";
  3. privateString name;
  4. privateintage =0;
  6. publicString getName() {
  7. returnname;
  8. }
  10. publicvoidsetName(String name) {
  11. this.name = name;
  12. }
  14. publicintgetAge() {
  15. returnage;
  16. }
  18. publicvoidsetAge(intage) {
  19. this.age = age;
  20. }
  22. @Override
  23. publicString toString() {
  24. finalStringBuilder sb =newStringBuilder();
  25. sb.append("SimpleBean");
  26. sb.append("{name='").append(name).append('\'');
  27. sb.append(", age=").append(age);
  28. sb.append('}');
  29. returnsb.toString();
  30. }
  32. publicvoidafterPropertiesSet()throwsException {
  33. System.out.println("initializing bean");
  34. if(this.name ==null) {
  35. System.out.println("No name specified, using default.");
  36. this.name = DEFAULT_NAME;
  37. }
  38. if(this.age ==0) {
  39. thrownewIllegalArgumentException("You must set the [age] property bean of type ["+ getClass().getName() +"]");
  40. }
  41. }
  42. }



决议顺序：
Spring首先调用InitializingBean.afterPropertiesSet()方法，然后再调用初始化方法。（建议如果存在顺序，都写入到afterPropertiesSet中调用。）


afterPropertiesSet方法和类的继承：
例子抽象父类实现了接口，但是把afterPropertiesSet定义成了final，不可被子类覆盖，也就是去实现一些通用的初始化，然后再调用了自己定义的initSimple()初始化方法。
父类：
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  1. publicabstractclassSimpleBeanSupportimplementsInitializingBean {
  2. privateString value;
  4. /**
  5. * Subclasses may override this method to perform additional initialization.
  6. * This method gets invoked after the initialization of the {@link SimpleBeanSupport}
  7. * completes.
  8. * @throws Exception If the subclass initialization fails.
  9. */
  10. protectedvoidinitSimple()throwsException {
  11. // do nothing
  12. }
  14. publicfinalvoidafterPropertiesSet()throwsException {
  15. Assert.notNull(this.value,"The [value] property of ["+ getClass().getName() +"] must be set.");
  16. initSimple();
  17. }
  19. publicfinalvoidsetValue(String value) {
  20. this.value = value;
  21. }
  23. protectedfinalString getValue() {
  24. returnthis.value;
  25. }
  26. }

继承：
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  1. publicclassSoutSimpleBeanextendsSimpleBeanSupport {
  2. privateString person;
  4. protectedvoidinitSimple()throwsException {
  5. Assert.notNull(this.person,"The [person] property of ["+ getClass().getName() +"] must be set.");
  6. }
  8. publicvoidsetPerson(String person) {
  9. this.person = person;
  10. }
  12. @Override
  13. publicString toString() {
  14. returnString.format("%s says \"%s\"",this.person, getValue());
  15. }
  16. }

配置文件：
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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="
  5. http://www.springframework.org/schema/beans
  6. http://www.springframework.org/schema/beans/spring-beans.xsd">
  8. <bean id="simple1"class="com.apress.prospring2.ch04.lifecycle.SoutSimpleBean">
  9. <property name="person"value="Winston Churchill"/>
  10. <property name="value"value="This report, by its very length, defends itself against the risk of being read."/>
  11. </bean>
  13. </beans>



嵌入bean的销毁：
1、bean销毁时执行某一方法
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  1. publicclassDestructiveBeanimplementsInitializingBean {
  2. privateInputStream is =null;
  3. privateString filePath =null;
  5. publicvoidafterPropertiesSet()throwsException {
  6. System.out.println("Initializing Bean");
  8. Assert.notNull(this.filePath,"The [filePath] property of ["+ getClass().getName() +"] must be set.");
  10. newFile(this.filePath).createNewFile();
  11. this.is =newFileInputStream(this.filePath);
  12. }
  14. publicvoiddestroy() {
  15. System.out.println("Destroying Bean");
  17. if(this.is !=null) {
  18. try{
  19. this.is.close();
  20. this.is =null;
  21. newFile(this.filePath).delete();
  22. }catch(IOException ex) {
  23. System.err.println("WARN: An IOException occured"
  24. +" while trying to close the InputStream");
  25. }
  26. }
  27. }
  29. publicvoidsetFilePath(String filePath) {
  30. this.filePath = filePath;
  31. }
  33. @Override
  34. publicString toString() {
  35. finalStringBuilder sb =newStringBuilder();
  36. sb.append("DestructiveBean");
  37. sb.append("{is=").append(is);
  38. sb.append(", filePath='").append(filePath).append('\'');
  39. sb.append('}');
  40. returnsb.toString();
  41. }
  42. }

配置文件：
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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="
  5. http://www.springframework.org/schema/beans
  6. http://www.springframework.org/schema/beans/spring-beans.xsd">
  8. <bean id="destructive"class="com.apress.prospring2.ch04.lifecycle.DestructiveBean"
  9. destroy-method="destroy">
  10. <property name="filePath"value="/tmp/prospring25"/>
  11. </bean>
  13. </beans>

2、实现DisposableBean接口
DisposableBean接口提供了destory方法。
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  1. publicclassDestructiveBeanIimplementsInitializingBean, DisposableBean {
  2. privateInputStream is =null;
  3. privateString filePath =null;
  5. publicvoidafterPropertiesSet()throwsException {
  6. System.out.println("Initializing Bean");
  8. Assert.notNull(this.filePath,"The [filePath] property of ["+ getClass().getName() +"] must be set.");
  10. newFile(this.filePath).createNewFile();
  11. this.is =newFileInputStream(this.filePath);
  12. }
  14. publicvoiddestroy() {
  15. System.out.println("Destroying Bean");
  17. if(this.is !=null) {
  18. try{
  19. this.is.close();
  20. this.is =null;
  21. newFile(this.filePath).delete();
  22. }catch(IOException ex) {
  23. System.err.println("WARN: An IOException occured"
  24. +" while trying to close the InputStream");
  25. }
  26. }
  27. }
  29. publicvoidsetFilePath(String filePath) {
  30. this.filePath = filePath;
  31. }
  33. @Override
  34. publicString toString() {
  35. finalStringBuilder sb =newStringBuilder();
  36. sb.append("DestructiveBean");
  37. sb.append("{is=").append(is);
  38. sb.append(", filePath='").append(filePath).append('\'');
  39. sb.append('}');
  40. returnsb.toString();
  41. }
  42. }

配置文件：
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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="
  5. http://www.springframework.org/schema/beans
  6. http://www.springframework.org/schema/beans/spring-beans.xsd">
  8. <bean id="destructive"class="com.apress.prospring2.ch04.lifecycle.DestructiveBeanI">
  9. <property name="filePath"value="/tmp/prospring25"/>
  10. </bean>
  12. </beans>

3、使用关闭钩子
注入关闭代码：
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  1. publicclassShutdownHookimplementsRunnable {
  2. privateConfigurableListableBeanFactory beanFactory;
  4. publicShutdownHook(ConfigurableListableBeanFactory beanFactory) {
  5. Assert.notNull(beanFactory,"The 'beanFactory' argument must not be null.");
  6. this.beanFactory = beanFactory;
  7. }
  9. publicvoidrun() {
  10. this.beanFactory.destroySingletons();
  11. }
  12. }

调用代码：
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  1. publicclassShutdownHookDemo {
  3. publicstaticvoidmain(String[] args)throwsIOException {
  4. XmlBeanFactory factory =newXmlBeanFactory(newClassPathResource("/META-INF/spring/lifecycledemo5-context.xml"));
  5. Runtime.getRuntime().addShutdownHook(newThread(newShutdownHook(factory)));
  6. newBufferedInputStream(System.in).read();
  7. }
  9. }
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