afterPropertiesSet方法和init-method区别和应用

InitializingBean

    spring的InitializingBean为bean提供了定义初始化方法的方式。InitializingBean是一个接口，只包含一个方法：afterPropertiesSet():

1.  
   public interface InitializingBean
2.  
   {
3.  
   public abstract void afterPropertiesSet()
4.  
   throws Exception;
5.  
   }

1.  
   import org.springframework.beans.factory.InitializingBean;
2.  
    
3.  
   publicclass LifeCycleBean implements InitializingBean{
4.  
   void afterPropertiesSet() throws Exception {
5.  
   System.out.println("LifeCycleBean initializing...");
6.  
   }
7.  
   }

在xml配置文件中并不需要对bean进行特殊的配置：

1.  
   <beans>
2.  
   <bean name ="lifeBean" class ="com.spring.LifeCycleBean"></beans >
3.  
   </beans>

编写测试程序进行测试：

1.  
   import org.springframework.beans.factory.xml.XmlBeanFactory;
2.  
   import org.springframework.core.io.ClassPathResource;
3.  
    
4.  
   public class LifeCycleTest {
5.  
   public static void main(String[] args) {
6.  
   XmlBeanFactory factory= new XmlBeanFactory( new ClassPathResource("com/spring/applicationcontext.xml"));
7.  
   factory.getBean("lifeBean");
8.  
   }
9.  
   }

bean实现：

1.  
   package com.spring;
2.  
    
3.  
   public class LifeCycleBean{
4.  
   publicvoid init(){
5.  
   System. out .println("LifeCycleBean.init...");
6.  
   }
7.  
   }

在Spring配置文件中配置这个bean：

1.  
   <beans>
2.  
   <bean name ="lifeBean" class ="research.spring.beanfactory.ch4.LifeCycleBean" init-method ="init"></bean>
3.  
   </beans>

1.  
   final protected void init() throws Exception{
2.  
   System.out.println("init method...");
3.  
   if(true)
4.  
   throw new Exception("init exception");
5.  
   }

源代码如下：

1.  
   //bean装配完成之后，执行bean初始化方法
2.  
   protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
3.  
   throws Throwable
4.  
   {
5.  
   //判断bean是否实现了InitializingBean接口
6.  
   boolean isInitializingBean = bean instanceof InitializingBean;
7.  
   if(isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet")))
8.  
   {
9.  
   if(logger.isDebugEnabled())
10.  
    logger.debug((new StringBuilder()).append("Invoking afterPropertiesSet() on bean with name ‘").append(beanName).append("‘").toString());
11.  
    if(System.getSecurityManager() != null)
12.  
    try
13.  
    {
14.  
    AccessController.doPrivileged(new PrivilegedExceptionAction() {
15.  
     
16.  
    public Object run()
17.  
    throws Exception
18.  
    {
19.  
    //调用afterPropertiesSet方法
20.  
    ((InitializingBean)bean).afterPropertiesSet();
21.  
    return null;
22.  
    }
23.  
     
24.  
    final Object val$bean;
25.  
    final AbstractAutowireCapableBeanFactory this$0;
26.  
     
27.  
     
28.  
    {
29.  
    this.this$0 = AbstractAutowireCapableBeanFactory.this;
30.  
    bean = obj;
31.  
    super();
32.  
    }
33.  
    }
34.  
    , getAccessControlContext());
35.  
    }
36.  
    catch(PrivilegedActionException pae)
37.  
    {
38.  
    throw pae.getException();
39.  
    }
40.  
    else
41.  
    ((InitializingBean)bean).afterPropertiesSet();调用afterPropertiesSet方法
42.  
    }
43.  
    if(mbd != null)
44.  
    {
45.  
    //判断bean是否定义了init-method方法
46.  
    String initMethodName = mbd.getInitMethodName();
47.  
    if(initMethodName != null && (!isInitializingBean || !"afterPropertiesSet".equals(initMethodName)) && !mbd.isExternallyManagedInitMethod(initMethodName))
48.  
    //调用invokeCustomInitMethod方法来执行init-method定义的方法
49.  
    invokeCustomInitMethod(beanName, bean, mbd);
50.  
    }
51.  
    }
52.  
     
53.  
    //执行bean定义的init-method方法
54.  
    protected void invokeCustomInitMethod(String beanName, final Object bean, RootBeanDefinition mbd)
55.  
    throws Throwable
56.  
    {
57.  
    String initMethodName = mbd.getInitMethodName();
58.  
    //使用方法名，反射Method对象
59.  
    final Method initMethod = mbd.isNonPublicAccessAllowed() ? BeanUtils.findMethod(bean.getClass(), initMethodName, new Class[0]) : ClassUtils.getMethodIfAvailable(bean.getClass(), initMethodName, new Class[0]);
60.  
    if(initMethod == null)
61.  
    {
62.  
    if(mbd.isEnforceInitMethod())
63.  
    throw new BeanDefinitionValidationException((new StringBuilder()).append("Couldn‘t find an init method named ‘").append(initMethodName).append("‘ on bean with name ‘").append(beanName).append("‘").toString());
64.  
    if(logger.isDebugEnabled())
65.  
    logger.debug((new StringBuilder()).append("No default init method named ‘").append(initMethodName).append("‘ found on bean with name ‘").append(beanName).append("‘").toString());
66.  
    return;
67.  
    }
68.  
    if(logger.isDebugEnabled())
69.  
    logger.debug((new StringBuilder()).append("Invoking init method ‘").append(initMethodName).append("‘ on bean with name ‘").append(beanName).append("‘").toString());
70.  
    if(System.getSecurityManager() != null)
71.  
    {
72.  
    AccessController.doPrivileged(new PrivilegedExceptionAction() {
73.  
     
74.  
    public Object run()
75.  
    throws Exception
76.  
    {
77.  
    ReflectionUtils.makeAccessible(initMethod);
78.  
    return null;
79.  
    }
80.  
     
81.  
    final Method val$initMethod;
82.  
    final AbstractAutowireCapableBeanFactory this$0;
83.  
     
84.  
     
85.  
    {
86.  
    this.this$0 = AbstractAutowireCapableBeanFactory.this;
87.  
    initMethod = method;
88.  
    super();
89.  
    }
90.  
    }
91.  
    );
92.  
    try
93.  
    {
94.  
    AccessController.doPrivileged(new PrivilegedExceptionAction() {
95.  
     
96.  
    public Object run()
97.  
    throws Exception
98.  
    {
99.  
    initMethod.invoke(bean, new Object[0]);//反射执行init-method方法
100.  
     return null;
101.  
     }
102.  
      
103.  
     final Method val$initMethod;
104.  
     final Object val$bean;
105.  
     final AbstractAutowireCapableBeanFactory this$0;
106.  
      
107.  
      
108.  
     {
109.  
     this.this$0 = AbstractAutowireCapableBeanFactory.this;
110.  
     initMethod = method;
111.  
     bean = obj;
112.  
     super();
113.  
     }
114.  
     }
115.  
     , getAccessControlContext());
116.  
     }
117.  
     catch(PrivilegedActionException pae)
118.  
     {
119.  
     InvocationTargetException ex = (InvocationTargetException)pae.getException();
120.  
     throw ex.getTargetException();
121.  
     }
122.  
     } else
123.  
     {
124.  
     try
125.  
     {
126.  
     ReflectionUtils.makeAccessible(initMethod);
127.  
     initMethod.invoke(bean, new Object[0]);//反射执行init-method方法
128.  
     }
129.  
     catch(InvocationTargetException ex)
130.  
     {
131.  
     throw ex.getTargetException();
132.  
     }
133.  
     }
134.  
     }

1.  
   <bean id="testServiceConfig" class="com.lmb.client.TestlServiceConfigImpl">
2.  
   <property name="folderName" value="test_config" />
3.  
   </bean>

调用代码：

1.  
   //bean初始化之后调用afterPropertiesSet方法根据配置目录，读取相应目录下的配置文件
2.  
   public class TestServiceConfigImpl implements InitializingBean {
3.  
   private String folderName;
4.  
    
5.  
   @Override
6.  
   public void afterPropertiesSet()throws Exception{
7.  
   folderName = folderName != null ? folderName : "test_config";
8.  
   reload(folderName);
9.  
   }
10.  
     
11.  
    //根据文件目录加载配置文件
12.  
    public void reload(String fileName) throws Exception {
13.  
     
14.  
    fileName = fileName.startsWith("/") ? fileName.substring(1) : fileName;
15.  
    //根据文件名称获取相应的文件
16.  
    File file = ResourceUtils.getFile("classpath:" + fileName);
17.  
    if (file.isDirectory()) {
18.  
    File[] files = file.listFiles();
19.  
    for (File configFile : files) {
20.  
    //加载文件……
21.  
    }
22.  
    }
23.  
    }
24.  
    }

afterPropertiesSet方法和init-method区别和应用

原文：https://www.cnblogs.com/zsw1024520/p/13731548.html