主要有两种方式:
1.通过实现InitializingBean接口的afterPropertiesSet()方法,在方法中处理业务
2.在配置文件中配置init-method
实现方式1:InitializingBean
<strong>@Component
public class InitializingMyBean implements InitializingBean {
@Autowired
private UserRepository userRepository;
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("》》》新增用户《《《 ");
User user =new User();
user.setName("admin");
user.setPassword("admin123");
user.setAge("23");
user.setSex("男");
User add = userRepository.save(user);
if(!StringUtils.isEmpty(add)){
System.out.println("新增用户成功！");
}else{
System.out.println("新增用户失败！");
}
}
}
</strong>
2.配置文件 ：init-method
xml version="1.0" encoding="UTF-8"?>DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN""http://www.springframework.org/dtd/spring-beans.dtd"><beans><bean name="lifeBean" class="research.spring.beanfactory.ch5.LifeCycleBean"
init-method="init">bean>beans>
3.两种方式的区别:
实现InitializingBean接口是直接调用afterPropertiesSet方法，比通过反射调用init-method指定的方法效率相对来说要高点。但是init-method方式消除了对spring的依赖
4.注意:如果在spring初始化bean的时候，如果该bean是实现了InitializingBean接口，并且同时在配置文件中指定了init- method，
* 系统则是先调用afterPropertiesSet方法，然后在调用init-method中指定的方法
5.InitializingBean和init-mthod同时执行的原理:
详见：org.springframework.beans.factory.support包下的抽象类AbstractAutowireCapableBeanFactory
主要处理代码如下:
/**
* Give a bean a chance to react now all its properties are set,
* and a chance to know about its owning bean factory (this object).
* This means checking whether the bean implements InitializingBean or defines
* a custom init method, and invoking the necessary callback(s) if it does.
* @param beanName the bean name in the factory (for debugging purposes)
* @param bean the new bean instance we may need to initialize
* @param mbd the merged bean definition that the bean was created with
* (can also be {@code null}, if given an existing bean instance)
* @throws Throwable if thrown by init methods or by the invocation process
* @see #invokeCustomInitMethod
*/
protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
throws Throwable {
//获取当前bean是否实现了InitializingMyBean接口,如果实现了就执行afterPropertiesSet方法
boolean isInitializingBean = (bean instanceof InitializingBean);
if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
if (logger.isDebugEnabled()) {
logger.debug("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");
}
if (System.getSecurityManager() != null) {
try {
AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
@Override
public Object run() throws Exception {
//调用afterPropertiesSet()
((InitializingBean) bean).afterPropertiesSet();
return null;
}
}, getAccessControlContext());
}
catch (PrivilegedActionException pae) {
throw pae.getException();
}
}
else {
//调用afterPropertiesSet()
((InitializingBean) bean).afterPropertiesSet();
}
}
//如果在配置文件中设置了init-mthod属性就通过反射调用init-method指定的方法
if (mbd != null) {
String initMethodName = mbd.getInitMethodName();
if (initMethodName != null && !(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&
!mbd.isExternallyManagedInitMethod(initMethodName)) {
invokeCustomInitMethod(beanName, bean, mbd);
}
}
}
/**
* Invoke the specified custom init method on the given bean.
* Called by invokeInitMethods.
* <p>Can be overridden in subclasses for custom resolution of init
* methods with arguments.
* @see #invokeInitMethods
*/
protected void invokeCustomInitMethod(String beanName, final Object bean, RootBeanDefinition mbd) throws Throwable {
String initMethodName = mbd.getInitMethodName();
final Method initMethod = (mbd.isNonPublicAccessAllowed() ?
BeanUtils.findMethod(bean.getClass(), initMethodName) :
ClassUtils.getMethodIfAvailable(bean.getClass(), initMethodName));
if (initMethod == null) {
if (mbd.isEnforceInitMethod()) {
throw new BeanDefinitionValidationException("Couldn't find an init method named '" +
initMethodName + "' on bean with name '" + beanName + "'");
}
else {
if (logger.isDebugEnabled()) {
logger.debug("No default init method named '" + initMethodName +
"' found on bean with name '" + beanName + "'");
}
// Ignore non-existent default lifecycle methods.
return;
}
}
if (logger.isDebugEnabled()) {
logger.debug("Invoking init method '" + initMethodName + "' on bean with name '" + beanName + "'");
}
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
@Override
public Object run() throws Exception {
ReflectionUtils.makeAccessible(initMethod);
return null;
}
});
try {
AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
@Override
public Object run() throws Exception {
initMethod.invoke(bean);
return null;
}
}, getAccessControlContext());
}
catch (PrivilegedActionException pae) {
InvocationTargetException ex = (InvocationTargetException) pae.getException();
throw ex.getTargetException();
}
}
else {
try {
ReflectionUtils.makeAccessible(initMethod);
initMethod.invoke(bean);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
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