spring 当spring由注解驱动配置时，如何为bean设置init-method？
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How to set up init-method for a bean when spring is configured by annotation driven?
提问by Charles
I use spring roo to build project and it's annotation driven, and there is no bean definition in XML file. All the configuration info is in *.aj file.
我使用spring roo构建项目，它是注解驱动的，XML文件中没有bean定义。所有配置信息都在 *.aj 文件中。
And now I want to set up an init method for a bean which don't have a default constructor (that bean is from the third party and it has a constructor with arguments, and I cannot remove them or give a default constructor to it.)
现在我想为一个没有默认构造函数的 bean 设置一个 init 方法（那个 bean 来自第三方并且它有一个带参数的构造函数，我不能删除它们或给它一个默认构造函数。 )
Is there anyone who can tell me how to do this, please?
有没有人可以告诉我如何做到这一点？
The reason I want to do this is because I want to use applicationContext.getBean("thatBeanName")to dynamically get the bean and use it. Because the bean don't have a default constructor, I always get the error: java.lang.NoSuchMethodException: com.to.that.bean.<init>()and this is why I want to add the init-method to the bean.
我要这样做的原因是因为我想使用applicationContext.getBean("thatBeanName")动态获取bean并使用它。因为 bean 没有默认构造函数，所以我总是得到错误：java.lang.NoSuchMethodException: com.to.that.bean.<init>()这就是为什么我想将 init-method 添加到 bean。
回答by Aravind Yarram
Use @PostConstructas shown in below example. It is equivalent to init-method="initialize()"
使用@PostConstruct如下例所示。它相当于init-method="initialize()"
@PostConstruct
public void initialize() {
messages.put("English", "Welcome");
messages.put("Deutsch", "Willkommen");
}
回答by BrentR
@Bean(initMethod="init")
public MyBean getMyBean() {
...
}
回答by magulla
In spring container it is "init" method that being called the last,
@postconstruct called before afterPropertiesSet. so it is safer if someone miss use.
"Multiple lifecycle mechanisms configured for the same bean, with different initialization methods, are called as follows:
在 spring 容器中，最后调用的是“init”方法，
@postconstruct 在 afterPropertiesSet 之前调用。所以如果有人错过使用会更安全。“为同一个bean配置的多个生命周期机制，具有不同的初始化方法，调用如下：
1.Methods annotated with @PostConstruct
2.afterPropertiesSet() as defined by the InitializingBean callback interface
- A custom configured init() method [https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#beans-java-lifecycle-callbacks][1]
1.方法注解@PostConstruct
2.afterPropertiesSet() 由 InitializingBean 回调接口定义
Although, today I would prefer to be more Spring independent and use either @Postconstract, or even configure default init method recognition. to have only meaningful method name indicate that it should be used for initialization - clear from frameworks, clear from annotations.
虽然，今天我更喜欢独立于 Spring 并使用 @Postconstract，甚至配置默认的 init 方法识别。只有有意义的方法名称表明它应该用于初始化 - 从框架中清除，从注释中清除。
回答by Aravind A
As @Pangea has put in , @PostConstructis the best choice. You could also implement initializingBean and do the initialization in afterPropertiesSet method .Check herefor this approach.
作为@Pangea已实施，@PostConstruct是最好的选择。您还可以实现 initializingBean 并在 afterPropertiesSet 方法中进行初始化。请在此处查看此方法。
回答by cinqS
I realized that there have been multiple answers trying to solve the problem. But with the newlyintroduced @Configurationwhich is popularly used within Spring Boot. Things are changed a little bit.
我意识到有多个答案试图解决这个问题。但是随着新引入的@Configuration在Spring Boot 中广泛使用。事情发生了一些变化。
If you are using @Beanannotation in @Configurationannotated class like:
如果您@Bean在带@Configuration注释的类中使用注释，例如：
@Configuration
class FooClass {
@Bean
public Bar bar() {
return new Bar();
}
}
If you want to use an automatically called method on the bean instance during initialization, you have two options below:
如果要在初始化期间在 bean 实例上使用自动调用的方法，则有以下两种选择：
Option1:
选项1：
@Configuration
class FooClass {
@Bean(initMethod="init")
public Bar bar() {
return new Bar();
}
}
Option2:
选项2：
@Configuration
class FooClass {
@Bean
public Bar bar() {
Bar bar = new Bar();
bar.init();
return bar;
}
}
BUT, as is explain in @BeanJava Doc here:
但是，正如@Bean这里的 Java Doc 中所解释的：
/**
* The optional name of a method to call on the bean instance during initialization.
* Not commonly used, given that the method may be called programmatically directly
* within the body of a Bean-annotated method.
* The default value is {@code ""}, indicating no init method to be called.
*/
The second is regarded as a better answer. See link here
第二个被认为是更好的答案。在这里查看链接
