将 @Service 自动装配到第三方库时出现问题

发布于 2024-12-05 18:05:49 字数 603 浏览 2 评论 0原文

目前，我正在将 Autowiring myService 集成到我的应用程序中的各种对象中，并且工作正常。

@Autowired
private MyService myService;

使用此配置：

<context:component-scan base-package="com.myapp.mypackage" />

但是，我添加了一个第三方库，并希望将 Autowire myService 也添加到该包中的某些对象中，但它不起作用。

我对组件扫描进行了此更改，但当我尝试在第三方包中访问 myService 时，我收到了 NullPointerException：

<context:component-scan 
base-package="com.myapp.mypackage, com.thirdparty.thirdpartypackage" />

我认为这会起作用吗？

原文

At the moment I'm Autowiring myService into various objects in my app and it works fine.

@Autowired
private MyService myService;

using this config:

<context:component-scan base-package="com.myapp.mypackage" />

However, I've added a third party library and want to Autowire myService into some objects in that package also but it's not working.

I made this change to my component scan but I'm getting a NullPointerException for myService when I try to access it in the third party package:

<context:component-scan 
base-package="com.myapp.mypackage, com.thirdparty.thirdpartypackage" />

I thought this would work?

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怀念你的温柔 2024-12-12 18:05:49

对于 3rd 方库，通常的方法是使用 xml：

<bean class="com.thirdparty.Foo">
    <property name="somePropertyWithASetter" ref="myService" />
</bean>

您不能依赖注释，因为 3rd 方库很可能不使用 @Autowired。

With 3rd party libraries the usual approach is to use xml:

<bean class="com.thirdparty.Foo">
    <property name="somePropertyWithASetter" ref="myService" />
</bean>

You can't rely on annotations, because the 3rd party library most likely does not use @Autowired.

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烂人 2024-12-12 18:05:49

如果第三方包是 spring 管理的，请忽略答案的其余部分

我认为在进行依赖项注入之前你应该问自己的问题是，对象是 spring 管理的吗，要做到这一点，你可以定义它们在 spring context xml 中或使用 (@component , @service springstereo type) 注释对象

让我们看看手头的案例

您是否有权访问此第三方源代码？
第三方是否使用依赖注入？
如果上述问题的答案是否定的，那么做到这一点并不容易。

让我们看一下（MyService）的例子，如果这个服务对象有状态（因为spring对象是单例），而且如果这个服务有没有被注入的协作对象

公共类MyService
{

 //取决于MyServiceOne的管理方式使得改造变得困难 
  //MyService 作为 spring bean
  私有 MyServiceOne 服务一；

  //如果您尝试将其用作弹簧管理，这也会产生不利影响
  //因为所有 Spring Bean 都是单例的
  私有字符串 someState；


}

If the third party package is spring managed, Please ignore the rest of the answer

I think the question you should ask yourself before do dependency injections is, Is the object spring managed, To do that either you define them in spring context xml or annotate the object with (@component , @service spring stereo type)

Let's look at the case in hand

Do you have access to this third party source code?
Is the third party using dependency injection?
If the answer to above questions is negative, then It is not easy to do this.

Let's look at the example of (MyService), what if this service object has state (since spring objects are singleton), Also if this service has collaborating objects that are not being injected

public class MyService
{

  //depending on how MyServiceOne is managed makes it hard to retrofit 
  //MyService as a spring bean
  private MyServiceOne serviceone;

  //this also would have an adverse affect if you try use this as a spring managed
  //since all spring beans are singleton
  private String someState;


}

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