Guice-Guice中的Spring Autowired等效于什么 [英] Guice - what is the equivalent of Spring Autowired in Guice

问题描述

我正在尝试使用Guice，而我来自Spring.

I am trying to use Guice and I am coming from Spring.

我想知道@Inject是否等于Spring中的@Autowired，是否可以像在Spring中一样使用它在Web应用程序中使用.

I am wondering if @Inject is the equivalent of @Autowired in Spring and if I can use it in web application exactly as I am using it in Spring.

想象一下，我有一个依赖于服务的Facade，在Spring中我可以为该服务定义一个bean，然后在服务器启动时就可以在Facade中获取该服务的实例.

Imagine I have a Facade which depends on a service, in Spring I can define a bean for that service and then when the server starts up I can get the instance of the service inside my facade.

class FacadeImpl{
  @Autowire Service service;
  ...
}

假设该服务具有具体的实现，并且在Spring中将自动注入它.

Assume that service has a concrete implementation and in Spring will automatically inject it.

Guice有类似的方法吗?我可以做类似的事情吗

Does Guice has a similar approach? can I do something like

class Facade{
  @Inject Service service;
}

还是只有春天才有的魔力?

or is it a magic that only spring does?

在我的Web应用程序中，我正在启动嵌入式tomcat，并且以这种方式使用了google guice模块

In my web application, I am starting embedded tomcat and I used google guice modules in such a way

Guice.createInjector(new ConfigurationModule());

希望这足以注入"用@Inject注释的内容.

hoping that this will be enough to "inject" whatever is annotated with @Inject.

但是，它不起作用(我并不感到惊讶). 你们可以帮我弄清楚哪个BP注入对我的Servlet或Facades等的依赖吗??

However, it is not working ( I am not surprised ). Can you guys help me to figure out which are the BP to inject dependencies on my Servlets or Facades etc..?

推荐答案

是的，在某些条件下，@Inject可以充当@Autowired....

Guice不需要Module，尽管它们很常用.因此，您可以根据需要摆脱它们.

Yes, @Inject can act as @Autowired... given some conditions.

Guice doesn't require Modules, though they're very often used. So you can get rid of them if you want to.

如果您的班级是具体班级，则可以像@Autowired一样直接@Inject班级，但是您可能还必须标记班级@Singleton，因为Guice中的默认作用域不是单例，而是新的实例所有人，与Spring不同.

If your class is a concrete class, you can directly @Inject it, just like @Autowired, but you also probably have to mark the class @Singleton because the default scope in Guice is not singleton, but a new instance everyone, unlike Spring.

Guice不是Spring，但是其中一个的最重要的特征存在于另一个.

Guice is not Spring, but the most important features of one are present in the other.

当您想将Guice与Tomcat一起使用时，几乎不需要进行任何配置，但是仍然需要进行配置.您将需要Module，但仅需要servlet.

When you want to use Guice with Tomcat, there is very little configuration to do, but there is still configuration. You will require a Module, but only the servlet.

在您的 web.xml 中，添加以下内容:

In your web.xml, add the following:

<listener>
  <listener-class>path.to.MyGuiceServletConfig</listener-class>
</listener>

<filter>
  <filter-name>guiceFilter</filter-name>
  <filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
</filter>

<filter-mapping>
  <filter-name>guiceFilter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>

MyGuiceServletConfig.java

MyGuiceServletConfig.java

public class MyGuiceServletConfig extends GuiceServletContextListener {
  @Override protected Injector getInjector() {
    return Guice.createInjector(new ServletModule() {
      @Override protected void configureServlets() {
        serve("/*").with(MyServlet.class); // Nothing else is needed.
      }
    });
  }
}

MyServlet.java

MyServlet.java

public class MyServlet extends HttpServlet {

  @Inject // Similar to @Autowired
  private MyService myService;

  @Override public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    resp.getWriter().write(myService.hello("Guice"));
  }
}

现在，您可以选择MyService:您可以从中创建一个接口，然后定义，绑定一个实现，或者从中创建一个具体的类.

Now you have a choice with MyService: either you make an interface out of it and you have to define, and bind an implementation, or you make a concrete class out of it.

MyService.java

MyService.java

@ImplementedBy(MyServiceImpl.class) // This says "hey Guice, the default implementation is MyServiceImpl."
public interface MyService {
  String hello(String name);
}

MyServiceImpl.java

MyServiceImpl.java

@Singleton // Use the same default scope as Spring
public class MyServiceImpl implements MyService {
  // @Inject dependencies as you wish.
  public String hello(String name) { return "Hello, " + name + "!"; }
}

如果要避免使用@ImplementedBy，仍然可以使用上面的模块，并添加bind(MyService.class).to(MyServiceImpl.class).in(Scopes.SINGLETON);，或在同一Module中编写提供程序方法:

If you want to avoid the @ImplementedBy, you can still use your module above, and add bind(MyService.class).to(MyServiceImpl.class).in(Scopes.SINGLETON);, or write a provider method in the same Module:

@Provides @Singleton MyService provideMyService() {
  return new MyServiceImpl();
}

MyService作为具体课程

MyService.java

MyService as a concrete class

MyService.java

@Singleton // Use the same default scope as Spring
public class MyService {
  // @Inject dependencies as you wish.
  public String hello(String name) { return "Hello, " + name + "!"; }
}

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