java 使用 Guice 注入特定实例
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/16748126/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Injecting specific instance with Guice
提问by halfwarp
I'm having a few problems injecting a specific field instance with Guice.
我在使用 Guice 注入特定字段实例时遇到了一些问题。
Here's what I currently have:
这是我目前拥有的：
class Driver {
private ThreadLocal<Database> db;
...
}
I'd usually just pass the db instance in a constructor. But this class will be intercepted, using guice.
我通常只是在构造函数中传递 db 实例。但是这个类会被拦截，使用guice。
Here's the module:
这是模块：
class MyGuiceModule extends AbstractModule {
private ThreadLocal<Database> dbToInject;
public MyGuiceModule(ThreadLocal<Database> dbToInject) {
this.dbToInject = dbToInject;
}
@Override
protected void configure() {
// Binds the interceptor.
bindInterceptor(....);
bind(ThreadLocal.class).toInstance(this.dbToInject);
}
}
And here's how I'm instantiating all the stuff:
这是我实例化所有东西的方式：
Injector injector = new Injector(new MyGuiceModule(db));
Driver driver = injector.getInstance(Driver.class);
I bet it's pretty obvious, but what am I doing wrong here?
我敢打赌这很明显，但我在这里做错了什么？
EDIT:
编辑：
Sorry if I wasn't clear. My problem is that this is not working. The instance is not being injected. I've annotated the field with @Inject and still doesn't work.
对不起，如果我不清楚。我的问题是这不起作用。未注入该实例。我已经用@Inject 注释了该字段，但仍然不起作用。
回答by Mingyu
I think you need to use Guice.createInjectorto create an injector instance.
Here's how I would create an injector:
Injector injector = Guice.createInjector(new MyGuiceModule(db));Another thing is you used the following code to perform binding:
bind(ThreadLocal.class).toInstance(this.dbToInject);Usually, it would be something like:
bind(MyInterface.class).toInstance(MyImplementation.class);Your ThreadLocal.class is not an interface class, and this.dbToInject is not your implementation class.
我认为您需要使用Guice.createInjector来创建一个注入器实例。
下面是我将如何创建一个注入器：
Injector injector = Guice.createInjector(new MyGuiceModule(db));另一件事是您使用以下代码执行绑定：
bind(ThreadLocal.class).toInstance(this.dbToInject);通常，它会是这样的：
bind(MyInterface.class).toInstance(MyImplementation.class);您的 ThreadLocal.class 不是接口类，而 this.dbToInject 也不是您的实现类。
Here's the documentation:
这是文档：
http://code.google.com/p/google-guice/wiki/Motivation
http://code.google.com/p/google-guice/wiki/Motivation
Hope this helps.
希望这可以帮助。
回答by condit
It would probably be better not to inject the ThreadLocaldirectly but to inject the Database into the constructor (as @Tobias suggested). And do you really want to use the same Database for all the instance of the Driver that are created (note the optional singleton in the comment)?
最好不要ThreadLocal直接注入，而是将数据库注入构造函数（如@Tobias 建议的那样）。并且您真的想对创建的所有驱动程序实例使用相同的数据库（注意注释中的可选单例）？
public class GuiceExample {
public static class MyGuiceModule extends AbstractModule {
@Override
protected void configure() {
bind(Driver.class);
}
@Provides
//Uncomment this to use the same Database for each Driver
//@Singleton
Database getDatabase() {
return new Database();
}
}
@Test
public void testInjection() {
Injector i = Guice.createInjector(new MyGuiceModule());
i.getInstance(Driver.class);
}
public static class Database {}
public static class Driver {
ThreadLocal<Database> db = new ThreadLocal<Database>();
@Inject
Driver(Database db) {
this.db.set(db);
}
}
}
