JavaGuice向类构造函数注入对象

Question

我刚开始找Guice做一个新项目。我有类似的东西

ConfigImpl类ans配置接口

 interface Config{...}

 class ConfigImpl implements Config {
   private static final Map<> propMap;
   public ConfigImpl(Map<> propMap) {
     this.propMap = someProps;
   }
 }

我想出的Guice注射法

public class MyInjector extends AbstractModule {
  protected void configure() {
    bind(Config.class).to(ConfigImpl.class)
  }
}

最后

public SomeClass {
  Config someConfig;
  Injector injector = Guice.createInjector(new MyInjector());
  someConfig = injector.getInstance(Config.class);          
}

现在我非常困惑，因为我找不到将propMap传递到ConfigImpl类的方法。我想知道用Guice做这件事的正确方法。谢谢

Answer 1

您应该从模块中注入propMaps：

public class MyInjector extends AbstractModule {
  private final Map<String,String> mapProps;
  public MyInjector(Map<String,String> mapProps) {
    this.mapProps = mapProps;
  }
  protected void configure() {
    bind(Config.class).to(ConfigImpl.class).in(Scope.SINGLETON);         // You most than likely want this
    bind(new TypeLiteral<Map<String,String>>() {}).toInstance(mapProps); // binding for the map.
  }
}

然后像这样使用它：

public class SomeClass {
  void doSomething() {
    Map<String,String> mapProps = ... ;
    Injector injector = Guice.createInjector(new MyInjector(mapProps));
    Config someConfig = injector.getInstance(Config.class);          
  }
}

另外，您应该修复ConfigImpl类：

class ConfigImpl implements Config {
  private final Map<String,String> propMap;
  @Inject                                         // mandatory since you use a non-default constructor
  public ConfigImpl(Map<String,String> propMap) { // add the generic type of the map
    this.propMap = propMap;
  }
}