在我的 GWT 项目中，我确实需要在多个叠加层(JavaScriptObject)之间实现相同的接口(interface)。

根据文档:

Starting with GWT 2.0, it is permissible for JavaScriptObject subtypes to implement interfaces. Every method defined in an interface may map to at most one method declared in a JavaScriptObject subtype. Practically speaking, this means that only one JavaScriptObject type may implement any given interface, but any number of non-JavaScriptObject types may also implement that interface.

请您参考如下方法:

如何创建包装 JSO 而不是继承它的类？

public class PersonJso extends JavaScriptObject{ 
    protected PersonJso() {} 
    public static native PersonJso create(String name) /*-{ 
        return {name : name}; 
    }-*/; 
    public final native String getName() /*-{ 
        return this.name; 
    }-*/; 
} 
 
public class AnimalJso extends JavaScriptObject{ 
    protected AnimalJso() {} 
    public static native PersonJso create(String name) /*-{ 
        return {name : name}; 
    }-*/; 
    public final native String getName() /*-{ 
        return this.name; 
    }-*/; 
} 
public class AnimalWrapper implements hasName{ 
    AnimalJso jso; 
    public AnimalWrapper(){} 
    public AnimalWrapper(AnimalJso jso){ 
        this.jso = jso; 
    } 
    @Override 
    public String getName() { 
        return jso.getName(); 
    } 
} 
public class PersonWrapper implements hasName{ 
    PersonJso jso;   
    public PersonWrapper(){} 
    public PersonWrapper(PersonJso jso){ 
        this.jso = jso; 
    } 
    @Override 
    public String getName() { 
        return jso.getName(); 
    }    
}