Gwt rpc AsyncCallbak之后的代码是不会被执行的？

Question

我无法理解为什么gwt rpc AsyncCallback之后的代码不会被执行？

例如,我有接口AppService扩展RemoteService,所以我将有AsyncAppService进行异步调用.

以下代码

            AppServiceAsync service = GWT.create (AppService.class);
        service.getCurrentUser(new AsyncCallback<Employee>(){

            public void onFailure(Throwable caught) {

            }

            public void onSuccess(Employee result) {
                currentUser = result;
            }

        });
 // if i have the code after the above call, these code will not be execute, what is the problem
//code following will not be executed if they are in the same function.
    boolean isAdmin = false;
        if(currentUser!=null){
            if(currentUser.getUserRole().equals("ROLE_ADMIN") ||
                    currentUser.getUserRole().equals("ROLE_MANAGER")){
                isAdmin = true;
            }
        }

谢谢你的解释

Answer 1

您应该了解异步调用的性质.当你打电话时,程序执行不会等待service.getCurrentUser.该PROGRAMM将继续到下一行(boolean isAdmin = false)和这将是真正的一段时间是(currentUser == null)直到方法getCurrentUser被执行.您应该将未执行的代码块移动到onSuccess处理程序中

此示例应如下所示:

service.getCurrentUser(new AsyncCallback<Employee>(){

    public void onFailure(Throwable caught) {

    }

    public void onSuccess(Employee result) {
        currentUser = result;
        if (currentUser != null) {
            if (currentUser.getUserRole().equals("ROLE_ADMIN") ||
                currentUser.getUserRole().equals("ROLE_MANAGER")) {
                isAdmin = true;
            }
        }

    }

});

我假设currentUser和isAdmin是类字段,但不是局部变量.如果isAdmin是本地的,你可以将这个变量包装到最终的数组中:final boolean[] isAdmin = new boolean[1]并调用它isAdmin[0]