在Android中实现方法回调

Implementing method callback in Android

提问by AlexCheuk

Currently in my project, I am making Http requests and I want different http response to be sent to different callback methods.

目前在我的项目中，我正在发出 Http 请求，并且我希望将不同的 http 响应发送到不同的回调方法。

I wrote a quick sample below to show what I want to do. I know it probably wont be possible the way i want it, but are there any clean solutions to achieve the same thing?

我在下面写了一个快速示例来展示我想要做什么。我知道这可能不可能像我想要的那样，但是有没有干净的解决方案来实现同样的目标？

Sample:

样本：

Activity Class:

活动类别：

public class Main extends Activity{  
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Services service = new Services();
        service.login("user", "password", **onLoginComplete()** );
    }

    public void onLoginComplete(String HTTPResponse){
        // Do something with the response
    }
}

Service Class:

服务等级：

public class Services{  

    public void login(String user, String password, CALLBACK){
        Request request = createLoginRequest(user, password);
        sendRequest(request, CALLBACK);
    }

    public class sendRequest extends AsyncTask{
        @Override
        protected Object doInBackground(Object... params) {
             // Do Http Request
             // Get Response
             CALLBACK(response);
        } 
    }
}

回答by Volodymyr Lykhonis

interface OnLoginCompleteListener {
    void onLoginComplete(String response);
}

And then

进而

public void login(String user, String password, OnLoginComplete listener) {
    mOnCompleteListener = listener;
}

and

和

protected Object doInBackground(Object... params) {
    mOnCompleteListener.onLoginComplete(response);
}

and finally

最后

service.login("user", "password", new OnLoginCompleteListener() {
    public void onLoginComplete(String response) {
        // Handle your response
    }
});

回答by Alexkin_Sky

I think I had the same problem as yours.

我想我和你有同样的问题。

I was looking for a good answer and this was the implementation that worked for me:

我一直在寻找一个好的答案，这是对我有用的实现：

First create an interface which contains your methods; in my case I use the typical onSuccessand onFailurebut you can make your own methods:

首先创建一个包含您的方法的接口；在我的情况下，我使用典型的onSuccess，onFailure但您可以制作自己的方法：

//MyInterface.java

public interface MyInterface
{
    void onSuccess(String response);
    void onFailure(String response);
}

Then create class Services:

然后创建类Services：

//Services.java

public class Services
{
    public void login(String user, String password, MyInterface myInterface)
    {
        Request request = createLoginRequest(user, password);

        if(/*Request successful*/)
            myInterface.onSuccess("Login succesful");

        else
            myInterface.onFailure("Login failed");
    }
}

And finally call the method on your Activity:

最后调用你的方法Activity：

//Main.java

public class Main extends Activity
{  
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Services service = new Services();
        service.login("user", "password", new Myinterface()
        {
            @Override
            public void onSuccess(String response)
            {
                Toast.makeText(getApplicationContext(), response, Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onFailure(String response)
            {
                Toast.makeText(getApplicationContext(), response, Toast.LENGTH_SHORT).show();
            }
        });
    }
}

回答by fsvives

If I understand you correctly, what you are trying to achieve is recommended to be done via the use of an AsyncTask. It's explained in a very simple way here http://developer.android.com/reference/android/os/AsyncTask.html

如果我理解正确，建议您通过使用 AsyncTask 来完成您要实现的目标。这里以非常简单的方式解释了 http://developer.android.com/reference/android/os/AsyncTask.html

Additionally, I share an example of how I execute (doInBackground) GET requests to a site and which result then I read (onPostExecute)... hope it helps!

此外，我还分享了一个示例，说明我如何执行 (doInBackground) 对站点的 GET 请求，然后我读取了结果 (onPostExecute)...希望对您有所帮助！

protected InputStream doInBackground(String... example) {
    JsonComm jc = new JsonComm();
    String baseUrl = "http://www.somewhere.com/get_request.php?data=";
    String jcString = jc.encodeJSON("nowyou","seeme");
    String url = "";

    try {
        url = baseUrl + URLEncoder.encode(jcString, "UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }

    HttpResponse response;
    HttpClient httpClient = new DefaultHttpClient();
    HttpGet request = new HttpGet(url);
    try {
        request.setHeader("Accept", "application/json");
        request.setHeader("Content-type", "application/json");
        response = httpClient.execute(request);
    } catch (Exception ex) {
        // handle exception here
    }finally {
        httpClient.getConnectionManager().shutdown();
    }
    return response.getEntity().getContent();
}

protected void onPostExecute(InputStream is) {
    BufferedReader reader = new BufferedReader(new InputStreamReader(is));
    StringBuilder sb = new StringBuilder();

    String line = null;
    try {
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
     System.out.println(sb.toString());

}

回答by kabuko

There are several ways you can handle this. You could pass in a Runnablefor your callback or you could provide a method to override in your Servicesclass and use an anonymous class derived from Servicesin your main activity. If you need to pass in a parameter, you could also define an interface for something equivalent to the Runnablewhere you can define a method with a response parameter.

有几种方法可以处理这个问题。您可以Runnable为您的回调传入一个，或者您可以提供一个方法来覆盖您的Services类并使用从Services您的主要活动中派生的匿名类。如果你需要传入一个参数，你也可以定义一个接口，相当于Runnable你可以定义一个带有响应参数的方法。

回答by hwrdprkns

How to implement callbacks in java:

如何在java中实现回调：

public interface SomeCallbackInterface {
    public void finished(Request req);
}

Then in your class you do:

然后在你的课堂上你做：

YourReqeust.instantiateWithCallback(new SomeCallbackInterface() {
   @Override
   public void finished(Request req){
      // do something here
   }
});

This pretty much the same thing your do with any View.OnClickListener

这几乎与你对任何 View.OnClickListener