这是 MainActivity.java

的代码

package com.example.wcfconsumer;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.util.concurrent.ExecutionException;
import com.example.wcfconsumer.R;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
    private Button button;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        button = (Button) findViewById(R.id.button1);
        button.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                try {
                    getdata();
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (ExecutionException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (MalformedURLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        });
    }

    private void getdata() throws InterruptedException, ExecutionException,
            MalformedURLException {
        String url = "GetNoPara";
        String toaststring = new String("");
        // AsyncTask<String, Integer, String> theString;
        DownloadWebPageTask task = new DownloadWebPageTask();
        task.execute(url);
        toaststring = ((TextView) findViewById(R.id.text_wcfconsumer_response))
                .getText().toString();
        Toast.makeText(this, toaststring + "\n", Toast.LENGTH_LONG).show();

    }

    private class DownloadWebPageTask extends
            AsyncTask<String, Integer, String> {

        private final static String SERVICE_URI = "http://192.168.0.104:80/Service1.svc/";

        protected void onPostExecute(String result) {
            ((TextView) findViewById(R.id.text_wcfconsumer_response))
                    .setText(result);
        }

        @Override
        protected String doInBackground(String... params) {
            String response = "";
            HttpGet httpGet = new HttpGet(SERVICE_URI + params[0].toString());
            httpGet.setHeader("Accept", "application/json");
            httpGet.setHeader("Content-type", "application/json");
            DefaultHttpClient client = new DefaultHttpClient();
            // JSONArray jsaPersons = null ;
            // String theString = new String("");
            try {
                HttpResponse execute = client.execute(httpGet);
                InputStream content = execute.getEntity().getContent();

                BufferedReader buffer = new BufferedReader(
                        new InputStreamReader(content));
                String s = "";
                while ((s = buffer.readLine()) != null) {
                    response += s;
                }

            } catch (Exception e) {
                e.printStackTrace();
            }
            return response;
        }
    }

}

但我现在正试图这样做，以便我可以调用不同的服务方法，后台结果将返回UI线程，我可以根据项目要求使用结果。我曾想过在不同的文件中定义这个后台任务（比如BackgroundTask.java），但是我不知道如何将结果返回给Main_Activity.java（从那里调用BackgroundTask.execute）？

请帮帮我... 谢谢你的回复。

此致 Sourabh

Answer 1

我找到了在非UI线程中执行后台任务的方法。为此你必须扩展AsyncTask并且必须实现doInBackground方法。要了解更多AsyncTask，您可以参考android开发者网站。

这是我完成的代码。

public class BackgroundTask extends AsyncTask<Object, Integer, String> {

    private final static String SERVICE_URI = "http://192.168.0.105:80/Service1.svc/";

    //runs after doInBackground completed
    protected void onPostExecute(String result) {
        Register_activity.emailV.setText(result);
    }

    @Override
    protected String doInBackground(Object... params) {
        Bitmap image = (Bitmap)params[1];
        String msg = new String();
        String methodname = params[0].toString();
         try {
                byte[] data = SaveImage.toByteArray(image);
                HttpClient httpClient = new DefaultHttpClient();
                HttpPost postRequest = new HttpPost(SERVICE_URI+methodname);
                postRequest.setHeader("Content-type","application/octet-stream");
                ByteArrayBody bab = new ByteArrayBody(data, Register_activity.mobileV.getText().toString()+".jpg");
                // File file= new File("/mnt/sdcard/forest.png");
                // FileBody bin = new FileBody(file);
                MultipartEntity reqEntity = new MultipartEntity(
                        HttpMultipartMode.BROWSER_COMPATIBLE);
                reqEntity.addPart("uploaded", bab);
                reqEntity.addPart("photoCaption", new StringBody("sfsdfsdf"));
                postRequest.setEntity(reqEntity);
                HttpResponse response = httpClient.execute(postRequest);
                BufferedReader reader = new BufferedReader(new InputStreamReader(
                        response.getEntity().getContent(), "UTF-8"));
                String sResponse;
                StringBuilder s = new StringBuilder();

                while ((sResponse = reader.readLine()) != null) {
                    s = s.append(sResponse);
                }
                System.out.println("Response: " + s);
                msg = s.toString();
            } catch (Exception e) {
                Log.e(e.getClass().getName(), e.getMessage());
            }
        return msg;
    }


}

这里AsyncTask有3种数据类型：
Object表示将传递给doInBackground方法的数组数据的类型整数表示将用于传递到onProgressUpdate方法的数据类型 String表示将用于传递到onPostExecute方法的数据类型
有很多选项可以在NonUI线程上执行任务，比如java thred。选项是你的。
快乐的编码...
问候，
Sourabh

返回后台任务结果到不同的不同java文件中定义的UI线程

这是 MainActivity.java

1 个答案: