如何进行同步或异步 HTTP Post/Get

Question

我需要同步或异步 HTTP Post/Get 从 Web 服务获取 HTML 数据。我搜索了整个互联网，但我无法给出好的结果。

我尝试使用以下示例：

• Android Series get/post and multipost requests
• Jcabi.com
• Execute HTTP Post request in android

但没有一个对我有用。

HttpClient 和 HttpGet 被划掉，错误是：

“org.apache.http.client.HttpClient 已弃用”

代码：

try
{
    HttpClient client = new DefaultHttpClient();
    String getURL = "google.com";
    HttpGet get = new HttpGet(getURL);
    HttpResponse responseGet = client.execute(get);
    HttpEntity resEntityGet = responseGet.getEntity();
    if (resEntityGet != null)
    {
        //do something with the response 
    }
}
catch (Exception e)
{
    e.printStackTrace();
}

Answer 1

我在下面发布的示例基于我在 Android 开发人员文档 上找到的示例。您可以找到该示例 HERE，查看该示例以获得更全面的示例。

您将能够通过以下方式发出任何 http 请求

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends Activity {
    private static final String TAG = MainActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        new DownloadTask().execute("http://www.google.com/");
    }

    private class DownloadTask extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... params) {
            //do your request in here so that you don't interrupt the UI thread
            try {
                return downloadContent(params[0]);
            } catch (IOException e) {
                return "Unable to retrieve data. URL may be invalid.";
            }
        }

        @Override
        protected void onPostExecute(String result) {
            //Here you are done with the task
            Toast.makeText(MainActivity.this, result, Toast.LENGTH_LONG).show();
        }
    }

    private String downloadContent(String myurl) throws IOException {
        InputStream is = null;
        int length = 500;

        try {
            URL url = new URL(myurl);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(10000 /* milliseconds */);
            conn.setConnectTimeout(15000 /* milliseconds */);
            conn.setRequestMethod("GET");
            conn.setDoInput(true);
            conn.connect();
            int response = conn.getResponseCode();
            Log.d(TAG, "The response is: " + response);
            is = conn.getInputStream();

            // Convert the InputStream into a string
            String contentAsString = convertInputStreamToString(is, length);
            return contentAsString;
        } finally {
            if (is != null) {
                is.close();
            }
        }
    }

    public String convertInputStreamToString(InputStream stream, int length) throws IOException, UnsupportedEncodingException {
        Reader reader = null;
        reader = new InputStreamReader(stream, "UTF-8");
        char[] buffer = new char[length];
        reader.read(buffer);
        return new String(buffer);
    }
}

您可以根据自己的需要使用代码

Answer 2

您可以使用Volley 它为您提供所需的一切。如果您决定使用 AsyncTask 并自己编程，我建议您不要在 Activity 中使用 AsyncTask，而是将其放在包装类中并使用回调。这使您的活动保持清洁并使网络代码可重用。这或多或少是他们在 Volley 中所做的。

Answer 3

**Async POST & GET request**

public class FetchFromServerTask extends AsyncTask<String, Void, String> {
    private FetchFromServerUser user;
    private int id;

    public FetchFromServerTask(FetchFromServerUser user, int id) {
        this.user = user;
        this.id = id;
    }
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        user.onPreFetch();
    }

    @Override
    protected String doInBackground(String... params) {

        URL urlCould;
        HttpURLConnection connection;
        InputStream inputStream = null;
        try {
            String url = params[0];
            urlCould = new URL(url);
            connection = (HttpURLConnection) urlCould.openConnection();
            connection.setConnectTimeout(30000);
            connection.setReadTimeout(30000);
            connection.setRequestMethod("GET");
            connection.connect();

            inputStream = connection.getInputStream();

        } catch (MalformedURLException MEx){

        } catch (IOException IOEx){
            Log.e("Utils", "HTTP failed to fetch data");
            return null;
        }
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        StringBuilder sb = new StringBuilder();
        String line;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line).append("\n");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }

    protected void onPostExecute(String string) {

        //Do your own implementation
    }
}


****---------------------------------------------------------------***


You can use GET request inn any class like this:
new FetchFromServerTask(this, 0).execute(/*Your url*/);

****---------------------------------------------------------------***

对于 Post 请求，只需更改：connection.setRequestMethod("GET");到

connection.setRequestMethod("POST");