使用HttpURLConnection发送HTTP请求

import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.ref.WeakReference;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    public static final int SHOW_RESPONSE = 0;
    private Button sendResquest;
    private TextView responseText;
    MyHandler handler = new MyHandler(this);

    static class MyHandler extends Handler{
        WeakReference mActivity;
        MyHandler(MainActivity mainActivity){
            mActivity = new WeakReference(mainActivity);

        }

        @Override
        public void handleMessage(Message msg) {
            MainActivity activity = mActivity.get();
            switch (msg.what){
                case SHOW_RESPONSE:
                    String response = (String)msg.obj;
                    activity.responseText.setText(response);
            }
        }
    }


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        sendResquest = (Button)findViewById(R.id.send_requset);
        responseText = (TextView)findViewById(R.id.response_text);
        sendResquest.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        if (v.getId()==R.id.send_requset){
            sendRequsetWithHttpURLConnection();
        }
    }

    private void sendRequsetWithHttpURLConnection(){

        new Thread(new Runnable() {
            @Override
            public void run() {

                HttpURLConnection connection = null;

                try {
                    URL url = new URL("http://www.baidu.com");
                    connection = (HttpURLConnection)url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(8000);
                    connection.setReadTimeout(8000);
                    InputStream in = connection.getInputStream();
                    BufferedReader br = new BufferedReader(new InputStreamReader(in));
                    StringBuilder sb = new StringBuilder();
                    String line;
                    while((line = br.readLine())!=null){
                        sb.append(line);
                    }
                    Message message = new Message();
                    message.what = SHOW_RESPONSE;
                    message.obj = sb.toString();
                    handler.sendMessage(message);

                }catch (Exception e){
                    e.printStackTrace();
                }
                finally {
                    if (connection!=null){
                        connection.disconnect();
                    }
                }

            }
        }).start();
    }
}