<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:id="@+id/activity_net"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context="com.example.waterlamp.NetActivity">
 <Button
  android:id="@+id/okhttp"
  android:text="okhttp请求"
  android:layout_width="150dp"
  android:layout_height="37dp"
  android:layout_alignBottom="@+id/http"
  android:layout_alignParentEnd="true"
  android:layout_alignParentTop="true" />

 <Button
  android:id="@+id/http"
  android:text="HTTP请求"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_alignParentTop="true"
  android:layout_alignParentStart="true" />

 <ScrollView
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:layout_alignParentStart="true"
 android:layout_below="@+id/okhttp"
 android:layout_alignParentBottom="true"
 android:layout_alignParentEnd="true" >
  <TextView
   android:id="@+id/stringData"
   android:layout_width="match_parent"
   android:layout_height="match_parent" />
 </ScrollView>
</RelativeLayout>

public class NetActivity extends AppCompatActivity implements View.OnClickListener{
private Button http,okhttp;
 private TextView stringData;
 private String web="https://www.baidu.com";
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_net);
  http= (Button) findViewById(R.id.http);
  okhttp= (Button) findViewById(R.id.okhttp);
  stringData= (TextView) findViewById(R.id.stringData);
  http.setOnClickListener(this);
  okhttp.setOnClickListener(this);
 }

 @Override
 public void onClick(View v) {
  switch (v.getId()){
   case R.id.http:
    sendRequestWithHttpURLConnection();
   break;
   case R.id.okhttp:
    sendRequestWithokHttp();
   break;
  }
 }
 private void sendRequestWithHttpURLConnection(){
  new Thread(new Runnable() {
   @Override
   public void run() {
    HttpURLConnection connection=null;
    BufferedReader reader=null;
    try {
     URL url=new URL(web);
     connection= (HttpURLConnection) url.openConnection();
     connection.setRequestMethod("GET");
     connection.setConnectTimeout(5000);
     connection.setReadTimeout(5000);
     InputStream in=connection.getInputStream();
     reader=new BufferedReader(new InputStreamReader(in));
     StringBuffer response=new StringBuffer();
     String line;
     while ((line=reader.readLine())!=null){
      response.append(line);
     }
     showRespond(response.toString());
    } catch (MalformedURLException e) {
     e.printStackTrace();
    } catch (IOException e) {
     e.printStackTrace();
    }finally {
     if (reader!=null){
      try {
       reader.close();
      } catch (IOException e) {
       e.printStackTrace();
      }
     }
    }
   }
  }).start();
 }

 private void showRespond(final String response) {
  runOnUiThread(new Runnable() {
   @Override
   public void run() {
    stringData.setText(response);
   }
  });
 }
 private void sendRequestWithokHttp(){
  new Thread(new Runnable() {
   @Override
   public void run() {

    try {
     OkHttpClient client=new OkHttpClient();
     Request request=new Request.Builder()
       .url(web).build();
     Response response=client.newCall(request).execute();
     String str=response.body().string();
     showRespond(str);
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  }).start();
 }
}

dependencies {
 compile fileTree(dir: 'libs', include: ['*.jar'])
 androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
  exclude group: 'com.android.support', module: 'support-annotations'
 })
 compile 'com.android.support:appcompat-v7:24.2.1'
 compile 'com.android.support:design:24.2.1'
 compile 'com.squareup.okhttp3:okhttp:3.4.1'//依赖
 testCompile 'junit:junit:4.12'
}