android如何请求网络获取JSON数据

这两天一直想学习android网络请求方面的知识，于是仔细看了《第一行代码》有关于网络请求这一章，主要看了如何网络请求获取JSON数据，想把自己的心得记录下来。
首先，我上网选取了一个接口（url）,这个接口要好，否则连不上就容易报错啦！
其次，用法详见《第一行代码》使用Http协议访问网络这一节，由于我用的是android studio
android sdk 23，不支持书中的HttpClient这个类进行访问（如果实在想用这个类的话，需要额外的导入相应的包），那么就用HttpURLConnection这个类进行访问，具体流程如下：

1. URL url = new URL("http://api.androidhive.info/contacts/");
   connection = (HttpURLConnection) url.openConnection();
   2.设置访问网络的方式：“POST”和“GET”两种，这里采取GET方式，
   connection.setRequestMethod("GET");
2. connection.setConnectTimeout(8000);
   connection.setReadTimeout(8000);
   这一步是设置访问连接或者读取超时；
3. 用输入流获取服务器端返回的数据信息，
   InputStream in = connection.getInputStream();
   BufferedReader reader = new BufferedReader(new InputStreamReader(in));
   备注：1.既然是网络请求，不免会受到网络影响；
   2.关于StringBuilder与String 的区别：
   String 定义为不可变字符串，StringBuilder定义为可变字符串，可以实现字符串的拼接，如:
   StringBuilder sb=StringBuilder();
   sb.append("aa");
   sb.append("bb");
   System.out.println(sb);
   此时sb为 aabb;
   放上代码：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {    
public static final int SHOW_RESPONSE = 0;    
private Button sendRequest;   
 private TextView responseText;    
JSONArray contacts = null;   
 private Handler handler = new Handler() {       
 public void handleMessage(Message msg) {            
switch (msg.what) {               
 case SHOW_RESPONSE:                   
 String response = (String) msg.obj;          // 在这里进行UI操作，将结果显示到界面上                    
responseText.setText(response);            
}       
 }    
};    
@Override   
 protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);      
  setContentView(R.layout.activity_main);    
    sendRequest = (Button) findViewById(R.id.send_request);       
 responseText = (TextView) findViewById(R.id.response_text);        sendRequest.setOnClickListener(this);    
}  
  @Override   
 public void onClick(View v) {      
  if (v.getId() == R.id.send_request) {          
  sendRequestWithHttpURLConnection();      
  }   
 }    
private void sendRequestWithHttpURLConnection() {        // 开启线程来发起网络请求        new Thread(new Runnable() {            
@Override            
public void run() {              
  HttpURLConnection connection = null;             
   try {                   
 URL url = new URL("http://api.androidhive.info/contacts/");                    connection = (HttpURLConnection) url.openConnection();                    connection.setRequestMethod("GET");                    connection.setConnectTimeout(8000);                    connection.setReadTimeout(8000);                   
 connection.setDoInput(true);                    
connection.setDoOutput(true);                  
  InputStream in = connection.getInputStream();                    // 下面对获取到的输入流进行读取                    
BufferedReader reader = new BufferedReader( new InputStreamReader(in));                    StringBuilder response = new StringBuilder();                   
 String line;                   
 while ((line = reader.readLine()) != null) {                     
   response.append(line);                  
  }                   
 Message message = new Message();                   
 message.what = SHOW_RESPONSE;                    // 将服务器返回的结果存放到Message中                 
   message.obj = response.toString();                
    handler.sendMessage(message);               
     parseJSON(response.toString());          
      } catch (Exception e) {                   
 e.printStackTrace();               
 } finally {                   
 if (connection != null) {             
           connection.disconnect();        
            }             
   }            
}        
}).start();   
 }    
private void parseJSON(String jsonData) {   
     try {          

  JSONObject jsonObj = new JSONObject(jsonData);   
         // Getting JSON Array node          
  contacts = jsonObj.getJSONArray("contacts");     
       for (int i=0;i<contacts.length();i++){               
 JSONObject jsonObject=contacts.getJSONObject(i);       
         String name=jsonObject.getString("name");        
        String email=jsonObject.getString("email");            
    String address=jsonObject.getString("address");                Log.d("MainActivity","name is "+name);                
Log.d("MainActivity","email is "+email);            
    Log.d("MainActivity","address is "+address);        
    }     
   } catch (Exception e) {         
   e.printStackTrace();        }    }}