android--------HttpURLConnection的get，post和图片加载

URLConnection是个抽象类，它有两个直接子类分别是HttpURLConnection和JarURLConnection。另外一个重要的类是URL，通常URL可以通过传给构造器一个String类型的参数来生成一个指向特定地址的URL实例。

JDK自带的请求方式，包名: java.net.HttpURLConnection;

HttpURLConnection请求的类别: 
分为二类,GET与POST请求。二者的区别在于： 
     1: get请求可以获取静态页面，也可以把参数放在URL字串后面，传递给servlet， 
     2: post与get的不同之处在于post的参数不是放在URL字串里面，而是放在http请求的正文内。

效果图：

 public class MainActivity extends Activity implements OnClickListener {
     public static String urls = "http://bajie.zhangwoo.cn/app.php?platform=android&appkey=5a379b5eed8aaae531df5f60b12100cfb6dff2c1";

     private TextView mTextView;
     private ImageView imagegvoew;
     String resultStr = "";
     String resultStr1 = "";

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

     private void initView() {
         findViewById(R.id.btn1).setOnClickListener(this);
         findViewById(R.id.btn2).setOnClickListener(this);
         findViewById(R.id.btn3).setOnClickListener(this);
         mTextView = (TextView) findViewById(R.id.Text);
         imagegvoew = (ImageView) findViewById(R.id.imagegvoew);

     }

     @Override
     public void onClick(View v) {
         switch (v.getId()) {
         case R.id.btn1:
             Thread visitBaiduThread = new Thread(new VisitWebRunnable());
             visitBaiduThread.start();
             try {
                 visitBaiduThread.join();
                 if (!resultStr.equals("")) {
                     mTextView.setText(resultStr);
                 }
             } catch (InterruptedException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             break;
         case R.id.btn2:

             Thread visitBaiduThreads = new Thread(new VisitWebRunnables());
             visitBaiduThreads.start();
             try {
                 visitBaiduThreads.join();
                 if (!resultStr1.equals("")) {
                     mTextView.setText(resultStr1);
                 }
             } catch (InterruptedException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             break;
         case R.id.btn3:
             new Thread(new Runnable() {

                 @Override
                 public void run() {
                     // TODO Auto-generated method stub
                     new DownImgAsyncTask()
                             .execute("http://avatar.csdn.net/8/6/0/2_dickyqie.jpg");
                 }
             }).start();

             break;
         default:
             break;
         }

     }

     class DownImgAsyncTask extends AsyncTask<String, Void, Bitmap> {

         @Override
         protected void onPreExecute() {
             // TODO Auto-generated method stub
             super.onPreExecute();

         }

         @Override
         protected Bitmap doInBackground(String... params) {
             // TODO Auto-generated method stub
             Bitmap b = Util.getImageBitmap(params[0]);
             return b;
         }

         @Override
         protected void onPostExecute(Bitmap result) {
             // TODO Auto-generated method stub
             super.onPostExecute(result);
             if (result != null) {
                 imagegvoew.setImageBitmap(result);
             }
         }

     }

     class VisitWebRunnable implements Runnable {

         @Override
         public void run() {
             // TODO Auto-generated method stub
             String data = Util.get(urls);
             resultStr = data;
         }

     }

     class VisitWebRunnables implements Runnable {

         @Override
         public void run() {
             // TODO Auto-generated method stub
             Map<String, String> params = new HashMap<String, String>();
             params.put("q", "test");
             params.put("showapi_appid", "11548");
             params.put("showapi_timestamp", "20160511151954");
             params.put("showapi_sign", "bb1d15ab7ce646ec87cc89d684ca4bcb");
             String data = Util.post("https://route.showapi.com/32-9", params);
             resultStr1 = data;
         }

     }
 }

• 注意：使用时常出现出现NetworkOnMainThreadException错误，Android.os.NetworkOnMainThreadException错误提示的原因
• 原因：不允许在主线程中进行网络访问
• 解决：将网络访问的操作单独放到一个线程中

记得加网络权限

<uses-permission android:name="android.permission.INTERNET"/>

源码点击下载： https://github.com/DickyQie/android-network-request