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：

  1 public class MainActivity extends Activity implements OnClickListener {
  2     public static String urls = "http://bajie.zhangwoo.cn/app.php?platform=android&appkey=5a379b5eed8aaae531df5f60b12100cfb6dff2c1";
  3 
  4     private TextView mTextView;
  5     private ImageView imagegvoew;
  6     String resultStr = "";
  7     String resultStr1 = "";
  8 
  9     @Override
 10     protected void onCreate(Bundle savedInstanceState) {
 11         super.onCreate(savedInstanceState);
 12         setContentView(R.layout.activity_main);
 13         initView();
 14     }
 15 
 16     private void initView() {
 17         findViewById(R.id.btn1).setOnClickListener(this);
 18         findViewById(R.id.btn2).setOnClickListener(this);
 19         findViewById(R.id.btn3).setOnClickListener(this);
 20         mTextView = (TextView) findViewById(R.id.Text);
 21         imagegvoew = (ImageView) findViewById(R.id.imagegvoew);
 22 
 23     }
 24 
 25     @Override
 26     public void onClick(View v) {
 27         switch (v.getId()) {
 28         case R.id.btn1:
 29             Thread visitBaiduThread = new Thread(new VisitWebRunnable());
 30             visitBaiduThread.start();
 31             try {
 32                 visitBaiduThread.join();
 33                 if (!resultStr.equals("")) {
 34                     mTextView.setText(resultStr);
 35                 }
 36             } catch (InterruptedException e) {
 37                 // TODO Auto-generated catch block
 38                 e.printStackTrace();
 39             }
 40             break;
 41         case R.id.btn2:
 42 
 43             Thread visitBaiduThreads = new Thread(new VisitWebRunnables());
 44             visitBaiduThreads.start();
 45             try {
 46                 visitBaiduThreads.join();
 47                 if (!resultStr1.equals("")) {
 48                     mTextView.setText(resultStr1);
 49                 }
 50             } catch (InterruptedException e) {
 51                 // TODO Auto-generated catch block
 52                 e.printStackTrace();
 53             }
 54             break;
 55         case R.id.btn3:
 56             new Thread(new Runnable() {
 57 
 58                 @Override
 59                 public void run() {
 60                     // TODO Auto-generated method stub
 61                     new DownImgAsyncTask()
 62                             .execute("http://avatar.csdn.net/8/6/0/2_dickyqie.jpg");
 63                 }
 64             }).start();
 65 
 66             break;
 67         default:
 68             break;
 69         }
 70 
 71     }
 72 
 73     class DownImgAsyncTask extends AsyncTask<String, Void, Bitmap> {
 74 
 75         @Override
 76         protected void onPreExecute() {
 77             // TODO Auto-generated method stub
 78             super.onPreExecute();
 79 
 80         }
 81 
 82         @Override
 83         protected Bitmap doInBackground(String... params) {
 84             // TODO Auto-generated method stub
 85             Bitmap b = Util.getImageBitmap(params[0]);
 86             return b;
 87         }
 88 
 89         @Override
 90         protected void onPostExecute(Bitmap result) {
 91             // TODO Auto-generated method stub
 92             super.onPostExecute(result);
 93             if (result != null) {
 94                 imagegvoew.setImageBitmap(result);
 95             }
 96         }
 97 
 98     }
 99 
100     class VisitWebRunnable implements Runnable {
101 
102         @Override
103         public void run() {
104             // TODO Auto-generated method stub
105             String data = Util.get(urls);
106             resultStr = data;
107         }
108 
109     }
110 
111     class VisitWebRunnables implements Runnable {
112 
113         @Override
114         public void run() {
115             // TODO Auto-generated method stub
116             Map<String, String> params = new HashMap<String, String>();
117             params.put("q", "test");
118             params.put("showapi_appid", "11548");
119             params.put("showapi_timestamp", "20160511151954");
120             params.put("showapi_sign", "bb1d15ab7ce646ec87cc89d684ca4bcb");
121             String data = Util.post("https://route.showapi.com/32-9", params);
122             resultStr1 = data;
123         }
124 
125     }
126 }

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