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