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