• 网页源码查看器
  • 代码实现步骤 
  • [1]搭建UI 
  • [2]httpurlconnection类基本用法

 @OnClick(R.id.btn) public void onViewClicked() { final String url = mEt.getText().toString().trim(); if (TextUtils.isEmpty(url)) { Toast.makeText(this, "网址不能为空" + url, Toast.LENGTH_SHORT).show(); } new Thread(new Runnable() { @Override public void run() { try { URL Url = new URL(url); HttpURLConnection conn = (HttpURLConnection) Url.openConnection(); int code = conn.getResponseCode(); Log.d(TAG, "run: " + code); if (code == 200) { InputStream is = conn.getInputStream(); Log.d(TAG, "run: " + is); String name = StreamUtils.StreamToString(is); Log.d(TAG, "run: " + name); Message message = mHandler.obtainMessage(); message.obj = name; mHandler.sendMessage(message); } } catch (Exception e) { e.printStackTrace(); } } }).start(); }

• • [3]把流转换为String工具类

public class StreamUtils { private static ByteArrayOutputStream mBaos; public static String StreamToString(InputStream is) { try { mBaos = new ByteArrayOutputStream(); byte[] buf = new byte[1024]; int len = 0; while ((len = is.read(buf)) != -1) { mBaos.write(buf, 0, len); } } catch (Exception e) { e.printStackTrace(); } return mBaos.toString(); }}

• • [4]联网要加上联网权限

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

• • • 当加上权限后 也会报如下错误
    •  android.os.NetworkOnMainThreadException  主线程(UI线程)访问网络的异常.  主线程这个概念是谷歌提出的.
    • 为什么会报这个异常.谷歌要求 在主线程不能进行耗时(拷贝数据 连接网络)的操作,如果在主线程中进行耗时操作会报anr(应用无响应)异常; 如何解决?我们可以自己创建一个线程 来访问网络. 
  • [5]当我们把访问访问的操作放到子线程又会报如下错误:
    • android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
    • 只有主线程(UI线程)才可以更新UI
  • [6].handler(助手)的使用 —->负责线程的切换 
    • 6.1创建handler对象

 @SuppressLint("HandlerLeak") private Handler mHandler = new Handler(new Handler.Callback() { @Override public boolean handleMessage(Message msg) { Log.d(TAG, "handleMessage: callback"); return false; } }) { @Override public void handleMessage(Message msg) { Log.d(TAG, "handleMessage: handlemessage"); String name = (String) msg.obj; mTv.setText(name); super.handleMessage(msg); } };

• • • 6.2 发消息

 Message message = mHandler.obtainMessage(); message.obj = name; mHandler.sendMessage(message);

• • 7.scrollView 垂直滚动的view

 <ScrollView android:layout_width="wrap_content" android:layout_height="wrap_content"> <TextView android:id="@+id/tv" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_weight="1" /> </ScrollView>

• • • 注意:scrollView控件只能包裹一个孩子.如果想包裹多个在外面套一个布局.