Android（java）学习笔记203：网页源码查看器（Handler消息机制）

1.项目框架图：

2.首先是布局文件activity_main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <EditText
        android:id="@+id/et_path"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="http://192.168.1.100:8080/hello.jsp" />

    <Button
        android:onClick="click"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="查看源码" />

    <ScrollView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >

        <TextView
            android:id="@+id/tv_result"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent" />
    </ScrollView>

</LinearLayout>

3.MainActivity.java:

 package com.itheima.netsourceviewer;

 import java.io.InputStream;
 import java.net.HttpURLConnection;
 import java.net.URL;

 import android.app.Activity;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.view.View;
 import android.widget.EditText;
 import android.widget.TextView;
 import android.widget.Toast;

 import com.itheima.netsourceviewer.utils.StreamTools;

 public class MainActivity extends Activity {
     protected static final int SUCCESS = 1;
     protected static final int ERROR = 2;

     private EditText et_path;
     private TextView tv_result;

     private Handler handler = new Handler(){
         public void handleMessage(android.os.Message msg) {
             switch (msg.what) {
             case SUCCESS:
                 String text = (String) msg.obj;
                 tv_result.setText(text);
                 break;
             case ERROR:
                 Toast.makeText(MainActivity.this, "请求失败", 1).show();
                 break;
             }
         };
     };

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         et_path = (EditText) findViewById(R.id.et_path);
         tv_result = (TextView) findViewById(R.id.tv_result);
     }
     /**
      * 查看源文件的点击事件
      * @param view
      */
     public void click(View view){
         final String path = et_path.getText().toString().trim();
         //访问网络，把html源文件下载下来
         new Thread(){
             public void run() {
                 try {
                     //获取url对象
                     URL url = new URL(path);
                     //获取链接对象
                     HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                     //获取请求方式，默认GET
                     conn.setRequestMethod("GET");//声明请求方式 默认get
                     //告诉服务器我是什么样的客户端
                     conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Linux; U; Android 2.3.3; zh-cn; sdk Build/GRI34) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1 MicroMessenger/6.0.0.57_r870003.501 NetType/internet");
                     //获取状态吗
                     int code = conn.getResponseCode();
                     //判断状态吗
                     if(code ==200){
                         InputStream is = conn.getInputStream();
                         //使用工具类， 把字节输入流的数据编程字符串
                         String result = StreamTools.readStream(is);

                         Message msg = Message.obtain();//减少消息创建的数量
                         msg.obj = result;
                         msg.what = SUCCESS;
                         handler.sendMessage(msg);
                     }
                 } catch (Exception e) {
                     Message msg = Message.obtain();//减少消息创建的数量
                     msg.what = ERROR;
                     handler.sendMessage(msg);
                     e.printStackTrace();
                 }
             };
         }.start();
     }
 }

 

4.这里的工具类是StreamTools.java:

 package com.itheima.netsourceviewer.utils;

 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;

 /**
  * 流的工具类
  * @author Administrator
  *
  */
 public class StreamTools {
     /**
      * 把输入流的内容转换成字符串
      * @param is
      * @return null解析失败， string读取成功
      */
     public static String readStream(InputStream is) {
         try {
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
             byte[] buffer = new byte[1024];
             int len = -1;
             while( (len = is.read(buffer))!=-1){
                 baos.write(buffer, 0, len);
             }
             is.close();
             String temptext = new String(baos.toByteArray());
             if(temptext.contains("charset=gb2312")){//解析meta标签
                 return new String(baos.toByteArray(),"gb2312");
             }else{
                 return new String(baos.toByteArray(),"utf-8");
             }
         } catch (IOException e) {
             e.printStackTrace();
             return null;
         }
     }
 }