Android（java）学习笔记146：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;
        }
    }
}