android 74 下载文本

页面：

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" 
    android:orientation="vertical"
    >

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="查看源文件" 
        android:onClick="click"
        />
    <ScrollView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >
    <TextView 
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
</ScrollView>
</LinearLayout>

JAVA:

package com.itheima.htmlviewer;

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

import com.itheima.htmlviewer.utils.Utils;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;
//请求网上的文本（网页）
public class MainActivity extends Activity {

    Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg) {
            TextView tv = (TextView) findViewById(R.id.tv);
            tv.setText((String)msg.obj);
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void click(View v){
        Thread t = new Thread(){
            @Override
            public void run() {
                String path = "http://192.168.13.13:8080/baidu.html";
                try {
                    URL url = new URL(path);
                    //获取连接对象，此时还未建立连接
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    conn.setRequestMethod("GET");
                    conn.setConnectTimeout(5000);
                    conn.setReadTimeout(5000);
                    //先建立连接，然后获取响应码
                    if(conn.getResponseCode() == 200){
                        //拿到服务器返回的输入流，流里的数据就是html的源文件
                        InputStream is = conn.getInputStream();
                        //从流里把文本数据取出来
                        String text = Utils.getTextFromStream(is);
                        
                        //发送消息，让主线程刷新ui，显示源文件
                        Message msg = handler.obtainMessage();
                        msg.obj = text;
                        handler.sendMessage(msg);
                    }
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        };
        t.start();
        
    }

}

package com.itheima.htmlviewer.utils;

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

public class Utils {

    public static String getTextFromStream(InputStream is){
        //乱码是因为服务器和客户端码表不一致
        byte[] b = new byte[1024];
        int len = 0;
        //创建字节数组输出流，读取输入流的文本数据时，同步把数据写入数组输出流
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            while((len = is.read(b)) != -1){
                bos.write(b, 0, len);//写入到数组输出流
            }
            //把字节数组输出流里的数据转换成字节数组
            String text = new String(bos.toByteArray(),"utf-8");//安卓默认是utf-8
            return text;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
}