Android中实现下载URL地址的网络资源的实例分享

package com.android.xiong.urltest;  import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.MalformedURLException; import java.net.URL;  import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.Menu; import android.widget.ImageView;  public class MainActivity extends Activity {   ImageView show;   Bitmap bitmap;   Handler handler = new Handler() {      @Override     public void handleMessage(Message msg) {       if (msg.what == 0x123) {         // 使用ImageView显示该图片         show.setImageBitmap(bitmap);        }     }    };    @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     show = (ImageView) findViewById(R.id.show);      new Thread() {        @Override       public void run() {         // 定义一个URL对象         URL url;         try {           url = new URL(               "http://img1.gtimg.com/news/pics/hv1/37/195/1468/95506462.jpg");           // 打开该URL的资源输入流           InputStream is = url.openStream();           // 从InputStream中解析出图片           bitmap = BitmapFactory.decodeStream(is);           // 发送消息           handler.sendEmptyMessage(0x123);           is.close();           // 再次打开RL对应的资源输入流           is = url.openStream();           // 打开手机文件对应的输出流           OutputStream os = openFileOutput("KEQIANG.JPG", MODE_APPEND);           byte[] buff = new byte[1024];           int hasRead = 0;           // 将URL资源下载到本地           while ((hasRead = is.read(buff)) > 0) {             os.write(buff, 0, hasRead);           }           is.close();           os.close();         } catch (MalformedURLException e) {           // TODO Auto-generated catch block           e.printStackTrace();         } catch (IOException e) {           // TODO Auto-generated catch block           e.printStackTrace();         }        }      }.start();   }    @Override   public boolean onCreateOptionsMenu(Menu menu) {     // Inflate the menu; this adds items to the action bar if it is present.     getMenuInflater().inflate(R.menu.main, menu);     return true;   }  } 

<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" >    <ImageView      android:id="@+id/show"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:contentDescription="@string/hello_world"/>  </LinearLayout> 

package com.example.threaddown;  import java.util.Timer; import java.util.TimerTask;  import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.ProgressBar;  public class MainActivity extends Activity {    EditText url;   EditText target;   Button downBn;   ProgressBar bar;   DownUtil downUtil;   private int mDownStatus;    @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     // 获取程序界面中的三个界面控制     url = (EditText) findViewById(R.id.url);     target = (EditText) findViewById(R.id.target);     downBn = (Button) findViewById(R.id.downBn);     bar = (ProgressBar) findViewById(R.id.br);     // 创建一个Handler对象     final Handler handler = new Handler() {        @Override       public void handleMessage(Message msg) {         if (msg.what == 0x123) {           bar.setProgress(mDownStatus);         }       }      };     downBn.setOnClickListener(new OnClickListener() {        @Override       public void onClick(View v) {         // 初始化DownUtil对象         downUtil = new DownUtil(url.getText().toString(), target             .getText().toString(), 6);         new Thread() {            @Override           public void run() {             try {               // 开始下载               downUtil.download();              } catch (Exception e) {               e.printStackTrace();             }             // 定义每秒调度获取一次系统的完成进度             final Timer timer = new Timer();             timer.schedule(new TimerTask() {                @Override               public void run() {                 // 获取下载任务的完成比例                 double completeRate = downUtil                     .getCompleteRate();                 mDownStatus = (int) (completeRate * 1000);                 // 发送消息通知届满更新的进度条                 handler.sendEmptyMessage(0x123);                 // 下载完成之后取消任务进度                 if (mDownStatus >= 100) {                   timer.cancel();                 }               }             }, 0, 1000);           }          }.start();       }     });   }    @Override   public boolean onCreateOptionsMenu(Menu menu) {     // Inflate the menu; this adds items to the action bar if it is present.     getMenuInflater().inflate(R.menu.main, menu);     return true;   }  } 

package com.example.threaddown;  import java.io.IOException; import java.io.InputStream; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL;  public class DownUtil {    // 定义下载资源的路径   private String path;   // 指定所下载的文件的保存位置   private String targetFile;   // 定义需要使用多少线程下载资源   private int threadNum;   // 定义下载的线程对象   private DownThread[] threads;   // 定义下载的文件总大小   private int fileSize;    public DownUtil(String path, String targetFile, int threadNum) {     this.path = path;     this.targetFile = targetFile;     this.threadNum = threadNum;   }    public void download() throws IOException {     URL url = new URL(path);     HttpURLConnection conn = (HttpURLConnection) url.openConnection();     conn.setConnectTimeout(5000);     conn.setRequestMethod("GET");     conn.setRequestProperty("Accept", "*/*");     conn.setRequestProperty("Accept-Language", "zh-CN");     conn.setRequestProperty("Charset", "UTF-8");     conn.setRequestProperty("Connection", "Keep-Alive");     // 得到文件的大小     fileSize = conn.getContentLength();     conn.disconnect();     int currentPartsSize = fileSize / threadNum + 1;     RandomAccessFile file = new RandomAccessFile(targetFile, "rw");     // 设置本地文件的大小     file.setLength(fileSize);     file.close();     for (int i = 0; i < threadNum; i++) {       // 计算每条线程的下载位置       int startPos = i * currentPartsSize;       // 每个线程使用一个RandomAccessFile进行下载       RandomAccessFile current = new RandomAccessFile(targetFile, "rw");       // 定义该线程的下载位置       current.seek(startPos);       // 创建下载线程       threads[i] = new DownThread(startPos, currentPartsSize, current);       // 启动线程下载       threads[i].start();     }    }    // 获取下载的完成百分比   public double getCompleteRate() {     // 统计多条线程已经下载的总大小     int sumSize = 0;     for (int i = 0; i < threadNum; i++) {       sumSize += threads[i].length;     }     return sumSize * 1.0 / fileSize;   }    private class DownThread extends Thread {     // 定义当前线程下载的位置     private int startPos;     // 定义当前线程下载文件的大小     private int currentPartsSize;     // 当前线程下载的文件块     private RandomAccessFile currentPart;     // 定义该线程已下载的字节数     private int length;      public DownThread(int startPos, int currentPartsSize,         RandomAccessFile currentPart) {       this.startPos = startPos;       this.currentPart = currentPart;       this.currentPartsSize = currentPartsSize;      }      @Override     public void run() {       try {         URL url = new URL(path);         HttpURLConnection conn = (HttpURLConnection) url             .openConnection();         conn.setConnectTimeout(5000);         conn.setRequestMethod("GET");         conn.setRequestProperty("Accept", "*/*");         conn.setRequestProperty("Accept-Language", "zh-CN");         conn.setRequestProperty("Charset", "UTF-8");         conn.setRequestProperty("Connection", "Keep-Alive");         InputStream in = conn.getInputStream();         in.skip(startPos);         int hasRead = 0;         byte[] buffer = new byte[1024];         // 读取网络数据，并写入本地文件         while (length < currentPartsSize             && (hasRead = in.read(buffer)) > 0) {           currentPart.write(buffer, 0, hasRead);           // 累计该线程下载的总大小           length += hasRead;         }         currentPart.close();         in.close();        } catch (Exception e) {         e.printStackTrace();       }      }    }  } 

<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/url"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:text="http://ksoap2-android.googlecode.com/svn/m2-repo/com/google/code/ksoap2-android/ksoap2-android-assembly/3.1.0/ksoap2-android-assembly-3.1.0-jar-with-dependencies.jar" />    <EditText     android:id="@+id/target"     android:layout_width="match_parent"     android:layout_height="wrap_content"      android:text="/mnt/sdcard/"/>    <Button     android:id="@+id/downBn"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:text="down" />    <ProgressBar     android:id="@+id/br"     style="?android:attr/progressBarStyleHorizontal"     android:layout_width="match_parent"     android:layout_height="wrap_content" />  </LinearLayout> 

<!-- 在SD卡中创建与删除文件的权限 --> <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" /> <!-- 在SD开中写入数据的权限 --> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <!-- 访问网路的权限 --> <uses-permission android:name="android.permission.INTERNET" />