Android中实现下载URL地址的网络资源的实例分享

通过url来获取网络资源并下载资源简单实例：

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> 

网络资源多线程下载：

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" />