Android中实现下载URL地址的网络资源的实例分享
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2024-02-28 23:38:22
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.i...
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" />