我要评论在android2.3以后android系统提供了一个系统组件来供其他app调用来下载东西，使用起来非常方便。
例如我们可以拿来下载app的新版本apk，同时在同时注册一个广播接收器来接收下载完成时downloadmanager发出的的广播，然后自动安装程序。
sdk在api level 9中加入了downloadmanager服务，可以将长时间的下载任务交给系统，完全由系统管理。
直接看实例代码：
package com.hebaijun.downloadtest;
import java.io.unsupportedencodingexception;
import java.net.urlencoder;
import android.app.activity;
import android.app.downloadmanager;
import android.app.downloadmanager.request;
import android.content.broadcastreceiver;
import android.content.context;
import android.content.intent;
import android.content.intentfilter;
import android.content.sharedpreferences;
import android.database.cursor;
import android.net.uri;
import android.os.bundle;
import android.preference.preferencemanager;
import android.util.log;
import android.webkit.mimetypemap;
public class downloadtestactivity extends activity {
private downloadmanager downloadmanager;
private sharedpreferences prefs;
private static final string dl_id = "downloadid";
/** called when the activity is first created. */
@override
public void oncreate(bundle savedinstancestate) {
super.oncreate(savedinstancestate);
setcontentview(r.layout.main);
downloadmanager = (downloadmanager)getsystemservice(download_service);
prefs = preferencemanager.getdefaultsharedpreferences(this);
}
@override
protected void onpause() {
// todo auto-generated method stub
super.onpause();
unregisterreceiver(receiver);
}
@override
protected void onresume() {
// todo auto-generated method stub
super.onresume();
if(!prefs.contains(dl_id)) {
string url = "http://10.0.2.2/android/film/g3.mp4";
//开始下载
uri resource = uri.parse(encodegb(url));
downloadmanager.request request = new downloadmanager.request(resource);
request.setallowednetworktypes(request.network_mobile | request.network_wifi);
request.setallowedoverroaming(false);
//设置文件类型
mimetypemap mimetypemap = mimetypemap.getsingleton();
string mimestring = mimetypemap.getmimetypefromextension(mimetypemap.getfileextensionfromurl(url));
request.setmimetype(mimestring);
//在通知栏中显示
request.setshowrunningnotification(true);
request.setvisibleindownloadsui(true);
//sdcard的目录下的download文件夹
request.setdestinationinexternalpublicdir("/download/", "g3.mp4");
request.settitle("移动g3广告");
long id = downloadmanager.enqueue(request);
//保存id
prefs.edit().putlong(dl_id, id).commit();
} else {
//下载已经开始，检查状态
querydownloadstatus();
}
registerreceiver(receiver, new intentfilter(downloadmanager.action_download_complete));
}
/**
* 如果服务器不支持中文路径的情况下需要转换url的编码。
* @param string
* @return
*/
public string encodegb(string string)
{
//转换中文编码
string split[] = string.split("/");
for (int i = 1; i < split.length; i++) {
try {
split[i] = urlencoder.encode(split[i], "gb2312");
} catch (unsupportedencodingexception e) {
e.printstacktrace();
}
split[0] = split[0]+"/"+split[i];
}
split[0] = split[0].replaceall("\\+", "%20");//处理空格
return split[0];
}
private broadcastreceiver receiver = new broadcastreceiver() {
@override
public void onreceive(context context, intent intent) {
//这里可以取得下载的id，这样就可以知道哪个文件下载完成了。适用与多个下载任务的监听
log.v("intent", ""+intent.getlongextra(downloadmanager.extra_download_id, 0));
querydownloadstatus();
}
};
private void querydownloadstatus() {
downloadmanager.query query = new downloadmanager.query();
query.setfilterbyid(prefs.getlong(dl_id, 0));
cursor c = downloadmanager.query(query);
if(c.movetofirst()) {
int status = c.getint(c.getcolumnindex(downloadmanager.column_status));
switch(status) {
case downloadmanager.status_paused:
log.v("down", "status_paused");
case downloadmanager.status_pending:
log.v("down", "status_pending");
case downloadmanager.status_running:
//正在下载，不做任何事情
log.v("down", "status_running");
break;
case downloadmanager.status_successful:
//完成
log.v("down", "下载完成");
break;
case downloadmanager.status_failed:
//清除已下载的内容，重新下载
log.v("down", "status_failed");
downloadmanager.remove(prefs.getlong(dl_id, 0));
prefs.edit().clear().commit();
break;
}
}
}
}
最后需要的权限是：
<uses-permission android:name="android.permission.internet"/> <uses-permission android:name="android.permission.write_external_storage"/>
如果需要隐藏下载工具的提示和显示，修改代码：
request.setshowrunningnotification(false); request.setvisibleindownloadsui(false);
加入下面的权限：
<uses-permission android:name="android.permission.download_without_notification"/>
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。
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