Android 如何使用AsyncTask下载文件?
我正在使用此类下载文件:Android 如何使用AsyncTask下载文件?,android,download,android-asynctask,Android,Download,Android Asynctask,我正在使用此类下载文件: public class DownloadService extends Service { String downloadUrl; LocalBroadcastManager mLocalBroadcastManager; ProgressBar progressBar; File sdCard = Environment.getExternalStorageDirectory(); File dir = new File (s
public class DownloadService extends Service {
String downloadUrl;
LocalBroadcastManager mLocalBroadcastManager;
ProgressBar progressBar;
File sdCard = Environment.getExternalStorageDirectory();
File dir = new File (sdCard.getAbsolutePath() + "/org.test.download/");
double fileSize = 0;
DownloadAsyncTask dat;
@Override
public IBinder onBind(Intent arg0) {
return null;
}
public DownloadService(String url,Context c, ProgressBar pBar){
downloadUrl = url;
mLocalBroadcastManager = LocalBroadcastManager.getInstance(c);
progressBar = pBar;
dat = new DownloadAsyncTask();
dat.execute(new String[]{downloadUrl});
}
private boolean checkDirs(){
if(!dir.exists()){
return dir.mkdirs();
}
return true;
}
public void cancel(){
dat.cancel(true);
}
public class DownloadAsyncTask extends AsyncTask<String, Integer, String>{
@Override
protected String doInBackground(String... params) {
String fileName = downloadUrl.substring(downloadUrl.lastIndexOf("/")+1);
if(!checkDirs()){
return "Making directories failed!";
}
try {
URL url = new URL(downloadUrl);
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.connect();
fileSize = urlConnection.getContentLength();
FileOutputStream fos = new FileOutputStream(new File(dir,fileName));
InputStream inputStream = urlConnection.getInputStream();
byte[] buffer = new byte[500];
int bufferLength = 0;
int percentage = 0;
double downloadedSize = 0;
while ( (bufferLength = inputStream.read(buffer)) > 0 )
{
if(isCancelled()){
break;
}
fos.write(buffer, 0, bufferLength);
downloadedSize += bufferLength;
percentage = (int) ((downloadedSize / fileSize) * 100);
publishProgress(percentage);
}
fos.close();
urlConnection.disconnect();
} catch (Exception e) {
Log.e("Download Failed",e.getMessage());
}
if(isCancelled()){
return "Download cancelled!";
}
return "Download complete";
}
@Override
protected void onProgressUpdate(Integer... values){
super.onProgressUpdate(values[0]);
if(progressBar != null){
progressBar.setProgress(values[0]);
}else{
Log.w("status", "ProgressBar is null, please supply one!");
}
}
@Override
protected void onPreExecute(){
mLocalBroadcastManager.sendBroadcast(new Intent("org.test.download.DOWNLOAD_STARTED"));
}
@Override
protected void onPostExecute(String str){
mLocalBroadcastManager.sendBroadcast(new Intent("org.test.download.DOWNLOAD_FINISHED"));
}
@Override
protected void onCancelled(){
mLocalBroadcastManager.sendBroadcast(new Intent("org.test.download.DOWNLOAD_CANCELLED"));
}
}
}
公共类下载服务扩展服务{
字符串下载URL;
本地广播经理mLocalBroadcastManager;
ProgressBar ProgressBar;
文件sdCard=Environment.getExternalStorageDirectory();
File dir=新文件(sdCard.getAbsolutePath()+“/org.test.download/”;
双文件大小=0;
下载异步任务数据;
@凌驾
公共IBinder onBind(意图arg0){
返回null;
}
公共下载服务(字符串url、上下文c、ProgressBar pBar){
下载url=url;
mLocalBroadcastManager=LocalBroadcastManager.getInstance(c);
progressBar=pBar;
dat=新的下载异步任务();
执行(新字符串[]{downloadUrl});
}
私有布尔checkDirs(){
如果(!dir.exists()){
return dir.mkdirs();
}
返回true;
}
公开作废取消(){
数据取消(真);
}
公共类DownloadAsyncTask扩展了AsyncTask{
@凌驾
受保护的字符串doInBackground(字符串…参数){
字符串文件名=downloadUrl.substring(downloadUrl.lastIndexOf(“/”)+1);
如果(!checkDirs()){
返回“创建目录失败!”;
}
试一试{
URL=新URL(下载URL);
HttpURLConnection urlConnection=(HttpURLConnection)url.openConnection();
urlConnection.setRequestMethod(“GET”);
urlConnection.setDoOutput(true);
urlConnection.connect();
fileSize=urlConnection.getContentLength();
FileOutputStream fos=新的FileOutputStream(新文件(dir,fileName));
InputStream InputStream=urlConnection.getInputStream();
字节[]缓冲区=新字节[500];
int bufferLength=0;
整数百分比=0;
双下载大小=0;
而((bufferLength=inputStream.read(buffer))>0)
{
如果(isCancelled()){
打破
}
fos.写入(缓冲区,0,缓冲区长度);
downloadedSize+=缓冲区长度;
百分比=(int)((下载大小/文件大小)*100);
出版进度(百分比);
}
fos.close();
urlConnection.disconnect();
}捕获(例外e){
Log.e(“下载失败”,e.getMessage());
}
如果(isCancelled()){
返回“下载已取消!”;
}
返回“下载完成”;
}
@凌驾
受保护的void onProgressUpdate(整型…值){
super.onProgressUpdate(值[0]);
if(progressBar!=null){
progressBar.setProgress(值[0]);
}否则{
Log.w(“状态”,“ProgressBar为空,请提供一个!”);
}
}
@凌驾
受保护的void onPreExecute(){
发送广播(新的意图(“org.test.download.download_start”);
}
@凌驾
受保护的void onPostExecute(字符串str){
mLocalBroadcastManager.sendbroadcastmanager(新意图(“org.test.download.download_FINISHED”);
}
@凌驾
受保护的void onCancelled(){
mLocalBroadcastManager.sendbroadcastmanager(新意图(“org.test.download.download\u已取消”);
}
}
}
我之所以使用它,是因为显然DownloadManager
在API9
之前不起作用,我的目标是API7
我有ListView
,它解析XML文件并显示可以下载的包
如何修改该类以接受包含URL的字符串数组并逐个下载它们
或者有什么好方法可以下载文件列表吗?使用IntentService。IntentService中的线程在后台运行,这意味着您不必处理所有混乱的线程处理 IntentService完成后会终止其线程,因此必须持久化数据
要与您的活动进行沟通,请使用广播接收器。您能提供示例代码吗?您的答案可能会留在这里: