我试图写一个简单的应用程序得到更新。为此，我需要一个简单的函数，可以下载文件并在ProgressDialog中显示当前进度。我知道如何做的ProgressDialog，但我不确定如何显示当前的进度，以及如何下载文件放在第一位。
当前回答
如果你要从网上下载东西，别忘了给你的manifest文件添加权限!
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.helloandroid"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="10" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
<application
android:icon="@drawable/icon"
android:label="@string/app_name"
android:debuggable="true">
</application>
</manifest>
其他回答
我遇到了一个简单文件下载库 获取，重要的是，它有存储访问框架，内容提供程序和URI支持。如果有人还在寻找，可能会有帮助。
//AndroidX .tonyodev.fetch2:xfetch2:3.1.6
实现"com.tonyodev.fetch2:fetch2:3.0.12" //支持lib
需要的权限，如果你不是使用应用程序特定的目录。
< uses-permission android: name = " android.permission.WRITE_EXTERNAL_STORAGE " / >
< uses-permission android: name = " android.permission.READ_EXTERNAL_STORAGE " / >
网络权限
< uses-permission android: name = " android.permission.INTERNET " / >
private Fetch fetch;
FetchConfiguration fetchConfiguration = new FetchConfiguration.Builder(this)
.setDownloadConcurrentLimit(3)//Concurrent Download limit
.build();
fetch = Fetch.Impl.getInstance(fetchConfiguration);
String url = "http:www.example.com/test.txt";//URL of file
String file = "/downloads/test.txt";//Path of file
final Request request = new Request(url, file);
request.setPriority(Priority.HIGH);
request.setNetworkType(NetworkType.ALL);//Preferred network type
request.addHeader("clientKey", "SD78DF93_3947&MVNGHE1WONG");//Auth header if any
fetch.enqueue(request, updatedRequest -> {
//Request was successfully enqueued for download.
}, error -> {
//An error occurred enqueuing the request.
});
}
倾听更新和进展
FetchListener fetchListener = new FetchListener() {
@Override
public void onQueued(@NotNull Download download, boolean waitingOnNetwork) {
if (request.getId() == download.getId()) {
showDownloadInList(download);
}
}
@Override
public void onCompleted(@NotNull Download download) {
}
@Override
public void onError(@NotNull Download download) {
Error error = download.getError();
}
@Override
public void onProgress(@NotNull Download download, long etaInMilliSeconds, long downloadedBytesPerSecond) {
if (request.getId() == download.getId()) {
updateDownload(download, etaInMilliSeconds);
}
int progress = download.getProgress();
}
@Override
public void onPaused(@NotNull Download download) {
}
@Override
public void onResumed(@NotNull Download download) {
}
@Override
public void onCancelled(@NotNull Download download) {
}
@Override
public void onRemoved(@NotNull Download download) {
}
@Override
public void onDeleted(@NotNull Download download) {
}
};
fetch.addListener(fetchListener);
//Remove listener when done.
fetch.removeListener(fetchListener);
此示例代码取自所有者页面，所有功劳都归于Tonyo Francis
使用Android查询库，确实很酷。你可以改变它使用ProgressDialog，就像你在其他例子中看到的那样，这个将从你的布局中显示进度视图，并在完成后隐藏它。
File target = new File(new File(Environment.getExternalStorageDirectory(), "ApplicationName"), "tmp.pdf");
new AQuery(this).progress(R.id.progress_view).download(_competition.qualificationScoreCardsPdf(), target, new AjaxCallback<File>() {
public void callback(String url, File file, AjaxStatus status) {
if (file != null) {
// do something with file
}
}
});
权限
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission
android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
使用HttpURLConnection
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.app.Activity;
import android.app.Dialog;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.Window;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
public class DownloadFileUseHttpURLConnection extends Activity {
ProgressBar pb;
Dialog dialog;
int downloadedSize = 0;
int totalSize = 0;
TextView cur_val;
String dwnload_file_path =
"http://coderzheaven.com/sample_folder/sample_file.png";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button b = (Button) findViewById(R.id.b1);
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
showProgress(dwnload_file_path);
new Thread(new Runnable() {
public void run() {
downloadFile();
}
}).start();
}
});
}
void downloadFile(){
try {
URL url = new URL(dwnload_file_path);
HttpURLConnection urlConnection = (HttpURLConnection)
url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
//connect
urlConnection.connect();
//set the path where we want to save the file
File SDCardRoot = Environment.getExternalStorageDirectory();
//create a new file, to save the downloaded file
File file = new File(SDCardRoot,"downloaded_file.png");
FileOutputStream fileOutput = new FileOutputStream(file);
//Stream used for reading the data from the internet
InputStream inputStream = urlConnection.getInputStream();
//this is the total size of the file which we are downloading
totalSize = urlConnection.getContentLength();
runOnUiThread(new Runnable() {
public void run() {
pb.setMax(totalSize);
}
});
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0;
while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
fileOutput.write(buffer, 0, bufferLength);
downloadedSize += bufferLength;
// update the progressbar //
runOnUiThread(new Runnable() {
public void run() {
pb.setProgress(downloadedSize);
float per = ((float)downloadedSize/totalSize) *
100;
cur_val.setText("Downloaded " + downloadedSize +
"KB / " + totalSize + "KB (" + (int)per + "%)" );
}
});
}
//close the output stream when complete //
fileOutput.close();
runOnUiThread(new Runnable() {
public void run() {
// pb.dismiss(); // if you want close it..
}
});
} catch (final MalformedURLException e) {
showError("Error : MalformedURLException " + e);
e.printStackTrace();
} catch (final IOException e) {
showError("Error : IOException " + e);
e.printStackTrace();
}
catch (final Exception e) {
showError("Error : Please check your internet connection " +
e);
}
}
void showError(final String err){
runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(DownloadFileDemo1.this, err,
Toast.LENGTH_LONG).show();
}
});
}
void showProgress(String file_path){
dialog = new Dialog(DownloadFileDemo1.this);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.myprogressdialog);
dialog.setTitle("Download Progress");
TextView text = (TextView) dialog.findViewById(R.id.tv1);
text.setText("Downloading file from ... " + file_path);
cur_val = (TextView) dialog.findViewById(R.id.cur_pg_tv);
cur_val.setText("Starting download...");
dialog.show();
pb = (ProgressBar)dialog.findViewById(R.id.progress_bar);
pb.setProgress(0);
pb.setProgressDrawable(
getResources().getDrawable(R.drawable.green_progress));
}
}
当我开始学习android开发时，我知道ProgressDialog是正确的方法。ProgressDialog的setProgress方法可以在下载文件时调用它来更新进度级别。
我在许多应用程序中看到的最好的情况是，它们自定义了进度对话框的属性，使进度对话框的外观和感觉比库存版本更好。很好地保持用户的一些动画，如青蛙，大象或可爱的猫/小狗。任何有进度对话框的动画都能吸引用户，他们不喜欢长时间等待。
我推荐你使用我的Project Netroid，它是基于Volley的。我添加了一些功能，如多事件回调，文件下载管理。这可能会有帮助。
