如何在安卓 App 中使用 PRDownloader 库？
原文:https://www . geesforgeks . org/使用方法-prdownloader-Android 中的库-app/
PRDownloader 库是安卓的文件下载器库。下载文件时，它会暂停并恢复支持。该库能够从互联网下载大文件，可以下载任何类型的文件，如图像、视频、pdf、apk 等。它提供了许多功能，可以帮助用户轻松高效地从互联网下载文件。使用该库，您还可以使用下载 id 检查下载状态，并可以使用下载 id 执行许多其他重要操作。这个库包含许多重要的方法，让用户可以完全控制文件的下载状态，如暂停、取消、恢复等。您可以使用此库提出以下请求:
暂停下载请求:
PRDownloader.pause(downloadId);
取消下载请求:
// Cancel with the download id
PRDownloader.cancel(downloadId);
// The tag can be set to any request and then can be used to cancel the request
PRDownloader.cancel(TAG);
// Cancel all the requests
PRDownloader.cancelAll();
恢复下载请求:
PRDownloader.resume(downloadId);
获取下载请求的状态:
Status status = PRDownloader.getStatus(downloadId);
本文我们要构建什么？
下面给出一个视频样本，了解一下在本文中我们要做什么。注意，我们将使用 Java 语言来实现这个项目。
[https://media.geeksforgeeks.org/wp-content/uploads/20210710182504/1625920841669.mp4](https://media.geeksforgeeks.org/wp-content/uploads/20210710182504/1625920841669.mp4)分步实施
第一步:创建新项目
在安卓工作室创建新项目请参考 【如何在安卓工作室创建/启动新项目】 。然后在名称字段中输入您的应用名称，并从语言下拉菜单中选择 Java。
第二步:添加依赖关系
要添加依赖项，请导航至应用程序>渐变脚本>渐变构建(模块:应用)，并在依赖项部分添加以下依赖项。添加依赖项后，同步您的项目。
implementation 'com.mindorks.android:prdownloader:0.6.0'
第三步:添加互联网权限
导航至 app >清单> AndroidManifest.xml 并添加互联网权限。
<uses-permission android:name="android.permission.INTERNET"/>
第 4 步:使用 activity_main.xml 文件
导航到 app > res >布局> activity_main.xml 并将下面的代码添加到该文件中。下面是activity _ main . XML文件的代码。
可扩展标记语言
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
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"
tools:context=".MainActivity">
<!-- EditText to take the url from the user -->
<EditText
android:id="@+id/url_etText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:hint="@string/type_or_paste_your_url_here" />
<!-- Button to start downloading from file -->
<Button
android:id="@+id/btn_download"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/url_etText"
android:layout_centerHorizontal="true"
android:text="@string/download" />
<!-- linear layout that contains widgets to show information -->
<LinearLayout
android:id="@+id/details_box"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/btn_download"
android:layout_margin="10dp"
android:layout_marginTop="20dp"
android:background="@drawable/box_design_layout"
android:orientation="vertical"
android:padding="10dp"
android:visibility="gone">
<!-- Textview to show the file name -->
<TextView
android:id="@+id/file_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/click_on_start_button_to_start_downloading"
android:textSize="20sp"
android:textStyle="bold" />
<!-- progress bar to show the progress of downloading -->
<ProgressBar
android:id="@+id/progress_horizontal"
style="@style/Widget.AppCompat.ProgressBar.Horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="4dp"
android:layout_marginRight="4dp"
android:progressTint="@color/purple_200"
tools:ignore="UnusedAttribute" />
<!-- textview to show the downloading percentage -->
<TextView
android:id="@+id/downloading_percentage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:textAlignment="center"
android:textSize="12sp"
android:textStyle="bold" />
<!-- this linear layout contains buttons -->
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:orientation="horizontal"
android:padding="10dp">
<!-- button to start the downloading -->
<Button
android:id="@+id/btn_start"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/start" />
<!-- button to cancel or stop the downloading -->
<Button
android:id="@+id/btn_stop"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/stop" />
</LinearLayout>
</LinearLayout>
<!-- this textview will show the path where
the downloaded file is stored -->
<TextView
android:id="@+id/txt_url"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/details_box"
android:layout_marginTop="10dp"
android:textSize="15sp"
android:textStyle="bold" />
</RelativeLayout>
下面是 Strings.xml 文件的代码
可扩展标记语言
<resources>
<string name="app_name">GFG PRDownloader Library</string>
<string name="download">DOWNLOAD</string>
<string name="type_or_paste_your_url_here">Type or Paste Your URL Here</string>
<string name="start">START</string>
<string name="stop">STOP</string>
<string name="click_on_start_button_to_start_downloading">Click on Start Button to Start Downloading</string>
</resources>
第五步:设计箱体布局
导航到应用程序>资源>可绘制>右键单击>新建>可绘制资源文件，并将该文件命名为 box_design_layout ，并将以下代码添加到该文件中。
可扩展标记语言
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<corners
android:bottomLeftRadius="0dp"
android:bottomRightRadius="0dp"
android:topLeftRadius="0dp"
android:topRightRadius="0dp" />
<stroke
android:width="1dp"
android:color="@android:color/black" />
<solid android:color="@android:color/transparent" />
</shape>
第 6 步:创建 Util 类
导航到应用程序> java >包名>右键单击>新建> Java 类，并将该文件命名为Utils.java。将以下代码添加到Utils.java。以下是Utils.java 的代码。
Java 语言(一种计算机语言，尤用于创建网站)
import android.content.Context;
import android.os.Environment;
import androidx.core.content.ContextCompat;
import java.io.File;
import java.util.Locale;
public final class Utils {
private Utils() {
}
public static String getRootDirPath(Context context) {
if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
File file = ContextCompat.getExternalFilesDirs(context.getApplicationContext(), null)[0];
return file.getAbsolutePath();
} else {
return context.getApplicationContext().getFilesDir().getAbsolutePath();
}
}
public static String getProgressDisplayLine(long currentBytes, long totalBytes) {
return getBytesToMBString(currentBytes) + "/" + getBytesToMBString(totalBytes);
}
private static String getBytesToMBString(long bytes) {
return String.format(Locale.ENGLISH, "%.2fMb", bytes / (1024.00 * 1024.00));
}
}
第七步:与 MainActivity.java 合作
转到MainActivity.java文件，参考以下代码。以下是MainActivity.java文件的代码。代码中添加了注释，以更详细地理解代码。
Java 语言(一种计算机语言，尤用于创建网站)
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.View;
import android.webkit.URLUtil;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.downloader.Error;
import com.downloader.OnCancelListener;
import com.downloader.OnDownloadListener;
import com.downloader.OnPauseListener;
import com.downloader.OnProgressListener;
import com.downloader.OnStartOrResumeListener;
import com.downloader.PRDownloader;
import com.downloader.Progress;
import com.downloader.Status;
public class MainActivity extends AppCompatActivity {
private EditText editTextUrl;
private String path;
private TextView file_downloaded_path, file_name, downloading_percent;
private ProgressBar progressBar;
private Button btnStart, btnCancel, buttonDownload;
private LinearLayout details;
int downloadID;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initializing PRDownloader library
PRDownloader.initialize(this);
// finding edittext by its id
editTextUrl = findViewById(R.id.url_etText);
// finding button by its id
buttonDownload = findViewById(R.id.btn_download);
// finding textview by its id
file_downloaded_path = findViewById(R.id.txt_url);
// finding textview by its id
file_name = findViewById(R.id.file_name);
// finding progressbar by its id
progressBar = findViewById(R.id.progress_horizontal);
// finding textview by its id
downloading_percent = findViewById(R.id.downloading_percentage);
// finding button by its id
btnStart = findViewById(R.id.btn_start);
// finding button by its id
btnCancel = findViewById(R.id.btn_stop);
// finding linear layout by its id
details = findViewById(R.id.details_box);
//storing the path of the file
path = Utils.getRootDirPath(this);
// handling onclick event on button
buttonDownload.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// getting the text from edittext
// and storing it to url variable
String url = editTextUrl.getText().toString().trim();
// setting the visibility of linear layout to visible
details.setVisibility(View.VISIBLE);
// calling method downloadFile passing url as parameter
downloadFile(url);
}
});
}
@SuppressLint("SetTextI18n")
private void downloadFile(final String url) {
// handing click event on start button
// which starts the downloading of the file
btnStart.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// checks if the process is already running
if (Status.RUNNING == PRDownloader.getStatus(downloadID)) {
// pauses the download if
// user click on pause button
PRDownloader.pause(downloadID);
return;
}
// enabling the start button
btnStart.setEnabled(false);
// checks if the status is paused
if (Status.PAUSED == PRDownloader.getStatus(downloadID)) {
// resume the download if download is paused
PRDownloader.resume(downloadID);
return;
}
// getting the filename
String fileName = URLUtil.guessFileName(url, null, null);
// setting the file name
file_name.setText("Downloading " + fileName);
// making the download request
downloadID = PRDownloader.download(url, path, fileName)
.build()
.setOnStartOrResumeListener(new OnStartOrResumeListener() {
@SuppressLint("SetTextI18n")
@Override
public void onStartOrResume() {
progressBar.setIndeterminate(false);
// enables the start button
btnStart.setEnabled(true);
// setting the text of start button to pause
btnStart.setText("Pause");
// enabling the stop button
btnCancel.setEnabled(true);
Toast.makeText(MainActivity.this, "Downloading started", Toast.LENGTH_SHORT).show();
}
})
.setOnPauseListener(new OnPauseListener() {
@Override
public void onPause() {
// setting the text of start button to resume
// when the download is in paused state
btnStart.setText("Resume");
Toast.makeText(MainActivity.this, "Downloading Paused", Toast.LENGTH_SHORT).show();
}
})
.setOnCancelListener(new OnCancelListener() {
@Override
public void onCancel() {
// resetting the downloadId when
// the download is cancelled
downloadID = 0;
// setting the text of start button to start
btnStart.setText("Start");
// disabling the cancel button
btnCancel.setEnabled(false);
// resetting the progress bar
progressBar.setProgress(0);
// restting the download precent
downloading_percent.setText("");
progressBar.setIndeterminate(false);
Toast.makeText(MainActivity.this, "Downloading Cancelled", Toast.LENGTH_SHORT).show();
}
})
.setOnProgressListener(new OnProgressListener() {
@Override
public void onProgress(Progress progress) {
// getting the progress of download
long progressPer = progress.currentBytes * 100 / progress.totalBytes;
// setting the progress to progressbar
progressBar.setProgress((int) progressPer);
// setting the download percent
downloading_percent.setText(Utils.getProgressDisplayLine(progress.currentBytes, progress.totalBytes));
progressBar.setIndeterminate(false);
}
})
.start(new OnDownloadListener() {
@Override
public void onDownloadComplete() {
// disabling the start button
btnStart.setEnabled(false);
// disabling the cancel button
btnCancel.setEnabled(false);
// setting the text completed to start button
btnStart.setText("Completed");
// will show the path after the file is downloaded
file_downloaded_path.setText("File stored at : " + path);
Toast.makeText(MainActivity.this, "Downloading Completed", Toast.LENGTH_SHORT).show();
}
@Override
public void onError(Error error) {
// setting the text start
btnStart.setText("Start");
// resetting the download percentage
downloading_percent.setText("0");
// resetting the progressbar
progressBar.setProgress(0);
// resetting the downloadID
downloadID = 0;
// enabling the start button
btnStart.setEnabled(true);
// disabling the cancel button
btnCancel.setEnabled(false);
progressBar.setIndeterminate(false);
Toast.makeText(MainActivity.this, "Error Occurred", Toast.LENGTH_SHORT).show();
}
});
// handling click event on cancel button
btnCancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
btnStart.setText("Start");
// cancels the download
PRDownloader.cancel(downloadID);
}
});
}
});
}
}
输出:
[https://media.geeksforgeeks.org/wp-content/uploads/20210710182504/1625920841669.mp4](https://media.geeksforgeeks.org/wp-content/uploads/20210710182504/1625920841669.mp4)版权属于：月萌API www.moonapi.com，转载请注明出处
