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Android 应用详情下载教程示例

清单文件

```xml

package="com.example.myapp">

android:name=".App"

android:allowBackup="true"

android:icon="@mipmap/ic_launcher"

android:label="@string/app_name"

android:roundIcon="@mipmap/ic_launcher_round"

android:supportsRtl="true"

android:theme="@style/Theme.MyApp">

```

主活动（MainActivity.java）

```java

package com.example.myapp;

import android.annotation.SuppressLint;

import android.app.DownloadManager;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.content.IntentFilter;

import android.net.Uri;

import android.os.Build;

import android.os.Bundle;

import android.os.Environment;

import android.util.Log;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

private EditText urlEditText;

private Button downloadButton;

private Button cancelButton;

private long downloadId;

private boolean isDownloading;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

urlEditText = findViewById(R.id.url_edit_text);

downloadButton = findViewById(R.id.download_button);

cancelButton = findViewById(R.id.cancel_button);

// Register a broadcast receiver to listen for download completion

IntentFilter filter = new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE);

registerReceiver(downloadCompleteReceiver, filter);

downloadButton.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

downloadFile(urlEditText.getText().toString());

}

});

cancelButton.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

cancelDownload();

}

});

}

@Override

protected void onDestroy() {

super.onDestroy();

unregisterReceiver(downloadCompleteReceiver);

}

// Request the download of a file

@SuppressLint("NewApi")

private void downloadFile(String url) {

if (isDownloading) {

Toast.makeText(getApplicationContext(), "Download already in progress", Toast.LENGTH_SHORT).show();

return;

}

DownloadManager downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);

DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));

// Set the destination for the downloaded file

request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "my_downloaded_file.apk");

// Enqueue the download request and save the download ID

downloadId = downloadManager.enqueue(request);

isDownloading = true;

Toast.makeText(getApplicationContext(), "Download started", Toast.LENGTH_SHORT).show();

}

// Cancel the current download if it is in progress

private void cancelDownload() {

if (!isDownloading) {

Toast.makeText(getApplicationContext(), "No download in progress", Toast.LENGTH_SHORT).show();

return;

}

DownloadManager downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);

downloadManager.remove(downloadId);

isDownloading = false;

Toast.makeText(getApplicationContext(), "Download cancelled", Toast.LENGTH_SHORT).show();

}

// Broadcast receiver to listen for download completion

private BroadcastReceiver downloadCompleteReceiver = new BroadcastReceiver() {

@Override

public void onReceive(Context context, Intent intent) {

if (intent.getAction().equals(DownloadManager.ACTION_DOWNLOAD_COMPLETE)) {

long id = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);

if (id == downloadId) {

isDownloading = false;

// Get the downloaded file path

DownloadManager downloadManager = (DownloadManager) context.getSystemService(DOWNLOAD_SERVICE);

Uri downloadedFileUri = downloadManager.getUriForDownloadedFile(downloadId);

// Open the downloaded file in an appropriate app

Intent openFileIntent = new Intent(Intent.ACTION_VIEW);

openFileIntent.setDataAndType(downloadedFileUri, "application/vnd.android.package-archive");

openFileIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

startActivity(openFileIntent);

}

}

}

};

}

```

使用指南

在 `AndroidManifest.xml` 中添加必要的权限和配置。

在 `MainActivity` 中添加一个 `EditText` 控件用于获取要详情下载教程的文件的 URL，以及两个按钮用于启动和取消详情下载教程。

注册一个广播接收器以监听详情下载教程完成事件。

4. 实现 `downloadFile()` 方法以请求文件详情下载教程。

5. 实现 `cancelDownload()` 方法以取消正在进行的详情下载教程。

6. 在广播接收器中，监听详情下载教程完成并打开已详情下载教程的文件。

运行

导入项目并运行它。

输入要详情下载教程的文件的 URL。

单击“详情下载教程”按钮开始详情下载教程。

4. 单击“取消”按钮取消详情下载教程（可选）。

5. 详情下载教程完成时，系统会自动打开已详情下载教程的文件。