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这篇文章主要讲解了“Android怎么实现文件下载功能”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“Android怎么实现文件下载功能”吧！
<!-- 文件读写权限 --> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <!-- 访问内存 --> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
DownloadOkHttp 使用（无显示）
下载完成地址: /storage/emulated/0/小红书/xiaohongshu.apk
DownloadUtil.DownloadOkHttp.get().download(apk, Environment.getExternalStorageDirectory() + "/" + "小红书", new DownloadUtil.DownloadOkHttp.OnDownloadListener() {
@Override
public void onDownloadSuccess() {
Log.e("下载","成功");
}
@Override
public void onDownloading(int progress) {
Log.e("下载", String.valueOf(progress));
}
@Override
public void onDownloadFailed() {
Log.e("下载","失败");
}
});Download 使用（有显示）
下载完成地址: /小红书/小红书.apk
new DownloadUtil.Download(this, apk, "小红书.apk", "小红书");
dialog_progress
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:padding="@dimen/dp_20" android:orientation="vertical"> <ProgressBar android:id="@+id/id_progress" android:layout_width="match_parent" android:layout_height="wrap_content" /> <TextView android:id="@+id/id_text" android:layout_width="match_parent" android:layout_marginTop="10dp" android:gravity="right" android:text="0 %" android:layout_height="wrap_content"/> </LinearLayout>
**工具类DownloadUtil（两个实现方法，自己悟！！！）
package com.simon.util;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.TextView;
import com.simon.app.R;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import androidx.annotation.NonNull;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
/**
* 创建者： Simon
* 创建时间：2021/6/7 13:58
* 描述：文件下载
*/
public class DownloadUtil {
public static class DownloadOkHttp {
private static DownloadOkHttp downloadUtil;
private final OkHttpClient okHttpClient;
public static DownloadOkHttp get() {
if (downloadUtil == null) {
downloadUtil = new DownloadOkHttp();
}
return downloadUtil;
}
private DownloadOkHttp() {
okHttpClient = new OkHttpClient();
}
/**
*
* @param url 下载连接
* @param saveDir 储存下载文件的SDCard目录
* @param listener 下载监听
*/
public void download( String url, final String saveDir, final OnDownloadListener listener) {
Request request = new Request.Builder().url(url).build();
okHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
// 下载失败
listener.onDownloadFailed();
}
@Override
public void onResponse(Call call, Response response) throws IOException {
InputStream is = null;
byte[] buf = new byte[2048];
int len = 0;
FileOutputStream fos = null;
// 储存下载文件的目录
String savePath = isExistDir(saveDir);
try {
is = response.body().byteStream();
long total = response.body().contentLength();
File file = new File(savePath, getNameFromUrl(url));
fos = new FileOutputStream(file);
long sum = 0;
while ((len = is.read(buf)) != -1) {
fos.write(buf, 0, len);
sum += len;
int progress = (int) (sum * 1.0f / total * 100);
// 下载中
listener.onDownloading(progress);
}
fos.flush();
// 下载完成
listener.onDownloadSuccess();
} catch (Exception e) {
listener.onDownloadFailed();
} finally {
try {
if (is != null)
is.close();
} catch (IOException e) {
}
try {
if (fos != null)
fos.close();
} catch (IOException e) {
}
}
}
});
}
/**
* 判断下载目录是否存在
* @param saveDir
* @return
* @throws IOException
*/
private String isExistDir(String saveDir) throws IOException {
// 下载位置
File downloadFile = new File(Environment.getExternalStorageDirectory(), saveDir);
if (!downloadFile.mkdirs()) {
downloadFile.createNewFile();
}
String savePath = downloadFile.getAbsolutePath();
return savePath;
}
/**
* url
* 从下载连接中解析出文件名
*/
@NonNull
public static String getNameFromUrl(String url) {
return url.substring(url.lastIndexOf("/") + 1);
}
public interface OnDownloadListener {
/**
* 下载成功
*/
void onDownloadSuccess();
/**
* @param progress
* 下载进度
*/
void onDownloading(int progress);
/**
* 下载失败
*/
void onDownloadFailed();
}
}
public static class Download {
private String fileSavePath = "";//保存文件的本地路径
private String fileDownLoad_path = "";//下载的URL
private String mfileName = "";//下载的文件名字
private boolean mIsCancel = false;
private int mProgress;
private ProgressBar mProgressBar;
private TextView text;
private Dialog mDownloadDialog;
private final Context context;
private static final int DOWNLOADING = 1;
private static final int DOWNLOAD_FINISH = 2;
private Handler mUpdateProgressHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case DOWNLOADING:
// 设置进度条
mProgressBar.setProgress(mProgress);
text.setText(String.valueOf(mProgress));
break;
case DOWNLOAD_FINISH:
// 隐藏当前下载对话框
mDownloadDialog.dismiss();
}
}
};
/**
* 下载初始化
* @param context 上下文
* @param fileDownLoad_path 下载的URL
* @param mfileName 下载的文件名字
* @param fileSavePath 保存文件的本地路径
*/
public Download(Context context, String fileDownLoad_path, String mfileName, String fileSavePath) {
this.context = context;
this.fileDownLoad_path = fileDownLoad_path;
this.mfileName = mfileName;
this.fileSavePath = Environment.getExternalStorageDirectory() + "/" + fileSavePath;
showDownloadDialog();
}
/**
* 显示正在下载的对话框
*/
protected void showDownloadDialog() {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle("下载中");
View view = LayoutInflater.from(context).inflate(R.layout.dialog_progress, null);
mProgressBar = (ProgressBar) view.findViewById(R.id.id_progress);
text = view.findViewById(R.id.id_text);
builder.setView(view);
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// 隐藏当前对话框
dialog.dismiss();
// 设置下载状态为取消
mIsCancel = true;
}
});
mDownloadDialog = builder.create();
mDownloadDialog.show();
// 下载文件
downloadFile();
}
/**
* 下载文件
*/
private void downloadFile() {
new Thread(new Runnable() {
@Override
public void run() {
try {
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
File dir = new File(fileSavePath);
if (!dir.exists()){
dir.mkdirs();
}
// 下载文件
HttpURLConnection conn = (HttpURLConnection) new URL(fileDownLoad_path).openConnection();
conn.connect();
InputStream is = conn.getInputStream();
int length = conn.getContentLength();
File apkFile = new File(fileSavePath, mfileName);
FileOutputStream fos = new FileOutputStream(apkFile);
int count = 0;
byte[] buffer = new byte[1024];
while (!mIsCancel) {
int numread = is.read(buffer);
count += numread;
// 计算进度条当前位置
mProgress = (int) (((float) count / length) * 100);
// 更新进度条
mUpdateProgressHandler.sendEmptyMessage(DOWNLOADING);
// 下载完成
if (numread < 0) {
mUpdateProgressHandler.sendEmptyMessage(DOWNLOAD_FINISH);
break;
}
fos.write(buffer, 0, numread);
}
fos.close();
is.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
}
}感谢各位的阅读，以上就是“Android怎么实现文件下载功能”的内容了，经过本文的学习后，相信大家对Android怎么实现文件下载功能这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是亿速云，小编将为大家推送更多相关知识点的文章，欢迎关注！
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