Android实现文件下载

前言

总体思路：下载文件到应用缓存路径，在相册创建文件夹，Copy过去，通知相册刷新。

下载文件到APP缓存路径，这样可避免Android高版本读取本地权限问题，

准备

implementation 'com.squareup.okhttp3:okhttp:3.6.0'
implementation 'com.squareup.okio:okio:1.11.0'

调用

url：文件url

path：储存的路径

应用缓存路径：getExternalCacheDir().getPath()

DownloadUtil.get().download(url, path, new DownloadUtil.OnDownloadListener() {
            @Override
            public void onDownloadSuccess(File file) {
                //下载成功
                handler.sendEmptyMessage(1);
            }

            @Override
            public void onDownloading(int progress) {
                //进度条
                handler.sendEmptyMessage(progress);
            }

            @Override
            public void onDownloadFailed() {
                //下载失败
                handler.sendEmptyMessage(-1);
            }
        });

复制到相册目录

DownloadUtil.createFiles(downLoadFile);

通知相册刷新

DownloadUtil.updateDCIM(this,downloadFile);

工具类

/**
 * 下载工具类
 * martin
 * 2021.7.21
 */
public class DownloadUtil {
    private static final String TAG = DownloadUtil.class.getName();
    private static DownloadUtil downloadUtil;
    private final OkHttpClient okHttpClient;

    public static DownloadUtil get() {
        if (downloadUtil == null) {
            downloadUtil = new DownloadUtil();
        }
        return downloadUtil;
    }

    private DownloadUtil() {
        okHttpClient = new OkHttpClient();
    }

    /**
     * 复制单个文件
     *
     * @param oldPath$Name String 原文件路径+文件名 如：data/user/0/com.test/files/abc.txt
     * @param newPath$Name String 复制后路径+文件名 如：data/user/0/com.test/cache/abc.txt
     * @return <code>true</code> if and only if the file was copied;
     * <code>false</code> otherwise
     */
    public static boolean copyFile(String oldPath$Name, String newPath$Name) {
        try {
            File oldFile = new File(oldPath$Name);
            if (!oldFile.exists()) {
                Log.e("--Method--", "copyFile:  oldFile not exist.");
                return false;
            } else if (!oldFile.isFile()) {
                Log.e("--Method--", "copyFile:  oldFile not file.");
                return false;
            } else if (!oldFile.canRead()) {
                Log.e("--Method--", "copyFile:  oldFile cannot read.");
                return false;
            }

            /* 如果不需要打log，可以使用下面的语句
            if (!oldFile.exists() || !oldFile.isFile() || !oldFile.canRead()) {
                return false;
            }
            */

            FileInputStream fileInputStream = new FileInputStream(oldPath$Name);
            FileOutputStream fileOutputStream = new FileOutputStream(newPath$Name);
            byte[] buffer = new byte[1024];
            int byteRead;
            while (-1 != (byteRead = fileInputStream.read(buffer))) {
                fileOutputStream.write(buffer, 0, byteRead);
            }
            fileInputStream.close();
            fileOutputStream.flush();
            fileOutputStream.close();
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 通知相册更新
     *
     * @param context
     * @param newFile
     */
    public void updateDCIM(Context context, File newFile) {
        File cameraPath = new File(dcimPath, "Camera");
        File imgFile = new File(cameraPath, newFile.getAbsolutePath());
        if (imgFile.exists()) {
            Uri uri = Uri.fromFile(imgFile);
            Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
            intent.setData(uri);
            context.sendBroadcast(intent);
        }
    }

    /**
     * url 下载连接
     * saveDir 储存下载文件的SDCard目录
     * listener 下载监听
     */
    public void download(final 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(file);
                } catch (Exception e) {
                    listener.onDownloadFailed();
                } finally {
                    try {
                        if (is != null)
                            is.close();
                    } catch (IOException e) {
                    }
                    try {
                        if (fos != null)
                            fos.close();
                    } catch (IOException e) {
                    }
                }
            }
        });
    }

    /**
     * saveDir
     * 判断下载目录是否存在
     */
    private static String isExistDir(String saveDir) throws IOException {
        // 下载位置
        File downloadFile = new File(saveDir);
        if (!downloadFile.mkdirs()) {
            downloadFile.createNewFile();
        }
        String savePath = downloadFile.getAbsolutePath();
        return savePath;
    }

    //系统相册路径
    static String dcimPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getAbsolutePath();

    /**
     * 创建文件夹
     */
    public static void createFiles(File oldFile) {
        try {
            File file = new File(isExistDir(dcimPath + "/xxx"));
            String newPath = file.getPath() + "/" + oldFile.getName();
            Log.d("TAG", "createFiles111: " + oldFile.getPath() + "--" + newPath);
            if (copyFile(oldFile.getPath(), newPath)) {
                Log.d("TAG", "createFiles222: " + oldFile.getPath() + "--" + newPath);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 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(File file);

        /**
         * @param progress 下载进度
         */
        void onDownloading(int progress);

        /**
         * 下载失败
         */
        void onDownloadFailed();
    }

}

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