我在资产文件夹里有几个文件。我需要把它们都复制到一个文件夹，比如/sdcard/folder。我想从一个线程中做这件事。我该怎么做?
当前回答
由于一些错误，上述解决方案无法工作:
目录创建失败 Android返回的资产也包含三个文件夹:图像，声音和webkit 增加了处理大文件的方法:在项目的资产文件夹中添加扩展名.mp3到文件，在复制目标文件时将没有.mp3扩展名
下面是代码(我留下了Log语句，但你现在可以删除它们):
final static String TARGET_BASE_PATH = "/sdcard/appname/voices/";
private void copyFilesToSdCard() {
copyFileOrDir(""); // copy all files in assets folder in my project
}
private void copyFileOrDir(String path) {
AssetManager assetManager = this.getAssets();
String assets[] = null;
try {
Log.i("tag", "copyFileOrDir() "+path);
assets = assetManager.list(path);
if (assets.length == 0) {
copyFile(path);
} else {
String fullPath = TARGET_BASE_PATH + path;
Log.i("tag", "path="+fullPath);
File dir = new File(fullPath);
if (!dir.exists() && !path.startsWith("images") && !path.startsWith("sounds") && !path.startsWith("webkit"))
if (!dir.mkdirs())
Log.i("tag", "could not create dir "+fullPath);
for (int i = 0; i < assets.length; ++i) {
String p;
if (path.equals(""))
p = "";
else
p = path + "/";
if (!path.startsWith("images") && !path.startsWith("sounds") && !path.startsWith("webkit"))
copyFileOrDir( p + assets[i]);
}
}
} catch (IOException ex) {
Log.e("tag", "I/O Exception", ex);
}
}
private void copyFile(String filename) {
AssetManager assetManager = this.getAssets();
InputStream in = null;
OutputStream out = null;
String newFileName = null;
try {
Log.i("tag", "copyFile() "+filename);
in = assetManager.open(filename);
if (filename.endsWith(".jpg")) // extension was added to avoid compression on APK file
newFileName = TARGET_BASE_PATH + filename.substring(0, filename.length()-4);
else
newFileName = TARGET_BASE_PATH + filename;
out = new FileOutputStream(newFileName);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch (Exception e) {
Log.e("tag", "Exception in copyFile() of "+newFileName);
Log.e("tag", "Exception in copyFile() "+e.toString());
}
}
编辑:更正了一个错位的“;”，这是抛出一个系统的“无法创建目录”错误。
其他回答
我知道这已经回答，但我有一个稍微更优雅的方式从资产目录复制到sdcard上的文件。它不需要“for”循环，而是使用文件流和通道来完成工作。
(注)如果使用任何类型的压缩文件，APK, PDF，…你可能想重命名文件扩展名之前插入到资产，然后重命名一旦你复制到SDcard)
AssetManager am = context.getAssets();
AssetFileDescriptor afd = null;
try {
afd = am.openFd( "MyFile.dat");
// Create new file to copy into.
File file = new File(Environment.getExternalStorageDirectory() + java.io.File.separator + "NewFile.dat");
file.createNewFile();
copyFdToFile(afd.getFileDescriptor(), file);
} catch (IOException e) {
e.printStackTrace();
}
一种复制文件而不必循环遍历它的方法。
public static void copyFdToFile(FileDescriptor src, File dst) throws IOException {
FileChannel inChannel = new FileInputStream(src).getChannel();
FileChannel outChannel = new FileOutputStream(dst).getChannel();
try {
inChannel.transferTo(0, inChannel.size(), outChannel);
} finally {
if (inChannel != null)
inChannel.close();
if (outChannel != null)
outChannel.close();
}
}
修改了@ danya的SO回答
private void copyAssets(String path, String outPath) {
AssetManager assetManager = this.getAssets();
String assets[];
try {
assets = assetManager.list(path);
if (assets.length == 0) {
copyFile(path, outPath);
} else {
String fullPath = outPath + "/" + path;
File dir = new File(fullPath);
if (!dir.exists())
if (!dir.mkdir()) Log.e(TAG, "No create external directory: " + dir );
for (String asset : assets) {
copyAssets(path + "/" + asset, outPath);
}
}
} catch (IOException ex) {
Log.e(TAG, "I/O Exception", ex);
}
}
private void copyFile(String filename, String outPath) {
AssetManager assetManager = this.getAssets();
InputStream in;
OutputStream out;
try {
in = assetManager.open(filename);
String newFileName = outPath + "/" + filename;
out = new FileOutputStream(newFileName);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
in.close();
out.flush();
out.close();
} catch (Exception e) {
Log.e(TAG, e.getMessage());
}
}
准备工作
在src /主/资产 添加名称折叠文件夹
使用
File outDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString());
copyAssets("fold",outDir.toString());
在外部目录中找到折叠资产内的所有文件和目录
这在Kotlin中是一种简洁的方式。
fun AssetManager.copyRecursively(assetPath: String, targetFile: File) {
val list = list(assetPath)
if (list.isEmpty()) { // assetPath is file
open(assetPath).use { input ->
FileOutputStream(targetFile.absolutePath).use { output ->
input.copyTo(output)
output.flush()
}
}
} else { // assetPath is folder
targetFile.delete()
targetFile.mkdir()
list.forEach {
copyRecursively("$assetPath/$it", File(targetFile, it))
}
}
}
基于Rohith Nandakumar的解决方案，我自己做了一些事情，从资产的子文件夹中复制文件。“资产/ MyFolder”)。此外，在尝试再次复制之前，我正在检查文件是否已经存在于sdcard中。
private void copyAssets() {
AssetManager assetManager = getAssets();
String[] files = null;
try {
files = assetManager.list("MyFolder");
} catch (IOException e) {
Log.e("tag", "Failed to get asset file list.", e);
}
if (files != null) for (String filename : files) {
InputStream in = null;
OutputStream out = null;
try {
in = assetManager.open("MyFolder/"+filename);
File outFile = new File(getExternalFilesDir(null), filename);
if (!(outFile.exists())) {// File does not exist...
out = new FileOutputStream(outFile);
copyFile(in, out);
}
} catch(IOException e) {
Log.e("tag", "Failed to copy asset file: " + filename, e);
}
finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
// NOOP
}
}
if (out != null) {
try {
out.close();
} catch (IOException e) {
// NOOP
}
}
}
}
}
private void copyFile(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int read;
while((read = in.read(buffer)) != -1){
out.write(buffer, 0, read);
}
}
由于一些错误，上述解决方案无法工作:
目录创建失败 Android返回的资产也包含三个文件夹:图像，声音和webkit 增加了处理大文件的方法:在项目的资产文件夹中添加扩展名.mp3到文件，在复制目标文件时将没有.mp3扩展名
下面是代码(我留下了Log语句，但你现在可以删除它们):
final static String TARGET_BASE_PATH = "/sdcard/appname/voices/";
private void copyFilesToSdCard() {
copyFileOrDir(""); // copy all files in assets folder in my project
}
private void copyFileOrDir(String path) {
AssetManager assetManager = this.getAssets();
String assets[] = null;
try {
Log.i("tag", "copyFileOrDir() "+path);
assets = assetManager.list(path);
if (assets.length == 0) {
copyFile(path);
} else {
String fullPath = TARGET_BASE_PATH + path;
Log.i("tag", "path="+fullPath);
File dir = new File(fullPath);
if (!dir.exists() && !path.startsWith("images") && !path.startsWith("sounds") && !path.startsWith("webkit"))
if (!dir.mkdirs())
Log.i("tag", "could not create dir "+fullPath);
for (int i = 0; i < assets.length; ++i) {
String p;
if (path.equals(""))
p = "";
else
p = path + "/";
if (!path.startsWith("images") && !path.startsWith("sounds") && !path.startsWith("webkit"))
copyFileOrDir( p + assets[i]);
}
}
} catch (IOException ex) {
Log.e("tag", "I/O Exception", ex);
}
}
private void copyFile(String filename) {
AssetManager assetManager = this.getAssets();
InputStream in = null;
OutputStream out = null;
String newFileName = null;
try {
Log.i("tag", "copyFile() "+filename);
in = assetManager.open(filename);
if (filename.endsWith(".jpg")) // extension was added to avoid compression on APK file
newFileName = TARGET_BASE_PATH + filename.substring(0, filename.length()-4);
else
newFileName = TARGET_BASE_PATH + filename;
out = new FileOutputStream(newFileName);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch (Exception e) {
Log.e("tag", "Exception in copyFile() of "+newFileName);
Log.e("tag", "Exception in copyFile() "+e.toString());
}
}
编辑:更正了一个错位的“;”，这是抛出一个系统的“无法创建目录”错误。
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