srcRelPath is the relative path of the source file relative to assets, and dstAbsPath is the absolute path of the target file.
When the target file already exists, if forceCopy is true, it will be overwritten; otherwise it will be skipped.
import android.content.Context;
import android.content.res.AssetManager;
import android.util.Log;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
public class AssetHelper {
private static final String TAG = AssetHelper.class.getSimpleName();
private AssetHelper() {
}
public static byte[] getAssetFileData(Context context, String fileName) {
try (InputStream in = context.getResources().getAssets()
.open(fileName, AssetManager.ACCESS_STREAMING)) {
final int size = in.available();
byte[] data = new byte[size];
in.read(data, 0, size);
return data;
} catch (IOException e) {
Log.e(TAG, "getAssetFileData: " + e);
return null;
}
}
public static boolean copyAssetFiles(Context context, String assetRelPath, String dstAbsPath,
boolean forceCopy) {
AssetManager assets = context.getResources().getAssets();
return copyAssetFiles(assets, assetRelPath, dstAbsPath, forceCopy);
}
private static boolean copyAssetFiles(AssetManager assets, String srcRelPath, String dstAbsPath,
boolean forceCopy) {
String[] subFiles;
try {
subFiles = assets.list(srcRelPath);
} catch (IOException e) {
Log.e(TAG, "copyAssetFiles: " + e);
return false;
}
if (subFiles.length == 0) {
return copyAssetFile(assets, srcRelPath, dstAbsPath, forceCopy);
} else {
File dstDir = new File(dstAbsPath);
if (!dstDir.isDirectory()) {
if (!deleteFileOrDir(dstDir)) {
Log.e(TAG, "copyAssetFiles: Can not delete " + dstDir.getAbsolutePath());
return false;
}
if (!dstDir.mkdirs()) {
Log.e(TAG, "copyAssetFiles: Can not create " + dstDir.getAbsolutePath());
return false;
}
}
boolean result = true;
for (String subFile : subFiles) {
result &= copyAssetFiles(assets, srcRelPath + File.separator + subFile,
dstAbsPath + File.separator + subFile, forceCopy);
}
return result;
}
}
private static boolean copyAssetFile(AssetManager assets, String srcRelPath, String dstAbsPath,
boolean forceCopy) {
File file = new File(dstAbsPath);
if (file.isFile() && !forceCopy) {
return true;
}
if (!deleteFileOrDir(file)) {
Log.e(TAG, "copyAssetFile: Can not delete " + file.getAbsolutePath());
return false;
}
try (InputStream is = assets.open(srcRelPath, AssetManager.ACCESS_STREAMING);
DataInputStream dis = new DataInputStream(is);
FileOutputStream fos = new FileOutputStream(file);
DataOutputStream dos = new DataOutputStream(fos);) {
final int size = 1024;
byte[] buffer = new byte[size];
int len = 0;
while ((len = dis.read(buffer, 0, size)) != -1) {
dos.write(buffer, 0, len);
dos.flush();
}
return true;
} catch (IOException e) {
Log.e(TAG, "copyAssetFile: " + e);
return false;
}
}
public static boolean deleteFileOrDir(File file) {
if (!file.exists()) {
return true;
}
if (file.isFile()) {
return file.delete();
}
// file.isDirectory()
File[] subFiles = file.listFiles();
boolean subDeleted = true;
if (subFiles != null) {
for (File subFile : subFiles) {
subDeleted &= deleteFileOrDir(subFile);
}
}
return subDeleted ? file.delete() : false;
}
}