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
基于Yoram Cohen的回答,这里有一个支持非静态目标目录的版本。
使用copyFileOrDir(getDataDir(), "")来写入应用程序内部存储文件夹/data/data/pkg_name/
Supports subfolders. Supports custom and non-static target directory Avoids copying "images" etc fake asset folders like private void copyFileOrDir(String TARGET_BASE_PATH, String path) { AssetManager assetManager = this.getAssets(); String assets[] = null; try { Log.i("tag", "copyFileOrDir() "+path); assets = assetManager.list(path); if (assets.length == 0) { copyFile(TARGET_BASE_PATH, 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(TARGET_BASE_PATH, p + assets[i]); } } } catch (IOException ex) { Log.e("tag", "I/O Exception", ex); } } private void copyFile(String TARGET_BASE_PATH, 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()); } }
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();
}
}
试试这个,它更简单,这将帮助你:
// Open your local db as the input stream
InputStream myInput = _context.getAssets().open(YOUR FILE NAME);
// Path to the just created empty db
String outFileName =SDCARD PATH + YOUR FILE NAME;
// Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
// transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
// Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
这就是我的个性化文本提取类,希望对大家有用。
package lorenzo.morelli.platedetector;
import android.content.Context;
import android.content.res.AssetManager;
import android.graphics.Bitmap;
import com.googlecode.tesseract.android.TessBaseAPI;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class TextExtractor {
private final Context context;
private final String dirName;
private final String language;
public TextExtractor(final Context context, final String dirName, final String language) {
this.context = context;
this.dirName = dirName;
this.language = language;
}
public String extractText(final Bitmap bitmap) {
final TessBaseAPI tessBaseApi = new TessBaseAPI();
final String datapath = this.context.getFilesDir()+ "/tesseract/";
checkFile(new File(datapath + this.dirName + "/"), datapath, this.dirName, this.language);
tessBaseApi.init(datapath, this.language);
tessBaseApi.setImage(bitmap);
final String extractedText = tessBaseApi.getUTF8Text();
tessBaseApi.end();
return extractedText;
}
private void checkFile(final File dir, final String datapath, final String dirName, final String language) {
//directory does not exist, but we can successfully create it
if (!dir.exists()&& dir.mkdirs()) {
copyFiles(datapath, dirName, language);
} //The directory exists, but there is no data file in it
if(dir.exists()) {
final String datafilepath = datapath + "/" + dirName + "/" + language + ".traineddata";
final File datafile = new File(datafilepath);
if (!datafile.exists()) {
copyFiles(datapath, dirName, language);
}
}
}
private void copyFiles(final String datapath, final String dirName, final String language) {
try {
//location we want the file to be at
final String filepath = datapath + "/" + dirName + "/" + language + ".traineddata";
//get access to AssetManager
final AssetManager assetManager = this.context.getAssets();
//open byte streams for reading/writing
final InputStream instream = assetManager.open(dirName + "/" + language + ".traineddata");
final OutputStream outstream = new FileOutputStream(filepath);
//copy the file to the location specified by filepath
byte[] buffer = new byte[1024];
int read;
while ((read = instream.read(buffer)) != -1) {
outstream.write(buffer, 0, read);
}
outstream.flush();
outstream.close();
instream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
要使用它,你需要训练过的数据文件。你可以从这个链接下载trainddata文件。
一旦你下载了你想要的traineddata文件,你需要在你的Android项目中创建一个名为assets的Android资源目录。在新创建的资产文件夹中,你需要创建一个名为“tessdata”的常规目录,在那里你可以放置你的训练数据文件。 最后你必须初始化MainActivity中的“TextExtractor”类。
final TextExtractor textExtractor = new TextExtractor(this, "tessdata", "eng");
第一个参数是上下文,第二个参数是刚刚创建的目录名,最后一个参数是刚刚下载的训练数据的语言。
要提取文本,你必须调用"extractText"方法:
final String text = textExtractor.extractText(imageWithText);
注意,extractText需要一个位图图像才能工作!! 你可以用这一行从你的可绘制文件中创建一个BitMap图像:
final BitMap image = BitmapFactory.decodeResource(getResources(), R.drawable.test_image);
如果你需要更多的支持,我建议你遵循这个有用的指南:https://github.com/SamVanRoy/Android_OCR_App
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);
}
}
使用AssetManager,它允许读取资产中的文件。然后使用常规的Java IO将文件写入sdcard。
谷歌是你的朋友,搜索一个例子。
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