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
你可以用Kotlin在几个步骤中做到这一点,在这里我只复制几个文件,而不是所有从资产到我的应用程序文件目录。
private fun copyRelatedAssets() {
val assets = arrayOf("myhome.html", "support.css", "myscript.js", "style.css")
assets.forEach {
val inputStream = requireContext().assets.open(it)
val nameSplit = it.split(".")
val name = nameSplit[0]
val extension = nameSplit[1]
val path = inputStream.getFilePath(requireContext().filesDir, name, extension)
Log.v(TAG, path)
}
}
这是扩展函数,
fun InputStream.getFilePath(dir: File, name: String, extension: String): String {
val file = File(dir, "$name.$extension")
val outputStream = FileOutputStream(file)
this.copyTo(outputStream, 4096)
return file.absolutePath
}
洛格猫
/data/user/0/com.***.***/files/myhome.html
/data/user/0/com.***.***/files/support.css
/data/user/0/com.***.***/files/myscript.js
/data/user/0/com.***.***/files/style.css
其他回答
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。
在Kotlin中,这可以用一行完成!
为InputStream添加扩展乐趣
fun InputStream.toFile(to: File){
this.use { input->
to.outputStream().use { out->
input.copyTo(out)
}
}
}
然后使用它
MainActivity.kt
assets.open("test.zip").toFile(File(filesDir,"test.zip"))
使用这个问题答案中的一些概念,我编写了一个名为assetcopyer的类来简化复制/assets/。它在github上可用,可以通过jitpack.io访问:
new AssetCopier(MainActivity.this)
.withFileScanning()
.copy("tocopy", destDir);
详情见https://github.com/flipagram/android-assetcopier。
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。
import android.app.Activity;
import android.content.Intent;
import android.content.res.AssetManager;
import android.net.Uri;
import android.os.Environment;
import android.os.Bundle;
import android.util.Log;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
copyReadAssets();
}
private void copyReadAssets()
{
AssetManager assetManager = getAssets();
InputStream in = null;
OutputStream out = null;
String strDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)+ File.separator + "Pdfs";
File fileDir = new File(strDir);
fileDir.mkdirs(); // crear la ruta si no existe
File file = new File(fileDir, "example2.pdf");
try
{
in = assetManager.open("example.pdf"); //leer el archivo de assets
out = new BufferedOutputStream(new FileOutputStream(file)); //crear el archivo
copyFile(in, out);
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch (Exception e)
{
Log.e("tag", e.getMessage());
}
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.parse("file://" + Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + File.separator + "Pdfs" + "/example2.pdf"), "application/pdf");
startActivity(intent);
}
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);
}
}
}
修改部分代码,如下所示:
out = new BufferedOutputStream(new FileOutputStream(file));
前面的例子是针对pdf文件的,如果是。txt
FileOutputStream fos = new FileOutputStream(file);
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