将目录从资产复制到数据文件夹

Question

我想将一个非常大的目录从我的应用程序的assets文件夹复制到第一次运行应用程序的数据文件夹.我怎么做？我已经尝试了一些例子,但没有任何效果,所以我没有任何东西.我的目标是Android 4.2.

谢谢,Yannik

Answer 1

试试你的应用程序实例的代码(你应该写在清单中的类):此代码复制资产的内容/文件的文件夹到应用程序的缓存文件夹(你可以把其他路径copyAssetFolder()函数).仅在App首次启动时

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.app.Application;
import android.content.Context;
import android.content.res.AssetManager;
import android.preference.PreferenceManager;

public class MyApplication extends Application {
    private static Context  s_sharedContext;

    @Override
    public void onCreate () {
        super.onCreate();   
        if (!PreferenceManager.getDefaultSharedPreferences(
                getApplicationContext())
            .getBoolean("installed", false)) {
            PreferenceManager.getDefaultSharedPreferences(
                    getApplicationContext())
                .edit().putBoolean("installed", true).commit();

            copyAssetFolder(getAssets(), "files", 
                    "/data/data/com.example.appname/files");
        }
    }

    private static boolean copyAssetFolder(AssetManager assetManager,
            String fromAssetPath, String toPath) {
        try {
            String[] files = assetManager.list(fromAssetPath);
            new File(toPath).mkdirs();
            boolean res = true;
            for (String file : files)
                if (file.contains("."))
                    res &= copyAsset(assetManager, 
                            fromAssetPath + "/" + file,
                            toPath + "/" + file);
                else 
                    res &= copyAssetFolder(assetManager, 
                            fromAssetPath + "/" + file,
                            toPath + "/" + file);
            return res;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    private static boolean copyAsset(AssetManager assetManager,
            String fromAssetPath, String toPath) {
        InputStream in = null;
        OutputStream out = null;
        try {
          in = assetManager.open(fromAssetPath);
          new File(toPath).createNewFile();
          out = new FileOutputStream(toPath);
          copyFile(in, out);
          in.close();
          in = null;
          out.flush();
          out.close();
          out = null;
          return true;
        } catch(Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    private static 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);
        }
    }

}