Android Android 复制Assets文件到SD卡

Assets文件介绍

assets文件夹里面的文件都是保持原始的文件格式，需要用AssetManager以字节流的形式读取文件。

1. 先在Activity里面调用getAssets() 来获取AssetManager引用。
2. 再用AssetManager的open(String fileName, int accessMode) 方法则指定读取的文件以及访问模式就能得到输入流InputStream。
3. 然后就是用已经open file 的inputStream读取文件，读取完成后记得inputStream.close() 。
4. 调用AssetManager.close() 关闭AssetManager。

FileUtils1.java

package com.serenegiant;

import android.content.Context;
import android.os.Environment;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;

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

public class FileUtils1 {

    private static FileUtils1 instance;
    private static final int SUCCESS = 1;
    private static final int FAILED = 0;
    private Context context;
    private FileOperateCallback callback;
    private volatile boolean isSuccess;
    private String errorStr;

    public static FileUtils1 getInstance(Context context) {
        if (instance == null)
            instance = new FileUtils1(context);
        return instance;
    }

    private FileUtils1(Context context) {
        this.context = context;
    }

    private Handler handler = new Handler(Looper.getMainLooper()) {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if (callback != null) {
                if (msg.what == SUCCESS) {
                    callback.onSuccess();
                }
                if (msg.what == FAILED) {
                    callback.onFailed(msg.obj.toString());
                }
            }
        }
    };

    public FileUtils1 copyAssetsToSD(final String srcPath, final String sdPath) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                copyAssetsToDst(context, srcPath, sdPath);
                if (isSuccess)
                    handler.obtainMessage(SUCCESS).sendToTarget();
                else
                    handler.obtainMessage(FAILED, errorStr).sendToTarget();
            }
        }).start();
        return this;
    }

    public void setFileOperateCallback(FileOperateCallback callback) {
        this.callback = callback;
    }

    private void copyAssetsToDst(Context context, String srcPath, String dstPath) {
        try {
            String fileNames[] = context.getAssets().list(srcPath);
            if (fileNames.length > 0) {
                File file = new File(Environment.getExternalStorageDirectory(), dstPath);
                if (!file.exists()) file.mkdirs();
                for (String fileName : fileNames) {
                    if (!srcPath.equals("")) { // assets 文件夹下的目录
                        copyAssetsToDst(context, srcPath + File.separator + fileName, dstPath + File.separator + fileName);
                    } else { // assets 文件夹
                        copyAssetsToDst(context, fileName, dstPath + File.separator + fileName);
                    }
                }
            } else {
                File outFile = new File(Environment.getExternalStorageDirectory(), dstPath);
                InputStream is = context.getAssets().open(srcPath);
                FileOutputStream fos = new FileOutputStream(outFile);
                byte[] buffer = new byte[1024];
                int byteCount;
                while ((byteCount = is.read(buffer)) != -1) {
                    fos.write(buffer, 0, byteCount);
                }
                fos.flush();
                is.close();
                fos.close();
            }
            isSuccess = true;
        } catch (Exception e) {
            e.printStackTrace();
            errorStr = e.getMessage();
            isSuccess = false;
        }
    }

    public interface FileOperateCallback {
        void onSuccess();

        void onFailed(String error);
    }

}

调用代码

如果你需要将如图所示的FackModel下的文件复制到SD卡的app/FackModel目录下，则这样调用：

 //将assets目录下FaceModel，复制到SD
        FileUtils1.getInstance(getApplicationContext()).copyAssetsToSD("FaceModel","app/FaceModel");

如果你需要收到文件复制完成的时的回调，则使用如下代码：

 FileUtils1.getInstance(getApplicationContext()).copyAssetsToSD("FaceModel", "app/FaceModel").setFileOperateCallback(new FileUtils1.FileOperateCallback() {
            @Override
            public void onSuccess() {
                Log.e(TAG, "onSuccess: ------------------");
                

            }

            @Override
            public void onFailed(String error) {

            }
        });

---

在上面代码中，通过单例模式传入一个context获得FileUtils1实例，通过实例去调用copyAssetsToSD()方法，方法参数：

1. String srcPath 传入assets文件夹下的某个文件夹名，如上述FaceModel，可传入为空”“字符，则复制到SD后，默认将assets文件夹下所有文件复制；

2. String sdPath 传入你希望将文件复制到的位置，如SD卡下的“FaceModel”文件夹，则传入”FaceModel”