Question

我在按钮点击时从URL加载图像，并将其存储为位图。现在我想知道如何将下载的图像保存到SD卡以及系统中。

我试图通过以下方式实现：

package com.v3.thread.fetchImage;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;

public class MainThreadActivity extends Activity {
    ImageView imView;
    EditText ed1;
    Bitmap bmImg;
    Button bt, btSave;
    String imageUrl = "";
    int visibilty = 0;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.main);
        ed1 = (EditText) findViewById(R.id.edURL);
        btSave = (Button) findViewById(R.id.btnSave);

        bt = (Button) findViewById(R.id.btnLoad);
        bt.setOnClickListener(getImgListener);

        imView = (ImageView) findViewById(R.id.imview);
        Log.i("img already downloaded", "img");
        btSave.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                Log.i("img url", "Under Save");
                saveImage();
            }
        });
    }

    View.OnClickListener getImgListener = new View.OnClickListener() {

        public void onClick(View view) {
            // TODO Auto-generated method stub
            imageUrl = ed1.getText().toString();
            if (imageUrl.equals(""))

                Toast.makeText(getApplicationContext(), "Enter an URL first",   1000).show();       
downloadFile(imageUrl);
            Log.i("im url", imageUrl);
            btSave.setVisibility(visibilty);
        }

    };

    void downloadFile(String fileUrl) {
        URL myFileUrl = null;
        try {
            myFileUrl = new URL(fileUrl);
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        try {
            HttpURLConnection conn = (HttpURLConnection) myFileUrl
                    .openConnection();
            conn.setDoInput(true);
            conn.connect();
            InputStream is = conn.getInputStream();
            Log.i("im connected", "Download");
            bmImg = BitmapFactory.decodeStream(is);

            imView.setImageBitmap(bmImg);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    void saveImage() {
        File filename;
        try {
            String path = Environment.getExternalStorageDirectory().toString();
            Log.i("in save()", "after mkdir");
            new File(path + "/mvc/mvc").mkdir();
            filename = new File(path + "/mvc/mvc/var3.jpg");
            Log.i("in save()", "after file");
            FileOutputStream out = new FileOutputStream(filename);
            Log.i("in save()", "after outputstream");
            bmImg.compress(Bitmap.CompressFormat.JPEG, 90, out);
            out.flush();
            out.close();
            Log.i("in save()", "after outputstream closed");
            MediaStore.Images.Media.insertImage(getContentResolver(),
                    filename.getAbsolutePath(), filename.getName(),
                    filename.getName());
            bt.setText("Saved...");
            Toast.makeText(getApplicationContext(),
                    "File is Saved in  " + filename, 1000).show();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

从URL加载图片工作正常，但是当我按下保存按钮进行保存时，会抛出异常

java.io.FileNotFoundException：/mnt/sdcard/mvc/mvc/var3.image(No such 文件或目录）

那么如何正确地将图像保存到SD卡？

Answer 1

您需要首先创建要在其中创建文件的目录和子目录。我看到你使用了mkdir（）方法。试试mkdirs（），它应该可以工作。

Answer 2

在你的Manifest中添加WRITE_EXTERNAL_STORAGE android权限：

然后

BitmapDrawable drawable = (BitmapDrawable) mImageView.getDrawable();
Bitmap bitmap = drawable.getBitmap();

从SD卡获取目录（文件对象），例如：

File sdCardDirectory = Environment.getExternalStorageDirectory();

为图像存储创建特定文件：

File image = new File(sdCardDirectory, "download.png");

然后，

boolean success = false;

// Encode the file as a PNG image.
FileOutputStream outStream;
try {

    outStream = new FileOutputStream(image);
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, outStream); 
    /* 100 to keep full quality of the image */

    outStream.flush();
    outStream.close();
    success = true;
} catch (FileNotFoundException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}

if (success) {
    //Display Downloaded
} else {
   // display Error in Downloading
}

Android - 将下载的图像从URL保存到SD卡

2 个答案: