Question

我是android的新手我想制作一个图像列表的应用程序，我希望将图像从相机保存到数据库并从数据库中检索。我想通过保存数据库的uri来做到这一点。我在下面做了办法 1.我将图像保存在文件中并进一步将其设置在图像视图中我要在数据库中保存图像uri。但我自己陷入了第一步。请帮助我。

package com.example.camerademo;

import java.io.File;
import java.net.URI;
import java.text.SimpleDateFormat;
import java.util.Date;

import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {
Button click;
ImageView image;
Intent intent;
final static int requestCode=100;
private static final int MEDIA_TYPE_IMAGE = 1;
private static final int MEDIA_TYPE_VIDEO = 2;
private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;
private static final int CAPTURE_VIDEO_ACTIVITY_REQUEST_CODE = 200;


    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        click= (Button) findViewById(R.id.clickbutton);
        image= (ImageView) findViewById(R.id.imageholder);
        intent =new Intent(MediaStore.ACTION_IMAGE_CAPTURE);



        Uri mediauri= getOutputMediaFileUri(MEDIA_TYPE_IMAGE);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, mediauri);
        click.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {

                startActivityForResult(intent, requestCode);

            }
        });

    }
    @Override
        protected void onActivityResult(int requestCode, int resultCode, Intent data) {
            // TODO Auto-generated method stub
            super.onActivityResult(requestCode, resultCode, data);




            if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
                if (resultCode == RESULT_OK) {
                    // Image captured and saved to fileUri specified in the Intent
                    Toast.makeText(this, "Image saved to:\n" +
                             data.getData(), Toast.LENGTH_LONG).show();
                    image.setImageURI(Uri.parse(data.getStringExtra(MediaStore.EXTRA_OUTPUT)));
                } else if (resultCode == RESULT_CANCELED) {
                    // User cancelled the image capture
                } else {
                    // Image capture failed, advise user
                }
            }

            if (requestCode == CAPTURE_VIDEO_ACTIVITY_REQUEST_CODE) {
                if (resultCode == RESULT_OK)
                    // Video captured and saved to fileUri specified in the Intent
                    Toast.makeText(this, "Video saved to:\n" +
                             data.getData(), Toast.LENGTH_LONG).show();
                } else if (resultCode == RESULT_CANCELED) {
                    // User cancelled the video capture
                } else {
                    // Video capture failed, advise user
                }
            }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;


    }


    private static Uri getOutputMediaFileUri(int type){
          return Uri.fromFile(getOutputMediaFile(type));
    }
    private static File getOutputMediaFile(int type){

        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                  Environment.DIRECTORY_PICTURES), "MyCameraApp");
            if (! mediaStorageDir.exists()){
            if (! mediaStorageDir.mkdirs()){
                Log.d("MyCameraApp", "failed to create directory");
                return null;
            }
        }

        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile;
        if (type == MEDIA_TYPE_IMAGE){
            mediaFile = new File(mediaStorageDir.getPath() + File.separator +
            "IMG_"+ timeStamp + ".jpg");
        } else if(type == MEDIA_TYPE_VIDEO) {
            mediaFile = new File(mediaStorageDir.getPath() + File.separator +
            "VID_"+ timeStamp + ".mp4");
        } else {
            return null;
        }

        return mediaFile;
    }

}

Answer 1

如果处理相当小的图像并且图像数量较少，则最好将图像作为BLOBS存储在数据库中。否则，如果您有大量的大图像，那么最好将图像保存在文件系统中并将其URI存储在数据库中

请阅读此链接以了解有关将图像字节[]插入数据库

的更多信息

How to store and retrieve a byte array (image data) to and from a SQLite database?

如何从文件/数据库中获取图像并在列表视图中显示？

1 个答案: