如何存储或保存，并在本地检索多个远程图像 [英] How to store or save and retrieve multiple remote images locally

问题描述

我要寻找一个在Android的解决方案来存储远程图像（从符检索到的URL）插入本地（SD卡或sqlite的分贝或高速缓存），使图像可以在离线模式下也可以显示。
因为我要在通话过程中，每次显示图片。

I am looking for a solution in Android to store remote images (URLs retrieved from webservices) into the local (SDcard or Sqlite db or cache) so the images can be displayed in offline-mode too. because I want to display each time a picture during a call.

是否有任何解决方案？

推荐答案

请按照下列步骤操作（只有一个图像检索一次）：

Please follow these steps (for only one image retrieval at a time):

1. 从URL中检索图像作为位图。


2. 转换位图到字节数组中。


3. 存储字节数组到的SQLite数据库表的BLOB字段。


4. 从SQLite的数据库表获取一滴。


5. 转换的Blob字节数组。


6. 转换字节数组转换为位图。


7. 最后，设置位图作为图像到活动图像映射。

公共类ImageStoreAndRetrievalActivity延伸活动{

public class ImageStoreAndRetrievalActivity extends Activity {

private ImageView imageView;
private DatabaseHandler dbHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_image_store);
    imageView = (ImageView)findViewById(R.id.imageView1);
    dbHandler = new DatabaseHandler(getApplicationContext());       
    new MyThread("http://www.fnordware.com/superpng/pnggrad8rgb.png");
    imageView.setImageBitmap(dbHandler.getBitmap(1));  // here 1 is id for the image into tbl_blob table in SQLite DB.
}

public class MyThread implements Runnable {
    private String url;
    private Bitmap bitmap = null;
    private Thread th;
    public MyThread(String url) {
        this.url = url;
        th = new Thread(this);
        th.start();
        try {
            th.join();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public void run() {
        URL fileUrl = null;  

        try {  
            fileUrl = new URL(url);  
            HttpURLConnection conn = (HttpURLConnection) fileUrl.openConnection();  
            conn.setConnectTimeout(0);  
            conn.setDoInput(true);  
            conn.connect();  
            InputStream is = conn.getInputStream();  
            bitmap = BitmapFactory.decodeStream(is);  
            is.close();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }   
        dbHandler.insertBitmap(bitmap);
        Log.i("URL", url);
    }

}

}

    public static final String DATABASE_NAME = "blobdb";
    public static final int DATABASE_VERSION = 1;
    public static final String CREATE_BLOB_TABLE = "CREATE TABLE IF NOT EXISTS tbl_blob " + "(id INTEGER PRIMARY KEY AUTOINCREMENT, img BLOB NOT NULL, description TEXT NULL)";

公共类数据库处理器扩展SQLiteOpenHelper
{
    私人上下文的背景下;

public class DatabaseHandler extends SQLiteOpenHelper { private Context context;

public DatabaseHandler(Context context) 
{
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    this.context = context;
}

// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) 
{
    // create all tables in 'btlocdb'
    createTables(db);
}

/** create all tables in 'btlocdb'.
 * @param db
 */
public void createTables(SQLiteDatabase db) {       
    db.execSQL(CREATE_BLOB_TABLE);
}

// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Drop older table if existed
    //db.execSQL("DROP TABLE IF EXISTS " + Consts.Table.DATABASE_NAME);

    // Create tables again
    //onCreate(db);
}

public void insertBitmap(Bitmap bm) 
{

    ByteArrayOutputStream out = new ByteArrayOutputStream();
    bm.compress(Bitmap.CompressFormat.PNG, 100, out);
    byte[] buffer=out.toByteArray();

    SQLiteDatabase db = this.getWritableDatabase();


    // Starts the transaction.
    db.beginTransaction();
    ContentValues values;        
    try 
    {
        values = new ContentValues();
        values.put("img", buffer); 
        values.put("description", "This is a description"); 
        // Inserting Row
        long i = db.insert("tbl_blob", null, values);
        Log.i("Insert", i + "");
        // Insert or update data into database successfully.
        db.setTransactionSuccessful();                                    
    }       
    catch (SQLiteException e) 
    {
        e.printStackTrace();
    }                      
    finally
    {
        db.endTransaction(); // Ending the transaction.
        db.close(); // Closing database connection
    }
}

public Bitmap getBitmap(int id){
    Bitmap bm = null;
    SQLiteDatabase db = this.getWritableDatabase();
    // Starts the transaction.
    db.beginTransaction();
    try 
    {                       
        String selectQuery = "select * from tbl_blob where id = " + id;
        Cursor cursor = db.rawQuery(selectQuery, null);
        Log.i("Cursor", cursor.getCount() + "");        
        if(cursor.getCount() > 0)
        {

            if (cursor.moveToFirst()) {
                do {                        
                    byte[] blob = cursor.getBlob(cursor.getColumnIndex("img"));
                    ByteArrayInputStream imageStream = new ByteArrayInputStream(blob);
                    bm = BitmapFactory.decodeStream(imageStream);
                } while (cursor.moveToNext());
            }               
        }                   
        db.setTransactionSuccessful();  
    }       
    catch (SQLiteException e) 
    {
        e.printStackTrace();
    }                      
    finally
    {
        db.endTransaction(); // Ending the transaction.
        db.close(); // Closing database connection
    }
    return bm;      
}

}

希望这会帮助你！
让我知道如果您有任何关于此问题的任何查询。谢谢..

Hope this will help you!!! Let me know if you have any query regarding this issue. Thanks..

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