如何在Sqlite中将图像存储为blob以及如何检索它？

Question

我想将图像(从url)存储到sqlite数据库中.

为此,我使用:

db = new DataBase(getApplicationContext());
URL url = new URL("http://sree.cc/wp-content/uploads/schogini_team.png");
URLConnection ucon = url.openConnection();
InputStream is = ucon.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is,128);
ByteArrayBuffer barb= new ByteArrayBuffer(128);

int current = 0;
while ((current = bis.read()) != -1) {
    barb.append((byte) current);
}

ContentValues filedata= new ContentValues();

filedata.put(DataBase.IMG_SRC,barb.toByteArray());

db.insert(DataBase.Table_Img, null, filedata);

在Insert():

public void insert(String tableImg, Object object,
        ContentValues dataToInsert) {
    // TODO Auto-generated method stub
    String sql = "INSERT INTO "+tableImg+" ("+ID+","+IMG_SRC+") " +
            "VALUES ('"+1+"','"+dataToInsert+"')";
    db.execSQL(sql);
}

用于检索图像:

Cursor cursor = db.selectDataToShow(DataBase.Table_Img, DataBase.IMG_SRC);

byte[] imageByteArray=cursor.getBlob(cursor.getColumnIndex(DataBase.IMG_SRC));      
cursor.close();

ByteArrayInputStream imageStream = new ByteArrayInputStream(imageByteArray);
Bitmap theImage = BitmapFactory.decodeStream(imageStream);

System.out.println(">>>>>>>>>>>>>>>>>>>>>> "+theImage);

所以我得到了null.

在我的数据库中,图像的值存储为: Image=[B@43e5ac48]

Answer 1

这里是我用于我的应用程序的代码

此代码将从url获取图像并将其转换为字节数组

byte[] logoImage = getLogoImage(IMAGEURL);

private byte[] getLogoImage(String url){
     try {
             URL imageUrl = new URL(url);
             URLConnection ucon = imageUrl.openConnection();

             InputStream is = ucon.getInputStream();
             BufferedInputStream bis = new BufferedInputStream(is);

             ByteArrayBuffer baf = new ByteArrayBuffer(500);
             int current = 0;
             while ((current = bis.read()) != -1) {
                  baf.append((byte) current);
             }

             return baf.toByteArray();
     } catch (Exception e) {
          Log.d("ImageManager", "Error: " + e.toString());
     }
     return null;
}

要将图像保存到db,我使用了此代码.

 public void insertUser(){
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        String delSql = "DELETE FROM ACCOUNTS";
        SQLiteStatement delStmt = db.compileStatement(delSql);
        delStmt.execute();

        String sql = "INSERT INTO ACCOUNTS (account_id,account_name,account_image) VALUES(?,?,?)";
        SQLiteStatement insertStmt = db.compileStatement(sql);
        insertStmt.clearBindings();
        insertStmt.bindString(1, Integer.toString(this.accId));
        insertStmt.bindString(2,this.accName);
        insertStmt.bindBlob(3, this.accImage);
        insertStmt.executeInsert();
        db.close();
}

要检索图像,这是我使用的代码.

public Account getCurrentAccount() {
    SQLiteDatabase db = dbHelper.getWritableDatabase();
    String sql = "SELECT * FROM ACCOUNTS";
    Cursor cursor = db.rawQuery(sql, new String[] {});

    if(cursor.moveToFirst()){
        this.accId  = cursor.getInt(0);
        this.accName = cursor.getString(1);
        this.accImage = cursor.getBlob(2);
    }
    if (cursor != null && !cursor.isClosed()) {
        cursor.close();
    }
    db.close();
    if(cursor.getCount() == 0){
        return null;
    } else {
        return this;
    }
}

最后将此图像加载到imageview

logoImage.setImageBitmap(BitmapFactory.decodeByteArray( currentAccount.accImage, 
        0,currentAccount.accImage.length));

Answer 2

在DBAdaper即Data Base助手类中声明这样的表

 private static final String USERDETAILS=
    "create table userdetails(usersno integer primary key autoincrement,userid text not null ,username text not null,password text not null,photo BLOB,visibility text not null);";

插入这样的值,

首先将图像转换为byte []

ByteArrayOutputStream baos = new ByteArrayOutputStream();  
Bitmap bitmap = ((BitmapDrawable)getResources().getDrawable(R.drawable.common)).getBitmap();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);   
byte[] photo = baos.toByteArray(); 
db.insertUserDetails(value1,value2, value3, photo,value2);

在DEAdaper类中

 public long insertUserDetails(String uname,String userid, String pass, byte[] photo,String visibility) 
{
    ContentValues initialValues = new ContentValues();
    initialValues.put("username", uname);
    initialValues.put("userid",userid);
    initialValues.put("password", pass);
    initialValues.put("photo",photo);
    initialValues.put("visibility",visibility);
    return db.insert("userdetails", null, initialValues);
}

检索图像如下

Cursor cur=your query;
while(cur.moveToNext())
{
     byte[] photo=cur.getBlob(index of blob cloumn);
}

将byte []转换为图像

ByteArrayInputStream imageStream = new ByteArrayInputStream(photo);
Bitmap theImage= BitmapFactory.decodeStream(imageStream);

我认为这个内容可以解决您的问题