如何在Sqlite中将图像存储为blob以及如何检索它?
我想存储一个图像(从URL)到一个SQLite数据库。
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); }
为了检索图像:
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);
所以在这里我得到了null
。
在我的数据库中,图像的值存储为: Image=[B@43e5ac48]
这里是我用于我的应用程序的代码
这段代码将从url中获取图片,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; }
要保存图像到数据库我使用这个代码。
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; } }
最后把这个图像加载到一个imageview
logoImage.setImageBitmap(BitmapFactory.decodeByteArray( currentAccount.accImage, 0,currentAccount.accImage.length));
在DBAdaper即数据库帮助类中声明这样的表
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);";
像这样插入值,
首先将图像转换为字节[]
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); }
将字节[]转换为图像
ByteArrayInputStream imageStream = new ByteArrayInputStream(photo); Bitmap theImage= BitmapFactory.decodeStream(imageStream);
我认为这个内容可能会解决你的问题
在insert()
public void insert(String tableImg, Object object, ContentValues dataToInsert) { db.insert(tablename, null, dataToInsert); }
希望它可以帮助你。
你也可能想要对base64进行编码和解码
function uncompress(str:String):ByteArray { import mx.utils.Base64Decoder; var dec:Base64Decoder = new Base64Decoder(); dec.decode(str); var newByteArr:ByteArray=dec.toByteArray(); return newByteArr; } // Compress a ByteArray into a Base64 String. function compress(bytes:ByteArray):String { import mx.utils.Base64Decoder; //Transform String in a ByteArray. import mx.utils.Base64Encoder; //Transform ByteArray in a readable string. var enc:Base64Encoder = new Base64Encoder(); enc.encodeBytes(bytes); return enc.drain().split("\n").join(""); }
为一个离子项目
var imgURI =“”; var imgBBDD =“”; // sqllite保存 函数takepicture(){ var options = { 质量:75, destinationType:Camera.DestinationType.DATA_URL, sourceType:Camera.PictureSourceType.CAMERA, allowEdit:true, encodingType:Camera.EncodingType.JPEG, targetWidth:300, targetHeight:300, popoverOptions:CameraPopoverOptions, saveToPhotoAlbum:false }; $ cordovaCamera.getPicture(options).then(function(imageData){ imgURI =“data:image / jpeg; base64,”+ imageData; imgBBDD = imageData; },函数(err){ // 发生错误。 向用户显示一条消息 }); }
现在我们把imgBBDD放到SqlLite中
函数saveImage = function(theId,themage){ var insertQuery =“INSERT INTO images(id,image)VALUES(”+ theId +“,'”+ theimage +“');” 的console.log( '>>>>>>>'); DDBB.SelectQuery(insertQuery) .then(function(result){ console.log(“保存图片”); }) .catch(function(err) { deferred.resolve(ERR); 返回cb(err); }); }
服务器端(PHP)
$ request = file_get_contents(“php:// input”); //获取原始数据 $ dades = json_decode($ request,true); // true返回数组 如果($ dades == “”){ $ array = array(); $ array ['error'] = -1; $ array ['descError'] =“获取文件时出错”; $ array ['logError'] =''; 回声json_encode($数组); 出口; } //将图像再次发送到客户端 标题('Content-Type:image / jpeg'); 回声“;
byte[] byteArray = rs.getBytes("columnname"); Bitmap bm = BitmapFactory.decodeByteArray(byteArray, 0 ,byteArray.length);