我是Android Studio的新手，我在获取已存储到数据库中的图像时遇到了一些麻烦，然后将它们显示到GridView中。有没有办法可以获取存储在数据库中的图像数量，然后逐个显示它们，每个图像都在GridView中的不同单元格中？到目前为止，这是我的代码：
NewsAddImageActivity类
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.Toast;
import java.io.ByteArrayOutputStream;
public class NewsAddImageActivity extends AppCompatActivity {
//public MyDatabaseHelper dbHelper;
MyDatabaseHelper dbHelper = new MyDatabaseHelper(this);
private static int RESULT_LOAD_IMG = 1;
String imgDecodableString;
Bitmap bitmap;
int tabNo;
Tab1Class t1;
Tab2Class t2;
Tab3Class t3;
Cursor cursor;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_newsaddimage);
final ImageButton imageButton = (ImageButton) findViewById(R.id.imageButton);
imageButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
loadImagefromGallery(v);
}
});
Button submit = (Button) findViewById(R.id.addButton);
submit.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
dbHelper.addEntry(dbHelper.getBytes(bitmap)); //add image to database
byte[] image = cursor.getBlob(1); //get image from database as byte
dbHelper.getImage(image); //converts byte to bitmap
if(tabNo==0){
//place image in the grid view of tab1
}else if(tabNo==1) {
//place image in the grid view of tab2
}else if(tabNo==2){
//place image in the grid view of tab3
}
finish();
Toast.makeText(getApplicationContext(),"Added",Toast.LENGTH_LONG).show();
}
});
Button cancel = (Button) findViewById(R.id.cancelButton);
cancel.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
finish();
Toast.makeText(getApplicationContext(),"Cancelled",Toast.LENGTH_LONG).show();
}
});
}
private byte[] imageButtonToByte(ImageButton image){
Bitmap bitmap=((BitmapDrawable)image.getDrawable()).getBitmap();
ByteArrayOutputStream stream=new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray=stream.toByteArray();
return byteArray;
}
public void loadImagefromGallery(View view) {
// Create intent to Open Image applications like Gallery, Google Photos
Intent galleryIntent = new Intent(Intent.ACTION_PICK,
android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
// Start the Intent
startActivityForResult(galleryIntent, RESULT_LOAD_IMG);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
try {
// When an Image is picked
if (requestCode == RESULT_LOAD_IMG && resultCode == RESULT_OK
&& null != data) {
// Get the Image from data
Uri selectedImage = data.getData();
String[] filePathColumn = {MediaStore.Images.Media.DATA};
// Get the cursor
Cursor cursor = getContentResolver().query(selectedImage,
filePathColumn, null, null, null);
// Move to first row
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
imgDecodableString = cursor.getString(columnIndex);
cursor.close();
ImageButton imageButton = (ImageButton) findViewById(R.id.imageButton);
bitmap = ((BitmapDrawable) imageButton.getDrawable()).getBitmap();
// Set the Image in ImageView after decoding the String
imageButton.setImageBitmap(BitmapFactory
.decodeFile(imgDecodableString));
} else {
Toast.makeText(this, "You haven't picked Image",
Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(this, "Something went wrong", Toast.LENGTH_LONG)
.show();
}
}
public void getTab(int num){
switch(num) {
case 0: tabNo=0;
case 1: tabNo=1;
case 2: tabNo=2;
}
}
}
MyDatabaseHelper Class
package com.example.mobilecomputingapplication;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import java.io.ByteArrayOutputStream;
public class MyDatabaseHelper extends SQLiteOpenHelper {
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "ImagesDB";
// Table Names
private static final String DB_TABLE = "imageTable";
// column names
private static final String KEY_NAME = "image_name";
private static final String KEY_IMAGE = "image_data";
// Table create statement
private static final String CREATE_TABLE_IMAGE = "CREATE TABLE " + DB_TABLE + "("+
KEY_NAME + " TEXT," +
KEY_IMAGE + " BLOB);";
public MyDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
// creating table
db.execSQL(CREATE_TABLE_IMAGE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// on upgrade drop older tables
db.execSQL("DROP TABLE IF EXISTS " + DB_TABLE);
// create new table
onCreate(db);
}
/* public void addEntry( String name, byte[] image) throws SQLiteException {
SQLiteDatabase database = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(KEY_NAME, name);
cv.put(KEY_IMAGE, image);
database.insert( DB_TABLE, null, cv );
}*/
public void addEntry( byte[] image) throws SQLiteException {
SQLiteDatabase database = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(KEY_IMAGE, image);
database.insert( DB_TABLE, null, cv );
}
// convert from bitmap to byte array
public static byte[] getBytes(Bitmap bitmap) {
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 0, stream);
return stream.toByteArray();
}
// convert from byte array to bitmap
public static Bitmap getImage(byte[] image) {
return BitmapFactory.decodeByteArray(image, 0, image.length);
}
}
答案 0 :(得分：0)
你可以创建一个你想要选择保存在db＆lt;中的图像位图。不保存图像保存图像的URI（路径），如下所示。在此代码中，所选图像是一个保存所选图像的数组。你应该在Dbhelper中插入图像的方法并传递这样的字符串。
Bitmap bitmap = thumbnails[i];
Uri uri = Utility.getImageUri(getContext(),bitmap);
byte[] path = Utility.getBytes(bitmap);
cnt++;
selecteddimages.add(uri);
String s = uri.toString();
databaseHelper.insertContact(s);
DBHELPER method of insert
public void insertContact (String name) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("name", name);
long result=db.insert("images", null, contentValues);
if (result==-1){
Toast.makeText(context,"not save",Toast.LENGTH_SHORT).show();
}else {
Toast.makeText(context,"save",Toast.LENGTH_SHORT).show();
}
}
UTILITIES CLass for getimage URI
public static byte[] getBytes(Bitmap bitmap) {
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 0, stream);
return stream.toByteArray();
}
public static Uri getImageUri(Context inContext, Bitmap inImage) {
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
inImage.compress(Bitmap.CompressFormat.JPEG, 100, bytes);
String path = MediaStore.Images.Media.insertImage(inContext.getContentResolver(), inImage, "title", null);
return Uri.parse(path);
}