4.8

创建数据库

package com.android.test;
import java.io.ByteArrayOutputStream;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.provider.BaseColumns;
public class PictureDatabase extends SQLiteOpenHelper {

//数据库的字段
public static class PictureColumns implements BaseColumns {
public static final String PICTURE = "picture";
}

private Context mContext;

//数据库名
private static final String DATABASE_NAME = "picture.db";
//数据库版本号
private static final int DATABASE_Version = 1;
//表名
private static final String TABLE_NAME = "picture";

//创建数据库
public PictureDatabase (Context context) {
super(context, DATABASE_NAME, null, DATABASE_Version);
this.mContext = context;
}
//创建表并初始化表
@Override
public void onCreate (SQLiteDatabase db) {
String sql = "Create table " + TABLE_NAME + "(" + BaseColumns._ID
+ " integer primary key autoincrement," + PictureColumns.PICTURE
+ " blob not null);";
db.execSQL(sql);

//初始化
initDataBase(db,mContext);
}

//将转换后的图片存入到数据库中
private void initDataBase (SQLiteDatabase db, Context context) {
Drawable drawable = context.getResources().getDrawable(R.drawable.test_icon_resizer);
ContentValues cv = new ContentValues();
cv.put(PictureColumns.PICTURE, getPicture(drawable));
db.insert(TABLE_NAME, null, cv);
}
//将drawable转换成可以用来存储的byte[]类型
private byte[] getPicture(Drawable drawable) {
if(drawable == null) {
return null;
}
BitmapDrawable bd = (BitmapDrawable) drawable;
Bitmap bitmap = bd.getBitmap();
ByteArrayOutputStream os = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.PNG, 100, os);
return os.toByteArray();
}

//更新数据库
@Override
public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) {
String sql = " DROP TABLE IF EXISTS " + TABLE_NAME;
db.execSQL(sql);
onCreate(db);
}

}