SQLite的使用------图片存储
在上篇有说到SQLite的文本存储，文本的增删改查，在本篇中主要说SQLite对单张图片的存储。
简单介绍：
SQLiteOpenHelper是一个抽象类。
SQLiteOpenHelper中有两个抽象方法，分别是onCreate()和onUpgrade()。
SQLiteOpenHelper中还有两个非常重要的实例方法，getReadableDatabase()和getWritableDatabase()。
在文章最后仍然会附上DEMO.
先附上一张图
一、此例与文本例互相独立，继承 SQLiteOpenHelper 类实现的 dbHelper 类。
public class BitmpUtil extends SQLiteOpenHelper {
public BitmpUtil(Context context) {
super(context, "djf", null, 2);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("Create table img ( id INTEGER PRIMARY KEY AUTOINCREMENT,uname TEXT,uimgae BLOB );");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}二、主界面中选择相册中图片，存储，预览
public class MainActivity extends Activity {
private Button btnSave, btnQuery;
private ImageView selectIcon;
private ImageView showIcon;
/*数据库操作*/
private BitmpUtil bu;
private Bitmap bit;
/*数据库操作*/
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bu = new BitmpUtil(MainActivity.this);
btnSave = (Button) findViewById(R.id.save);
btnQuery = (Button) findViewById(R.id.query);
selectIcon = (ImageView) findViewById(R.id.iv_icon);
showIcon = (ImageView) findViewById(R.id.iv_showIcon);
/**
* 选择图片
*/
selectIcon.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(Intent.ACTION_PICK, null);
intent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
"image/*");
startActivityForResult(intent, 0x1);
}
});
/**
* 增加
*/
btnSave.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = bu.getWritableDatabase();
ContentValues values = new ContentValues();
final ByteArrayOutputStream os = new ByteArrayOutputStream();
bit.compress(Bitmap.CompressFormat.PNG, 100, os);
values.put("uimgae", os.toByteArray());
values.put("uname", "zhangsan");
db.insert("img", null, values);
db.close();
Toast.makeText(MainActivity.this, "Success!", Toast.LENGTH_SHORT).show();
}
});
/**
* 显示图片
*/
btnQuery.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = null;
db = bu.getReadableDatabase();
Cursor c = db.query("img", new String[]{"id", "uname", "uimgae"}, "uname=?", new String[]{"zhangsan"}, null, null, null);
while (c.moveToNext()) {
String id = c.getString(c.getColumnIndex("id"));
String name = c.getString(c.getColumnIndex("uname"));
byte[] in = c.getBlob(c.getColumnIndex("uimgae"));
Bitmap bit = BitmapFactory.decodeByteArray(in, 0, in.length);
showIcon.setImageBitmap(bit);
}
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 0x1 && resultCode == RESULT_OK) {
Uri u = data.getData();
ContentResolver cr = MainActivity.this.getContentResolver();
try {
bit = BitmapFactory.decodeStream(cr.openInputStream(u));
selectIcon.setImageBitmap(bit);
} catch (Exception e) {
e.printStackTrace();
}
}
super.onActivityResult(requestCode, resultCode, data);
}
三、存储核心代码
SQLiteDatabase db = bu.getWritableDatabase();
ContentValues values = new ContentValues();
final ByteArrayOutputStream os = new ByteArrayOutputStream();
bit.compress(Bitmap.CompressFormat.PNG, 100, os);
values.put("uimgae", os.toByteArray());
values.put("uname", "zhangsan");
db.insert("img", null, values);
db.close();SQLiteDatabase db = bu.getWritableDatabase();获取数据库，使用ContentValues的对象进行数据插入，使用流写入，最后关闭数据库。四、读取存储中图片预览
SQLiteDatabase db = null;
db = bu.getReadableDatabase();
Cursor c = db.query("img", new String[]{"id", "uname", "uimgae"}, "uname=?", new String[]{"zhangsan"}, null, null, null);
while (c.moveToNext()) {
String id = c.getString(c.getColumnIndex("id"));
String name = c.getString(c.getColumnIndex("uname"));
byte[] in = c.getBlob(c.getColumnIndex("uimgae"));
Bitmap bit = BitmapFactory.decodeByteArray(in, 0, in.length);
showIcon.setImageBitmap(bit);
}
}
});主要代码已贴
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