Android使用SQLiteDatabase直接存取数据与图像

Android使用SQLiteDatabase直接存取数据与图像的简单方法如下：

package com.test;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;

import com.test.R;

import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Bitmap.Config;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class SQLiteDatabaseTest extends Activity {
/** Called when the activity is first created. */
private Button btnSave;
private Button btnLoad;
private Button btnClear;
private ImageView imgView;
private ImageView imgView2;
private TextView txtView;
private Bitmap bmp;
private static SQLiteDatabase db;
private Context mContext;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

btnSave = (Button) findViewById(R.id.btnSave);
btnLoad = (Button) findViewById(R.id.btnLoad);
btnClear = (Button) findViewById(R.id.btnClear);
imgView = (ImageView) findViewById(R.id.imgView);
imgView2 = (ImageView) findViewById(R.id.imgView2);
txtView = (TextView) findViewById(R.id.txtView);
btnSave.setOnClickListener(new ClickEvent());
btnLoad.setOnClickListener(new ClickEvent());
btnClear.setOnClickListener(new ClickEvent());
imgView2.setImageBitmap(BitmapFactory.decodeResource(getResources(),
R.drawable.bg));
mContext = SQLiteDatabaseTest.this;

// 创建数据库文件
File path = mContext.getDir("databases", Context.MODE_WORLD_WRITEABLE);
path = new File(path, "test.db");
int flag = SQLiteDatabase.OPEN_READWRITE;
flag = flag | SQLiteDatabase.CREATE_IF_NECESSARY;
flag = flag | SQLiteDatabase.NO_LOCALIZED_COLLATORS;
db = SQLiteDatabase.openDatabase(path.getAbsolutePath(), null, flag);
// 创建表
String sql = "create table if not exists info("
+ "id integer primary key autoincrement,name varchar(20),"
+ "time varchar(20),img BLOB)";
db.execSQL(sql);
}

@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
if (db.isOpen()) {
db.close();
}
if(!bmp.isRecycled()){
bmp.recycle();
}
}

class ClickEvent implements View.OnClickListener {

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (v == btnSave) {
Cursor c = db.rawQuery("select * from info", null);
ContentValues values = new ContentValues();
c.moveToFirst();
values.put("name", "test" + (c.getCount() + 1));
SimpleDateFormat sDateFormat = new SimpleDateFormat(
"yyyy-MM-dd hh:mm:ss");
String time = sDateFormat.format(new java.util.Date());
values.put("time", time);
Bitmap bmp = BitmapFactory.decodeResource(getResources(),
R.drawable.bg);

if (null != bmp) {
//在Bitmap上绘制标签
Bitmap drawBmp = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), Config.ARGB_8888);
Canvas cvs = new Canvas(drawBmp);
Paint p = new Paint();
p.setColor(Color.RED);
p.setTextSize(22);
cvs.drawBitmap(bmp, 0, 0, p);
cvs.drawText("test" + (c.getCount() + 1), 10, 20,p);
//将绘制后Bitmap转为Byte[]并加入values
values.put("img", bmpToByteArray(drawBmp));
drawBmp.recycle();
}
db.insert("info", null, values);
c.close();
bmp.recycle();

} else if (v == btnLoad) {
Cursor c = db.rawQuery("select * from info", null);
c.moveToLast();
if (c.isLast()) {
String name = c.getString(c.getColumnIndex("name"));
txtView.setText("name:" + name + " 共计：" + c.getCount()
+ " 条");
bmp = cursorToBmp(c, c.getColumnIndex("img"));
imgView.setImageBitmap(bmp);
}
c.close();

} else if (v == btnClear) {
imgView.setImageBitmap(null);
}

}

}

// Bitmap to byte[]
public byte[] bmpToByteArray(Bitmap bmp) {
// Default size is 32 bytes
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try {
bmp.compress(Bitmap.CompressFormat.JPEG, 100, bos);
bos.close();
} catch (IOException e) {
e.printStackTrace();
}
return bos.toByteArray();
}

// Cursor to bitmap
Bitmap cursorToBmp(Cursor c, int columnIndex) {

byte[] data = c.getBlob(columnIndex);
try {
return BitmapFactory.decodeByteArray(data, 0, data.length);
} catch (Exception e) {
return null;
}
}

}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="horizontal">
<ImageView
android:id="@+id/imgView"
android:layout_width="640dip"
android:layout_height="fill_parent"/>

<LinearLayout
android:id="@+id/LinearLayout01"
android:layout_width="150dip"
android:layout_height="fill_parent"
android:layout_marginLeft="5dip"
android:layout_marginRight="5dip"
android:orientation="vertical">
<ImageView
android:id="@+id/imgView2"
android:layout_width="fill_parent"
android:layout_height="150dip"
android:layout_marginTop="10dip"/>
<Button
android:id="@+id/btnSave"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="保存图像"/>
<Button
android:id="@+id/btnLoad"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="载入图像"/>
<Button
android:id="@+id/btnClear"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="清除图像"/>
<TextView
android:id="@+id/txtView"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textColor="#FFFFFF"
android:textSize="22sp"
android:text="..."/>

</LinearLayout>

</LinearLayout>

开发环境：XP3+Eclipse+Android2.2+JDK6.0

测试环境：Android2.2，5寸屏，分辨率640X480

源代码：http://download.csdn.net/detail/xinzheng_wang/4420817