使用SQLite的Blob储存*.mp3档案-技术开发专区

使用SQLite的Blob储存*.mp3档案

作者：高焕堂编辑：徐威特 2009-03-30 16:40 来源：IT168�

　　【IT168 技术文档】这是一个Android范例，兹说明如下：

　　Step-1:首先将.mp3档案放入Project的/res/raw/里，如下：

　　程式一开始执行，建立一个资料库，含有BLOB栏位，如下之指令：

sql = "create table mySong("

+ "song_no text not null, "

+ "song_mp3 blob );";

try {

db.execSQL(sql);

} catch (SQLException e) {

Log.e("ERROR", e.toString());

return;

}

　　Step-2:从Project的/res/raw/读取*.mp3歌曲，然后分段储存到SQLite的BLOB里，如下之指令：

InputStream is = getResources().openRawResource(rid);

int bufSize = 63*1024;

byte[] buffer = new byte[bufSize];

try {

int size = is.read(buffer);

while(size >= 0){

ByteArrayOutputStream out = new ByteArrayOutputStream(size);

out.write(buffer, 0, size);

out.flush();

out.close();

cv.put("song_mp3", out.toByteArray());

db.insert("mySong", null, cv);

size = is.read(buffer);

}

} catch (IOException e) {

Log.e("ERROR", e.toString());

}

　　Step-3:从SQLite的BLOB里，读取歌曲并存入

/data/data/com.misoo.SQ01/files/song.mp3，

　　如下之指令：

FileOutputStream os = null;

try{

os = openFileOutput("song.mp3", MODE_WORLD_READABLE);

} catch(FileNotFoundException e){

Log.e("ERROR", e.toString());

}

byte[] red_buf;

//----------------------------------------

mOpenHelper = new DatabaseHelper(this);

SQLiteDatabase db = mOpenHelper.getReadableDatabase();

String col[] = {"song_no", "song_mp3" };

cur = db.query("mySong", col, cond, null, null, null, null);

int k =0;

cur.moveToFirst();

try{

while(!cur.isAfterLast()){

red_buf = cur.getBlob(1);

os.write(red_buf);

k++;

cur.moveToNext();

}

os.flush();

os.close();

}catch(Exception e){

Log.e("ERROR", e.toString());

return;

}

　　Step-4:使用MediaPlayer将

/data/data/com.misoo.SQ01/files/song.mp3，

　　播放出来，如下之指令：

String path = "/data/data/com.misoo.SQ01/files/song.mp3";

mPlayer = new MediaPlayer();

try {

mPlayer.setDataSource(path);

mPlayer.prepare();

} catch (IOException e) {

e.printStackTrace();

}

mPlayer.start();

}

　　其实，BLOB栏位可储存很大的资料量，在本范例里，刻意将歌曲切成许多段，逐一存入资料库里。其目的只是为了举例而已。

package com.misoo.SQ01;

import java.io.ByteArrayOutputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import android.app.Activity;

import android.content.ContentValues;

import android.content.Context;

import android.database.Cursor;

import android.database.SQLException;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

import android.media.MediaPlayer;

import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.LinearLayout;

public class ac01 extends Activity implements OnClickListener{

private static final String DB_NAME = "mp3Song.db";

private static final int DB_VERSION = 2;

private Button btn, btn2, btn3;

private Cursor cur;

private MediaPlayer mPlayer;

private static class DatabaseHelper extends SQLiteOpenHelper {

DatabaseHelper(Context context) {

super(context, DB_NAME, null, DB_VERSION);

}

@Override

public void onCreate(SQLiteDatabase db) {

}

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

}

@Override

public void onCreate(Bundle icicle) {

super.onCreate(icicle);

LinearLayout layout = new LinearLayout(this);

layout.setOrientation(LinearLayout.VERTICAL);

btn = new Button(this);

btn.setId(101);

btn.setText("play");

btn.setBackgroundResource(R.drawable.heart);

btn.setOnClickListener(this);

LinearLayout.LayoutParams param

= new LinearLayout.LayoutParams(80, 50);

param.topMargin = 10;

layout.addView(btn, param);

btn2 = new Button(this);

btn2.setId(102);

btn2.setText("stop");

btn2.setBackgroundResource(R.drawable.heart);

btn2.setOnClickListener(this);

layout.addView(btn2, param);

btn3 = new Button(this);

btn3.setId(103);

btn3.setText("exit");

btn3.setBackgroundResource(R.drawable.heart);

btn3.setOnClickListener(this);

layout.addView(btn3, param);

setContentView(layout);

setTitle("Saving into SQliteDB...");

//---------------------------------

init();

setTitle("Saved in SQliteDB.");

}

private DatabaseHelper mOpenHelper;

public void init(){

mOpenHelper = new DatabaseHelper(this);

SQLiteDatabase db = mOpenHelper.getWritableDatabase();

//-----------------------------------

String sql = "drop table mySong";

try {

db.execSQL(sql);

} catch (SQLException e) {

Log.e("ERROR", e.toString());

}

//-----------------------------------

sql = "create table mySong("

+ "song_no text not null, "

+ "song_mp3 blob );";

try {

db.execSQL(sql);

} catch (SQLException e) {

Log.e("ERROR", e.toString());

return;

}

//---------------------------------

SaveOneSong(db,"s01", R.raw.den_li_guing);

}

public void SaveOneSong(SQLiteDatabase db, String key, int rid){

ContentValues cv = new ContentValues();

cv.put("song_no", key);

InputStream is = getResources().openRawResource(rid);

int bufSize = 63*1024;

byte[] buffer = new byte[bufSize];

try {

int size = is.read(buffer);

while(size >= 0){

ByteArrayOutputStream out = new ByteArrayOutputStream(size);

out.write(buffer, 0, size);

out.flush();

out.close();

cv.put("song_mp3", out.toByteArray());

db.insert("mySong", null, cv);

size = is.read(buffer);

}

} catch (IOException e) {

Log.e("ERROR", e.toString());

}

}

public void play(String cond){

FileOutputStream os = null;

try{

os = openFileOutput("song.mp3", MODE_WORLD_READABLE);

} catch(FileNotFoundException e){

Log.e("ERROR", e.toString());

}

byte[] red_buf;

//----------------------------------------

mOpenHelper = new DatabaseHelper(this);

SQLiteDatabase db = mOpenHelper.getReadableDatabase();

String col[] = {"song_no", "song_mp3" };

cur = db.query("mySong", col, cond, null, null, null, null);

int k =0;

cur.moveToFirst();

try{

while(!cur.isAfterLast()){

red_buf = cur.getBlob(1);

os.write(red_buf);

k++;

cur.moveToNext();

}

os.flush();

os.close();

}catch(Exception e){

Log.e("ERROR", e.toString());

return;

}

String path = "/data/data/com.misoo.SQ01/files/song.mp3";

mPlayer = new MediaPlayer();

try {

mPlayer.setDataSource(path);

mPlayer.prepare();

} catch (IOException e) {

e.printStackTrace();

}

mPlayer.start();

}

public void onClick(View v) {

switch (v.getId()) {

case 101:

String cond = "song_no='s01'";

play(cond);

break;

case 102:

stop();

break;

case 103:

stop();

finish();

break;

}

}

public void stop() {

if (mPlayer != null) {

mPlayer.stop();

mPlayer.release();

mPlayer = null;

}

}

}

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