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import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

* 將把assets下的數(shù)據(jù)庫文件直接復(fù)制到DB_PATH，但數(shù)據(jù)庫文件大小限制在1M以下
* 如果有超過1M的大文件，則需要先分割為N個小文件，然后使用copyBigDatabase()替換copyDatabase()
*/
public class DBManager extends SQLiteOpenHelper {
//用戶數(shù)據(jù)庫文件的版本
private static final int DB_VERSION = 1;
//數(shù)據(jù)庫文件目標(biāo)存放路徑為系統(tǒng)默認(rèn)位置，com.rys.lb 是你的包名
private static String DB_PATH = "/data/data/com.rys.lb/databases/";

//如果你想把數(shù)據(jù)庫文件存放在SD卡的話
// private static String DB_PATH = android.os.Environment.getExternalStorageDirectory().getAbsolutePath()
// + "/arthurcn/drivertest/packfiles/";

private static String DB_NAME = "data.db";
private static String ASSETS_NAME = "data.db";

private SQLiteDatabase myDataBase;
private final Context myContext;

/**
* 如果數(shù)據(jù)庫文件較大，使用FileSplit分割為小于1M的小文件
* 此例中分割為 data.db.100 data.db.101 data.db.102....
*/
//第一個文件名后綴
private static final int ASSETS_SUFFIX_BEGIN = 100;
//最后一個文件名后綴
private static final int ASSETS_SUFFIX_END = 110;

/**
* 在SQLiteOpenHelper的子類當(dāng)中，必須有該構(gòu)造函數(shù)
* @param context 上下文對象
* @param name 數(shù)據(jù)庫名稱
* @param factory 一般都是null
* @param version 當(dāng)前數(shù)據(jù)庫的版本，值必須是整數(shù)并且是遞增的狀態(tài)
*/
public DBManager(Context context, String name, CursorFactory factory, int version) {
//必須通過super調(diào)用父類當(dāng)中的構(gòu)造函數(shù)
super(context, name, null, version);
this.myContext = context;
}

public DBManager(Context context, String name, int version){
this(context,name,null,version);
}

public DBManager(Context context, String name){
this(context,name,DB_VERSION);
}

public DBManager (Context context) {
this(context, DB_PATH + DB_NAME);
}

public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
//數(shù)據(jù)庫已存在，do nothing.

System.out.println("數(shù)據(jù)庫已經(jīng)存在");

}else{
//創(chuàng)建數(shù)據(jù)庫
try {
File dir = new File(DB_PATH);
if(!dir.exists()){
dir.mkdirs();
}
File dbf = new File(DB_PATH + DB_NAME);
if(dbf.exists()){
dbf.delete();
}
SQLiteDatabase.openOrCreateDatabase(dbf, null);
// 復(fù)制asseets中的db文件到DB_PATH下
//copyDataBase();
copyBigDataBase();
} catch (IOException e) {
throw new Error("數(shù)據(jù)庫創(chuàng)建失敗");
}
}
}

//檢查數(shù)據(jù)庫是否有效
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
String myPath = DB_PATH + DB_NAME;
try{
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
System.out.println("關(guān)閉");
}
return checkDB != null ? true : false;
}
public DBManager open1(){
String myPath = DB_PATH + DB_NAME;
System.out.println("數(shù)據(jù)庫已經(jīng)...");
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
System.out.println("數(shù)據(jù)庫打開");
return this;

}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(ASSETS_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}

//復(fù)制assets下的大數(shù)據(jù)庫文件時用這個
private void copyBigDataBase() throws IOException{
InputStream myInput;
String outFileName = DB_PATH + DB_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
for (int i = ASSETS_SUFFIX_BEGIN; i < ASSETS_SUFFIX_END+1; i++) {
myInput = myContext.getAssets().open(ASSETS_NAME + "." + i);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myInput.close();
}
myOutput.close();
System.out.println("數(shù)據(jù)庫已經(jīng)復(fù)制");
}

@Override
public synchronized void close() {
if(myDataBase != null){
myDataBase.close();
System.out.println("關(guān)閉成功1");
}
super.close();
System.out.println("關(guān)閉成功2");
}

/**
* 該函數(shù)是在第一次創(chuàng)建的時候執(zhí)行，
* 實際上是第一次得到SQLiteDatabase對象的時候才會調(diào)用這個方法
*/
@Override
public void onCreate(SQLiteDatabase db) {
}

/**
* 數(shù)據(jù)庫表結(jié)構(gòu)有變化時采用
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void open(){
SQLiteDatabase DataBase=this.openOrCreateDatabase("data.db",
null);
} private SQLiteDatabase openOrCreateDatabase(String string, Object object) {
// TODO Auto-generated method stub
return null;
} 3.用SD卡要加權(quán)限