随Android程序发布SQLite数据库

在发布前我们需要在assets目录下放置我们需要的数据库文件。在Android Studio下默认是没有assets文件夹的，我们需要在/app/src/main/下新建assets文件夹。这里我放置在assets下的数据库名称为test.db

接下来是打开这一文件夹。

新建一个DatabaseHelper

package com.liu.dbhelper;

import android.content.Context;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.SQLException;

/**
* Created by deonte on 15-10-31.
*/
public class DataBaseHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "test.db"; //数据库名称
private static String DBPATH="/data/data/com.liu.dbhelper/databases/";
private static final int version = 1; //数据库版本
private SQLiteDatabase myDatabase;
private Context context;
public DataBaseHelper(Context con) {
super(con,DB_NAME,null,version);
context=con;

}

@Override
public void onCreate(SQLiteDatabase db) {
//创建DatabaseHelper
}
public synchronized void close(){
if (myDatabase!=null){
myDatabase.close();
}
super.close();
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}
//创建一个空的db,然后替换所选db
public void creatDataBase() throws IOException{
if (!checkDatabase()){
this.getWritableDatabase();
try{
copyDatabase();
}catch (IOException e){
Log.i("database--->","Error copying database from assets");
}
}
}
//检查数据库是否存在
private boolean checkDatabase(){
SQLiteDatabase checkableDatabase=null;
try{
checkableDatabase=SQLiteDatabase.openDatabase(outDBPATH+DB_NAME,null,SQLiteDatabase.OPEN_READONLY);
}catch (SQLiteException e){
//数据库不存在，返回false
}
if (checkableDatabase!=null){
checkableDatabase.close();
}
return checkableDatabase!=null?true:false;
}
//从应用程序资产中复制数据库
//越过空使用数据库
private void copyDatabase()throws IOException{
InputStream myInput=context.getAssets().open(DB_NAME);
//打开任一目录下数据库
// InputStream myInput=new FileInputStream(DBPATH+DB_NAME);

OutputStream myOutput=new FileOutputStream(outDBPATH+DB_NAME);

byte[] buffer=new byte[1024];
int length;
while ((length=myInput.read(buffer))>0){
myOutput.write(buffer,0,length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDatabase()throws SQLException{
myDatabase=SQLiteDatabase.openDatabase(DBPATH+DB_NAME,null,SQLiteDatabase.OPEN_READWRITE);

}

}

DataBaseHelper dataBaseHelper=new DataBaseHelper(this);
try{

dataBaseHelper.creatDataBase();
}catch (IOException E)
{
Log.i("database---->",E.toString());
}

“`