在Android的数据文件夹拷贝数据库

本文介绍了在Android的数据文件夹拷贝数据库的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我用这code从资产复制我的SQLite数据库中的数据机器人。

私有静态字符串DB_PATH =/data/data/com.project.writing/databases/; 私有静态字符串DB_NAME =Fonts.sqlite; 私人SQLiteDatabase schoolDataBase;     / **     *在系统上创建一个空数据库，并与自己的数据库重写它。     * * /     公共无效的CreateDatabase（）抛出IOException异常{         布尔dbExist = checkDataBase（）;         如果（dbExist）{             //什么也不做 - 数据库中已存在         }其他{             //通过调用这个方法和空的数据库将被创建到系统​​默认路径                //你的应用程序，所以我们要能够覆盖数据库，我们的数据库。             this.getReadableDatabase（）;             尝试 {                 copyDataBase（）;             }赶上（IOException异常E）{                 抛出新的错误（错误复制数据库）;             }         }     }     / **      *检查数据库中已存在，以避免重新复制每次打开应用程序时，该文件。      * @返回true，如果它存在，虚假的，如果它不     * /     私人布尔checkDataBase（）{         SQLiteDatabase CHECKDB = NULL;         尝试{             字符串mypath中= DB_PATH + DB_NAME;             CHECKDB = SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READONLY）;         }赶上（SQLiteException E）{             //数据库的简化版，存在。             的System.out.println（数据库不存在+ E）;         }         如果（CHECKDB！= NULL）{             checkDB.close（）;         }         返回CHECKDB！= NULL？真假;     }     / **      *复制你的数据库从当地的资产文件夹在刚才创建的空数据库      *系统文件夹，从那里它可以被访问和处理。      *这是通过transfering字节流进行。      *      * * /     私人无效copyDataBase（）抛出IOException异常{         //打开本地数据库作为输入流         InputStream的myInput = myContext.getAssets（）开（DB_NAME）。         //路径刚刚创建的空分贝         字符串outFileName = DB_PATH + DB_NAME;         //打开空分贝的输出流         的OutputStream myOutput =新的FileOutputStream（outFileName）;         //传输的字节从inputfile中的OUTPUTFILE         byte []的缓冲区=新的字节[1024];         INT长;         而（（长度= myInput.read（缓冲液））大于0）{             myOutput.write（缓冲液，0，长度）;         }         //关闭流         myOutput.flush（）;         myOutput.close（）;         myInput.close（）;         //Toast.makeText(myContext，复制完成，300）.show（）;     }

解决方案

不要推倒重来。有好的包，确实要在2号线的code什么： https：//开头github/jgilfelt/android-sqlite-asset-helper

I am using this code copy my sqlite database from asset to data in android .

private static String DB_PATH= "/data/data/com.project.writing/databases/"; private static String DB_NAME = "Fonts.sqlite"; private SQLiteDatabase schoolDataBase; /** * Creates a empty database on the system and rewrites it with your own database. * */ public void createDataBase() throws IOException{ boolean dbExist = checkDataBase(); if(dbExist){ //do nothing - database already exist }else{ //By calling this method and empty database will be created into the default system path //of your application so we are gonna be able to overwrite that database with our database. this.getReadableDatabase(); try { copyDataBase(); } catch (IOException e) { throw new Error("Error copying database"); } } } /** * Check if the database already exist to avoid re-copying the file each time you open the application. * @return true if it exists, false if it doesn't */ private boolean checkDataBase(){ SQLiteDatabase checkDB = null; try{ String myPath = DB_PATH + DB_NAME; checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); }catch(SQLiteException e){ //database does't exist yet. System.out.println("data base does not exist"+e); } if(checkDB != null){ checkDB.close(); } return checkDB != null ? true : false; } /** * 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(DB_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(); //Toast.makeText(myContext, "Copy Done", 300).show(); }

解决方案

Do not reinvent the wheel. There's nice package that does what you want in 2 lines of code: github/jgilfelt/android-sqlite-asset-helper