android导入外部已存在的数据库大于1M的数据库文件方法
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1.如果数据库文件大于1M，就用Filesplit工具切割。先去下载这个软件工具
2.首先把已有的数据库放到assets文件夹下面，如果没有这个文件就先在android项目中建立这个文件夹。
代码如下：
import java.io.File;
import java.io.FileOutputStream; import java.io.IOException;
import java.io.InputStream; import java.io.OutputStream; 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; * 将把assets下的数据库文件直接复制到DB_PATH，但数据库文件大小限制在1M以下 * 如果有超过1M的大文件，则需要先分割为N个小文件，然后使用copyBigDatabase()替换copyDatabase() */ public class DBManager extends SQLiteOpenHelper { //用户数据库文件的版本 private static final int DB_VERSION = 1; //数据库文件目标存放路径为系统默认位置，com.rys.lb 是你的包名 private static String DB_PATH = "/data/data/com.rys.lb/databases/"; //如果你想把数据库文件存放在SD卡的话 // 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; /** * 如果数据库文件较大，使用FileSplit分割为小于1M的小文件 * 此例中分割为 data.db.100 data.db.101 data.db.102.... */ //第一个文件名后缀 private static final int ASSETS_SUFFIX_BEGIN = 100; //最后一个文件名后缀 private static final int ASSETS_SUFFIX_END = 110; /** * 在SQLiteOpenHelper的子类当中，必须有该构造函数 * @param context 上下文对象 * @param name 数据库名称 * @param factory 一般都是null * @param version 当前数据库的版本，值必须是整数并且是递增的状态 */ public DBManager(Context context, String name, CursorFactory factory, int version) { //必须通过super调用父类当中的构造函数 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){ //数据库已存在，do nothing. System.out.println("数据库已经存在"); }else{ //创建数据库 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); // 复制asseets中的db文件到DB_PATH下 //copyDataBase(); copyBigDataBase(); } catch (IOException e) { throw new Error("数据库创建失败"); } } } //检查数据库是否有效 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("关闭"); } return checkDB != null ? true : false; } public DBManager open1(){ String myPath = DB_PATH + DB_NAME; System.out.println("数据库已经..."); myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); System.out.println("数据库打开"); 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(); } //复制assets下的大数据库文件时用这个 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("数据库已经复制"); } @Override public synchronized void close() { if(myDataBase != null){ myDataBase.close(); System.out.println("关闭成功1"); } super.close(); System.out.println("关闭成功2"); } /** * 该函数是在第一次创建的时候执行， * 实际上是第一次得到SQLiteDatabase对象的时候才会调用这个方法 */ @Override public void onCreate(SQLiteDatabase db) { } /** * 数据库表结构有变化时采用 */ @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卡要加权限
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission> |
