Android - 无法打开资产文件

Question

我在资产文件夹中有一个sqlite文件。我使用的是已被引用上千次在其他堆栈溢出职位数据库管理器类：http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/

private void copyDatabase() throws IOException { 
     // Open your local db as the input stream 
     InputStream myInput = context.getAssets().open(DB_NAME); 

的问题是open（）方法（或getAssets？）是不断抛出IOException异常。我的路径和文件名：

private static final String DB_NAME = "attractioninfo"; 
private static final String DB_PATH = "/data/data/seattle.tourists/"; 

我的另一个相关问题是关于路径。我检查了测试手机上的文件（samsung galaxy sII），但我没有看到/ data/data/mypackagename/...任何地方。内部存储在哪里？我正在使用Android 2.2。

编辑：我做了更多的测试，我也发现，在第一次安装（这意味着没有数据库文件的电话内部存储，但它需要复制那里）这条线也不工作（我得到一个SQLiteException）

private boolean checkDatabase() { 
    SQLiteDatabase checkDB = null; 

    try { 
     String myPath = DB_PATH + DB_NAME; 
     checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); 

全码：

package seattle.tourists; 

import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.OutputStream; 

import android.content.Context; 
import android.content.res.AssetManager; 
import android.database.SQLException; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteException; 
import android.database.sqlite.SQLiteOpenHelper; 

public class DatabaseHelper extends SQLiteOpenHelper { 
    private static final String DB_NAME = "attractioninfo"; 
    private static final String DB_PATH = "/data/data/seattle.tourists/databases/"; 
    private static final int DB_VERSION = 1; 
    private static final String TABLE_NAME = "ExtraInfo"; 

    private SQLiteDatabase db; 
    private final Context context; 

    /** 
    * Constructor 
    * @param context application context 
    */ 
    public DatabaseHelper(Context context) { 
     super(context, DB_NAME, null, DB_VERSION); 
     this.context = context; 
    } 

    /** 
    * Creates empty database on system and rewrites it with existing database 
    * @throws IOException 
    */ 
    public void createDatabase() throws IOException { 
     boolean dbExist = checkDatabase(); 

     if (dbExist) { 
      // do nothing, the database already exists; 
     } 
     else { 
      this.getReadableDatabase(); 

      try { 
       copyDatabase(); 
      } 
      catch (IOException e) { 
       throw new Error("Error copying database"); 
      } 
     } 
    } 

    /** 
    * Check to see if a database exists 
    * @return true if database exists, false otherwise; 
    */ 
    private boolean checkDatabase() { 
     SQLiteDatabase checkDB = null; 

     try { 
      String myPath = DB_PATH + DB_NAME; 
      checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); 
     } 
     catch (SQLiteException e) { 
      int x = 5; 
     } 

     if (checkDB != null) 
      checkDB.close(); 

     return checkDB != null ? true : false; 
    } 

    /** 
    * Copes database from assets-folder to system folder, where it can be 
    * accessed and handled. This is done by transferring byte-stream. 
    * @throws IOException 
    */ 
    private void copyDatabase() throws IOException { 
     // Open your local db as the input stream 
     AssetManager assets = context.getAssets(); 
     InputStream myInput = assets.open(DB_NAME); 

     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(); 
    } 

    public SQLiteDatabase openDataBase() throws SQLException { 
     // Open the database 
     String myPath = DB_PATH + DB_NAME; 
     return db = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); 
    } 

    public synchronized void close() { 
     if (db != null) 
      db.close(); 

     super.close(); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     // do nothing 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     // do nothing 
    } 
} 

Answer 1

发现我使用了错误的文件格式。我使用的是txt/SQL格式，而不是sqlite。

Answer 2

从资产使用

AssetManager am = myContext.getAssets(); 
InputStream is = am.open("DB Name"); 

打开一个数据库

Another related question I have is about the path. I've checked the files on my testing phone (samsung galaxy sII) but I don't see a /data/data/mypackagename/..

由于安全原因，您无法在设备上看到数据库。如果你真的想看你的数据库。然后，你需要在模拟器安装您的应用

编辑：

代码复制的数据库

private static String db_path = "/data/data/your.package.name/databases/"; 
private static final String database_name = "search"; 

private void copyDataBase() throws IOException { 

    String outFileName = db_path + database_name+".db"; 
    // 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 i, r; 
    AssetManager am = myContext.getAssets(); 
    String fn = String.format(database_name); 
     InputStream is = am.open(fn); 
    while ((r = is.read(buffer)) != -1) 
     myOutput.write(buffer, 0, r); 
     is.close(); 

    // Close the streams 
    myOutput.flush(); 
    myOutput.close(); 

} 

检查DB

private boolean checkDataBase() { 
    SQLiteDatabase checkDB = null; 
    try { 
     String myPath = db_path + database_name+".db"; 

     checkDB = SQLiteDatabase.openDatabase(myPath, null, 
       SQLiteDatabase.NO_LOCALIZED_COLLATORS); 
    } catch (SQLiteException e) { 
     // database does't exist yet. 
    } 
    if (checkDB != null) { 
     checkDB.close(); 
    } 
    return checkDB != null ? true : false; 
} 

确保您已经添加

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

in you manifest file。

Answer 3

在你的路径

：

私有静态最后弦乐DB_PATH = “/data/data/seattle.tourists/”;

---

有一个丢失的目录wc是包名后面的“/ database /”。