android - android Galaxy的真机数据库文件到空点异常

Question

我正在加载一个名为 mydb 的资产中的数据库文件。然后我使用下面的代码将数据库文件加载到模拟器上。这有时有效，但并非总是如此。我重置了 eclipse 并且数据库文件正确加载。我根本无法让它在真实设备上工作。我已经在其他实验文件项目中尝试过这个。我认为有一个设置我没有正确配置，但我不确定。任何帮助将不胜感激。

尝试过的方法

我尝试使用 android_meta 表，因为它建议修复未加载数据库的问题。
我也可以使用这种语法记录。这甚至适用于生活设备 long id = db.insertContact("Wei-Meng Lee", "weimenglee@learn2develop.net"); 这段代码摘自本书 android development
我正在对示例中指定的代码进行更改

整个故障日志

06-21 15:17:56.792：E/AndroidRuntime(556)：致命异常：主要 06-21 15:17:56.792：E/AndroidRuntime(556)：java.lang.RuntimeException：无法启动活动 ComponentInfo{alex. android.test.db/alex.android.test.db.AndroidtestdbActivity}：android.database.sqlite.SQLiteException：没有这样的表：联系人：，编译时：SELECT DISTINCT _id，name，email FROM contacts WHERE _id=2 06- 21 15:17:56.792: E/AndroidRuntime(556): 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.app。 ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.app.ActivityThread.access$600(ActivityThread.java:123) 06-21 15:17:56.792 : E/AndroidRuntime(556): 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.os.Handler.dispatchMessage(Handler.java:99) 06-21 15:17:56.792: E/AndroidRuntime(556): 在android.os.Looper.loop(Looper.java:137) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.app.ActivityThread.main(ActivityThread.java:4424) 06-21 15: 17:56.792: E/AndroidRuntime(556): 在 java.lang.reflect.Method.invokeNative(Native Method) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 java.lang.reflect.Method。调用（Method.java:511）06-21 15:17:56.792：E/AndroidRuntime（556）：在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run（ZygoteInit.java:784）06-21 15： 17:56.792: E/AndroidRuntime(556): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 dalvik.system .NativeStart.main(Native Method) 06-21 15:17:56.792:E/AndroidRuntime(556)：引起：android.database.sqlite.SQLiteException：没有这样的表：联系人：，编译时：SELECT DISTINCT _id, name, email FROM contacts WHERE _id=2 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite.SQLiteCompiledSql.(SQLiteCompiledSql.java :68) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite.SQLiteProgram.compileSql(SQLiteProgram.java:143) 06-21 15:17:56.792: E/AndroidRuntime(556 ): 在 android.database.sqlite.SQLiteProgram.compileAndbindAllArgs(SQLiteProgram.java:361) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite.SQLiteProgram.(SQLiteProgram.java:127 ) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite。SQLiteProgram.(SQLiteProgram.java:94) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite.SQLiteQuery.(SQLiteQuery.java:53) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite.SQLiteDatabase.rawQueryWithFactory (SQLiteDatabase.java:1564) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1449) 06-21 15:17:56.792: E /AndroidRuntime(556): 在 android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1405) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 alex.android.test.db.DBAdapter。 getContact(DBAdapter.java:163) 06-21 15:17:56.792: E/AndroidRuntime(556): at alex.android.test.db.AndroidtestdbActivity。onCreate(AndroidtestdbActivity.java:32) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.app.Activity.performCreate(Activity.java:4465) 06-21 15:17:56.792: E/ AndroidRuntime(556): 在 android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 06-21 15:17:56.792: E/AndroidRuntime(556): 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920 )

公共类 DBAdapter {

 private static final String DB_NAME = "MyDB";
private static final int DB_VERSION = 1;
 public static final String KEY_ROWID = "_id";
    public static final String KEY_NAME = "name";
    public static final String KEY_EMAIL = "email";
    private static final String TAG = "DBAdapter";
    private static final String DATABASE_TABLE = "contacts";

private static Context c;
private SQLiteDatabase db;
private SQLiteOpenHelper sqlDBHelp;

/**
 * Constructor for the SQL DB Adapter, copy DB from assets if not exists in /data/data/<package-name>/databases
 * 
 * @param c
 */
public DBAdapter(Context c) {
    super();
    DBAdapter.c = c;
    sqlDBHelp = new SqlDBHelper();
}

/**
 * Open the SQL DB as Writable
 */
public void openDB() {
    try {
        db = sqlDBHelp.getWritableDatabase();
    } catch (SQLiteException ex) {
        Toast.makeText(c, "DB with filename " + DB_NAME + "coudn't be opend!", Toast.LENGTH_SHORT);
    }
}

/**
 * Close the SQL DB
 */
public void closeDB() {
    db.close();
}

/**
 * Helper class for the SQL DB Adapter
 */
static class SqlDBHelper extends SQLiteOpenHelper {

    private static final String DB_PATH = "/data/data/" + c.getPackageName() + "/databases/" + DB_NAME;

    public SqlDBHelper() {
        super(c, DB_NAME, null, DB_VERSION);
        createDB();     
    }

    private void createDB() {

        SharedPreferences prefs = c.getSharedPreferences("sharedPrefs", 0);
        boolean dbExists = prefs.getBoolean("dbExists", false);
        Log.d("PM.ADA.SDA", "DB Exists : " + dbExists);
        if (!dbExists) {
            this.getReadableDatabase();
            copyDB();
            prefs.edit().putBoolean("dbExists", true).commit();
        }
    }


    public void onCreate(SQLiteDatabase db) {
        /*
        try {
            db.execSQL(DATABASE_TABLE); 
        } catch (SQLException e) {
            e.printStackTrace();
        }   
        */

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

         Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                    + newVersion + ", which will destroy all old data");
            db.execSQL("DROP TABLE IF EXISTS contacts");
            onCreate(db);


    }

    public void copyDB() {
        try {               
            InputStream is = c.getAssets().open(DB_NAME);
            BufferedInputStream bis = new BufferedInputStream(is);
            OutputStream os = new FileOutputStream(DB_PATH);
            BufferedOutputStream bos = new BufferedOutputStream(os);

            byte[] buffer = new byte[64];
            int length;

            while ((length = bis.read(buffer)) > 0) {
                bos.write(buffer, 0, length);
            }

            bos.flush();
            bos.close();
            bis.close();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

public long insertContact(String name, String email) 
{
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_NAME, name);
    initialValues.put(KEY_EMAIL, email);
    return db.insert(DATABASE_TABLE, null, initialValues);
}

//---deletes a particular contact---
public boolean deleteContact(long rowId) 
{
    return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}

//---retrieves all the contacts---
public Cursor getAllContacts() 
{
    return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_NAME,
            KEY_EMAIL}, null, null, null, null, null);
}

//---retrieves a particular contact---
public Cursor getContact(long rowId) throws SQLException 
{
    Cursor mCursor =
            db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
            KEY_NAME, KEY_EMAIL}, KEY_ROWID + "=" + rowId, null,
            null, null, null, null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}

//---updates a contact---
public boolean updateContact(long rowId, String name, String email) 
{
    ContentValues args = new ContentValues();
    args.put(KEY_NAME, name);
    args.put(KEY_EMAIL, email);
    return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}

}

其他活动 TextView 名称；

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    DBAdapter db = new DBAdapter(this); 
    name = (TextView)findViewById(R.id.name);



    //---get a contact---
    db.openDB();
    Cursor c = db.getContact(2);
    if (c.moveToFirst())  
    {
        DisplayContact(c);
    name.setText(String.valueOf(c.getString(1)));
    }
    else
        name.setText("not found");
        Toast.makeText(this, "No contact found", Toast.LENGTH_LONG).show();
    db.closeDB();

}

public void DisplayContact(Cursor c)
{
    Toast.makeText(this, 
            "id: " + c.getString(0) + "\n" +
            "Name: " + c.getString(1) + "\n" +
            "Email:  " + c.getString(2),
            Toast.LENGTH_LONG).show();  


}

}

score 1 · Accepted Answer

我发现与我的操作方式有一些不同...您缺少一个outputStream.flush()，我this.getReadableDatabase();在开始复制过程之前和this.close();之后打电话。

供您参考，这是我的做法，效果很好：

private static class DatabaseHelper extends SQLiteOpenHelper {
    DatabaseHelper(Context context, String dbname, int dbversion) {
        super(context, dbname, null, dbversion);
        if (checkDataBase(dbname)) {
            openDataBase(dbname);
        } else {
            try {
                this.getReadableDatabase();
                copyDataBase(dbname);
                this.close();
                openDataBase(dbname);
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
            Toast.makeText(context,
                    "Initial " + dbname + " database has been created",
                    Toast.LENGTH_LONG).show();
        }
    }


public DBAdapter(Context ctx) {
    DBAdapter.mCtx = ctx;
}

private static boolean checkDataBase(String dbname) {
    SQLiteDatabase checkDB = null;
    boolean exist = false;
    try {
        String db = MAIN_DB_PATH + dbname;
        checkDB = SQLiteDatabase.openDatabase(db, null,
                SQLiteDatabase.OPEN_READONLY);
    } catch (SQLiteException e) {
        Log.v("db log", "database does't exist");
    }
    if (checkDB != null) {
        exist = true;
        checkDB.close();
    }
    return exist;
}

private static void copyDataBase(String dbname) throws IOException {
    InputStream myInput = mCtx.getAssets().open(dbname);
    String outFileName = MAIN_DB_PATH + dbname;
    OutputStream myOutput = new FileOutputStream(outFileName);
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }
    myOutput.flush();
    myOutput.close();
    myInput.close();
}

android - android Galaxy的真机数据库文件到空点异常

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