编辑: 我在我的手机上试过了，它可以工作，谁能告诉我为什么它不能在模拟器上工作？

我试图在 android 上打开一个数据库，但它抛出一个“无法打开数据库文件”异常。在调试器中，错误似乎发生在行 mDb = mDbHelper.getWritableDatabase();

我的代码如下:

package com.track.map;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;


    public class DBAdapter {

        protected static final String DATABASE_NAME = "data";
        protected static final int DATABASE_VERSION = 1;

        //database tables
        //track table
        protected static final String TRACK_TABLE = "tracks";
        protected static final String TRACK_ID = "_id";
        protected static final String TRACK_DATE_TIME_START = "date_time_start";
        protected static final String TRACK_DATE_TIME_END = "date_time_end";

        //tables create
        protected static final String TRACK_TABLE_CREATE = 
                                "create table " + TRACK_TABLE + " ("
                                    + TRACK_ID + " integet promary key not null, "
                                    + TRACK_DATE_TIME_START + " text not null, "
                                    + TRACK_DATE_TIME_END + " text not null);";

        protected DatabaseHelper mDbHelper;
        protected SQLiteDatabase mDb;

        protected final Context mContext;

        public DBAdapter(Context context) {
            mContext = context;
        }

        public DBAdapter open() throws android.database.SQLException {
            mDbHelper = new DatabaseHelper(mContext);
            mDb = mDbHelper.getWritableDatabase();
            return this;
        }

        public void close() {
            mDb.close();
        }

        protected static class DatabaseHelper extends SQLiteOpenHelper {

            public DatabaseHelper(Context context) {
                super(context, DATABASE_NAME, null, DATABASE_VERSION);
            }

            @Override
            public void onCreate(SQLiteDatabase db) {
                db.execSQL(TRACK_TABLE_CREATE);
            }

            @Override
            public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
                onCreate(db); //for now just recreate the database
            }

        }

    }

和

package com.track.map;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

    private DBAdapter db;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        db = new DBAdapter(this);
        db.open();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

有人知道问题出在哪里吗？

编辑:

logcat 是:

03-24 11:43:42.022: I/Database(758): sqlite returned: error code = 14, msg = cannot open file at source line 25467
03-24 11:43:42.022: E/Database(758): sqlite3_open_v2("/data/data/com.track.map/databases/data", &handle, 6, NULL) failed
03-24 11:43:42.032: D/AndroidRuntime(758): Shutting down VM
03-24 11:43:42.032: W/dalvikvm(758): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
03-24 11:43:42.062: E/AndroidRuntime(758): FATAL EXCEPTION: main
03-24 11:43:42.062: E/AndroidRuntime(758): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.track.map/com.track.map.MainActivity}: android.database.sqlite.SQLiteException: unable to open database file
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.os.Handler.dispatchMessage(Handler.java:99)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.os.Looper.loop(Looper.java:123)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.app.ActivityThread.main(ActivityThread.java:4627)
03-24 11:43:42.062: E/AndroidRuntime(758):  at java.lang.reflect.Method.invokeNative(Native Method)
03-24 11:43:42.062: E/AndroidRuntime(758):  at java.lang.reflect.Method.invoke(Method.java:521)
03-24 11:43:42.062: E/AndroidRuntime(758):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-24 11:43:42.062: E/AndroidRuntime(758):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-24 11:43:42.062: E/AndroidRuntime(758):  at dalvik.system.NativeStart.main(Native Method)
03-24 11:43:42.062: E/AndroidRuntime(758): Caused by: android.database.sqlite.SQLiteException: unable to open database file
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.database.sqlite.SQLiteDatabase.dbopen(Native Method)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1812)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:817)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:851)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:844)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:540)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:98)
03-24 11:43:42.062: E/AndroidRuntime(758):  at com.track.map.DBAdapter.open(DBAdapter.java:37)
03-24 11:43:42.062: E/AndroidRuntime(758):  at com.track.map.MainActivity.onCreate(MainActivity.java:17)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-24 11:43:42.062: E/AndroidRuntime(758):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
03-24 11:43:42.062: E/AndroidRuntime(758):  ... 11 more

最佳答案

这可能有点晚了，但希望这对遇到这个问题的人有所帮助(因为我找不到确定的解决方案)。

我想我知道这个原因的原因(至少对我来说是这样)。查看 DDMS --> File Explorer，您会发现数据库文件夹 (/data/data//databases/)不存在，这就是应用程序无法在该不存在的文件夹中创建数据库文件的原因。如果您可以通过某种方式创建数据库文件夹，则可以避免此问题。

因为我比较懒，我只是在模拟器模式下使用了/data/data//files/文件夹。您可以使用此获取文件目录:

context.getFilesDir().getPath()

这在模拟器中对我来说效果很好。

希望这对某人有帮助。

如果你想看一些代码:

String dbFilename = "example.db";
try
{       
    File databaseFile = getDatabasePath(dbFilename);        
    SQLiteDatabase _db = SQLiteDatabase.openOrCreateDatabase(databaseFile);
} catch (Exception e)
{
    String databasePath =  getFilesDir().getPath() +  "/" + dbFilename;
    File databaseFile = new File(databasePath); 
    _db = SQLiteDatabase.openOrCreateDatabase(databaseFile);
}

编辑:

我尝试在模拟器上登录 Facebook(我的应用程序具有 FB 集成)，之后出现了/databases 文件夹(并持续存在)。不确定发生了什么，但可以以某种方式创建该文件夹。这里的另一位专家可以阐明一些问题。

关于android - SQLite Android无法打开数据库文件，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15597078/