我已经确认该表存在正确的名称,但仍然无效.

我能够使用原始查询,但我希望我们使用ContentProvider模式进行练习.

谢谢,如果您需要更多信息,请与我们联系.

sqliteOpenHelper

public class DatabaseHelper extends sqliteOpenHelper {

    private static final String TAG = DatabaseHelper.class.getSimpleName();

    private static final String DB_PATH = 
            "/data/data/ashton.android.personal.worktc/databases/";

    private static final String DB_NAME = "worktc.db";

    private static final int DB_VERSION = 1;

    private sqliteDatabase myDatabase;

    private final Context context;

    public DatabaseHelper(Context context) {
        super(context,DB_NAME,null,DB_VERSION);
        this.context = context;
    }

    /**
     * Creates a empty database on the system and rewrites it with your own database.
     * */
    public void createDataBase() throws IOException {

        boolean dbExist = this.checkDataBase();

        if (dbExist) {
            //do nothing - database already exist
        } else {

            Log.e(TAG,"Database does not exist when trying to create it.");

            //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();
            this.close();

            try {

                this.copyDataBase();

                Log.e(TAG,"createDatabase database created");

            } 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(){

        File dbFile = new File(DB_PATH + DB_NAME);
        return dbFile.exists();

    }

    /**
     * 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 = this.context.getAssets().open(DB_NAME);

        //Open the empty db as the output stream
        OutputStream myOutput = new FileOutputStream(DB_PATH + DB_NAME);

        //transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer))>0){
            myOutput.write(buffer,length);
        }

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

    }

    public boolean openDataBase() throws sqlException {

        //Open the database
        String myPath = DB_PATH + DB_NAME;
        this.myDatabase = sqliteDatabase.openDatabase(myPath,sqliteDatabase.CREATE_IF_NECESSARY);
        return this.myDatabase != null;
    }

    @Override
    public synchronized void close() {

        if(this.myDatabase != null)
            this.myDatabase.close();

        super.close();

    }

    @Override
    public void onCreate(sqliteDatabase db) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onUpgrade(sqliteDatabase db,int oldVersion,int newVersion) {
        // TODO Auto-generated method stub

    }
}

内容提供商

public class WorkTCContentProvider extends ContentProvider {

    private static final String TAG = WorkTCContentProvider.class.getSimpleName();

    public static final String AUTHORITY = 
            "ashton.android.personal.worktc.database";

    private static final UriMatcher sURIMatcher = new UriMatcher(UriMatcher.NO_MATCH);
    static {
        sURIMatcher.addURI(
                AUTHORITY,ProfessionTable.TABLE_NAME,ProfessionTable.PROFESSIONS);

        sURIMatcher.addURI(
                AUTHORITY,ProfessionTable.TABLE_NAME + "/#",ProfessionTable.PROFESSIONS_ID);
    }

    private DatabaseHelper database;

    @Override
    public int delete(Uri uri,String selection,String[] selectionArgs) {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public String getType(Uri uri) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Uri insert(Uri uri,ContentValues values) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public boolean onCreate() {

        Log.d(TAG,"before database creation");

        this.database = new DatabaseHelper(getContext());
        try {
            this.database.createDataBase();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        this.database.openDataBase();
        this.database.close();

        Log.d(TAG,"after database creation");

//      this.database.getWritableDatabase().execsql( "pragma foreign_keys = on;" );

        return false;
    }

    @Override
    public Cursor query(Uri uri,String[] projection,String[] selectionArgs,String sortOrder) {

        sqliteQueryBuilder queryBuilder = new sqliteQueryBuilder();

        switch (sURIMatcher.match(uri)) {
        case ProfessionTable.PROFESSIONS:

            /*
             * Dont do anything,just do the normal query.
             */

            break;

        case ProfessionTable.PROFESSIONS_ID:

            queryBuilder.appendWhere(ProfessionTable._ID + "=" + uri.getLastPathSegment());

            break;

        default:
            throw new IllegalArgumentException("Unknown URI: " + uri);
        }

        sqliteDatabase db = this.database.getReadableDatabase();

        Cursor cursor = queryBuilder.query(
                db,projection,selection,selectionArgs,sortOrder);

        cursor.setNotificationUri(WorkTCApp.getContext().getContentResolver(),uri);

        return cursor;
    }

    @Override
    public int update(Uri uri,ContentValues values,String[] selectionArgs) {
        // TODO Auto-generated method stub
        return 0;
    }
}

ProfessionTable

public final class ProfessionTable implements BaseColumns {

    public static final String TABLE_NAME = "Professions";

    public static final Uri URI = 
            Uri.parse("content://" + WorkTCContentProvider.AUTHORITY + "/" + TABLE_NAME);

    public static final int PROFESSIONS = 10;

    public static final int PROFESSIONS_ID = 11;

    public static final String NAME = "name";

    public static final String ICON = "icon";

    private ProfessionTable() {}
}

错误

09-08 11:16:18.285: E/AndroidRuntime(11651): FATAL EXCEPTION: main
09-08 11:16:18.285: E/AndroidRuntime(11651): java.lang.RuntimeException: Unable to start activity ComponentInfo{ashton.android.personal.worktc/ashton.android.personal.worktc.controllers.WorkActivity}: java.lang.IllegalStateException: Invalid tables
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.os.Handler.dispatchMessage(Handler.java:99)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.os.Looper.loop(Looper.java:130)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.app.ActivityThread.main(ActivityThread.java:3687)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at java.lang.reflect.Method.invokeNative(Native Method)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at java.lang.reflect.Method.invoke(Method.java:507)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:842)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at dalvik.system.NativeStart.main(Native Method)
09-08 11:16:18.285: E/AndroidRuntime(11651): Caused by: java.lang.IllegalStateException: Invalid tables
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.database.sqlite.sqliteDatabase.findEditTable(sqliteDatabase.java:1127)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.database.sqlite.sqliteQueryBuilder.query(sqliteQueryBuilder.java:330)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.database.sqlite.sqliteQueryBuilder.query(sqliteQueryBuilder.java:280)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at ashton.android.personal.worktc.database.worktcContentProvider.query(worktcContentProvider.java:104)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.content.ContentProvider$Transport.query(ContentProvider.java:187)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.content.ContentResolver.query(ContentResolver.java:267)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at ashton.android.personal.worktc.views.WorkView.onFinishInflate(WorkView.java:96)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:631)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.view.LayoutInflater.inflate(LayoutInflater.java:408)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.view.LayoutInflater.inflate(LayoutInflater.java:320)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.view.LayoutInflater.inflate(LayoutInflater.java:276)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.view.View.inflate(View.java:8884)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at ashton.android.personal.worktc.controllers.WorkActivity.onCreate(WorkActivity.java:30)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-08 11:16:18.285: E/AndroidRuntime(11651):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
09-08 11:16:18.285: E/AndroidRuntime(11651):    ... 11 more