ContentResolver.insert始终返回null

Question

我想在数据库表用户中使用我的自定义提供程序userProvider插入用户记录。但getcontentresolver.insert始终返回null。我不知道什么是错误....

我的自定义提供程序类：

public class userProvider extends ContentProvider {

static final String PROVIDER_NAME = "com.codeworm.pickmeup";
static final String URL = "content://" + PROVIDER_NAME + "/user";
static final Uri CONTENT_URI = Uri.parse(URL);

private SQLiteDatabase db;
static final String DATABASE_NAME = "pickmeupDB";
static final String USER_TABLE_NAME = "user";

static final int DATABASE_VERSION = 2;
static final String CREATE_DB_TABLE =
        " CREATE TABLE " + USER_TABLE_NAME +
                " (_id INTEGER PRIMARY KEY AUTOINCREMENT, " +
                " name TEXT NOT NULL, " +
                " email TEXT NOT NULL,pass TEXT NOT NULL,phone TEXT NOT NULL," +
                "ride TEXT NOT NULL,city TEXT NOT NULL,country TEXT NOT NULL,location TEXT NOT NULL);";

static final String _ID = "_id";
static final String NAME = "name";
static final String EMAIL = "email";
static final String PASS = "pass";
static final String PHONE = "phone";
static final String RIDE = "ride";
static final String CITY = "city";
static final String COUNTRY = "country";
static final String LOCATION = "location"+CITY+COUNTRY;

private static class DatabaseHelper extends SQLiteOpenHelper {
    DatabaseHelper(Context context){
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
    @Override
    public void onCreate(SQLiteDatabase db)
    {

        db.execSQL(CREATE_DB_TABLE);
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " +  USER_TABLE_NAME);
        onCreate(db);
    }
}
static final int user = 1;
static final int getride = 2;
static final int shareride = 3;

static final UriMatcher uriMatcher;
static{
    uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

    uriMatcher.addURI(PROVIDER_NAME, "user", user);
    //uriMatcher.addURI(PROVIDER_NAME, "students/#", STUDENT_ID);
}


@Override
public boolean onCreate() {
    Context context = getContext();
    DatabaseHelper dbHelper = new DatabaseHelper(context);
    db = dbHelper.getWritableDatabase();
    return (db == null)? false:true;
}

@Nullable
@Override
public Uri insert(Uri uri, ContentValues values) {
    long rowID = db.insert( USER_TABLE_NAME, "", values);
    /**
     * If record is added successfully
     */
    if (rowID > 0)
    {
        // this  response that data is inserted    and      what is the URI of the inserted data

        Uri _uri=Uri.withAppendedPath(CONTENT_URI, "" + rowID);
        return _uri;
    }
    throw new SQLException("Failed to add a record into " + uri);
}

@Nullable
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
    Cursor c;
    if (sortOrder == null || sortOrder == ""){
        // By default sort on student names
        sortOrder = _ID;
    }
    switch (uriMatcher.match(uri)) {
        case user:
            c=db.query(USER_TABLE_NAME,projection,selection,selectionArgs,null,null,sortOrder);
            break;
        /*case STUDENT_ID:
            c=db.query(STUDENTS_TABLE_NAME,projection,
                    _ID + " = " + uri.getPathSegments().get(1) + (!TextUtils.isEmpty(selection) ? " AND (" +selection + ')' : "")
                    ,selectionArgs,null,null,sortOrder);
            break;*/
        default:
            throw new IllegalArgumentException("Unknown URI " + uri);
    }
    return c;
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
    int count = 0;
    switch (uriMatcher.match(uri)) {
        case user:
            count = db.delete(USER_TABLE_NAME, selection, selectionArgs);
            break;
        /*case STUDENT_ID:
            String id = uri.getPathSegments().get(1);
            count = db.delete( STUDENTS_TABLE_NAME, _ID +  " = " + id + (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""), selectionArgs);
            break;*/
        default:
            throw new IllegalArgumentException("Unknown URI " + uri);
    }
    return count;
}

@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
    int count = 0;
    switch (uriMatcher.match(uri)){
        case user:
            count = db.update(USER_TABLE_NAME, values, selection, selectionArgs);
            break;

       /* case STUDENT_ID:
            count = db.update(STUDENTS_TABLE_NAME, values, _ID + " = " + uri.getPathSegments().get(1) +
                    (!TextUtils.isEmpty(selection) ? " AND (" +selection + ')' : ""), selectionArgs);
            break;*/
        default:
            throw new IllegalArgumentException("Unknown URI " + uri );
    }
    getContext().getContentResolver().notifyChange(uri, null);
    return count;
}

@Nullable
@Override
public String getType(Uri uri) {
    switch (uriMatcher.match(uri))
    {
        /**
         * Get all student records
         */
        case user:
            return "vnd.android.cursor.dir/vnd.example.user";
        /**
         * Get a particular student
         */
        /*case STUDENT_ID:
            return "vnd.android.cursor.item/vnd.example.students";*/
        default:
            throw new IllegalArgumentException("Unsupported URI: " + uri);
    }
}
}

主要课程：

 public void onClick(View v) {
            ContentValues values = new ContentValues();

            values.put(userProvider.NAME, (name.getText().toString()));
            values.put(userProvider.EMAIL, (email.getText().toString()));
            values.put(userProvider.PASS, (pass.getText().toString()));
            values.put(userProvider.PHONE, (phone.getText().toString()));
            values.put(userProvider.CITY, (city.getText().toString()));
            values.put(userProvider.COUNTRY, (country.getText().toString()));
            values.put(userProvider.LOCATION, (locatioin.getText().toString()));
            if (ride) {
                values.put(userProvider.RIDE, "True".toString());
            } else {
                values.put(userProvider.RIDE, "False".toString());
            }
            uri = getContentResolver().insert(userProvider.CONTENT_URI, values);

        }
    });