尝试使用下面显示的自定义ContentProvider查询我的数据库时,我收到以下错误.
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
解决方法
从错误：
Caused by: java.lang.IllegalStateException: Invalid tables
我注意到你没有调用setTables()：
SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder(); queryBuilder.setTables(ProfessionalTable.TABLE_NAME);
在尝试运行查询之前.
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