package com.lcjian.library.content;
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import java.io.FileDescriptor;
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import java.io.PrintWriter;
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import java.util.Arrays;
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import android.content.Context;
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import android.database.Cursor;
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import android.database.sqlite.SQLiteDatabase;
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import android.net.Uri;
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import androidx.loader.content.AsyncTaskLoader;
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public class CursorLoader extends AsyncTaskLoader<Cursor> {
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final ForceLoadContentObserver mObserver;
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SQLiteDatabase mSQLiteDatabase;
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Uri mUri;
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String mSql;
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String[] mSelectionArgs;
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Cursor mCursor;
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/* Runs on a worker thread */
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@Override
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public Cursor loadInBackground() {
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Cursor cursor = mSQLiteDatabase.rawQuery(mSql, mSelectionArgs);
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if (cursor != null) {
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// Ensure the cursor window is filled
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cursor.getCount();
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cursor.setNotificationUri(getContext().getContentResolver(), mUri);
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cursor.registerContentObserver(mObserver);
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}
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return cursor;
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}
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/* Runs on the UI thread */
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@Override
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public void deliverResult(Cursor cursor) {
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if (isReset()) {
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// An async query came in while the loader is stopped
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if (cursor != null) {
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cursor.close();
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}
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return;
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}
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Cursor oldCursor = mCursor;
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mCursor = cursor;
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if (isStarted()) {
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super.deliverResult(cursor);
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}
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if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) {
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oldCursor.close();
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}
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}
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/**
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* Creates an empty unspecified CursorLoader. You must override
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* {@link #loadInBackground()} to specify the query to perform.
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*/
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public CursorLoader(Context context) {
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super(context);
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mObserver = new ForceLoadContentObserver();
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}
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/**
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* Creates an empty unspecified CursorLoader. You must follow this with
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* calls to {@link #setUri(Uri)}, {@link #setSelectionArgs(String[])}, etc
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* to specify the query to perform.
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*/
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public CursorLoader(Context context, SQLiteDatabase sqliteDatabase) {
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super(context);
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mObserver = new ForceLoadContentObserver();
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mSQLiteDatabase = sqliteDatabase;
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}
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/**
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* Creates a fully-specified CursorLoader. See
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* {@link android.database.sqlite.SQLiteDatabase#rawQuery(String, String[])}
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* for documentation on the meaning of the
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* parameters. These will be passed as-is to that call.
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*/
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public CursorLoader(Context context, SQLiteDatabase sqliteDatabase,
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Uri uri, String sql, String[] selectionArgs) {
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super(context);
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mObserver = new ForceLoadContentObserver();
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mSQLiteDatabase = sqliteDatabase;
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mUri = uri;
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mSql = sql;
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mSelectionArgs = selectionArgs;
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}
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/**
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* Starts an asynchronous load of the contacts list data. When the result is ready the callbacks
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* will be called on the UI thread. If a previous load has been completed and is still valid
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* the result may be passed to the callbacks immediately.
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*
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* Must be called from the UI thread
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*/
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@Override
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protected void onStartLoading() {
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if (mCursor != null) {
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deliverResult(mCursor);
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}
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if (takeContentChanged() || mCursor == null) {
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forceLoad();
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}
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}
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/**
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* Must be called from the UI thread
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*/
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@Override
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protected void onStopLoading() {
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// Attempt to cancel the current load task if possible.
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cancelLoad();
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}
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@Override
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public void onCanceled(Cursor cursor) {
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if (cursor != null && !cursor.isClosed()) {
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cursor.close();
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}
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}
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@Override
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protected void onReset() {
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super.onReset();
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// Ensure the loader is stopped
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onStopLoading();
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if (mCursor != null && !mCursor.isClosed()) {
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mCursor.close();
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}
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mCursor = null;
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}
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public Uri getUri() {
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return mUri;
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}
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public void setUri(Uri uri) {
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mUri = uri;
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}
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public String[] getSelectionArgs() {
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return mSelectionArgs;
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}
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public void setSelectionArgs(String[] selectionArgs) {
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mSelectionArgs = selectionArgs;
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}
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public String getSql() {
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return mSql;
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}
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public void setSql(String sql) {
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this.mSql = sql;
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}
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@Override
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public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) {
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super.dump(prefix, fd, writer, args);
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writer.print(prefix); writer.print("mUri="); writer.println(mUri);
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writer.print(prefix); writer.print("mSql="); writer.println(mSql);
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writer.print(prefix); writer.print("mSelectionArgs=");
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writer.println(Arrays.toString(mSelectionArgs));
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writer.print(prefix); writer.print("mCursor="); writer.println(mCursor);
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}
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}
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