Android初学第53天

14_LocalDatabases

代码

Criminalintent

CrimeLab.java

package com.bignerdranch.android.criminalintent;import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;import com.bignerdranch.android.criminalintent.database.CrimeBaseHelper;
import com.bignerdranch.android.criminalintent.database.CrimeCursorWrapper;
import com.bignerdranch.android.criminalintent.database.CrimeDbSchema;
import com.bignerdranch.android.criminalintent.database.CrimeDbSchema.CrimeTable;import java.util.ArrayList;
import java.util.List;
import java.util.UUID;import static com.bignerdranch.android.criminalintent.database.CrimeDbSchema.CrimeTable.*;
import static com.bignerdranch.android.criminalintent.database.CrimeDbSchema.CrimeTable.Cols.*;public class CrimeLab {private static CrimeLab sCrimeLab;private Context mContext;private SQLiteDatabase mDatabase;public static CrimeLab get(Context context) {if (sCrimeLab == null) {sCrimeLab = new CrimeLab(context);}return sCrimeLab;}private CrimeLab(Context context) {mContext = context.getApplicationContext();mDatabase = new CrimeBaseHelper(mContext).getWritableDatabase();}public void addCrime(Crime c) {ContentValues values = getContentValues(c);mDatabase.insert(CrimeTable.NAME, null, values);}public List<Crime> getCrimes() {List<Crime> crimes = new ArrayList<>();CrimeCursorWrapper cursor = queryCrimes(null, null);try {cursor.moveToFirst();while (!cursor.isAfterLast()) {crimes.add(cursor.getCrime());cursor.moveToNext();}} finally {cursor.close();}return crimes;}public Crime getCrime(UUID id) {CrimeCursorWrapper cursor = queryCrimes(CrimeTable.Cols.UUID + " = ?",new String[]{id.toString()});try {if (cursor.getCount() == 0) {return null;}cursor.moveToFirst();return cursor.getCrime();} finally {cursor.close();}}public void updateCrime(Crime crime) {String uuidString = crime.getId().toString();ContentValues values = getContentValues(crime);mDatabase.update(CrimeTable.NAME, values,CrimeTable.Cols.UUID + " = ?",new String[]{uuidString});}private CrimeCursorWrapper queryCrimes(String whereClause, String[] whereArgs) {Cursor cursor = mDatabase.query(CrimeTable.NAME,null, // Columns - null selects all columnswhereClause,whereArgs,null, // groupBynull, // havingnull  // orderBy);return new CrimeCursorWrapper(cursor);}private static ContentValues getContentValues(Crime crime) {ContentValues values = new ContentValues();values.put(UUID, crime.getId().toString());values.put(TITLE, crime.getTitle());values.put(DATE, crime.getDate().getTime());values.put(SOLVED, crime.isSolved() ? 1 : 0);return values;}}