单例模式数据库

定义三张数据库

public class CleanMarsterDatabase {    public static final String DATABASE_NAME = "cleanmarter.db";    public static final int DATABASE_VERSION = 1;    /**     * 卸载残留垃圾清理     */    public static class Uninstall {        public final static String TABLE_NAME = "apk_uninstall";        public static final String KEY_PACKNAME = "packagename";    }    /**     * 缓存垃圾     */    public static class Cache {        public final static String TABLE_NAME = "cache";        public static final String KEY_PACKNAME = "packagename";        public static final String KEY_CACHE_SIZE = "cache_size";        public static final String KEY_MIN_CACHE_SIZE = "min_cache_size";        public static final String KEY_LAST_TIME = "last_time";    }    /**     * 静默卸载     */    public static class PackageSize {        public final static String TABLE_NAME = "save_uninstall_info";        public static final String KEY_PACKNAME = "packagename";        public static final String KEY_LAST_TIME = "last_time";        public static final String KEY_PACKAGE_SIZE = "package_size";    }

单例模式数据库

典型单例模式

    private static CleanMarsterHelp mInstance;    public static CleanMarsterHelp getInstance(Context mContext) {        if (mInstance == null) {            synchronized (CleanMarsterHelp.class) {                mInstance = new CleanMarsterHelp(mContext);            }        }        return mInstance;    }

比较完整示例

import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class CleanMarsterHelp extends SQLiteOpenHelper {    private static CleanMarsterHelp mInstance;    public static CleanMarsterHelp getInstance(Context mContext) {        if (mInstance == null) {            synchronized (CleanMarsterHelp.class) {                mInstance = new CleanMarsterHelp(mContext);            }        }        return mInstance;    }    public CleanMarsterHelp(Context mContext) {        super(mContext, CleanMarsterDatabase.DATABASE_NAME, null, CleanMarsterDatabase.DATABASE_VERSION);    }    @Override    public void onCreate(SQLiteDatabase db) {        db.execSQL("create table " + CleanMarsterDatabase.Uninstall.TABLE_NAME                + "("                + CleanMarsterDatabase.Uninstall.KEY_PACKNAME + " TEXT PRIMARY KEY"                + ");");        db.execSQL("create table " + CleanMarsterDatabase.PackageSize.TABLE_NAME                + "("                + CleanMarsterDatabase.PackageSize.KEY_PACKNAME + " TEXT PRIMARY KEY,"                + CleanMarsterDatabase.PackageSize.KEY_PACKAGE_SIZE + " integer DEFAULT 0,"                + CleanMarsterDatabase.PackageSize.KEY_LAST_TIME + " integer DEFAULT 0"                + ");");        db.execSQL("create table " + CleanMarsterDatabase.Cache.TABLE_NAME                + "("                + CleanMarsterDatabase.Cache.KEY_PACKNAME + " TEXT PRIMARY KEY,"                + CleanMarsterDatabase.Cache.KEY_CACHE_SIZE + " integer DEFAULT 12288,"                + CleanMarsterDatabase.Cache.KEY_MIN_CACHE_SIZE + " integer DEFAULT 12288,"                + CleanMarsterDatabase.Cache.KEY_LAST_TIME + " integer DEFAULT 0"                + ");");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {        db.execSQL("DROP TABLE IF EXISTS clean_master");        onCreate(db);    }}

使用单例模式

建立一个BaseDao的基类，便于子类获得相同的实例及其共同方法

import android.content.Context;public class BaseDao {    private CleanMarsterHelp mCleanMarsterHelp;    public CleanMarsterHelp openDB(Context mContext) {        if (null == mCleanMarsterHelp) {            mCleanMarsterHelp = CleanMarsterHelp.getInstance(mContext);        }        return mCleanMarsterHelp;    }    public void closeDB() {        if (mCleanMarsterHelp != null) {            mCleanMarsterHelp.getWritableDatabase().close();        }    }}

子类调用单例 openDb()

子类1

注意这里的openDb()使用单例获取实例

import java.util.HashMap;import java.util.List;import com.cleanmaster.domain.CacheInfo;import com.cleanmaster.utils.CleanMasterUtil;import com.cleanmaster.utils.ConstantUtil;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.util.Log;public class CacheDao extends BaseDao {    private static final String TAG = CacheDao.class.getSimpleName();    private Context mContext;    public CacheDao(Context mContext) {        this.mContext = mContext;    }    public void insertCacheSize(Context context, String packageName, Long size) {        ContentValues mContentValues = new ContentValues();        mContentValues.put(CleanMarsterDatabase.Cache.KEY_PACKNAME, packageName);        mContentValues.put(CleanMarsterDatabase.Cache.KEY_CACHE_SIZE, size);        mContentValues.put(CleanMarsterDatabase.Cache.KEY_LAST_TIME, System.currentTimeMillis());        openDB(mContext).getWritableDatabase().insert(CleanMarsterDatabase.Cache.TABLE_NAME, null, mContentValues);        if (ConstantUtil.DEBUG)            Log.i(TAG, "shz insertCacheDb packageName = " + packageName);    }

子类2

import java.util.ArrayList;import java.util.HashMap;import java.util.List;import com.cleanmaster.domain.UninstallInfo;import com.cleanmaster.utils.CleanMasterUtil;import com.cleanmaster.utils.ConstantUtil;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.util.Log;public class SilentUninstallDao extends BaseDao {    private static final String TAG = SilentUninstallDao.class.getSimpleName();    private Context mContext;    public SilentUninstallDao(Context mContext) {        this.mContext = mContext;    }    public void insertApkInstall(Context context, String packageName, Long size) {        ContentValues mContentValues = new ContentValues();        mContentValues.put(CleanMarsterDatabase.PackageSize.KEY_PACKNAME, packageName);        mContentValues.put(CleanMarsterDatabase.PackageSize.KEY_PACKAGE_SIZE, size);        mContentValues.put(CleanMarsterDatabase.PackageSize.KEY_LAST_TIME, System.currentTimeMillis());        openDB(mContext).getWritableDatabase().insert(CleanMarsterDatabase.PackageSize.TABLE_NAME, null, mContentValues);        if (ConstantUtil.DEBUG)            Log.i(TAG, "shz insertApkInstallDb packageName = " + packageName);    }

子类3

import java.util.ArrayList;import java.util.List;import com.cleanmaster.utils.ConstantUtil;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.util.Log;public class UninstallResidueDao extends BaseDao {    private static final String TAG = UninstallResidueDao.class.getSimpleName();    private Context mContext;    public UninstallResidueDao(Context mContext) {        this.mContext = mContext;    }    public void insertSaveUninstallInfoDb(Context context, String packageName) {        ContentValues mContentValues = new ContentValues();        mContentValues.put(CleanMarsterDatabase.Uninstall.KEY_PACKNAME, packageName);        openDB(mContext).getWritableDatabase().insert(CleanMarsterDatabase.Uninstall.TABLE_NAME, null, mContentValues);        if (ConstantUtil.DEBUG)            Log.i(TAG, "shz insertSaveUninstallInfoDb packageName = " + packageName);    }