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Mysqliteopenhelper-Sqlitedatabase

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class AppLockOpenHelper extends SQLiteOpenHelper {
// Set the database name version number
     public AppLockOpenHelper (Context context) {
         super (context, AppLockConstants.DB_NAME, null, AppLockConstants.DB_VERSION);
     }
    // Create database table structure operation
     @Override
     public void onCreate (SQLiteDatabase db) {
         db.execSQL (AppLockConstants.CREATE_TABLE);
     } 

public static final String create_table = "CREATE TABLE" + table_name
+ "(" + ID + "Integer primary key AutoIncrement," + PackageName
+ "varchar (100))";

// when the database version has changed

 @Override @Override
    public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) {
    }
}
public class AppLockDao {

    private AppLockOpenHelper openHelper;
    private Context mContext;

    public AppLockDao (Context context) {
        openHelper = new AppLockOpenHelper (context);
        this.mContext = context;
    }
public boolean add (String packageName) {
        SQLiteDatabase database = openHelper.getWritableDatabase ();
        ContentValues values = new ContentValues ();
        // parameter 1: the name of the field in the table
        // Parameter 2: the value corresponding to the field
        values.put (AppLockConstants.PACKAGENAME, packageName);
        // Parameter 1: table name
        // Parameter 2: When adding data, you can add null data
        // Parameter 3: added data
        long insert = database
                .insert (AppLockConstants.TABLE_NAME, null, values);

        // Notify the content observer that the database has been updated
        ContentResolver contentResolver = mContext.getContentResolver ();
        // notify the content observer that the data has changed
        Uri uri = Uri.parse ("content: //com.z.mobliesafe.unlock");
        // Parameter 1: uri address
        // Parameter 2: which content observer to notify, if it is null, it means to notify all content observers registered through uri
        contentResolver.notifyChange (uri, null);

        // determine whether the addition was successful
        return insert! = -1;
    }
public boolean delete (String packageName) {
        SQLiteDatabase database = openHelper.getWritableDatabase ();
        // Parameter 2: query condition where id = ...
        // Parameter 3: parameter of query condition
        int delete = database.delete (AppLockConstants.TABLE_NAME,
                AppLockConstants.PACKAGENAME + "=?",
                new String [] {packageName});

        // Notify the content observer that the database has been updated
        ContentResolver contentResolver = mContext.getContentResolver ();
        // notify the content observer that the data has changed
        Uri uri = Uri.parse ("content: //com.z.mobliesafe.unlock");
        // Parameter 1: uri address
        // Parameter 2: which content observer to notify, if it is null, it means to notify all content observers registered through uri
        contentResolver.notifyChange (uri, null);

        // determine whether the deletion was successful
        return delete! = 0;
    }
// Query a single data
    / **
     * Check whether the package name of the application is in the database and determine whether the application is locked. True: locked, false: unlocked (no lock)
     * 3:09:23 pm
     * /
    public boolean queryOne (String packageName) {
        boolean isHave = false;
        SQLiteDatabase database = openHelper.getReadableDatabase ();
        // Parameter 2: Set which data to query
        // Parameter 3,4: query conditions and parameters of query conditions
        // Parameter 5: grouping
        // Parameter 6: deduplication
        // parameter 7: sort
        Cursor cursor = database.query (AppLockConstants.TABLE_NAME,
                new String [] {AppLockConstants.PACKAGENAME},
                AppLockConstants.PACKAGENAME + "=?",
                new String [] {packageName}, null, null, null);
        // If there is only one data query, you can use if without using while
        if (cursor.moveToNext ()) {
            // Because you only need to know whether the package name of the application is in the database, you don't need to use the query data
            isHave = true;
        }
        // close the database
        cursor.close ();
        database.close ();
        return isHave;
    }
// Query a single data
    / **
     * Check whether the package name of the application is in the database and determine whether the application is locked. True: locked, false: unlocked (no lock) 2016-11-21
     * 3:09:23 pm
     * /
    public boolean queryOne (String packageName) {
        boolean isHave = false;
        SQLiteDatabase database = openHelper.getReadableDatabase ();
        // Parameter 2: Set which data to query
        // Parameter 3,4: query conditions and parameters of query conditions
        // Parameter 5: grouping
        // Parameter 6: deduplication
        // parameter 7: sort
        Cursor cursor = database.query (AppLockConstants.TABLE_NAME,
                new String [] {AppLockConstants.PACKAGENAME},
                AppLockConstants.PACKAGENAME + "=?",
                new String [] {packageName}, null, null, null);
        // If there is only one data query, you can use if without using while
        if (cursor.moveToNext ()) {
            // Because you only need to know whether the package name of the application is in the database, you don't need to use the query data
            isHave = true;
        }
        // close the database
        cursor.close ();
        database.close ();
        return isHave;
    }
// query all data
    / **
     * Query all locked applications
     *
     * 2016-11-21 3:19:38 PM
     * /
    public List <String> queryAll () {

        SystemClock.sleep (2000);

        List <String> list = new ArrayList <String> ();

        SQLiteDatabase database = openHelper.getReadableDatabase ();
        // Parameter 2: Set which data to query
        // Parameter 3,4: query conditions and parameters of query conditions
        // Parameter 5: grouping
        // Parameter 6: deduplication
        // parameter 7: sort
        Cursor cursor = database.query (AppLockConstants.TABLE_NAME,
                new String [] {AppLockConstants.PACKAGENAME}, null, null,
                null, null, null);
        while (cursor.moveToNext ()) {
            String packageName = cursor.getString (0);

            // In order to facilitate listview display data, save the bean class to the collection
            list.add (packageName);
        }
        // close the database
        cursor.close ();
        database.close ();
        return list;
    } 

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