android 单例模式 数据库操作

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;


public class BlackNumberOpenHelper extends SQLiteOpenHelper {
public BlackNumberOpenHelper(Context context) {
super(context, "blacknumber.db", null, 1);
}


@Override
public void onCreate(SQLiteDatabase db) {
//创建数据库中表的方法
db.execSQL("create table blacknumber " +
"(_id integer primary key autoincrement , phone varchar(20), mode varchar(5));");
}


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


}

}

import java.util.ArrayList;
import java.util.List;


import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;




public class BlackNumberDao {
private BlackNumberOpenHelper blackNumberOpenHelper;
//BlackNumberDao单例模式
//1,私有化构造方法
private BlackNumberDao(Context context){
//创建数据库已经其表机构
blackNumberOpenHelper = new BlackNumberOpenHelper(context);
}
//2,声明一个当前类的对象
private static BlackNumberDao blackNumberDao = null;
//3,提供一个静态方法,如果当前类的对象为空,创建一个新的
public static BlackNumberDao getInstance(Context context){
if(blackNumberDao == null){
blackNumberDao = new BlackNumberDao(context);
}
return blackNumberDao;
}

/**增加一个条目
* @param phone拦截的电话号码
* @param mode 拦截类型(1:短信 2:电话3:拦截所有(短信+电话))
*/
public void insert(String phone,String mode){
//1,开启数据库,准备做写入操作
SQLiteDatabase db = blackNumberOpenHelper.getWritableDatabase();


ContentValues values = new ContentValues();
values.put("phone", phone);
values.put("mode", mode);
db.insert("blacknumber", null, values);

db.close();
}

/**从数据库中删除一条电话号码
* @param phone删除电话号码
*/
public void delete(String phone){
SQLiteDatabase db = blackNumberOpenHelper.getWritableDatabase();


db.delete("blacknumber", "phone = ?", new String[]{phone});

db.close();
}

/**
* 根据电话号码去,更新拦截模式
* @param phone更新拦截模式的电话号码
* @param mode 要更新为的模式(1:短信 2:电话3:拦截所有(短信+电话)
*/
public void update(String phone,String mode){
SQLiteDatabase db = blackNumberOpenHelper.getWritableDatabase();


ContentValues contentValues = new ContentValues();
contentValues.put("mode", mode);

db.update("blacknumber", contentValues, "phone = ?", new String[]{phone});

db.close();
}

/**
* @return 查询到数据库中所有的号码以及拦截类型所在的集合
*/
public List<BlackNumberInfo> findAll(){
SQLiteDatabase db = blackNumberOpenHelper.getWritableDatabase();


Cursor cursor = db.query("blacknumber", new String[]{"phone","mode"}, null, null, null, null, "_id desc");
List<BlackNumberInfo> blackNumberList = new ArrayList<BlackNumberInfo>();
while(cursor.moveToNext()){
BlackNumberInfo blackNumberInfo = new BlackNumberInfo();
blackNumberInfo.phone = cursor.getString(0);
blackNumberInfo.mode = cursor.getString(1);
blackNumberList.add(blackNumberInfo);
}
cursor.close();
db.close();

return blackNumberList;
}

/**
* 每次查询20条数据
* @param index查询的索引值
*/
public List<BlackNumberInfo> find(int index){
SQLiteDatabase db = blackNumberOpenHelper.getWritableDatabase();


Cursor cursor = db.rawQuery("select phone,mode from blacknumber order by _id desc limit ?,20;", new String[]{index+""});

List<BlackNumberInfo> blackNumberList = new ArrayList<BlackNumberInfo>();
while(cursor.moveToNext()){
BlackNumberInfo blackNumberInfo = new BlackNumberInfo();
blackNumberInfo.phone = cursor.getString(0);
blackNumberInfo.mode = cursor.getString(1);
blackNumberList.add(blackNumberInfo);
}
cursor.close();
db.close();

return blackNumberList;
}

/**
* @return 数据库中数据的总条目个数,返回0代表没有数据或异常
*/
public int getCount(){
SQLiteDatabase db = blackNumberOpenHelper.getWritableDatabase();
int count = 0;
Cursor cursor = db.rawQuery("select count(*) from blacknumber;", null);
if(cursor.moveToNext()){
count = cursor.getInt(0);
}

cursor.close();
db.close();
return count;
}

/**
* @param phone作为查询条件的电话号码
* @return 传入电话号码的拦截模式 1:短信2:电话 3:所有0:没有此条数据
*/
public int getMode(String phone){
SQLiteDatabase db = blackNumberOpenHelper.getWritableDatabase();
int mode = 0;
Cursor cursor = db.query("blacknumber", new String[]{"mode"}, "phone = ?", new String[]{phone}, null, null,null);
if(cursor.moveToNext()){
mode = cursor.getInt(0);
}

cursor.close();
db.close();
return mode;
}
}