利用android 的api实现 curd

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package com.itheima.dao;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;import android.util.Log;import com.itheima.db.PersonSQLiteOpenHelper;import com.itheima.domain.Person;public class PersonDao2 {private PersonSQLiteOpenHelper helper;/** *在构造方法里面完成helper的初始化 */public PersonDao2(Context context){helper = new PersonSQLiteOpenHelper(context);}/** * 添加一条记录 * @param name * @param nunber */public void add(String name,String number){SQLiteDatabase  db = helper.getWritableDatabase();ContentValues values = new ContentValues();values.put("name",name);values.put("number",number);//表名   返回值 返回-1 有错误 大于0 新添加行的iddb.insert("person",null,values);db.close();}/* * 查询记录是否存在； */public boolean find(String name){SQLiteDatabase db = helper.getReadableDatabase();//表名  null所有的列  条件  ?代表的占位符Cursor cursor = db.query("person",null,"name=?",new String[]{name},null,null,null);boolean result = cursor.moveToNext();db.close();return result;}/** * 修改 */public void update(String name,String number){SQLiteDatabase db = helper.getWritableDatabase();//表名  更新的数据 ContentValues values = new ContentValues();values.put("number",number);//返回值是 影响了多少行db.update("person", values,"name = ?",new String[]{number});db.close();}/** * 删除一条记录 * @param name */public void delete(String name){SQLiteDatabase db = helper.getWritableDatabase();//返回 影响的行数db.delete("person","name=?",new String[]{name});db.close();}//返回全部的数据库信息public List<Person> getAll(){SQLiteDatabase db =helper.getReadableDatabase();Cursor rs = db.query("person",new String[]{"name","id","number"},null, null, null, null, null);//Cursor rs = db.rawQuery("select * from person",null);List<Person> list = new ArrayList<Person>();while(rs.moveToNext()){int id = rs.getInt(1);String name = rs.getString(2);String number = rs.getString(rs.getColumnIndex("number"));Person p = new Person();p.setId(id);p.setName(name);p.setNumber(number);list.add(p);}rs.close();db.close();return list;}}
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