自己复习sql,然后总结的2种数据库类

来源：互联网发布：java零基础入门书籍pdf 编辑：程序博客网时间：2024/05/17 08:21
//第一种package cn.itcast.service;import java.util.ArrayList;import java.util.List;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import cn.itcast.domain.Person;public class PersonService {    private DBOpenHelper dbOpenHelper;    public PersonService(Context context) {        this.dbOpenHelper = new DBOpenHelper(context);    }        public void payment(){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        db.beginTransaction();//开启事务        try{            db.execSQL("update person set amount=amount-10 where personid=1");            db.execSQL("update person set amount=amount+10 where personid=2");            db.setTransactionSuccessful();//设置事务的标志为True        }finally{            db.endTransaction();//结束事务,有两种情况：commit,rollback,        //事务的提交或回滚是由事务的标志决定的,如果事务的标志为True，事务就会提交，否侧回滚,默认情况下事务的标志为False        }    }    /**     * 添加记录     * @param person     */    public void save(Person person){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        db.execSQL("insert into person(name, phone, amount) values(?,?,?)",                new Object[]{person.getName(), person.getPhone(), person.getAmount()});    }    /**     * 删除记录     * @param id 记录ID     */    public void delete(Integer id){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        db.execSQL("delete from person where personid=?", new Object[]{id});    }    /**     * 更新记录     * @param person     */    public void update(Person person){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        db.execSQL("update person set name=?,phone=?,amount=? where personid=?",                new Object[]{person.getName(), person.getPhone(),  person.getAmount(), person.getId()});    }    /**     * 查询记录     * @param id 记录ID     * @return     */    public Person find(Integer id){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.rawQuery("select * from person where personid=?", new String[]{id.toString()});        if(cursor.moveToFirst()){            int personid = cursor.getInt(cursor.getColumnIndex("personid"));            int amount = cursor.getInt(cursor.getColumnIndex("amount"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String phone = cursor.getString(cursor.getColumnIndex("phone"));            return new Person(personid, name, phone, amount);        }        cursor.close();        return null;    }    /**     * 分页获取记录     * @param offset 跳过前面多少条记录     * @param maxResult 每页获取多少条记录     * @return     */    public List<Person> getScrollData(int offset, int maxResult){        List<Person> persons = new ArrayList<Person>();        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.rawQuery("select * from person order by personid asc limit ?,?",                new String[]{String.valueOf(offset), String.valueOf(maxResult)});        while(cursor.moveToNext()){            int personid = cursor.getInt(cursor.getColumnIndex("personid"));            int amount = cursor.getInt(cursor.getColumnIndex("amount"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String phone = cursor.getString(cursor.getColumnIndex("phone"));            persons.add(new Person(personid, name, phone, amount));        }        cursor.close();        return persons;    }    /**     * 分页获取记录     * @param offset 跳过前面多少条记录     * @param maxResult 每页获取多少条记录     * @return     */    public Cursor getCursorScrollData(int offset, int maxResult){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.rawQuery("select personid as _id,name,phone,amount from person order by personid asc limit ?,?",                new String[]{String.valueOf(offset), String.valueOf(maxResult)});        return cursor;    }        /**     * 获取记录总数     * @return     */    public long getCount(){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.rawQuery("select count(*) from person", null);        cursor.moveToFirst();        long result = cursor.getLong(0);        cursor.close();        return result;    }}//第二种package com.example.admin.xmltest678;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 PersonService {    private DBOpenHelper dbOpenHelper;    public PersonService(Context context) {        this.dbOpenHelper = new DBOpenHelper(context);    }    /**     * 添加记录     * @param person     */    public void save(Person person){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        ContentValues values = new ContentValues();        values.put("name", person.getName());        values.put("phone", person.getPhone());        values.put("amount", person.getAmount());        db.insert("person", null, values);    }    /**     * 删除记录     * @param id 记录ID     */    public void delete(Integer id){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        db.delete("person", "personid=?", new String[]{id.toString()});    }    /**     * 更新记录     * @param person     */    public void update(Person person){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        ContentValues values = new ContentValues();        values.put("name", person.getName());        values.put("phone", person.getPhone());        values.put("amount", person.getAmount());        db.update("person", values, "personid=?", new String[]{person.getId().toString()});    }    /**     * 查询记录     * @param id 记录ID     * @return     */    public Person find(Integer id){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.query("person", null, "personid=?", new String[]{id.toString()}, null, null, null);        if(cursor.moveToFirst()){            int personid = cursor.getInt(cursor.getColumnIndex("personid"));            int amount = cursor.getInt(cursor.getColumnIndex("amount"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String phone = cursor.getString(cursor.getColumnIndex("phone"));            return new Person(personid, name, phone, amount);        }        cursor.close();        return null;    }    /**     * 分页获取记录     * @param offset 跳过前面多少条记录     * @param maxResult 每页获取多少条记录     * @return     */    public List<Person> getScrollData(int offset, int maxResult){        List<Person> persons = new ArrayList<Person>();        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.query("person", null, null, null, null, null, "personid asc", offset+ ","+ maxResult);        while(cursor.moveToNext()){            int personid = cursor.getInt(cursor.getColumnIndex("personid"));            int amount = cursor.getInt(cursor.getColumnIndex("amount"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String phone = cursor.getString(cursor.getColumnIndex("phone"));            persons.add(new Person(personid, name, phone, amount));        }        cursor.close();        return persons;    }    /**     * 获取记录总数     * @return     */    public long getCount(){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.query("person", new String[]{"count(*)"}, null, null, null, null, null);        cursor.moveToFirst();        long result = cursor.getLong(0);        cursor.close();        return result;    }}
0 0