App的前后台数据同步

前言

     在开发一个点餐软件时，app的订单数据是使用本地Sqlite数据库，在提交订单数据后，当订单数据在后台（Mysql数据库）发生变化时（如：已买单），本地数据如何改变呢？

思路

     前台在查询时，将后台订单数据以数组方式发送到前台进行更新(update)

实现

服务端实现

定义一类订单类

package yybwb;

public class orderdetail {
 public Integer id;    //,
 public Integer orderID; 
 public Integer menuID; 
 public String num; 
 public Integer state; 
    public String Tno;    //    //
    public String remark; 
  
 
 public   orderdetail(int id,int orderID, int menuID,String num, int state,String Tno,String remark) 
    {
  this.id = id;
  this.orderID = orderID;
  this.menuID =  menuID;
  this.num = num;
  this.state = state;
  this.Tno= Tno;
  this.remark= remark;
   
 }
}

通过一方法获取订单信息

public static ArrayList<orderdetail> getorderdetaillists(String Tabno){
  ArrayList< orderdetail> result = new ArrayList< orderdetail>();
  Connection con = null;   //声明Connection对象
  PreparedStatement ps = null;
  ResultSet rs = null;
  /*
   * tabletal的数据在新订单生成时修改
   */
  String sql = "select orderID,menuID,num,state,Tno,remark from orderdetailtal where state=1";
  
   try{
   con = getConnection();  //获得连接
   ps = con.prepareStatement(sql); //获得预编译语句
   //ps.setInt(1, Integer.valueOf(r_id)); //设置参数
   rs = ps.executeQuery();   //执行查询
   while(rs.next()){
     
    String remark = rs.getString(6);
    String Tno = rs.getString(5);
   // int orderID = rs.getInt(1); 
    int menuID = rs.getInt(2); 
    double num = rs.getDouble(3); 
     String.format("%.2f", num); //1.23
    int state =rs.getInt(4);
    
    //new String(rs.getString(2).getBytes("ISO-8859-1"),CHAR_ENCODING);
     // new String(rs.getString(3).getBytes("ISO-8859-1"),CHAR_ENCODING);
    orderdetail c = new orderdetail(1,1,menuID, String.format("%.2f", num),state,Tno,remark);
    result.add(c);
    
    //System.out.println(Tno+','+remark); 
   }
   System.out.println("get orderdetail lists");
  }catch(Exception e){
   e.printStackTrace();
  }
  finally{
   try{
    if(rs != null){
     rs.close();
     rs = null;
    }
   }catch(Exception e){
    e.printStackTrace();
   }
   try{
    if(ps != null){
     ps.close();
     ps = null;
    }
   }catch(Exception e){
    e.printStackTrace();
   }
   try{
    if(con != null){
     con.close();
     con = null;
    }
   }catch(Exception e){
    e.printStackTrace();
   }
  }
  return result;
 }
 

将订单信息传递到客户端

else if(msg.startsWith("<#GET_ORDERDETAIL#>")){//消息为获取台表2014-7-22
     msg = msg.substring(19);      //提取内容
     ArrayList<orderdetail> cmList = DBUtil.getorderdetaillists(msg); //获得台列表
     int size = cmList.size();   //个数
     dout.writeInt(size);    //返回个数
     String reply = din.readUTF();  //等待客户端反馈
     if(reply.equals("<#READY_TO_ORDERDETAIL#>")){ //如果客户端已经准备好
      for(orderdetail c:cmList){
       StringBuilder sb = new StringBuilder();
       
       sb.append(String.valueOf(c.id));
       sb.append("|");
       sb.append(String.valueOf(c.orderID));
       sb.append("|");
       sb.append(String.valueOf(c.menuID));
       sb.append("|");
          sb.append(c.num);
       sb.append("|");
       sb.append(String.valueOf(c.state));
       sb.append("|");
       sb.append(c.Tno);
       sb.append("|");
       sb.append(c.remark);
       
       dout.writeUTF(sb.toString());  //发送消息到客户端
           }
            }
    }
    

客户端实现

定义一个订单类

package com.realhope.rmeal.bean;

/**
 * 
 * @author Wuchunyuan
 * 订单明细类
 */
public class OrderDetail{ 
 private Integer _id;       
    private Integer orderID;    
    private Integer menuID;     
    private String num;    // 数量
    private Integer state;    // 状态 
    private String remark;    // 备注
    private String Tno;
    
 public OrderDetail() {
  super();
 }
 public OrderDetail(Integer _id, Integer orderID, Integer menuID,
   String num, Integer state, String Tno,String remark) {
  super();
  this._id = _id;
  this.orderID = orderID;
  this.menuID = menuID;
  this.num = num;
  this.state = state;
  this.remark = remark;
  this.Tno = Tno;
 }
 public Integer get_id() {
  return _id;
 }
 public void set_id(Integer _id) {
  this._id = _id;
 }
 public Integer getOrderID() {
  return orderID;
 }
 public void setOrderID(Integer orderID) {
  this.orderID = orderID;
 }
 public Integer getMenuID() {
  return menuID;
 }
 public void setMenuID(Integer menuID) {
  this.menuID = menuID;
 }
 public String getNum() {
  return num;
 }
 public void setNum(String num) {
  this.num = num;
 }
 public Integer getState() {
  return state;
 }
 public void setState(Integer state) {
  this.state = state;
 }
 public String getRemark() {
  return remark;
 }
 public void setRemark(String remark) {
  this.remark = remark;
 }
 
 public String getTno() {
  return Tno;
 }
 public void setTno(String Tno) {
  this.Tno = Tno;
 }
 
}

发送获取订单的消息到服务器，得到服务器发来数据
    

 String msg = "<#GET_ORDERDETAIL#>"+TableN;
     mc.dout.writeUTF(msg); //发出获取新菜单表请求
     mc.dout.flush(); 
     int size = mc.din.readInt();   //获取个数 
      
     mc.dout.writeUTF("<#READY_TO_ORDERDETAIL#>");
     mc.dout.flush(); 
      
     for(int i=0;i<size;i++){
       msg = mc.din.readUTF();  //读取每条信息
       String [] sa = msg.split("\\|"); //切割字符串
    
    OrderDetail OrderDetaillists = new OrderDetail(Integer.valueOf(sa[0]),Integer.valueOf(sa[1]),
    Integer.valueOf(sa[2]),String.valueOf(sa[3]),Integer.valueOf(sa[4]),String.valueOf(sa[5]),
    String.valueOf(sa[6]));
     ((MenuActivity)mContext).lstDate_OrderDetailLists.add(OrderDetaillists);
    }        
   

执行SQl语句更新本地Sqlite数据库

/  * 2014-10-14
  * @param lstDate_OrderDetailLists
  */
 
 public void updateOrderDetail(List<OrderDetail>  lstDate_OrderDetailLists){
  DBHelper dbM = new DBHelper(this.context);
  SQLiteDatabase db = dbM.getReadableDatabase();
  db.execSQL("DROP TABLE IF EXISTS OrderDetailTal");
  //db.execSQL("delete from   OrderDetailTal");
  int Count=lstDate_OrderDetailLists.size();
 //创建表
  db.execSQL("CREATE TABLE " + OrderDetails.TABLE+ " ("
    + OrderDetails._ID + " INTEGER PRIMARY KEY,"
   + OrderDetails.ORDERID+ " INTEGER,"
    + OrderDetails.MENUID+ " INTEGER,"
    + OrderDetails.NUM + " REAL,"
    + OrderDetails.STATE + " INTEGER,"
    + OrderDetails.Tno + " TEXT,"
    + OrderDetails.REMARK + " TEXT"
     
   + ");");
 //逐一更新本地数据   
   for(int i=0 ; i<Count ;){
      db.execSQL("insert into "+OrderDetails.TABLE+" ("+OrderDetails.ORDERID+","+      OrderDetails.MENUID+","+
   OrderDetails.NUM +","+
   OrderDetails.STATE+","+OrderDetails.Tno +","+OrderDetails.REMARK +") " + 
     "values ('"+String.valueOf(lstDate_OrderDetailLists.get(i).getOrderID())+"','"+
   String.valueOf(lstDate_OrderDetailLists.get(i).getMenuID()) +"','"+
   lstDate_OrderDetailLists.get(i).getNum() +"','"+
   String.valueOf(lstDate_OrderDetailLists.get(i).getState()) +
   "','"+String.valueOf(lstDate_OrderDetailLists.get(i).getTno()) +
   "','"+String.valueOf(lstDate_OrderDetailLists.get(i).getRemark())+"')");
  i++;
  }
  
    db.close();
 return;
}