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;
 }