针对目前功能越来越强大的智能手机来说,在PC端支持对手机中的用户数据作同步、备份以及恢复等保护措施的应用已经急需完善。不仅
小记:针对目前功能越来越强大的智能手机来说,在PC端支持对手机中的用户数据作同步、备份以及恢复等保护措施的应用已经急需完善。不仅要对数据作保护,而且用户更希望自己的手机跟PC能够一体化,以及和远程服务器的一体化。用户希望在手机端的操作能够转移到PC端,对于PC端大屏幕的电脑来说,完成同样的操作可以大量的节省用户的时间。对于功能强大的手机来说,,有近1/2的应用可以在PC端同步。所以对PC端应用的规划要以系统的角度来对待。同时要保证手机端和PC端的主流交互模式应保持一致。个人观点:数据的一体化和管理的多元化是以后发展的一个趋势。下面进行今天的学习,今天的实验室移动端和PC端的数据交互及解析。
1,如何实现移动端和PC端的数据交互?
答:1,蓝牙 2,NFC技术 3,红外 4,Socket.
NFC和蓝牙的异同点:
相同点:都是近距离传输。
不同点: NFC优于红外和蓝牙传输方式。作为一种面向消费者的交易机制,NFC比红外更快、更可靠而且简单得多,不用向红外那样必须严格的对齐才能传输数据。与蓝牙相比,NFC面向近距离交易,适用于交换财务信息或敏感的个人信息等重要数据;蓝牙能够弥补NFC通信距离不足的缺点,适用于较长距离数据通信。因此,NFC和蓝牙互为补充,共同存在。事实上,快捷轻型的NFC 协议可以用于引导两台设备之间的蓝牙配对过程,促进了蓝牙的使用。但是要实现远距离的数据传输那就只能用Socket了,
下面进行代码的分析:
首先在PC上建立服务端Server.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
using System.Threading;
namespace TcpServer
{
class Program
{
public static Socket serverSocket;
static Thread threadSend;
static Thread sendDataToClient;
static int count = 1;
static void Main(string[] args)
{
//确定端口号
int port = 121;
//设定连接IP
string host = "192.168.1.100";
//将IP地址字符串转化为IP地址实例
IPAddress ip = IPAddress.Parse(host);
//将网络端点表示为 IP 地址和端口号
IPEndPoint ipe = new IPEndPoint(ip, port);
//建立Socket
//addressFamily 参数指定 Socket 类使用的寻址方案
//socketType 参数指定 Socket 类的类型
//protocolType 参数指定 Socket 使用的协议。
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
//socket与本地终结点建立关联
socket.Bind(ipe);
while (true)
{
//开始监听端口
socket.Listen(0);
Console.WriteLine("服务已开启,请等待....." + DateTime.Now.ToString() + DateTime.Now.Millisecond.ToString());
//为新建的连接建立新的Socket目的为客户端将要建立连接
serverSocket = socket.Accept();
Console.WriteLine("连接已建立......" + DateTime.Now.ToString() + DateTime.Now.Millisecond.ToString());
Console.WriteLine("客户端IP:"+serverSocket.RemoteEndPoint);
string recStr =string.Empty;
//定义缓冲区用于接收客户端的数据
byte[] recbyte = new byte[1024];
ReceiveData();
sendDataToClient = new Thread(sendData);
sendDataToClient.Start();
}
}
public static void sendData()
{
while (true)
{
Console.WriteLine("send to client\n");
//服务端给客户端回送消息
string strSend = "Hello Android Client!" + DateTime.Now.Second;
//string strSend = "HelloClient1HelloClient2HelloClient3HelloClient4HelloClient5HelloClient6HelloClient7HelloClient8HelloClient9HelloClient10HelloClient11HelloClien12HelloClien13HelloClien14HelloClien15HelloClient16";
byte[] sendByte = new byte[1024];
//将发送的字符串转换为byte[]
sendByte = UTF8Encoding.UTF8.GetBytes(strSend);
//服务端发送数据
serverSocket.Send(sendByte, sendByte.Length, 0);
Thread.Sleep(1000);
}
}

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Indexes in MySQL are an ordered structure of one or more columns in a database table, used to speed up data retrieval. 1) Indexes improve query speed by reducing the amount of scanned data. 2) B-Tree index uses a balanced tree structure, which is suitable for range query and sorting. 3) Use CREATEINDEX statements to create indexes, such as CREATEINDEXidx_customer_idONorders(customer_id). 4) Composite indexes can optimize multi-column queries, such as CREATEINDEXidx_customer_orderONorders(customer_id,order_date). 5) Use EXPLAIN to analyze query plans and avoid

Using transactions in MySQL ensures data consistency. 1) Start the transaction through STARTTRANSACTION, and then execute SQL operations and submit it with COMMIT or ROLLBACK. 2) Use SAVEPOINT to set a save point to allow partial rollback. 3) Performance optimization suggestions include shortening transaction time, avoiding large-scale queries and using isolation levels reasonably.

Scenarios where PostgreSQL is chosen instead of MySQL include: 1) complex queries and advanced SQL functions, 2) strict data integrity and ACID compliance, 3) advanced spatial functions are required, and 4) high performance is required when processing large data sets. PostgreSQL performs well in these aspects and is suitable for projects that require complex data processing and high data integrity.

The security of MySQL database can be achieved through the following measures: 1. User permission management: Strictly control access rights through CREATEUSER and GRANT commands. 2. Encrypted transmission: Configure SSL/TLS to ensure data transmission security. 3. Database backup and recovery: Use mysqldump or mysqlpump to regularly backup data. 4. Advanced security policy: Use a firewall to restrict access and enable audit logging operations. 5. Performance optimization and best practices: Take into account both safety and performance through indexing and query optimization and regular maintenance.

How to effectively monitor MySQL performance? Use tools such as mysqladmin, SHOWGLOBALSTATUS, PerconaMonitoring and Management (PMM), and MySQL EnterpriseMonitor. 1. Use mysqladmin to view the number of connections. 2. Use SHOWGLOBALSTATUS to view the query number. 3.PMM provides detailed performance data and graphical interface. 4.MySQLEnterpriseMonitor provides rich monitoring functions and alarm mechanisms.

The difference between MySQL and SQLServer is: 1) MySQL is open source and suitable for web and embedded systems, 2) SQLServer is a commercial product of Microsoft and is suitable for enterprise-level applications. There are significant differences between the two in storage engine, performance optimization and application scenarios. When choosing, you need to consider project size and future scalability.

In enterprise-level application scenarios that require high availability, advanced security and good integration, SQLServer should be chosen instead of MySQL. 1) SQLServer provides enterprise-level features such as high availability and advanced security. 2) It is closely integrated with Microsoft ecosystems such as VisualStudio and PowerBI. 3) SQLServer performs excellent in performance optimization and supports memory-optimized tables and column storage indexes.


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