TCP服务端开发为例--web开发不同url请求为何会走不同方法

拿java的web开发为例子，相信有很多小伙伴是做j2EE开发的，htpp请求，json数据传输都是工作中经常用的，查询请求，添加请求，修改请求前端配个url，例如https://localhost/intsmaze/user/add?name=intsmaze。然后后端建立一个controler类（类上配置url映射/user），然后创建一个addUser方法(在方法上配置映射/add)。然后启动web应用，前端发送的请求就会自动走到后端的addUser方法了。

但是你知道为什么这个请求走对应的方法吗？下面让我拿我大三期间基于TCP写的服务端程序做例子来看看背后的原理吧。这个程序时一个超市管理系统，客户端使用javaSwing编写，服务端使用javaSE编写，双方通信使用TCP协议，数据存储在mysql中。完整的项目上传在github上https://github.com/intsmaze/Swing-TCP-mysql。

服务端启动类，绑定端口。

public class LoginServer {        
    private int port=1000;
    private ServerSocket serversocket;
    private ExecutorService executorservice;
    private final int POOL_SIZE=1;//一个CPU线程池中工作线程的数目
    public LoginServer() throws Exception
    {    
        serversocket=new ServerSocket();
        serversocket.bind(new InetSocketAddress("127.0.0.1",port));    
        executorservice=Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors()*POOL_SIZE);    
        //当前CPU数*1就是总线程池数目
    }
    public void service()
    {
        while(true)
        {
            Socket socket=null;    
            try
            {
                socket=serversocket.accept();
                executorservice.execute(new Handler(socket));
            }catch(IOException e)
            {
                e.printStackTrace();
            }
        }
    }    
    public static void main(String[] args) throws Exception {
        new LoginServer().service();                    
    }
}

路径映射方法

localhost/intsmaze/后面不同的路径就是截取对应的字符串然后调用对应的方法

public class Handler implements Runnable{
    public static final int SOLDERCONNECTION=0;//售货员登录
    
    public static final int MANAGERADDSOLDER=7;//管理员添加售货员
    public static final int MANAGERDELETESOLDER=8;//管理员删除售货员
    public static final int MANAGERMOIDFYSOLDER=9;//管理员修改售货员
    
    private Socket socket;    
    private BufferedReader bufIn=null;
    private BufferedWriter bufOut=null;        
    private Connection connection=null;    
    private PreparedStatement preparedstatement=null;
    private ResultSet resultset=null;
    public Handler(Socket socket) throws IOException
    {
        this.socket=socket;
        bufIn=new BufferedReader(new InputStreamReader(socket.getInputStream()));
        bufOut=new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));    
    }        
    
    public void run() 
    {
        try
        {                                                                
                String line=bufIn.readLine();
                //读取第一个选着功能    
                int i=Integer.valueOf(line);                
                switch(i)            
                {
                        case SOLDERCONNECTION:
                            solderConnection();//售货员登录0
                            break;
                        case MANAGERADDSOLDER:
                            managerAddSolder();//管理员添加售货员7
                            break;
                        case MANAGERDELETESOLDER:
                            managerDeleteSolder();//管理员删除售货员8
                            break;
                        case  MANAGERMOIDFYSOLDER:
                            managerModifySolder();//管理员修改售货员9
                            break;                
                }
        }catch(Exception e)
            {
            socketUtil.close(socket);
            }
        }            
    public void solderConnection() throws Exception
    {
        String sr=null;    
        //读取账号和密码
        String arr[] =bufIn.readLine().split("#");;            
        
        connection=JdbcUtil.getConnection();
        preparedstatement=connection.prepareStatement("SELECT * FROM solder WHERE solder_number=? and solder_password=?");
        preparedstatement.setString(1,arr[0]);
        preparedstatement.setString(2,arr[1]);        
        resultset=preparedstatement.executeQuery();            
        if(resultset.next()){    
            bufOut.write("ok\n");//回馈查询信心
            bufOut.flush();                        
            sr=resultset.getInt(1)+"#"+resultset.getString(2)+"#"+resultset.getString(3)+"\n";
            bufOut.write(sr);
            bufOut.flush();            
            }
            else
            {
                bufOut.write("no");//回馈查询信心
                bufOut.flush();        
            }
            JdbcUtil.release(resultset, preparedstatement, connection);
        }    
                
        public void managerAddSolder() throws Exception
        {
            connection=JdbcUtil.getConnection();                
            String name=bufIn.readLine();    
            System.out.println(name);
            preparedstatement=connection.prepareStatement("insert into solder(solder_name) values(?) ");
            preparedstatement.setString(1,name);    
            preparedstatement.executeUpdate();//执行更新                            
            preparedstatement=connection.prepareStatement("select *from solder where solder_number=(select MAX(solder_number)from solder) ");
            resultset=preparedstatement.executeQuery();//执行更新        
            if(resultset.next())
            {
                bufOut.write("ok\n");//回馈查询信心
                bufOut.flush();
                String str=resultset.getString(1)+"#"+resultset.getString(2)+"#"+resultset.getString(3);
                bufOut.write(str+"\n");//回馈查询信心
                bufOut.flush();    
            }
            else
            {
                bufOut.write("no\n");//回馈查询信心
                bufOut.flush();
            }    
            
            JdbcUtil.release(resultset, preparedstatement, connection);
        }
        
        public void managerModifySolder() throws Exception
        {
            connection=JdbcUtil.getConnection();
            String arr[] = null;
            String line=null;
            
            
            String number=bufIn.readLine();
            preparedstatement=connection.prepareStatement("select *from solder  WHERE solder_number=? ");
            preparedstatement.setString(1,number);    
            resultset=preparedstatement.executeQuery();
            
            if(resultset.next())
            {
                bufOut.write("ok\n");//回馈查询信心
                bufOut.flush();    
                
                line=bufIn.readLine();
                arr=line.split("#");
                preparedstatement=connection.prepareStatement("update  solder set solder_password=?,solder_name=? WHERE solder_number=? ");
                preparedstatement.setString(1,arr[2]);    
                preparedstatement.setString(2,arr[1]);    
                preparedstatement.setString(3,arr[0]);    
                preparedstatement.executeUpdate();//执行更新        
            }
            else
            {
                bufOut.write("no\n");//回馈查询信心
                bufOut.flush();                    
            }    
            socket.close();
            JdbcUtil.release(resultset, preparedstatement, connection);
        }
        

        public void managerDeleteSolder() throws Exception
        {
            connection=JdbcUtil.getConnection();        
            String number=bufIn.readLine();
            preparedstatement=connection.prepareStatement("select *from solder WHERE solder_number=? ");
            preparedstatement.setString(1,number);    
            resultset=preparedstatement.executeQuery();
            
            if(resultset.next())
            {
                bufOut.write("ok\n");//回馈查询信心
                bufOut.flush();                        
                preparedstatement=connection.prepareStatement("delete from solder  WHERE solder_number=? ");
                preparedstatement.setString(1,number);    
                preparedstatement.executeUpdate();//执行更新                    
            }
            else
            {
                bufOut.write("no\n");//回馈查询信心
                bufOut.flush();    
            }    
            socket.close();
            JdbcUtil.release(resultset, preparedstatement, connection);
        }
    
        
}

 以localhost/intsmaze/user/add?name=intsmaze的url来反向剖析tcp服务端如何接收，并调用对应方法。localhost是与服务器建立连接，然后发送intsmaze/user/add?name=intsmaze为一个数据到服务器，服务器接收到该字符串后，根据/截取，然后判断该请求是发给intsmaze的应用。然后通过user知道这个请求时user模块（用户管理模块），然后通过add知道是调用添加用户方法。?后面就是对于的参数获取存入数据库即可.

对上面的方法改进如下即可实现

                String line=bufIn.readLine();
                //读取第一个选着功能  line的值为intsmaze/user/add?name=intsmaze  
                String arr[]=line.split("/");
                String model=arr[1];
                String method=arr[2].split("?")[0];
                String param=arr[2].split("?")[1];
                if(model.endsWith("user"))
                {
                    if(method.equals("add"))
                    {
                        user.add(param);
                    }
                }
                else if(model.equals("goods"))
                {
                    ...
                }
                else if
                ...