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。
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 ???????????????...TCP服务端开发为例--web开发不同url请求为何会走不同方法
原文地址：http://www.cnblogs.com/intsmaze/p/8098173.html