1 通过ping查看网络是否畅通，ping工作在TCP层，不能证明主机上是否开发某个端口。
查看机器中正在与哪些网络服务通信，使用netstat –an，由于只有TCP是面向协议的，因此只有TCP协议有状态说明。
2 创建简单服务器：
public class ChatServer {
public static void main(String[] args) {
// TODO Auto-generated method stub
ChatServer cs = new ChatServer();
cs.setUpServer(9090);
}private void setUpServer(int port) {
// TODO Auto-generated method stub
try {
ServerSocket server = new ServerSocket(port);
System.out.println("服务器创建成功!" + port);
while(true){//让服务器循环等待
Socket client = server.accept();
OutputStream out = client.getOutputStream();
InputStream ins = client.getInputStream();
String s = "你好，欢迎连接到服务器\r\n";
byte[] data = s.getBytes();
out.write(data);
out.flush();
int in=0;//一个字节一个字节地读取客户端输入
while(in!=13){//输入不是回车
in=ins.read();
System.out.println("读到的是："+in);
}
System.out.println("客户按了回车，退出"+in);
client.close();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}}
}
启动Telnet连接服务器：
3 接收客户端字符串，并返回响应
private void setUpServer(int port) {
// TODO Auto-generated method stub
try {
ServerSocket server = new ServerSocket(port);
System.out.println("服务器创建成功,等待连接......!" + port);
while (true) {// 让服务器循环等待
Socket client = server.accept();
System.out.println("Incoming Client"
+ client.getRemoteSocketAddress());
processChat(client);
}} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}}
private void processChat(Socket client) throws IOException {
// TODO Auto-generated method stub
OutputStream out = client.getOutputStream();
InputStream ins = client.getInputStream();
String s = "你好，欢迎来到服务器!";
byte[] data = s.getBytes();
out.write(data);
out.flush();String inputS = readString(ins);
while (!inputS .endsWith("bye")) {
System.out.println("客户端说:" + inputS);
s = "服务器收到：" + inputS + "\r\n";
data = s.getBytes();
out.write(data);
out.flush();
inputS = readString(ins);
}
client.close();
}private String readString(InputStream ins) throws IOException {
// TODO Auto-generated method stub
StringBuffer sb = new StringBuffer();
char c = 0;
while (c != 13) {
int i = ins.read();
c = (char) i;
sb.append(c);
}
String inputS = sb.toString().trim();
return inputS;
}
4 多线程服务器端
private void setUpServer(int port) {
// TODO Auto-generated method stub
try {
ServerSocket server = new ServerSocket(port);
System.out.println("服务器创建成功,等待连接......!" + port);
while (true) {// 让服务器循环等待
Socket client=server.accept();
ServerThread st=new ServerThread(client);
st.start();
}} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}}
ServerThread.java
public class ServerThread extends Thread{
Socket client;
public ServerThread(Socket sc){
this.client=sc;
}
public void run(){
try {
processChat(this.client);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private void processChat(Socket client) throws IOException {
// TODO Auto-generated method stub
OutputStream out = client.getOutputStream();
InputStream ins = client.getInputStream();……
