Java利用Socket实现通讯客户端的代码怎么写

具体客户端代码如下：

import java.net.*;  
import java.io.*;  
import org.apache.log4j.Logger;  
public class SocketClient {  
static Logger log = Logger.getLogger(SocketClient.class.
getName()); //日志记录信息  
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private String hostName;  
private int portNum;  
private int delaySecond; // 发文接收返回报文延时  
public SocketClient() {  
this.hostName = "192.168.0.1";  
this.portNum = 7000;  
this.delaySecond = 50000;  
pFileOp = null;  
}  
private Socket getSocket() {  
Socket socket = null;  
try {  
socket = new Socket(hostName, portNum);  
} catch (UnknownHostException e) {  
System.out.println("-->未知的主机名:" + hostName + " 异常");  
} catch (IOException e) {  
System.out.println("-hostName=" + hostName + " portNum="  
+ portNum + "---->IO异常错误" + e.getMessage());  
}  
return socket;  
}  
public String sendMessage(String strMessage) {  
String str = "";  
String serverString = "";  
Socket socket;  
try {  
socket = getSocket();  
// socket.setKeepAlive(true);  
if (socket == null) { // 未能得到指定的Socket对象,Socket通讯为空  
return "0001";  
}  
PrintWriter out = new PrintWriter(socket.getOutputStream());  
//log.info("---->发送报文="+strMessage);  
out.println(strMessage);  
out.flush();  
BufferedReader in = new BufferedReader(new InputStreamReader(  
socket.getInputStream()));  
long sendTime = System.currentTimeMillis();  
long receiveTime = System.currentTimeMillis();  
boolean received = false; // 成功接收报文  
boolean delayTooLong = false;  
serverString = null;  
while (!received && !delayTooLong) {  

							

								
								

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if (socket.getInputStream().available() > 0) {  
// serverString = in.readLine();  
char tagChar[];  
tagChar = new char[1024];  
int len;  
String temp;  
String rev = "";  
if ((len = in.read(tagChar)) != -1) {  
temp = new String(tagChar, 0, len);  
rev += temp;  
temp = null;  
}  
serverString = rev;  
}  
receiveTime = System.currentTimeMillis();  
if (serverString != null)  
received = true; // 字符串不为空，接收成功  
if ((receiveTime - sendTime) > delaySecond)  
delayTooLong = true; // 接收等待时间过长，超时  
}  
in.close();  
out.close();  
str=serverString;  
if (delayTooLong) str="2190"; //超时标志为真，返回超时码  
if (!received) str ="2190";  
socket.close();  
} catch (UnknownHostException e) {  
log.error("---->出现未知主机错误! 主机信息=" + this.hostName + 
" 端口号="  
+ this.portNum + " 出错信息=" + e.getMessage());  
str = "2191";  
// System.exit(1);  
} catch (IOException e) {  
log.error("---->出现IO异常! 主机信息=" + this.hostName + 
" 端口号="  
+ this.portNum + " 出错信息=" + e.getMessage());  
e.printStackTrace();  
str = "2191";  
} catch (Exception e) {  
str="2177";  
log.error("---->出现未知异常" + e.getMessage());  
} finally {  
socket = null;  
str.trim();  
//log.info("--->返回的socket通讯字符串="+str);  
return str;  
}  
}  
}