java 开源长连接_JAVA Socket长连接

做了一个指纹门锁，需要用TCP长连接进行服务端和门锁间的数据通信。

目前JAVA写socket服务端，门锁连接JAVA服务端。

服务端开了一个线程在监听门锁发来的数据(此处必须实时监听数据)

在监听的同时，若用socket发送数据的话，会出现异常报错。

第一个类负责接收socket连接 import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; import com.lock.util.StaticResource; /** * 侦听类 * 不断侦听Socket连接，将连接的Socket记录，并开启线程接受传来的数据 * @author plzwb */ public class ListenSocket implements Runnable{ ServerSocket serverSocket = null; @Override public void run() { try { serverSocket = new ServerSocket(2333); } catch (IOException e) { e.printStackTrace(); System.out.println("2333端口被占用"); } while (true) { try { Socket socket = serverSocket.accept(); StaticResource.socketList.add(socket); new Thread(new OpenRecordSocket(socket)).start(); System.out.println("Socket已连接"); } catch (IOException e) { e.printStackTrace(); System.out.println("accept异常"); } } } }

第二个类负责不断侦听数据 import java.io.IOException; import java.net.Socket; import com.lock.util.SocketUtil; import com.lock.util.StaticResource; public class OpenRecordSocket implements Runnable{ Socket socket = null; SocketUtil socketUtil = null; boolean state = true; public OpenRecordSocket(Socket socket) { this.socket = socket; socketUtil = new SocketUtil(socket); } @Override public void run() { while(state){ try { System.out.println("准备接受"); String text = socketUtil.receiveData(); System.out.println(text); } catch (IOException e) { StaticResource.socketList.remove(socket); state = false; System.out.println("Socket已经删除"); } } } }

一个Servlet，访问即可调用socket发送消息 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Socket socket = StaticResource.socketList.get(0); SocketUtil socketUtil = new SocketUtil(socket); socketUtil.sendData("hello"); }

Socket发送接收工具 import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.Socket; public class SocketUtil { Socket socket = null; public SocketUtil(Socket socket) { super(); this.socket = socket; } //发送数据 public void sendData(String data) throws IOException { OutputStream outputStream = socket.getOutputStream(); outputStream.write(data.getBytes()); } //接收数据 public String receiveData() throws IOException { InputStream inputStream = socket.getInputStream(); byte[] buf = new byte[1024]; int len = inputStream.read(buf); String text = new String(buf, 0, len); return text; } }

异常信息如下 Exception in thread "Thread-3" java.lang.StringIndexOutOfBoundsException: String index out of range: -1 at java.lang.String.checkBounds(String.java:381) at java.lang.String.(String.java:545) at com.lock.util.SocketUtil.receiveData(SocketUtil.java:27) at com.lock.socket.OpenRecordSocket.run(OpenRecordSocket.java:25) at java.lang.Thread.run(Thread.java:745)