我有一个问题，我不知道如何解决它。我正在尝试从服务器向客户端发送消息，但它不起作用，我甚至不知道为什么。 这是Java套接字服务器代码：
/*
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* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package homeautomation;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
/**
*
* @author WisterDeisgns
*/
public class GUI_TCPServer extends javax.swing.JFrame {
/**
* Creates new form GUI_TCPServer
*/
//TCP server Code.
static ServerSocket server;
static Socket client;
static BufferedReader in;
static BufferedWriter out;
static String ServerPort = "";
public GUI_TCPServer() {
initComponents();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jScrollPane1 = new javax.swing.JScrollPane();
ConsoleBox = new javax.swing.JTextArea();
jLabel1 = new javax.swing.JLabel();
MessageField = new javax.swing.JTextField();
SendButton = new javax.swing.JButton();
jLabel3 = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
ConsoleBox.setColumns(20);
ConsoleBox.setRows(5);
jScrollPane1.setViewportView(ConsoleBox);
jLabel1.setText("Console");
SendButton.setText("Send");
SendButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
SendButtonActionPerformed(evt);
}
});
jLabel3.setText("Message");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 371, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel1)
.addComponent(jLabel3)
.addGroup(layout.createSequentialGroup()
.addComponent(MessageField, javax.swing.GroupLayout.PREFERRED_SIZE, 200, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(SendButton, javax.swing.GroupLayout.PREFERRED_SIZE, 85, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(19, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(13, 13, 13)
.addComponent(jLabel1)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 111, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel3)
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(MessageField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(SendButton))
.addContainerGap(106, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void SendButtonActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
try{
String msgout = "";
msgout = MessageField.getText().trim();
out = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));
out.write(msgout , 0 , msgout.length());
out.flush();
out.close();
//dout.writeUTF(msgout); //Sending server message to client...
}catch(Exception e){
//Handle the exception here...
}
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) throws IOException {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(GUI_TCPServer.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(GUI_TCPServer.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(GUI_TCPServer.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(GUI_TCPServer.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new GUI_TCPServer().setVisible(true);
}
});
String msgin = "";
try{
server = new ServerSocket(8442); //server starts at 8442 port number
//if(client == null)
//ConsoleBox.setText(ConsoleBox.getText().trim() + "\n" + "Server > client is null!");
client = server.accept(); //Server accepts the connections
//din = new DataInputStream(client.getInputStream());
//dout = new DataOutputStream(client.getOutputStream());
ConsoleBox.setText(ConsoleBox.getText().trim() + "\n" + "Server > Has successfully started!");
ConsoleBox.setText(ConsoleBox.getText().trim() + "\n" + "Server > Port: 8442");
ConsoleBox.setText(ConsoleBox.getText().trim() + "\n" + "Server > Client connected, " + client.getInetAddress());
in = new BufferedReader(new InputStreamReader(client.getInputStream()));
//InputStream is = client.getInputStream();
//InputStreamReader isr = new InputStreamReader(is);
//BufferedReader br = new BufferedReader(isr);
//String inputText = br.readLine();
msgin = in.readLine();
//msgin = din.readUTF();
ConsoleBox.setText(ConsoleBox.getText().trim() + "\n" + msgin); //displaying the incomming message... - from client
//din.close();
}catch(Exception e){
}
}
// Variables declaration - do not modify
private static javax.swing.JTextArea ConsoleBox;
private javax.swing.JTextField MessageField;
private javax.swing.JButton SendButton;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel3;
private javax.swing.JScrollPane jScrollPane1;
// End of variables declaration
}
这是ESP8266代码：
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
const char* ssid = "HotBox";
const char* pass = "";
const char* host = "192.168.1.112";
void setup() {
delay(500);
Serial.begin(115200);
Serial.println();
Serial.print("conecting to: ");
Serial.println(ssid);
Serial.println("Try to connect to server: ");
Serial.println(host);
WiFi.mode(WIFI_STA);
delay(1000);
WiFi.begin(ssid, pass);
//IPAddress subnet(255,255,255,0);
//WiFi.config(IPAddress(192,168,1,150),IPAddress(192,168,1,10),subnet);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.print(".");
}
Serial.println();
Serial.print("My IP: ");
Serial.println(WiFi.localIP());
long rssi = WiFi.RSSI();
Serial.print("RSSI: ");
Serial.print(rssi);
Serial.println(" dBm");
}
void loop() {
WiFiClient client;
if (!client.connect(host,8442)) { //The problem start here
Serial.println(".");
return;
}
//Serial.println();
//Serial.print("Conected to IP: ");
//Serial.println(host);
//Serial.println("Sending string to server: ");
client.println("OK");
String line = client.readStringUntil('\n');
if(line != "")
Serial.println("Server > Data string: " + line);
//Serial.println();
//Serial.println("Closing connection");
client.flush();
client.stop();
//Serial.println("Connection Closed");
}
答案 0 :(得分：0)
在同一个应用程序中执行套接字通信客户端 - >服务器至少涉及两个线程。一个线程是服务器，一个是客户端。服务器线程使用server.accept（）等待客户端连接。客户端线程基本上打开一个Socket，写一条消息并等待回答。
两个线程都需要一个Socket实例来读写通信。您的代码从两侧使用相同的实例。我想这个构造在你第一次点击按钮后会抛出一个NullPointerException。
客户端线程 - 这里是ButtonAction - 必须创建一个自己的Socket实例：
new Socket( "localhost", 8842).