最近在完成软件体系结构上机实验时，遇到一个有点点小难度的选做题，题目信息如下：
利用套接字技术实现应用程序中对数据库的访问。应用程序只是利用套接字连接向服务器发送一个查询的条件，而服务器负责对数据库的查询，然后服务器再将查询的结果利用建立的套接字返回给客户端，如下图所示。
本来吧，选做题，不太想做的，但是考虑到以后工作的方向和后端相关，那还是做吧。
本次实验需要做一个GUI界面和一个连接查询功能，在论坛上借鉴了其他大佬获取网站内容的部分代码，然后自己做了一个及其简陋的swing界面，算是把这个实验完成了。
本次实验项目结构如下
--socketProject |--Client.java |--GUI.java |--SearchInfo.java |--Server.java |--ServerThread.java Client.java
客户端使用dis.readUTF()时，要注意再发送个字符或者空字符，这里发送end，表示关闭连接。不然会出现EOFException。
package socketProject; import java.io.*; import java.net.*; public class Client { String studentNum = null; String result = null; public void setStudentNum(String num) { this.studentNum = num; System.out.println("stu: " + studentNum); } public void run() throws IOException { Socket ss = new Socket("127.0.0.1", 8888); System.out.println("Socket: " + ss); try { DataInputStream dis = new DataInputStream(ss.getInputStream()); DataOutputStream dos = new DataOutputStream(ss.getOutputStream()); // the interaction dos.writeUTF(studentNum); // 向服务器发送学号 dos.flush(); result = dis.readUTF().toString(); // 获得客户端的json字符串 System.out.println(result); dos.writeUTF("end"); // 不加这句会报错 dos.flush(); if (dos != null) dos.close(); if (dis != null) dis.close(); } catch (IOException e) { e.printStackTrace(); } finally { if (ss != null) ss.close(); } } // gui界面用于获取json结果 public String getResult() { return result; } } Server.java
package socketProject; import java.io.*; import java.net.*; public class Server extends Thread { public static final int PORT = 8888; // public static void main(String[] args) throws IOException { public void run() { try (ServerSocket serverSocket = new ServerSocket(PORT)) { System.out.println("ServerSocket: " + serverSocket); try { while (true) { Socket socket = serverSocket.accept(); System.out.println("Socket accept: " + socket); Thread thread = new Thread(new ServerThread(socket)); thread.start(); // 开启一个线程，使之支持接收多个客户端的请求 } } finally { serverSocket.close(); } } catch (IOException e) { e.printStackTrace(); } } } ServerThread.java
package socketProject; import java.io.*; import java.net.*; public class ServerThread extends Thread { Socket socket = null; public ServerThread(Socket socket) { this.socket = socket; } public void run() { try { DataInputStream dis = new DataInputStream(socket.getInputStream()); DataOutputStream dos = new DataOutputStream(socket.getOutputStream()); while (true) { String str = dis.readUTF().toString(); String data = new SearchInfo().run(str); if (str.equals("end")) break; dos.writeUTF(data); } dos.close(); dis.close(); } catch (IOException e) { e.printStackTrace(); } } } SearchInfo.java
package socketProject; import java.io.*; import java.net.*; public class SearchInfo { public String run(String s) { String url = "your database interface"; String param = s; String sendGET = GetUrl(url, param); return sendGET; } public static String GetUrl(String url, String param) { String result = ""; // define the result str BufferedReader read = null; // define the access result try { URL realUrl = new URL(url + param); URLConnection connection = realUrl.openConnection(); connection.setRequestProperty("accept", "*/*"); connection.setRequestProperty("connection", "Keep-Alive"); connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)"); // 这里补充通用的请求属性 connection.connect(); // 建立实际的连接 read = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8")); String line; while ((line = read.readLine()) != null) { result += line; } } catch (Exception e) { e.printStackTrace(); } finally { if (read != null) {// 关闭流 try { read.close(); } catch (Exception e) { e.printStackTrace(); } } } return result; } public String getJSON(String param) { return param; } } GUI.java
package socketProject; import java.awt.*; import java.awt.event.*; import java.io.IOException; import javax.swing.*; public class GUI extends JFrame { private JButton connectDataBase; private JLabel entryStudentNum; private JTextField studentNum; private JButton sendRequest; private JLabel showResponseMsg; private JPanel northPanel; private JPanel southPanel; public GUI() { init(); } public void init() { setTitle("没啥技术含量的东西"); // define the component for the window connectDataBase = new JButton("连接数据库"); entryStudentNum = new JLabel("输入学号"); studentNum = new JTextField(); sendRequest = new JButton("发送"); showResponseMsg = new JLabel(); // add the component to the panel this.setLayout(new GridLayout(2, 1)); northPanel = new JPanel(new GridLayout(1, 4)); northPanel.add(connectDataBase); northPanel.add(entryStudentNum); northPanel.add(studentNum); northPanel.add(sendRequest); southPanel = new JPanel(new GridLayout(1, 1)); southPanel.add(showResponseMsg); setButtons(); this.add(northPanel); this.add(southPanel); // initial the window setBounds(400, 200, 600, 120); setResizable(false); setDefaultCloseOperation(EXIT_ON_CLOSE); setVisible(true); } public void setButtons() { connectDataBase.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { // 这里初始化服务端 Server server1 = new Server(); Thread th1 = new Thread(server1); th1.start(); // 这里一定要开启服务端线程，否则在点击此按钮后，整个界面会卡住，无法进行下一步操作 } }); sendRequest.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { Client client1 = new Client(); client1.setStudentNum(studentNum.getText()); // 获取文本框的文字，并赋给客户端的studentNum保存 try { client1.run(); } catch (IOException e1) { e1.printStackTrace(); } showResponseMsg.setText(client1.getResult()); // 将得到的数据显示在界面上 } }); } public static void main(String[] args) { new GUI(); } } 最终效果如下：
使用时，先点击连接数据库，然后根据学校提供的接口，输入自己的学号，点击发送，即可查询个人信息。
不过由于项目工作区非maven以及未来方向非Java的缘故，没有去深究如何提取json的值 (偷个懒)。
参考链接
Java请求一个URL，获取返回的数据_杜岚特的博客-CSDN博客
java.io.datainputstream.readunsignedshort_socket编程报异常java.io.EOFException_窦月汐的博客-CSDN博客
