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
