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Java是一种面向对象的编程语言,它具有丰富的模块和项目实战经验。在Java中,可以利用模块将代码组织成可重用的单元,从而提高代码的可维护性和可扩展性。下面是一些Java典型模块和项目实战的示例代码:
1. 数据库模块:Java中常用的数据库模块是JDBC(Java Database Connectivity),它提供了一种与数据库交互的标准方式。以下是一个使用JDBC连接到MySQL数据库并执行查询的示例代码:
import java.sql.*;
public class DatabaseModule {
public static void main(String[] args) {
String url = "jdbc:mysql://localhost:3306/mydatabase";
String username = "root";
String password = "password";
try {
Connection connection = DriverManager.getConnection(url, username, password);
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery("SELECT * FROM users");
while (resultSet.next()) {
int id = resultSet.getInt("id");
String name = resultSet.getString("name");
System.out.println("ID: " + id + ", Name: " + name);
}
resultSet.close();
statement.close();
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
2. 网络模块:Java中的网络模块可以用于创建客户端和服务器应用程序。以下是一个简单的服务器示例代码,它监听指定端口并接受客户端连接:
import java.io.*;
import java.net.*;
public class NetworkModule {
public static void main(String[] args) {
int port = 8080;
try {
ServerSocket serverSocket = new ServerSocket(port);
System.out.println("Server started on port " + port);
while (true) {
Socket clientSocket = serverSocket.accept();
System.out.println("Client connected: " + clientSocket.getInetAddress());
BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true);
String request = reader.readLine();
System.out.println("Received request: " + request);
String response = "Hello, client!";
writer.println(response);
System.out.println("Sent response: " + response);
reader.close();
writer.close();
clientSocket.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
3. Web模块:Java中的Web模块可以用于开发Web应用程序。以下是一个使用Java Servlet技术创建的简单Web应用程序示例代码:
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class HelloWorldServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><body>");
out.println("<h1>Hello, World!</h1>");
out.println("</body></html>");
}
}
以上是Java典型模块和项目实战的一些示例代码。这些模块和项目实战经验可以帮助Java开发人员更好地组织和开发代码,并实现各种功能和应用。