用ServletContext读取.properties文件

可以通过以下代码使用ServletContext读取.properties文件：

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/read-properties")
public class ReadPropertiesServlet extends HttpServlet {

  @Override
  protected void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    ServletContext context = getServletContext();
    InputStream inputStream = context.getResourceAsStream("/WEB-INF/config.properties");

    Properties properties = new Properties();
    properties.load(inputStream);

    String databaseUrl = properties.getProperty("database.url");
    String databaseUsername = properties.getProperty("database.username");
    String databasePassword = properties.getProperty("database.password");

    response.getWriter().println("Database URL: " + databaseUrl);
    response.getWriter().println("Database Username: " + databaseUsername);
    response.getWriter().println("Database Password: " + databasePassword);
  }
}

其中，读取.properties文件的代码是：

ServletContext context = getServletContext();
InputStream inputStream = context.getResourceAsStream("/WEB-INF/config.properties");
Properties properties = new Properties();
properties.load(inputStream);

注意，这里的.properties文件需要放在WEB-INF目录下，以保证安全性。