MemShellParty/vul/vul-webapp-expression/src/main/java/ELServlet.java

import de.odysseus.el.ExpressionFactoryImpl;
import de.odysseus.el.util.SimpleContext;

import javax.el.ExpressionFactory;
import javax.el.ValueExpression;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @author ReaJason
 * @since 2024/12/14
 */
@WebServlet("/el")
public class ELServlet extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String data = req.getParameter("data");
        ExpressionFactory factory = new ExpressionFactoryImpl();
        SimpleContext context = new SimpleContext();
        ValueExpression ve = factory.createValueExpression(context, "${" + data + "}", Object.class);
        Object value = ve.getValue(context);
        resp.getWriter().write(value.toString());
    }
}