让servlet被spring管理

写一个代理类DelegatingServletProxy

import java.io.IOException;

import javax.servlet.GenericServlet;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

public class DelegatingServletProxy extends GenericServlet{

    private static final long serialVersionUID = 1L;
    private String targetBean;
    private Servlet proxy;

    @Override
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        proxy.service(req, res);
        
    }
    
    @Override
    public void init() throws ServletException {
        this.targetBean = getServletName();
        getServletBean();
        proxy.init(getServletConfig());
    }

    private void getServletBean() {
        WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(getServletContext());
        this.proxy = (Servlet) wac.getBean(targetBean);
    }
}

web.xml添加URL映射

<servlet>  
        <servlet-name>userController</servlet-name>  
        <servlet-class>proxy.DelegatingServletProxy</servlet-class>  
    </servlet>  
  
    <servlet-mapping>  
        <servlet-name>userController</servlet-name>  
        <url-pattern>/UserController</url-pattern>  
    </servlet-mapping>

被代理的sevlet不需要加@WebServlet("")

Tips:被代理的servlet bean id 要和web.xml的servlet-name相同