editServlet里面的///////////////////////////////////////////////
int id = Integer.parseInt(request.getParameter("id"));

		Hero hero = new HeroDao().get(id);
		request.setAttribute("hero", hero);
		try {
			request.getRequestDispatcher("edit.jsp").forward(request, response);

edit.jsp里面的///////////////////////////////////////////////////
<form action="update" method="post">
	id：<input  name="id" value="${hero.id}"><br>
	名字：<input name="name" value="${hero.name}"><br>
	血量：<input name="blood" value="${hero.blood}"><br>
	伤害：<input name="damage" value="${hero.damage}"><br>
	<input type="submit" value="修改">
</form>

listHero里面的/////////////////////////////////////////////
<a href = "edit?id=${hero.id}">编辑</a>

xml文件/////////////////////////////////////////
 <servlet>
        <servlet-name>hero.HeroEdit</servlet-name>
        <servlet-class>hero.HeroEdit</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>hero.HeroEdit</servlet-name>
        <url-pattern>/edit</url-pattern>
    </servlet-mapping>

package servlet;

import java.io.IOException;

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 bean.Hero;
import dao.HeroDAO;

@WebServlet("/updateHero")
public class HeroUpdateServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String name = request.getParameter("name");
		int hp = Integer.parseInt(request.getParameter("hp"));
		int id = Integer.parseInt(request.getParameter("id"));
		Hero hero = new Hero();
		hero.setName(name);
		hero.setHp(hp);
		hero.setId(id);
		new HeroDAO().update(hero);

		response.sendRedirect("listHero");
	}

}

java.lang.NumberFormatException: For input string: "486.0"
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Integer.parseInt(Integer.java:580)
	at java.lang.Integer.parseInt(Integer.java:615)
	at servlet.HeroUpdateServlet.service(HeroUpdateServlet.java:21)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)