Servlet CRUD-Servlet提供更新功能、使用Servlet进行CRUD开发的弊端

SERVLET 提供更新功能

编写 HeroUpdateServlet

HeroUpdateServlet

根据浏览器提交的id name hp damage创建一个Hero对象

然后调用HeroDAO的update，进行更新

更新结束后，客户端跳转到 /listHero

package servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import bean.Hero;
import dao.HeroDAO;

public class HeroUpdateServlet extends HttpServlet {

protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

request.setCharacterEncoding("UTF-8");

Hero hero = new Hero();
hero.setId(Integer.parseInt(request.getParameter("id")));
hero.setName(request.getParameter("name"));
hero.setHp(Float.parseFloat(request.getParameter("hp")));
hero.setDamage(Integer.parseInt(request.getParameter("damage")));

new HeroDAO().update(hero);

response.sendRedirect("/listHero");

}
}

配置web.xml

新增对路径 /updateHero的映射

<?xml version="1.0" encoding="UTF-8"?>
<web-app>

<servlet>
<servlet-name>HelloServlet</servlet-name>
<servlet-class>HelloServlet</servlet-class>
<load-on-startup>10</load-on-startup>
</servlet>

<servlet-mapping>
<servlet-name>HelloServlet</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>

<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>LoginServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>RegisterServlet</servlet-name>
<servlet-class>RegisterServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>RegisterServlet</servlet-name>
<url-pattern>/register</url-pattern>
</servlet-mapping>

<servlet>
<servlet-name>HeroListServlet</servlet-name>
<servlet-class>servlet.HeroListServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>HeroListServlet</servlet-name>
<url-pattern>/listHero</url-pattern>
</servlet-mapping>

<servlet>
<servlet-name>HeroAddServlet</servlet-name>
<servlet-class>servlet.HeroAddServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>HeroAddServlet</servlet-name>
<url-pattern>/addHero</url-pattern>
</servlet-mapping>

<servlet>
<servlet-name>HeroDeleteServlet</servlet-name>
<servlet-class>servlet.HeroDeleteServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>HeroDeleteServlet</servlet-name>
<url-pattern>/deleteHero</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>HeroEditServlet</servlet-name>
<servlet-class>servlet.HeroEditServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>HeroEditServlet</servlet-name>
<url-pattern>/editHero</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>HeroUpdateServlet</servlet-name>
<servlet-class>servlet.HeroUpdateServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>HeroUpdateServlet</servlet-name>
<url-pattern>/updateHero</url-pattern>
</servlet-mapping>

</web-app>

使用Servlet进行CRUD开发的弊端

用到这里，大家对使用Servlet进行CRUD开发就有比较全面感性认识了。 其中一个比较明显的弊端就是在Servlet编写html代码很痛苦，效率不高，可读性差，难以维护。

最好可以在html文件里面写html代码，同时又能在里面调用java的变量，那么这样就需要学习JSP了。