Servlet查询

CRUD是常见的页面功能，即我们常说的增删查改

• C - Creation 增加
• R - Retrieve 查询
• U - Update 修改
• D - Delete 删除

为web应用导入mysql-jdbc的jar包

• 放在WEB-INF/lib 下指的是能够web应用中找到对应的class
• 如果要在eclipse中做调试，还是需要为项目添加该jar才可以

编写HeroListServlet

• 命名规范：[表][行为]Servlet这样一种命名规范
• 增加：HeroAddServlet

package servlet;

import java.io.IOException;
import java.util.List;

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 HeroListServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html; charset=UTF-8");
        
        List heros = new HeroDAO().list();
        
        StringBuffer sb = new StringBuffer();
        sb.append("\r\n");
        sb.append("\r\n");
        String trFormat = "\r\n";
        
        for (Hero hero : heros) {
            String tr = String.format(trFormat, hero.getId(), hero.getName(), hero.getHp(), hero.getDamage());
            sb.append(tr);
        }
 
        sb.append("
id
name
hp
damage
%d
%s
%f
%d
");
        
        response.getWriter().write(sb.toString());
    }
}

配置web.xml

• 把路径listHero映射到HeroListServlet上
• 加上包名

        HeroListServlet
        servlet.HeroListServlet
    
    
    
        HeroListServlet
        /listHero
    

重启tomcat，访问http://localhost/j2ee_dynamic/listHero

image.png