重写HttpServlet的doGet、doPost方法验证用户登录

首先在mvnrepository.com上搜索javax.servlet-api插件包，复制maven项目类代码，粘贴到pom.xml中的dependencies下

<dependencies>
 
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
 
  </dependencies>

在src->main目录下新建java目录（New Directory）并标记此目录作为source的根目录

在java目录下建包：cn.edu.mju.projrct1.comtroller控制层

创建一个验证用户登录的Servlet

继承于HttpServlet

使用@WebServlet注解方式调用映射Servlet容器@webServlet("/login")

@WebServlet("/login")
public class LoginController extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append("
");
        stringBuilder.append("登录名称：
");
        stringBuilder.append("登录密码：
");
        stringBuilder.append("
");
        stringBuilder.append(""
);
        showMsg(resp,stringBuilder.toString());
    }
 
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String loginName = req.getParameter("loginName");
        String loginPwd = req.getParameter("loginPwd");
      //如果用户名是你的学号，密码是1234 那么显示你好，登录名称，如果不对，那么显示账号或密码错误
        String str = null;
        if("5197101101".equals(loginName) && "1234".equals(loginPwd)){
            str = "你好" + loginName;
        }else {
            str = "账号或密码错误";
        }
        showMsg(resp,str);
    }
    private void showMsg(HttpServletResponse resp,String msg){
        resp.setCharacterEncoding("utf-8");
        try {
            PrintWriter out = resp.getWriter();
            out.println("");
            out.println("");
            out.println("
");
            out.println("");
            out.println("
");
            out.println("");
            out.println(msg);
            out.println("");
            out.println("");
            out.close();
        }
        catch(Exception ex) {
            System.out.println(ex.getMessage());
        }
    }
}