Model
Model 层主要包含数据的类，这些数据一般是现实中的实体，所以，Model 层中类的定义常常和数据库 DDL 中的 create 语句类似。
通常数据库的表和类是一对一的关系，但是有的时候由于需求变化或者方便起见，Model 层的类有时不和数据库中表相互对应。比如面向对象之组合属性，在 Java 中可以用一个类组合另一个类，表示测试信息、对应多组测试用例的组合，（正常情况下，应该是一张表而不是两张表），而数据库是用两张表存储数据，利用外键关系表示测试信息、对应多组测试用例的关系。
由于数据繁多，为了简化对象的映射，不使用JDBC，而采用持久化框架 MyBatis。
MyBatis 首先需要配置数据源：
之后创建工厂对象，再用它创建数据访问对象（DataAccessObject，DAO）：
@Bean public SqlSessionFactory sqlSessionFactory() throws IOException { ClassLoader classLoader = RootConfig.class.getClassLoader(); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(classLoader.getResourceAsStream("config/mybatis/mybatis-config.xml")); return sqlSessionFactory; } @Autowired @Bean public DataAccessObject dataAccessObject(SqlSessionFactory sqlSessionFactory) { return new DataAccessObject(sqlSessionFactory); } DAO 对象负责数据访问。首先以 Mapper 接口的方式定义访问数据库的函数，之后在 XML 文件中实现该函数，并提供具体实现（SQL 语句细节）。这样做的好处一方面是防止命名错误，传统 MyBatis 方式是根据函数名执行相关 SQL 语句的，不用接口书写很容易出错；另一方面有助于设计（接口）和实现分离，降低耦合性。
public interface UserMapper { public int insertUser(@Param("user")User user); public int updateUser(@Param("user")User user); public int deleteUser(@Param("user") User user); public User selectUser(@Param("user") User user);} INSERT INTO users (email, password, name, sex, role, enabled) VALUES (#{user.email}, #{user.password}, #{user.name}, #{user.sex}, #{user.role}, #{user.enabled}) UPDATE users WHERE id = #{user.id} email = #{user.email}, password = #{user.password}, name = #{user.name}, sex = #{user.sex}, role = #{user.role}, enabled = #{user.enabled}, DELETE FROM users WHERE id = #{user.id}
MyBatis的可以处理基本类型，但有些类型需要自定义转换，就需要 MyBatis 提供的 BaseTypeHandler 进行转换。首先编写 BaseTypeHandler（见下），之后在 MyBatis 配置文件中注册（见上）。
package per.piers.onlineJudge.handler;import org.apache.ibatis.type.BaseTypeHandler;import org.apache.ibatis.type.JdbcType;import per.piers.onlineJudge.model.Sex;import java.sql.CallableStatement;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;public class SexTypeHandler extends BaseTypeHandler{ @Override public void setNonNullParameter(PreparedStatement preparedStatement, int i, Sex sex, JdbcType jdbcType) throws SQLException { preparedStatement.setInt(i, sex.getId()); } @Override public Sex getNullableResult(ResultSet resultSet, String s) throws SQLException { int sex = resultSet.getInt(s); if (resultSet.wasNull()) { return null; } else { return Sex.getSexType(sex); } } @Override public Sex getNullableResult(ResultSet resultSet, int i) throws SQLException { int sex = resultSet.getInt(i); if (resultSet.wasNull()) { return null; } else { return Sex.getSexType(i); } } @Override public Sex getNullableResult(CallableStatement callableStatement, int i) throws SQLException { int sex = callableStatement.getInt(i); if (callableStatement.wasNull()) { return null; } else { return Sex.getSexType(i); } }}
View
view 层主要是界面（页面）。这里主要是 JSP 页面，因为需要动态展示一些内容。其中还运用了 JavaScript 技术和 AJAX 技术，JavaScript 主要用作页面输入域校验，AJAX 主要用于异步提交需要更新的内容。
<%@page contentType="text/html; charset=UTF-8" %><%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><%@taglib uri="http://www.springframework.org/tags/form" prefix="sf" %><%@taglib uri="http://www.springframework.org/security/tags" prefix="security" %> <%@include file="../common/header.jspf" %>注册 <%@include file="../common/navbar.jspf" %><%@include file="../common/footer.jspf" %>注册
邮箱*密码*确认密码*姓名性别
function satisfySubmit() { var submit = document.getElementById("submit"); if (isEmailValid() && isPasswordValid() && isRepasswordValid()) { submit.setAttribute("type", "submit"); submit.setAttribute("value", "提交注册"); submit.setAttribute("class", "btn btn-success"); submit.removeAttribute("disabled") } else { submit.setAttribute("type", "button"); submit.setAttribute("value", "不能注册，请检查相关项填写是否正确"); submit.setAttribute("class", "btn btn-danger"); submit.setAttribute("disabled", ""); }} function registerUser() { xmlhttp = new XMLHttpRequest(); if (xmlhttp != null) { var email = document.getElementById("email").value; var password = document.getElementById("password").value; var name = document.getElementById("name").value; var sexes = document.getElementsByName("sex"); var sex; for (var i = 0; i < sexes.length; i++) { if (sexes[i].checked) sex = sexes[i].value.toUpperCase(); } var enabled = document.getElementById("enabled").value; var role = document.getElementById("role").value; var csrf = document.getElementsByName("_csrf")[0].value; xmlhttp.onreadystatechange = stateChange; xmlhttp.open("POST", window.location.pathname, true); xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); xmlhttp.send("&email=" + email + "&password=" + password + "&name=" + name + "&sex=" + sex + "&enabled=" + enabled + "&role=" + role + "&_csrf=" + csrf); }}function stateChange() { var success = document.getElementById("success"); if (xmlhttp.readyState == 4) { // 4 = "loaded" if (xmlhttp.status == 200) { // 200 = "OK" success.setAttribute("class", "text-success"); success.innerHTML = "注册成功"; alert("注册成功，点击确定进行登录") window.location.href = getContextPath() + "/user/information" } else if (xmlhttp.status == 409) { success.setAttribute("class", "text-danger"); success.innerHTML = "用户邮箱已存在"; } else if (xmlhttp.status == 500) { success.setAttribute("class", "text-danger"); success.innerHTML = "服务器可能出现了问题"; } }} Controller
Controller 是 Model 和 View 的粘合剂。Model 的增删改查的操作由 Controller 负责，View 的显示由 Controller 负责。Controller 实质上是 Java EE 的 Servlet。
在 Spring MVC 中，首先配置相关 DispatcherServlet，之后再编写 Controller。
package per.piers.onlineJudge.config;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.ViewResolver;import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;import org.springframework.web.servlet.config.annotation.EnableWebMvc;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;import org.springframework.web.servlet.view.InternalResourceViewResolver;@Configuration@EnableWebMvc@ComponentScan("per.piers.onlineJudge.controller")public class WebConfig extends WebMvcConfigurerAdapter { @Bean public ViewResolver viewResolver() { InternalResourceViewResolver resolver = new InternalResourceViewResolver(); resolver.setPrefix("/WEB-INF/jsp/"); resolver.setExposeContextBeansAsAttributes(true); resolver.setSuffix(".jsp"); return resolver; } @Override public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) { configurer.enable(); }} package per.piers.onlineJudge.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.security.core.context.SecurityContextHolder;import org.springframework.security.core.userdetails.UserDetails;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RequestPart;import org.springframework.web.multipart.MultipartFile;import per.piers.onlineJudge.model.User;import per.piers.onlineJudge.util.DataAccessObject;import per.piers.onlineJudge.util.ExcelUtil;import javax.servlet.http.HttpServletRequest;import java.io.File;import java.io.IOException;import java.util.HashMap;import java.util.HashSet;@Controller@RequestMapping("/testManager")public class UserImportController { private DataAccessObject dao; @Autowired public UserImportController(DataAccessObject dao) { this.dao = dao; } @RequestMapping("/import/user") public String importUser() { return "import/user"; } @RequestMapping(path = "/import/user", method = RequestMethod.POST) public String importResult(@RequestPart("usersFile") MultipartFile usersFile, HttpServletRequest request, Model model) throws IOException { String path = request.getSession().getServletContext().getRealPath("/") + "/tmp/" + usersFile.getOriginalFilename(); File file = new File(path); file.getParentFile().mkdirs(); file.createNewFile(); usersFile.transferTo(file); ExcelUtil excelUtil = new ExcelUtil(); HashSet emails = excelUtil.readColumns(file, "用户邮箱"); try { if (emails == null) { model.addAttribute("failure", "读取列用户邮箱出错，可能是没有列用户邮箱"); } else { User selectUser = new User(); selectUser.setEmail(((UserDetails) SecurityContextHolder.getContext().getAuthentication().getPrincipal()).getUsername()); Integer uidAdmin = dao.selectUser(selectUser).getId(); HashMap status = dao.importUser(emails, uidAdmin); StringBuilder builder = new StringBuilder(); for (String key : status.keySet()) { builder.append(String.format("%s,%s\n", key, status.get(key))); } model.addAttribute("success", builder.toString()); } } catch (Exception e) { model.addAttribute("failure", e.getMessage()); } finally { return "import/result"; } }} Spring 技术：这里的 Controller 是由 Spring MVC 提供的。本系统还设计了一个 ErrorController，用户异常处理的 Controller，返回错误的页面。
package per.piers.onlineJudge.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;@Controllerpublic class ErrorController { @RequestMapping(path = "/error/401") public String error401() { return "error/401"; } @RequestMapping(path = "/error/403") public String error403() { return "error/403"; } @RequestMapping(path = "/error/404") public String error404() { return "error/404"; } @RequestMapping(path = "/error/409") public String error409() { return "error/409"; } @RequestMapping(path = "/error/500") public String error500() { return "error/500"; }} Spring 技术：异常的捕获和处理是由标有 @ControllerAdvice 注解的类处理，需要定义捕获的异常类型、如何处理（返回的 HTTP 状态码，返回的页面）。
package per.piers.onlineJudge.controller;import org.apache.ibatis.exceptions.PersistenceException;import org.springframework.http.HttpStatus;import org.springframework.security.authentication.BadCredentialsException;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.ResponseStatus;import per.piers.onlineJudge.Exception.CRUDException;import per.piers.onlineJudge.Exception.ExistenceException;import per.piers.onlineJudge.Exception.ExpiryException;import javax.mail.MessagingException;import java.io.IOException;import java.io.PrintWriter;import java.io.StringWriter;@ControllerAdvicepublic class GlobalExceptionHandler { @ResponseStatus(value = HttpStatus.UNAUTHORIZED) @ExceptionHandler(BadCredentialsException.class) public String badCredentialsExceptionHandler(Exception e, Model model) { model.addAttribute("exception", getExceptionMessage(e)); return "error/401"; } @ResponseStatus(value = HttpStatus.FORBIDDEN) @ExceptionHandler(value = {ExpiryException.class, IllegalArgumentException.class}) public String illegalStateExceptionHandler(Exception e, Model model) { model.addAttribute("exception", getExceptionMessage(e)); return "error/403"; } @ResponseStatus(value = HttpStatus.CONFLICT) @ExceptionHandler(ExistenceException.class) public String existenceExceptionHandler(Exception e, Model model) { model.addAttribute("exception", getExceptionMessage(e)); return "error/409"; } @ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR) @ExceptionHandler(value = {CRUDException.class, IOException.class, IllegalStateException.class, MessagingException.class, PersistenceException.class}) public String CRUDExceptionHandler(Exception e, Model model) { model.addAttribute("exception", getExceptionMessage(e)); return "error/500"; } public String getExceptionMessage(Exception e) { StringWriter stringWriter = new StringWriter(); PrintWriter printWriter = new PrintWriter(stringWriter); e.printStackTrace(printWriter); return stringWriter.toString(); }}