int[][][][] dp = new int[N][N][N][N];

for (int i1 = 1; i1 < N; i1 += 1) {
    for (int i2 = 1; i2 < N; i2 += 1) {
        for (int j1 = 1; j1 < N; j1 += 1) {
            for (int j2 = 1; j2 < N; j2 += 1) {
                int step = map[i1][j1];
                if (i2 != i1 && j2 != j1) step += map[i2][j2];
                
                dp[i1][j1][i2][j2] = 
                    Math.max(dp[i1-1][j1][i2-1][j2], 
                    Math.max(dp[i1-1][j1][i2][j2-1], 
                    Math.max(dp[i1][j1-1][i2-1][j2], 
                             dp[i1][j1-1][i2][j2-1]))) + step;
            }
        }
    }
}
System.out.println(dp[N-1][N-1][N-1][N-1]);

public class MybatisUtil {

    //在类加载时就进行创建
    private static SqlSessionFactory sqlSessionFactory;
    static {
        try {
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(new FileInputStream("mybatis-config.xml"));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取一个新的会话
     * @param autoCommit 是否开启自动提交（跟JDBC是一样的，如果不自动提交，则会变成事务操作）
     * @return SqlSession对象
     */
    public static SqlSession getSession(boolean autoCommit){
        return sqlSessionFactory.openSession(autoCommit);
    }
}

@Resource
JavaMailSender sender;

@PostMapping("/verification-email")
public String sendVerificationEmail(@RequestParam String targetEmail,
                                    HttpSession session) {
        SimpleMailMessage message = new SimpleMailMessage();
        message.setSubject(EMAIL_TITLE);
        int vCode = getVerificationCode();
        session.setAttribute("vcode", vCode);
        session.setAttribute("uemail", email);

        message.setText(EMAIL_CONTEXT + code);
        message.setTo(targetEmail);
        message.setFrom(EMAIL_SERVEREMAIL); // 与配置文件中的保持一致

        sender.send(message);
        return "发送成功"; // 前端弹窗可以接受此参数
}

@PostMapping("/register")
public String register(@RequestParam String username,
                       @RequestParam String email,
                       @RequestParam String code,
                       @RequestParam String password,
                       HttpSession session) {
    String sessionCode = session.getAttribute("vcode").toString;
    String sessionEmail = session.getAttribute("uemail").toString;

    if (sessionCode == null) {
        return "验证码为空";
    }
    if (!sessionCode.equals(code)) {
        return "验证码错误！";
    }
    if (!sessionEmail.equals(email)) {
        return "请获取验证码";
    }
}

package com.example.init
public class SecurityInitializer extends AbstractSecurityWebApplicationInitializer {
    //不用重写任何内容
      //这里实际上会自动注册一个Filter，SpringSecurity底层就是依靠N个过滤器实现的，我们之后再探讨
}

package com.example.config
@Configuration
@EnableWebSecurity   //开启WebSecurity相关功能
public class SecurityConfiguration {
        
}

@Override
protected Class<?>[] getRootConfigClasses() {
    return new Class[]{MainConfiguration.class, SecurityConfiguration.class};
}

@Configuration
@EnableWebSecurity
public class SecurityConfiguration {
    
      //将BCryptPasswordEncoder直接注册为Bean，Security会自动进行选择
    @Bean
    public PasswordEncoder passwordEncoder(){
        return new BCryptPasswordEncoder();
    }
}

encoder.encode(yourPassword);

@Configuration
@EnableWebSecurity
public class SecurityConfiguration {

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        return http
                .csfr(conf -> {
                    // 关闭CSFR
                    conf.disable();
                })
    }
}

@Configuration
@EnableWebSecurity
public class SecurityConfiguration {

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        return http
                // 验证请求拦截和放行配置
                .authorizeHttpRequests(auth -> {
                    // 将所有请求全部拦截，一律需要验证
                    auth.anyRequest().authenticated();    
                })
                // 表单登录相关配置
                .formLogin(conf -> {
                    conf.loginPage("/login");   // 将登录页设置为我们自己的登录页面
                    conf.loginProcessingUrl("/doLogin"); // 登录表单提交的地址，可以自定义
                    conf.defaultSuccessUrl("/");   // 登录成功后跳转的页面
                    conf.permitAll();    // 将登录相关的地址放行，否则未登录的用户无法进入登录界面
                      // 用户名和密码的表单字段名称
                    conf.usernameParameter("username");
                    conf.passwordParameter("password");
                })
                // 退出登录
                .logout(conf -> {
                    ...
                })
                .build();
    }
}

@Configuration
@EnableWebSecurity
public class SecurityConfiguration {

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        return http
                .rememberMe(conf -> {
                    conf.alwaysRemember(false);
                })
 

@Controller   //直接添加注解即可
public class HelloController {

    @RequestMapping("/index")   //直接填写访问路径
    public ModelAndView index(){
        ModelAndView modelAndView = new ModelAndView("index");
        modelAndView.getModel().put("arg", "value");   //将name传递给Model
        return modelAndView;
          //返回后会经过视图解析器进行处理
    }

    @RequestMapping(value = "/index")
    public String index(Model model){  //这里不仅仅可以是Model，还可以是Map、ModelMap
        model.addAttribute("arg", "value");
        return "index";
    }
}

@RequestMapping("/index")
public String index(){
    return "redirect:page";
}

@RequestMapping("/index")
public String index(){
    return "forward:home";
}

@RequestMapping("/index/{str}")
public String index(@PathVariable String str) {
    System.out.println(str);
    return "index";
}

public class MainInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    ...

    @Override
    protected void customizeRegistration(ServletRegistration.Dynamic registration) {
          // 直接通过registration配置Multipart相关配置，必须配置临时上传路径，建议选择方便打开的
        // 同样可以设置其他属性：maxFileSize, maxRequestSize, fileSizeThreshold
        registration.setMultipartConfig(new MultipartConfigElement("/path/to/save"));
    }
}

@RequestMapping(value = "/upload", method = RequestMethod.POST)
@ResponseBody
public String upload(@RequestParam MultipartFile file) throws IOException {
    File fileObj = new File("filename.png");
    file.transferTo(fileObj);
    System.out.println("用户上传的文件已保存到："+fileObj.getAbsolutePath());
    return "文件上传成功！";
}

@Value("{argue.argument}")
String argu;

public class ComplexBusinessService {
  SortAlgorithm sortAlgorithm = new BubbleSortAlgorithm;
}
public class BubbleSortAlgorithm implements SortAlgorithm {...}

public class ComplexBusinessService {
  SortAlgorithm sortAlgorithm; // = new BubbleSortAlgorithm();
  
  public ComplexBusinessService(SortAlgorithm sortAlgorithm) { // 创建构造函数
      this.sortAlgorithm = sortAlgorithm;
  }

public classBubbleSortAlgorithm implements SortAlgorithm {...}