一、发送邮件

发送邮件主要使用JavaMailSender类，使用send方法，send方法需要MimeMessage类型的参数。

void send(MimeMessage var1)

使用createMimeMessage()方法并用MimeMessage类型接收。再创建MimeMessageHelper()对象，添加一些数据。

MimeMessage message = mailSender.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(message);
helper.setFrom(from);
helper.setTo(to);
helper.setSubject(subject);
helper.setText(content, true);

最后发送邮件

mailSender.send(helper.getMimeMessage());

二、Cookie和Session的使用 

 Cookie

        因为是服务器发送给浏览器的，所以加上HttpServletResponse对象，给浏览器返回数据。创建cookie直接new Cookie对象就可以了，然后设置cookie的内容，生效范围，生存时间，最后通过response发送cookie。得到cookie直接使用注解@CookieValue，很方便。

//cookie示例@RequestMapping(path = "/cookie/set", method = RequestMethod.GET)@ResponseBodypublic String setCookie(HttpServletResponse response) {//创建cookieCookie cookie = new Cookie("code", CommunityUtil.generateUUID());//设置cookie生效的范围cookie.setPath("/community/alpha");//设置cookie生存时间cookie.setMaxAge(60 * 10);//10min//发送cookieresponse.addCookie(cookie);return "set cookie";}@RequestMapping(path = "/cookie/get", method = RequestMethod.GET)@ResponseBodypublic String getCookie(@CookieValue("code") String code) {System.out.println(code);return "get cookie";}

Session

 Session是存在服务端的，使用HttpSession对象创建，然后setAttribute信息。

//session示例@RequestMapping(path = "/session/set", method = RequestMethod.GET)@ResponseBodypublic String setSession(HttpSession session) {session.setAttribute("id", 1);session.setAttribute("name", "Test");return "set session";}@RequestMapping(path = "/session/get", method = RequestMethod.GET)@ResponseBodypublic String getSession(HttpSession session) {System.out.println(session.getAttribute("id"));System.out.println(session.getAttribute("name"));return "get session";}

三、生成验证码

package com.nowcoder.community.config;import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.impl.DefaultKaptcha;
import com.google.code.kaptcha.util.Config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import java.util.Properties;@Configuration
public class KaptchaConfig {@Beanpublic Producer kaptchaProducer() {Properties properties = new Properties();properties.setProperty("kaptcha.image.width", "100");properties.setProperty("kaptcha.image.height", "40");properties.setProperty("kaptcha.textproducer.font.size", "32");properties.setProperty("kaptcha.textproducer.font.color", "0,0,0");properties.setProperty("kaptcha.textproducer.char.string", "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYAZ");properties.setProperty("kaptcha.textproducer.char.length", "4");properties.setProperty("kaptcha.noise.impl", "com.google.code.kaptcha.impl.NoNoise");DefaultKaptcha kaptcha = new DefaultKaptcha();Config config = new Config(properties);kaptcha.setConfig(config);return kaptcha;}}

 生成文字的验证码放入session中，方便后续登录输入的验证码是否正确，最后生成图片验证码输出到浏览器中。

@RequestMapping(path = "/kaptcha", method = RequestMethod.GET)public void getKaptcha(HttpServletResponse response, HttpSession session) {// 生成验证码String text = kaptchaProducer.createText();BufferedImage image = kaptchaProducer.createImage(text);// 将验证码存入sessionsession.setAttribute("kaptcha", text);// 将图片输出给浏览器response.setContentType("image/png");try {OutputStream os = response.getOutputStream();ImageIO.write(image, "png", os);//image：图片对象，"bmg" ：图片格式, filWriterOne 需要写入的地方} catch (IOException e) {logger.error("响应验证码失败:" + e.getMessage());}}

ServletOutputStream getOutputStream()

获得字节流，通过该字节流的write(byte[] bytes)可以向response缓冲区中写入字节，再由Tomcat服务器将字节内容组成Http响应返回给浏览器。

response.getWriter().write("字符串")，这个方法只能写字符串。如果要写字节，比如，传个图片，怎么办呢？就要靠response.getOutputStream()

四、登录功能实现
 

 @RequestMapping(path = "/login", method = RequestMethod.POST)public String login(String username, String password, String code, boolean rememberme,Model model, HttpSession session, HttpServletResponse response) {// 检查验证码String kaptcha = (String) session.getAttribute("kaptcha");if (StringUtils.isBlank(kaptcha) || StringUtils.isBlank(code) || !kaptcha.equalsIgnoreCase(code)) {model.addAttribute("codeMsg", "验证码不正确!");return "/site/login";}// 检查账号,密码int expiredSeconds = rememberme ? REMEMBER_EXPIRED_SECONDS : DEFAULT_EXPIRED_SECONDS;Map map = userService.login(username, password, expiredSeconds);if (map.containsKey("ticket")) {Cookie cookie = new Cookie("ticket", map.get("ticket").toString());cookie.setPath(contextPath);cookie.setMaxAge(expiredSeconds);response.addCookie(cookie);return "redirect:/index";} else {model.addAttribute("usernameMsg", map.get("usernameMsg"));model.addAttribute("passwordMsg", map.get("passwordMsg"));return "/site/login";}}

@RequestMapping(path = "/logout", method = RequestMethod.GET)public String logout(@CookieValue("ticket") String ticket) {userService.logout(ticket);return "redirect:/login";}

五、拦截器的应用

        有许多请求同一个方法，统一对这些请求处理，比如访问账号设置一定要在用户登录的情况下才能访问，那么访问用户是否登录这个功能便可以使用拦截器进行实现。

package com.nowcoder.community.controller.interceptor;import com.nowcoder.community.annotation.LoginRequired;
import com.nowcoder.community.util.HostHolder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;@Component
public class LoginRequiredInterceptor implements HandlerInterceptor {@Autowiredprivate HostHolder hostHolder;@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {if (handler instanceof HandlerMethod) {HandlerMethod handlerMethod = (HandlerMethod) handler;Method method = handlerMethod.getMethod();LoginRequired loginRequired = method.getAnnotation(LoginRequired.class);if (loginRequired != null && hostHolder.getUser() == null) {response.sendRedirect(request.getContextPath() + "/login");return false;}}return true;}
}

 六、账号设置

@LoginRequired@RequestMapping(path = "/upload", method = RequestMethod.POST)public String uploadHeader(MultipartFile headerImage, Model model) {if (headerImage == null) {model.addAttribute("error", "您还没有选择图片!");return "/site/setting";}String fileName = headerImage.getOriginalFilename();String suffix = fileName.substring(fileName.lastIndexOf("."));if (StringUtils.isBlank(suffix)) {model.addAttribute("error", "文件的格式不正确!");return "/site/setting";}// 生成随机文件名fileName = CommunityUtil.generateUUID() + suffix;// 确定文件存放的路径File dest = new File(uploadPath + "/" + fileName);try {// 存储文件headerImage.transferTo(dest);} catch (IOException e) {logger.error("上传文件失败: " + e.getMessage());throw new RuntimeException("上传文件失败,服务器发生异常!", e);}// 更新当前用户的头像的路径(web访问路径)// http://localhost:8080/community/user/header/xxx.pngUser user = hostHolder.getUser();String headerUrl = domain + contextPath + "/user/header/" + fileName;userService.updateHeader(user.getId(), headerUrl);return "redirect:/index";}@RequestMapping(path = "/header/{fileName}", method = RequestMethod.GET)public void getHeader(@PathVariable("fileName") String fileName, HttpServletResponse response) {// 服务器存放路径fileName = uploadPath + "/" + fileName;// 文件后缀String suffix = fileName.substring(fileName.lastIndexOf("."));// 响应图片response.setContentType("image/" + suffix);try (FileInputStream fis = new FileInputStream(fileName);//需要自己关闭OutputStream os = response.getOutputStream();//SpringMVC会自动关闭) {byte[] buffer = new byte[1024];int b = 0;while ((b = fis.read(buffer)) != -1) {os.write(buffer, 0, b);}} catch (IOException e) {logger.error("读取头像失败: " + e.getMessage());}}