SpringMVC高级开发功能实现过程解析

//继承Exception
public class UserException extends Exception{

  private static final long serialVersionUID = -8469276157483476569L;

  public UserException() {
    super();
  }

  public UserException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
    super(message, cause, enableSuppression, writableStackTrace);
  }

  public UserException(String message, Throwable cause) {
    super(message, cause);
  }

  public UserException(String message) {
    super(message);
  }

  public UserException(Throwable cause) {
    super(cause);
  }

//将异常处理类交给spring容器管理
@Component
public class MyExceptionHandler implements HandlerExceptionResolver {
  @Override
  public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler,
      Exception ex) {
    // ex 接收是抛出的异常对象
    // 分类处理, 自定义异常, 直接响应 错误信息
    // 系统异常, 响应的: 系统错误, 请联系管理员
    ModelAndView modelAndView = new ModelAndView();if (ex instanceof UserException) {//用户异常
      modelAndView.addObject("error", ex.getMessage());
    } else {//系统异常
      modelAndView.addObject("error", "系统错误，联系管理员！！！");
    }
    modelAndView.setViewName("error");
    return modelAndView;
  }

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.10.0</version>
</dependency>

//前端发送json, 响应json
@RequestMapping("/queryUserByCondition.action")
@ResponseBody
public User  queryUserByCondition( @RequestBody User user) throws Exception{
  return user;
}

//请求的是json
    function requestJson(){
      //请求参数是json
      // 默认情况下, data中json, 变成js对象, 变成key/value
      //contentType:"application/json;charset=utf-8", 改为json 格式的传输
      $.ajax({
      url:"${pageContext.request.contextPath }/user/queryUserByCondition.action",
      type:"post",
      //data:"id=2&username=张三&sex=男&brithday=1999-12-21",
      contentType:"application/json;charset=utf-8", 
      data:'{"id":3,"username":"李四","sex":"男","brithday":"2012-12-12"}',
      success:function(rs){
        alert(rs.username+"-->"+rs.sex); // json 字符串转换为js对象
      },
      dataType:"json"
        });
    }

<dependency>
  <groupId>commons-fileupload</groupId>
  <artifactId>commons-fileupload</artifactId>
  <version>1.4</version>
</dependency>

<!-- 文件上传 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
 <!-- 设置最大的上传文件大小 :10M-->
<property name="maxUploadSize" value="10485760"></property>
</bean>

@PostMapping("/addUser.action")
  public String addUser(User user, MultipartFile photo,Model model) throws Exception{
    if(photo == null) {
      throw new UserException("请选择图片");
    }else {
      //保存文件
      String savePath = "D:\\upload";
      //File类
      File pathFile = new File(savePath);
      if(!pathFile.exists()) {
        //创建文件夹
        pathFile.mkdirs();
      }
      //文件名取名: 时间戳   UUID 
      //获取上传文件的后缀名
      String uploadFileName = photo.getOriginalFilename();
      String suffix = uploadFileName.substring(uploadFileName.lastIndexOf("."));
      String saveFilename = UUID.randomUUID().toString().replace("-", "").toUpperCase()+suffix;
      //保存
      photo.transferTo(new File(savePath,saveFilename));
      //给user对象的photoPath属性赋值
      user.setPhotoPath(saveFilename);
      
      //调用业务层,保存用户
      userService.saveUser(user);
      model.addAttribute("msg", "保存成功");
    }
    return "msg";
  }