5.3接受请求的输入
@RequestParam(value="", defaultValue="") long max
尽管defaultValue是String类型的值，但是绑定到max参数时，会转换成Long类型
"/spittles/12345" vs "/spittles/show?spittle_id=12345"
前者能够识别出要查询的资源，后者描述的是带有参数的一个操作-本质上是通过HTTP发起的RPC
7.1配置的替代方案
添加其他的Servlet与Filter
实现WebApplicationInitializer，注册其他组件
7.2Multipart
- MultipartResolver
A. StandardServletMultipartResolver 配置信息在DispatcherServlet之中
@Bean
public MultipartResolver multipartResolver() throws IOException {
return new StandardServletMultipartResolver();
}
// 1.WebApplicationInitializer
DispatcherServlet ds = new DispatcherServlet();
Dynamic registration = context.addServlet("appServlet", ds);
registration.addMapping("/");
registration.setMultipartConfig(
new MultipartConfigElement("/tmp/spittr/uploads"));
//
// 2.AbstractAnnotationConfigDispatcherServletInitializer
@Override
protected void customizeRegistration(Dynamic registration) {
registration.setMultipartConfig(
new MultipartConfigElement("/tmp/spittr/uploads"));
}
//
// 3.web.xml
<servlet>
<servlet-name>SpringDispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<multipart-config>
<location>/tmp</location>
<max-file-size>5242880</max-file-size><!--5MB-->
<max-request-size>20971520</max-request-size><!--20MB-->
<file-size-threshold>0</file-size-threshold>
</multipart-config>
</servlet>
B. CommonsMultipartResolver
只需要配置bean
@Bean
public MultipartResolver multipartResolver() throws IOException {
CommonsMultipartResolver multipartResolver =
new CommonsMultipartResolver();
multipartResolver.setUploadTempDir(
new FileSystemResource("/tmp/spittr/uploads"));
multipartResolver.setMaxUploadSize(2097152);
multipartResolver.setMaxInMemorySize(0);
return multipartResolver;
}
MultipartResolver在DispatcherServlet转发请求之前对request进行处理，如果是Multipart的请求，就分解为MultipartHttpServletRequest
- 请求
POST enctype="multipart/form-data"
<input type="file" name="" accept="" /> - 处理Multipart请求
A. @RequestPart("name") byte[] filebyte
B. @RequestPart("name") MultipartFile/Part file
[Facepalm][Facepalm]如果使用Part参数接收文件，就不需要配置MultipartResolver了
7.3异常处理
- 使用@ResponseStatus(value=HttpStatus.NOT_FOUND, reason="Not Found")标注异常，将异常映射到状态码
- 使用@ExceptionHandler(Exception.class)标注异常处理方法，处理同一个Controller中handle method（RequestMapping）抛出的此类异常
- 使用@ControllerAdvice进行全局的异常处理，处理所有Controller抛出的此类异常
Any Spring bean declared in the DispatcherServlet’s application context that implements HandlerExceptionResolver will be used to intercept and process any exception raised in the MVC system and not handled by a Controller. The interface looks like this:
public interface HandlerExceptionResolver {
/**
* Try to resolve the given exception that got thrown during on handler execution,
* returning a ModelAndView that represents a specific error page if appropriate.
* <p>The returned ModelAndView may be {@linkplain ModelAndView#isEmpty() empty}
* to indicate that the exception has been resolved successfully but that no view
* should be rendered, for instance by setting a status code.
* @param request current HTTP request
* @param response current HTTP response
* @param handler the executed handler, or {@code null} if none chosen at the
* time of the exception (for example, if multipart resolution failed)
* @param ex the exception that got thrown during handler execution
* @return a corresponding ModelAndView to forward to,
* or {@code null} for default processing
*/
ModelAndView resolveException(
HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex);
}
