Spring MVC：带有CNVR卷的REST应用程序。 2

在上一篇文章中，我快速概述了带有CNVR的Spring MVC REST项目的设置环境。在这一部分中，我可以直接关注控制器和REST服务的演示。通常，我将做一个简短的介绍，然后我将介绍控制器方法并解释所有关键时刻。

由于我将进一步讨论REST服务，因此我需要说一些有关REST基本概念的句子。您可能之前听说过提供API来使用其功能的站点。借助REST或SOAP，这成为可能，但是在本文中，我将讨论REST。

例如，您想为大学图书馆开发一个可以与学生和书籍一起使用的应用程序。您可以使用REST实现所有控制器。该决定将使您的应用程序打开，以便与可以使用该应用程序API的其他应用程序进行协作。有关REST功能的更多信息，您需要访问特殊站点。

Spring MVC REST控制器

Smartphone应用程序面向HTTP客户端（例如浏览器）和JSON客户端。 JSON格式可由各种类型的客户端使用，但现在不再重要。

让我们考虑整个控制器代码：

@Controller
@RequestMapping(value="/smartphones")
public class SmartphoneController {@Autowiredprivate SmartphoneService smartphoneService;@RequestMapping(value="/create", method=RequestMethod.GET)public ModelAndView createSmartphonePage() {ModelAndView mav = new ModelAndView("phones/new-phone");mav.addObject("sPhone", new Smartphone());return mav;}@RequestMapping(value="/create", method=RequestMethod.POST)public ModelAndView createSmartphone(@ModelAttribute Smartphone smartphone,final RedirectAttributes attributes) {ModelAndView mav = new ModelAndView("redirect:/index.html");createSmartphone(smartphone);attributes.addFlashAttribute("msg", "New Smartphone "+smartphone+" was successfully created.");return mav;}@RequestMapping(value="/create", method=RequestMethod.POST, produces = "application/json", consumes = "application/json")@ResponseBodypublic Smartphone createSmartphone(@RequestBody Smartphone smartphone) {return smartphoneService.create(smartphone);}@RequestMapping(value="/edit/{id}", method=RequestMethod.GET)public ModelAndView editSmartphonePage(@PathVariable int id) {ModelAndView mav = new ModelAndView("phones/edit-phone");Smartphone smartphone = smartphoneService.get(id);mav.addObject("sPhone", smartphone);return mav;}@RequestMapping(value="/edit/{id}", method=RequestMethod.PUT, produces = "application/json", consumes = "application/json")@ResponseBodypublic Smartphone editSmartphone(@PathVariable int id, @RequestBody Smartphone smartphone) {smartphone.setId(id);return smartphoneService.update(smartphone);}@RequestMapping(value="/edit/{id}", method=RequestMethod.PUT)public ModelAndView editSmartphone(@PathVariable int id,@ModelAttribute Smartphone smartphone,final RedirectAttributes attributes) {ModelAndView mav = new ModelAndView("redirect:/index.html");editSmartphone(id, smartphone);attributes.addFlashAttribute("msg", "The Smartphone "+smartphone+" was successfully updated.");return mav;}@RequestMapping(value="/delete/{id}", method=RequestMethod.DELETE, produces = "application/json", consumes = "application/json")@ResponseBodypublic Smartphone deleteSmartphone(@PathVariable int id) {return smartphoneService.delete(id);}@RequestMapping(value="/delete/{id}", method=RequestMethod.GET)public ModelAndView deleteSmartphone(@PathVariable int id,final RedirectAttributes attributes) {ModelAndView mav = new ModelAndView("redirect:/index.html");Smartphone deletedSphone = deleteSmartphone(id);attributes.addFlashAttribute("msg", "The Smartphone "+deletedSphone+" was successfully deleted.");return mav;}@RequestMapping(value="", method=RequestMethod.GET,produces = "application/json", consumes = "application/json")@ResponseBodypublic List< Smartphone > allPhones() {return smartphoneService.getAll();}@RequestMapping(value="", method=RequestMethod.GET)public ModelAndView allPhonesPage() {ModelAndView mav = new ModelAndView("phones/all-phones");List< Smartphone > smartphones = new ArrayList< Smartphone >();smartphones.addAll(allPhones());mav.addObject("smartphones", smartphones);return mav;}}

Smartphone控制器确实很冗长，并且有很多方法。在控制器的开头，您可以看到自动连线的SmartphoneService 。反过来，SmartphoneService具有五种方法：

公共智能手机创建（Smartphone sp）；
公用智能手机get（整数id）;
公共列表<Smartphone> getAll（）;
公共智能手机更新（Smartphone sp）抛出SmartphoneNotFoundException;
公共智能手机delete（Integer id）抛出SmartphoneNotFoundException;

控制器中的每种方法都对应于服务的特定方法。因此，让我们在以下部分中检查这种对应关系。

REST：创建

以下代码段负责创建新的智能手机实体：

...@RequestMapping(value="/create", method=RequestMethod.POST)public ModelAndView createSmartphone(@ModelAttribute Smartphone smartphone,final RedirectAttributes attributes) {ModelAndView mav = new ModelAndView("redirect:/index.html");createSmartphone(smartphone);attributes.addFlashAttribute("msg", "New Smartphone "+smartphone+" was successfully created.");return mav;}@RequestMapping(value="/create", method=RequestMethod.POST, produces = "application/json", consumes = "application/json")@ResponseBodypublic Smartphone createSmartphone(@RequestBody Smartphone smartphone) {return smartphoneService.create(smartphone);}
...

第一种方法是简单的Spring MVC控制器。我在以前的文章中多次解释了如何使用Spring MVC控制器。但是您会注意到该方法是不寻常的，因为它包含第二个方法的调用。第二种方法是具有标准REST注释的REST方法： @ResponseBody和@RequestBody 。

当您将包含有关新智能手机的数据的表单提交到“ ../smartphones/create.html”进行处理时， 内容协商视图解析器将确定您需要接收html页面。如果您将URL称为“ ../smartphones/create.json”，则会返回JSON文档。因为我在WebAppConfig中指定CNVR需要根据URL sufix做出决定。

您可以问：如果我们仍然需要为同一操作创建几种方法，那么使用CNVR的原因是什么？让我们假设智能手机应用程序必须支持2种额外的内容类型：XML和PDF。在这种情况下，CNVR将使我们的生活更轻松，并且我们不会开发其他方法，只需在WebAppConfig中添加适当的视图解析器即可。如果我们开始在应用程序中使用AJAX，这种情况将变得非常理想。这意味着我们可以消除返回ModelAndView对象的方法。

REST：获取所有记录

在上一段中，我对CNVR原则进行了详细的概述。因此，现在我将发布与相应操作相对应的具体代码段。

...@RequestMapping(value="", method=RequestMethod.GET,produces = "application/json", consumes = "application/json")@ResponseBodypublic List< Smartphone > allPhones() {return smartphoneService.getAll();}@RequestMapping(value="", method=RequestMethod.GET)public ModelAndView allPhonesPage() {ModelAndView mav = new ModelAndView("phones/all-phones");List< Smartphone > smartphones = new ArrayList< Smartphone >();smartphones.addAll(allPhones());mav.addObject("smartphones", smartphones);return mav;}
...

这些方法负责检索智能手机列表。

REST：更新

以下是执行现有智能手机更新的方法。

...@RequestMapping(value="/edit/{id}", method=RequestMethod.PUT, produces = "application/json", consumes = "application/json")@ResponseBodypublic Smartphone editSmartphone(@PathVariable int id, @RequestBody Smartphone smartphone) {smartphone.setId(id);return smartphoneService.update(smartphone);}@RequestMapping(value="/edit/{id}", method=RequestMethod.PUT)public ModelAndView editSmartphone(@PathVariable int id,@ModelAttribute Smartphone smartphone,final RedirectAttributes attributes) {ModelAndView mav = new ModelAndView("redirect:/index.html");editSmartphone(id, smartphone);attributes.addFlashAttribute("msg", "The Smartphone "+smartphone+" was successfully updated.");return mav;}
...

休息：删除

以下是执行删除现有智能手机的方法。

...@RequestMapping(value="/delete/{id}", method=RequestMethod.DELETE, produces = "application/json", consumes = "application/json")@ResponseBodypublic Smartphone deleteSmartphone(@PathVariable int id) {return smartphoneService.delete(id);}@RequestMapping(value="/delete/{id}", method=RequestMethod.GET)public ModelAndView deleteSmartphone(@PathVariable int id,final RedirectAttributes attributes) {ModelAndView mav = new ModelAndView("redirect:/index.html");Smartphone deletedSphone = deleteSmartphone(id);attributes.addFlashAttribute("msg", "The Smartphone "+deletedSphone+" was successfully deleted.");return mav;}
...