springMVC09("REST"的快速开发)

一、"REST"的快速开发：

解释： "快速开发"和"入门案例"的区别：（省略了很多重复的代码）

1.1-给大家看一下区别：

二、详细解析：

2.1-"@ResponseBody "的简化

解析:因为每个代码块都有这个注解，我们干脆直接把它放到外面去。

2.2-"@Controller"的简化

解析：因为"@ResponseBody "来到外面，可以和"@Controller"集合，所以"@Controller"这个注解可以不用写了。把他们合并成"@RestController"

2.3-"@RestController"的出现：

解析： 他是由"@ResponseBody"注解和"@Controller"注解的结合。

2.4-"XXX"，"Mapping"的简化

@RequestMapping(value = "/users", method = RequestMethod.POST)
@RequestMapping(value = "{id}", method = RequestMethod.DELETE)
@RequestMapping(value = "/users", method = RequestMethod.PUT)
@RequestMapping(value = "/users/{id}", method = RequestMethod.GET)
@RequestMapping(value = "/users", method = RequestMethod.GET)

解析："value = "/users" ----> value这个部分，用提到外面的"@RequestMapping("/books")",来简化了

2.4.1- 对2.4进行继续简化

剩下：

@RequestMapping(method = RequestMethod.POST)
@RequestMapping(method = RequestMethod.DELETE)
@RequestMapping(method = RequestMethod.PUT)
@RequestMapping( method = RequestMethod.GET)
@RequestMapping( method = RequestMethod.GET)

解析：这部分统一用：

@PostMapping
@DeleteMapping("/{id}")
@PutMapping
@GetMapping("/{id}")
@GetMapping

三、来对比一下"简化前"和"简化后的代码块"

简化前（没删除之前）：

//@Controller
//@ResponseBody
@RestController //@Controller和@ResponseBody的结合版本
@RequestMapping("/books")
public class BookController {
    //@RequestMapping(value = "/users", method = RequestMethod.POST)
    @PostMapping//代替了@RequestMapping(method = RequestMethod.POST)
    //@ResponseBody 提到最外面了
    public String save(@RequestBody User user) {
        System.out.println("book save..." + user);
        return "module: Book save...";
    }

    //@RequestMapping(value = "{id}", method = RequestMethod.DELETE)
    @DeleteMapping("/{id}")
    //@ResponseBody 提到最外面了
    public String delete(@PathVariable Integer id) { //形参里面加上@PathVariable注解，和"/users{id}"呼应
        System.out.println("Bookdelete..." + id);
        return "module: Book delete...";
    }

    //@RequestMapping(value = "/Book", method = RequestMethod.PUT)
    @PutMapping
    //@ResponseBody 提到最外面了
    public String update(@RequestBody User user) {
        System.out.println("Book update..." + user);
        return "module: Book update...";
    }

    //@RequestMapping(value = "/users/{id}", method = RequestMethod.GET) //GET是用来做查询的
    @GetMapping("/{id}")
    //@ResponseBody 提到最外面了
    public String getById(@PathVariable Integer id) {
        System.out.println("Book getById..." + id);
        return "module: Bookr getById...";
    }

    //@RequestMapping(value = "/users", method = RequestMethod.GET)
    @GetMapping
    //@ResponseBody 提到最外面了
    public String getAll() {
        System.out.println("Book getAll...");
        return "module: Book getAll...";
    }

}

简化后：（已经删除）

@RestController
@RequestMapping("/books")
public class BookController {
   
    @PostMapping
    public String save(@RequestBody User user) {
        System.out.println("book save..." + user);
        return "module: Book save...";
    }
    @DeleteMapping("/{id}")
    
    public String delete(@PathVariable Integer id) { 
        System.out.println("Book delete..." + id);
        return "module: Book delete...";
    }
    @PutMapping
    public String update(@RequestBody User user) {
        System.out.println("Book update..." + user);
        return "module: Book update...";
    }
    @GetMapping("/{id}")
    public String getById(@PathVariable Integer id) {
        System.out.println("Book getById..." + id);
        return "module: Book getById...";
    }
    @GetMapping
    public String getAll() {
        System.out.println("Book getAll...");
        return "module: Book getAll...";
    }
}

四、总结：

4.1：

4.2:

4.3:小结：