restcontroller的作用
理解一下@RestControlle的作用。
This code uses Spring 4’s new @RestController annotation, which marks the class as a controller where every method returns a domain object instead of a view. It’s shorthand for @Controller and @ResponseBody rolled together.
上文摘自官网。
由上面可见，@RestController=@Controller+@ResponseBody，下一步，理解@Controller。
Classic controllers can be annotated with the @Controller annotation. This is simply a specialization of the @Component class and allows implementation classes to be autodetected through the classpath scanning.
@Controller is typically used in combination with a @RequestMapping annotation used on request handling methods.
摘自这里，可以看出以下几点：
@Controller 是一种特殊化的@Component 类。
@Controller 习惯于和@RequestMapping绑定来使用，后者是用来指定路由映射的。
下一步，理解@ResponseBody。
The request handling method is annotated with @ResponseBody. This annotation enables automatic serialization of the return object into the HttpResponse.
摘自同样的地方，这里可以看出：
@ResponseBody 是用来把返回对象自动序列化成HttpResponse的。
再参考这里：
3. @ResponseBody
The @ResponseBody annotation tells a controller that the object returned is automatically serialized into JSON and passed back into the HttpResponse object.
Suppose we have a custom Response object:
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public class ResponseTransfer {
private String text;
// standard getters/setters
}
Next, the associated controller can be implemented:
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@Controller
@RequestMapping("/post")
public class ExamplePostController {
@Autowired
ExampleService exampleService;
@PostMapping("/response")
@ResponseBody
public ResponseTransfer postResponseController(
@RequestBody LoginForm loginForm) {
return new ResponseTransfer("Thanks For Posting!!!");
}
}
In the developer console of our browser or using a tool like Postman, we can see the following response:
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{"text":"Thanks For Posting!!!"}
Remember, we don’t need to annotate the @RestController-annotated controllers with the @ResponseBody annotation since it’s done by default here.
从上面可以看出：
@ResponseBody告诉控制器返回对象会被自动序列化成JSON，并且传回HttpResponse这个对象。
再补充一下@RequestBody：
Simply put, the @RequestBody annotation maps the HttpRequest body to a transfer or domain object, enabling automatic deserialization of the inbound HttpRequest body onto a Java object.
First, let’s have a look at a Spring controller method:
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@PostMapping("/request")
public ResponseEntity postController(
@RequestBody LoginForm loginForm) {
exampleService.fakeAuthenticate(loginForm);
return ResponseEntity.ok(HttpStatus.OK);
}
Spring automatically deserializes the JSON into a Java type assuming an appropriate one is specified. By default, the type we annotate with the @RequestBody annotation must correspond to the JSON sent from our client-side controller:
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public class LoginForm {
private String username;
private String password;
// ...
}
Here, the object we use to represent the HttpRequest body maps to our LoginForm object.
Let’s test this using CURL:
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curl -i \
-H "Accept: application/json" \
-H "Content-Type:application/json" \
-X POST --data
'{"username": "johnny", "password": "password"}' "https://localhost:8080/.../request"
This is all that is needed for a Spring REST API and an Angular client using the @RequestBody annotation!
@RequestBody把HttpRequest body映射成一个 transfer or domain object（DTO或者DO），把一个入境（inbound）的HttpRequest的body反序列化成一个Java对象。
