【隨手記錄】關於@RequestPart 與 @RequestParam

 

 

 

@RequestPart :看源碼備注:

Annotation that can be used to associate the part of a "multipart/form-data" request
 * with a method argument.
 *
 * <p>Supported method argument types include {@link MultipartFile} in conjunction with
 * Spring's {@link MultipartResolver} abstraction, {@code javax.servlet.http.Part} in
 * conjunction with Servlet 3.0 multipart requests, or otherwise for any other method
 * argument, the content of the part is passed through an {@link HttpMessageConverter}
 * taking into consideration the 'Content-Type' header of the request part. This is
 * analogous to what @{@link RequestBody} does to resolve an argument based on the
 * content of a non-multipart regular request.
 *
 * <p>Note that @{@link RequestParam} annotation can also be used to associate the part
 * of a "multipart/form-data" request with a method argument supporting the same method
 * argument types. The main difference is that when the method argument is not a String
 * or raw {@code MultipartFile} / {@code Part}, {@code @RequestParam} relies on type
 * conversion via a registered {@link Converter} or {@link PropertyEditor} while
 * {@link RequestPart} relies on {@link HttpMessageConverter HttpMessageConverters}
 * taking into consideration the 'Content-Type' header of the request part.
 * {@link RequestParam} is likely to be used with name-value form fields while
 * {@link RequestPart} is likely to be used with parts containing more complex content
 * e.g. JSON, XML).

@RequestPart主要用來處理content-type為 multipart/form-data 或 multipart/mixed stream 發起的請求,可以獲取請求中的參數,包括普通文本、文件或復雜對象比如json、xml等,針對json等復雜對象,需要明確對應的content-type,例如:

 發出來的請求頭:

Content-Type: multipart/form-data; boundary=xxxxxxxxxx

----xxxxxxxxxx

Content-Disposition: form-data; name= "jsonData"

Content-Type: applicatoin/json

{ "name" : "jack" ,  "age" : 25 }

----xxxxxxxxxxxx

@RequestParam:看源碼備注:

Annotation which indicates that a method parameter should be bound to a web
 * request parameter.
 *
 * <p>Supported for annotated handler methods in Spring MVC and Spring WebFlux
 * as follows:
 * <ul>
 * <li>In Spring MVC, "request parameters" map to query parameters, form data,
 * and parts in multipart requests. This is because the Servlet API combines
 * query parameters and form data into a single map called "parameters", and
 * that includes automatic parsing of the request body.
 * <li>In Spring WebFlux, "request parameters" map to query parameters only.
 * To work with all 3, query, form data, and multipart data, you can use data
 * binding to a command object annotated with {@link ModelAttribute}.
 * </ul>
 *
 * <p>If the method parameter type is {@link Map} and a request parameter name
 * is specified, then the request parameter value is converted to a {@link Map}
 * assuming an appropriate conversion strategy is available.
 *
 * <p>If the method parameter is {@link java.util.Map Map&lt;String, String&gt;} or
 * {@link org.springframework.util.MultiValueMap MultiValueMap&lt;String, String&gt;}
 * and a parameter name is not specified, then the map parameter is populated
 * with all request parameter names and values.

@RequestParam默認主要來處理query parameters, form data,and parts in multipart requests, 且是 key-value鍵值對這種文本,要區分 

　　Spring MVC:

　　　　會把query parameters, form data,and parts in multipart requests 里面的參數組合到一起存放在一個參數Map里(key相同的參數,值會追加)

　　Spring WebFlux:

　　　　只會處理query parameters

另外 SpringMVC處理multipart請求 可以看這里