聊聊webflux参数校验

序

本文主要研究下webflux如何进行参数校验

使用javax.validation

domain

import javax.validation.constraints.Min;
import javax.validation.constraints.NotEmpty;

public class User {

    @Min(1)
    private long id;

    @NotEmpty
    private String name;

    @Min(20)
    private int age;
    //...
}    

通过onErrorResume处理异常

• form表单提交

    /**
     * curl -i -X POST -d 'id=-1&name=a&age=10' http://localhost:8080/user/validate-mono
     *
     * curl -i -X POST -d 'id=2&name=a&age=10' http://localhost:8080/user/validate-mono
     *
     * curl -i -X POST -d 'id=2&name=a&age=30' http://localhost:8080/user/validate-mono
     * @param user
     * @return
     */
    @PostMapping("/validate-mono")
    public Mono<String> formValidate(@Validated Mono<User> user) {
        return user
                .map(u -> "Hello " + u.getName())
                .onErrorResume(WebExchangeBindException.class, e -> Mono.just(bindingResult2String(e.getBindingResult())));
    }

• post json

    /**
     * curl -i -H "Content-Type: application/json" -X POST -d '{"id":-11,"name":"a"}' http://localhost:8080/user/validate-mono-json-body
     *
     * curl -i -H "Content-Type: application/json" -X POST -d '{"id":12,"name":"a","age":30}' http://localhost:8080/user/validate-mono-json-body
     * @param user
     * @return
     */
    @PostMapping(value = "/validate-mono-json-body",produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    @ResponseBody
    public Mono<String> requestBodyValidate(@Validated @RequestBody Mono<User> user) {

        return user
                .map(u -> "Hello " + u.getName())
                .onErrorResume(WebExchangeBindException.class, e -> Mono.just(bindingResult2String(e.getBindingResult())));
    }

注意这里catch住WebExchangeBindException

通过ExceptionHandler处理WebExchangeBindException

• ExceptionHandler

    @ExceptionHandler(WebExchangeBindException.class)
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ResponseBody
    public String handleBindException(WebExchangeBindException bindException) {
        return bindingResult2String(bindException.getBindingResult());
    }

• from表单提交

    /**
     * curl -i -X POST -d 'id=-1&name=a&age=10' http://localhost:8080/user/validate-mono
     *
     * curl -i -X POST -d 'id=2&name=a&age=10' http://localhost:8080/user/validate-mono
     *
     * curl -i -X POST -d 'id=2&name=a&age=30' http://localhost:8080/user/validate-mono
     * @param user
     * @return
     */
    @PostMapping(value = "/validate-mono",produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    public Mono<String> formValidate(@Validated Mono<User> user) {
        return user
                .map(u -> "Hello " + u.getName());
    }

注意这里要标注produces = MediaType.APPLICATION_JSON_UTF8_VALUE，否则报406 Not Acceptable

• post json

    /**
     * curl -i -H "Content-Type: application/json" -X POST -d '{"id":-11,"name":"a"}' http://localhost:8080/user/validate-mono-json-body
     *
     * curl -i -H "Content-Type: application/json" -X POST -d '{"id":12,"name":"a","age":30}' http://localhost:8080/user/validate-mono-json-body
     * @param user
     * @return
     */
    @PostMapping(value = "/validate-mono-json-body",produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    @ResponseBody
    public Mono<String> requestBodyValidate(@Validated @RequestBody Mono<User> user) {

        return user
                .map(u -> "Hello " + u.getName());
    }

注意这里没有使用onErrorResume来处理WebExchangeBindException，而是交给ExceptionHandler处理

手工校验

javax.validation虽然是方便，但是具体业务场景非常复杂，不是简单的单个字段校验就完事的，有的需要关联校验，这个时候javax.validation就无能为力了。这个时候可能就需要手工来写校验。

    /**
     * curl -i -X POST -d 'id=-1&name=a&age=10' http://localhost:8080/user/manual-validate
     *
     * curl -i -X POST -d 'id=2&name=a&age=-1' http://localhost:8080/user/manual-validate
     * @param user
     * @return
     */
    @PostMapping(value = "/manual-validate",produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    public Mono<String> manualValidate(Mono<User> user){
        return user.flatMap(u -> {
            if(u.getAge() < 0){
                return Mono.error(new RuntimeException("age < 0"));
            }else{
                return Mono.just("success");
            }
        });
    }

小结

通过使用javax.validation自动校验及Mono.error手工校验，基本可以处理大多数webflux参数校验场景。

doc

• Webflux-Validation
• How to validate Mono when using Spring Reactive