自定义 Spring Boot 请求体字符串校验教程

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.*;

import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Target({PARAMETER})
@Retention(RUNTIME)
@Constraint(validatedBy = {JsonSyntaxValidator.class})
@Documented
public @interface MyValidator {

    String message() default "{Token is not in Json syntax}";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};
}

import com.google.gson.JsonParser;
import com.google.gson.JsonSyntaxException;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

public class JsonSyntaxValidator implements ConstraintValidator<MyValidator, String> {

    @Override
    public void initialize(MyValidator constraintAnnotation) {
        // 可以进行一些初始化操作，例如读取配置信息
    }

    @Override
    public boolean isValid(String token, ConstraintValidatorContext constraintValidatorContext) {
        if (token == null || token.isEmpty()) {
            return false; // 空字符串不认为是有效的 JSON
        }

        try {
            JsonParser.parseString(token);
            return true; // 成功解析，说明是有效的 JSON
        } catch (JsonSyntaxException e) {
            return false; // 解析失败，说明不是有效的 JSON
        }
    }
}

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import javax.validation.Valid;

@RestController
public class MyController {

    @RequestMapping(value = "/endpoint", method = {RequestMethod.POST})
    @ResponseBody
    public ResponseEntity<String> authorize(@Valid @RequestBody String token) {
        // logic
        return ResponseEntity.ok("Token is valid");
    }
}