spring boot 自定义请求参数解析注解

介绍

一些请求参数, 需要解析成某个自定义的类, 而spring boot中并没有提供这样自动转换的注解, 但是,spring boot 预留了扩展接口,所以,我们可以自定义实现一个注解.

例如: http://localhost:8999/new/test?a={"name":"aaa", "age":18}&b=123
我们可以通过自定义注解,来把 a 对应的值转换成我们系统中的类

创建注解

package com.example.demo.conf;import java.lang.annotation.*;@Target(ElementType.PARAMETER)@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface RequestJson {    String value();}

创建请求参数解析实现类

package com.example.demo.conf;import com.alibaba.fastjson.JSONObject;import org.springframework.core.MethodParameter;import org.springframework.stereotype.Component;import org.springframework.web.bind.support.WebDataBinderFactory;import org.springframework.web.context.request.NativeWebRequest;import org.springframework.web.method.support.HandlerMethodArgumentResolver;import org.springframework.web.method.support.ModelAndViewContainer;public class RequestJsonHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver {    @Override    public boolean supportsParameter(MethodParameter parameter) {        return parameter.hasParameterAnnotation(RequestJson.class);    }    @Override    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,                                  NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {        RequestJson requestJson = parameter.getParameterAnnotation(RequestJson.class);        String value = requestJson.value();        Class clazz = parameter.getParameterType();        String jsonData = webRequest.getParameter(value);        if (jsonData == null) {            return clazz.newInstance();        }        Object object = JSONObject.parseObject(jsonData, clazz);        return object;    }}

注入spring boot

package com.example.demo;import com.example.demo.conf.RequestJsonHandlerMethodArgumentResolver;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.transaction.annotation.EnableTransactionManagement;import org.springframework.web.method.support.HandlerMethodArgumentResolver;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;import java.util.List;@SpringBootApplicationpublic class DemoApplication extends WebMvcConfigurerAdapter{    public static void main(String[] args) {        SpringApplication.run(DemoApplication.class, args);    }    @Override    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {        argumentResolvers.add(new RequestJsonHandlerMethodArgumentResolver());        super.addArgumentResolvers(argumentResolvers);    }}

测试

Controller

package com.example.demo.controller;import com.alibaba.fastjson.JSONObject;import com.example.demo.conf.RequestJson;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class MyController {    @GetMapping("/new/test")    public Object newTest(@RequestJson("a") Person person, @RequestParam("b") Integer b) {        System.out.println("a : " + JSONObject.toJSONString(person));        System.out.println("b : " + b);        return "ok";    }    public static class Person {        private String name;        private Integer age;        public String getName() {            return name;        }        public void setName(String name) {            this.name = name;        }        public Integer getAge() {            return age;        }        public void setAge(Integer age) {            this.age = age;        }    }}

请求

请求url: http://localhost:8999/new/test?a={"name":"aaa", "age":18}&b=123

打印结果:

a : {“age”:18,”name”:”aaa”}
b : 123