springBoot 自定参数解析器（HandlerMethodArgumentResolver）

清疚 2022-04-22 13:40 227阅读 0赞

spring 自定参数解析器（HandlerMethodArgumentResolver）

由于之前用@RequestParam无法接收request payload 正文格式为json格式的字符串，只能使用@RequestBody整个接收，觉得麻烦，但是spring自带的参数解析器不具有这种功能，只能尝试着用自定义参数解析器去解决。

自定义解析器需要实现HandlerMethodArgumentResolver接口，HandlerMethodArgumentResolver接口包含两个接口：

接口说明：  
supportsParameter：用于判定是否需要处理该参数分解，返回true为需要，并会去调用下面的方法resolveArgument。  
resolveArgument：真正用于处理参数分解的方法，返回的Object就是controller方法上的形参对象。

1、自定义注解

package com.manqian.crm.resolver;

import java.lang.annotation.ElementType;  
import java.lang.annotation.Retention;  
import java.lang.annotation.RetentionPolicy;  
import java.lang.annotation.Target;

@Target(ElementType.PARAMETER)  
@Retention(RetentionPolicy.RUNTIME)  
public @interface JsonParam \{

String value();
    
    boolean required() default true;
    
    String defaultValue() default "";

若不想自定义注解，可以直接在实现HandlerMethodArgumentResolver的supportsParameter直接返回true

2、自定义参数解析器，实现HandlerMethodArgumentResolver接口

package com.manqian.crm.resolver;

import com.jayway.jsonpath.JsonPath;  
import com.jayway.jsonpath.PathNotFoundException;  
import com.manqian.crm.api.exception.ParamCheckException;  
import org.apache.commons.io.IOUtils;  
import org.springframework.context.annotation.Configuration;  
import org.springframework.core.MethodParameter;  
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;

import javax.servlet.http.HttpServletRequest;  
import java.io.IOException;

public class JsonPathArgumentResolver implements HandlerMethodArgumentResolver \{

private static final String JSON_REQUEST_BODY = "JSON_REQUEST_BODY";
    
    //判断是否支持要转换的参数类型
    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.hasParameterAnnotation(JsonParam.class);
    }
    
    //当支持后进行相应的转换
    @Override
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
        String body = getRequestBody(webRequest);
        Object val = null;
    
        try {
            val = JsonPath.read(body, parameter.getParameterAnnotation(JsonParam.class).value());
            if (parameter.getParameterAnnotation(JsonParam.class).required() && val == null) {
                throw new ParamCheckException(parameter.getParameterAnnotation(JsonParam.class).value() + "不能为空");
            }
        } catch (PathNotFoundException exception) {
            System.out.println(exception.getStackTrace());
            if (parameter.getParameterAnnotation(JsonParam.class).required()) {

// throw new ParamCheckException(parameter.getParameterAnnotation(JsonParam.class).value() + “不能为空”);  
throw exception;  
\}  
\}  
return val;  
\}

private String getRequestBody(NativeWebRequest webRequest) {
        HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
        String jsonBody = (String) servletRequest.getAttribute(JSON_REQUEST_BODY);
        if (jsonBody == null) {
            try {
                jsonBody = IOUtils.toString(servletRequest.getInputStream());
                servletRequest.setAttribute(JSON_REQUEST_BODY, jsonBody);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return jsonBody;
    
    }

3、注册自定义参数解析器  
springboot方式：

package com.demo;

import java.util.List;

import org.springframework.boot.autoconfigure.SpringBootApplication;  
import org.springframework.web.method.support.HandlerMethodArgumentResolver;  
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

import com.demo.mvc.component.MultiPersonArgumentResolver;  
import com.demo.mvc.component.PersonArgumentResolver;

@SpringBootApplication  
public class WebMvcConfiguration extends WebMvcConfigurationSupport \{

@Override
    protected void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
    
        // 注册JsonPathArgumentResolver的参数分解器
        argumentResolvers.add(new JsonPathArgumentResolver());
    }

package com.manqian.crm.resolver;

import org.springframework.context.annotation.Configuration;  
import org.springframework.web.method.support.HandlerMethodArgumentResolver;  
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import java.util.List;

@Configuration  
public class ClientResourcesConfig extends WebMvcConfigurerAdapter \{

@Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {

// super.addArgumentResolvers(argumentResolvers);  
argumentResolvers.add(new JsonPathArgumentResolver());  
\}  
\}

传统XML格式：

mvc:annotation-driven  
mvc:argument-resolvers  
  
</mvc:argument-resolvers>  
</mvc:annotation-driven>

使用：  
1、依赖：

com.jayway.jsonpath  
json-path  
2、controller方法使用@JsonParam接收参数

参考：[https://stackoverflow.com/questions/12893566/passing-multiple-variables-in-requestbody-to-a-spring-mvc-controller-using-ajax/12897632\#12897632][https_stackoverflow.com_questions_12893566_passing-multiple-variables-in-requestbody-to-a-spring-mvc-controller-using-ajax_12897632_12897632]

## [https://my.oschina.net/sugarZone/blog/704575][https_my.oschina.net_sugarZone_blog_704575] ##

作者：逆流\_Jun  
来源：CSDN  
原文：[https://blog.csdn.net/u010187242/article/details/73647670][https_blog.csdn.net_u010187242_article_details_73647670]  
版权声明：本文为博主原创文章，转载请附上博文链接！

[https_stackoverflow.com_questions_12893566_passing-multiple-variables-in-requestbody-to-a-spring-mvc-controller-using-ajax_12897632_12897632]: https://stackoverflow.com/questions/12893566/passing-multiple-variables-in-requestbody-to-a-spring-mvc-controller-using-ajax/12897632#12897632
[https_my.oschina.net_sugarZone_blog_704575]: https://my.oschina.net/sugarZone/blog/704575
[https_blog.csdn.net_u010187242_article_details_73647670]: https://blog.csdn.net/u010187242/article/details/73647670