springBoot 自定参数解析器(HandlerMethodArgumentResolver)

Posted by lizhao on 11-05,2018

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
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