springMvc HandlerMethodArgumentResolver - HelloWorld开发者社区

SpringMvc 在配置多个mvc:argument-resolvers(目前是分开在不同的配置文件)

会出现覆盖问题；

实际spring容器中只会有一个文件里配置的bean

原因

debug 后发现，MVC实际是在调用一个name为org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter 的RequestMappingHandlerAdapter 同时多个配置文件会导致初始化多个RequestMappingHandlerAdapter，但是其他name的都没有用

解决方案

结合RequestMappingHandlerAdapter存储HandlerMethodArgumentResolver的原理

自定义类如下

package com.hui.handler;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
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;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.List;

/**
 * 处理注入参数处理
 * <p>当在多个context.xml中配置arm -resolver时，会因为加载顺序导致覆盖问题</p>
 *
 * @author 墨盒
 * @date 19-4-9
 */
public abstract class AbstractResolverHandler implements HandlerMethodArgumentResolver, InitializingBean {

    protected Logger logger = LoggerFactory.getLogger(getClass());

    @Resource(name = "org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter")
    protected RequestMappingHandlerAdapter adapter;

    @Override
    public void afterPropertiesSet() throws Exception {
        if (!adapter.getArgumentResolvers().contains(this)) {
            List<HandlerMethodArgumentResolver> list = adapter.getArgumentResolvers();
            List<HandlerMethodArgumentResolver> nList = new ArrayList<>(list.subList(0, list.size() - 2));//原list为不可修改list，因此需要重新new一个普通list,同时可在此调整顺序
            nList.add(this);//必须放过最后两个
            nList.addAll(list.subList(list.size() - 2, list.size()));
            adapter.setArgumentResolvers(nList);

        }
        //查看此时bean里注册的数据
//        String[] names = context.getBeanDefinitionNames();
//        for (int i = 0; i < names.length; i++) {
//            logger.debug("name={},class={}", names[i], context.getBean(names[i]));
//        }

    }

    @Override
    public abstract boolean supportsParameter(MethodParameter parameter);

    @Override
    public abstract Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception;
}