一,@requestBody

公司的框架中对于入参做了json的处理，但是再用的时候发现list不能解析。此处是分析如何做到list的解析。首先配置拦截器

1.拦截器配置

https://www.cnblogs.com/yangzhilong/p/3725849.html
这篇文章介绍了xml配置方法，还不错。

<!-- 可选 设置根据请求头的内容来解析请求body-->
<mvc:annotation-driven>
    <!-- default -->
    <mvc:message-converters>
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"></bean>
        <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter"></bean>
        <bean class="org.springframework.http.converter.StringHttpMessageConverter"></bean>
        <bean class="org.springframework.http.converter.ResourceHttpMessageConverter"></bean>
        <bean class="org.springframework.http.converter.xml.SourceHttpMessageConverter"></bean>
    </mvc:message-converters>

    <!-- 对入参使用这些个类进行处理 可以使用annotation来区别不同的入参使用不同的解析方法-->
    <mvc:argument-resolvers>
        <bean class="com..JsonMapperArgumentResolver"/>
        <bean class="com..JsonListArgumentResolver"/>
    </mvc:argument-resolvers>

    <!-- 可选 对出参使用这些个类进行处理 可以使用annotation来区别不同的入参使用不同的解析方法 -->
    <mvc:return-value-handlers>
        <bean class="com..ResponseJsonMethodProcessor">
            <property name="messageConverter" ref="jsonMessageConverter"/>
            <property name="beanWrappers">
                <list>
                    <bean class="com..impl.ResponseWrapper"/>
                    <bean class="com..impl.DefaultBeanWrapper"/>
                </list>
            </property>
        </bean>
    </mvc:return-value-handlers>
</mvc:annotation-driven>

配置好拦截器，就可以在JsonMapperArgumentResolver和JsonListArgumentResolver方法类中处理解析过程。

2.方法类要实现HandlerMethodArgumentResolver接口

@Override
public boolean supportsParameter(MethodParameter parameter) {
    return parameter.hasParameterAnnotation(JsonList.class);
}

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

2.获取请求的参数,post方法用reader，其他的用getQueryString()

HttpServletRequest httpServletRequest = (HttpServletRequest)webRequest.getNativeRequest(HttpServletRequest.class);
String method = httpServletRequest.getMethod();
if (!method.equals("GET") && !method.equals("DELETE")) {
    StringBuilder buffer = new StringBuilder();
    BufferedReader reader = httpServletRequest.getReader();

    String line;
    while((line = reader.readLine()) != null) {
        buffer.append(line);
    }

    return buffer.toString();
} else {
    return httpServletRequest.getQueryString();
}

3.针对list的入参做处理

就是再resolveArgument方法的实现。

HttpServletRequest httpServletRequest = (HttpServletRequest)webRequest.getNativeRequest(HttpServletRequest.class);

Type type = parameter.getGenericParameterType();
ParameterizedType p = (ParameterizedType) type;
Type[] actualTypeArguments = p.getActualTypeArguments();

BufferedReader reader = httpServletRequest.getReader();
StringBuffer buffer = new StringBuffer();
String line;
while ((line = reader.readLine()) != null) {
    buffer.append(line);
}
String inputString = buffer.toString();

List<?> objects = JsonUtil.toList(inputString, Class.forName(actualTypeArguments[0].getTypeName()));
return objects;

jsonUtil的方法实现大致就是objectMapper的方法，比如readValue等，可参考第4节。

4.ObjectMapper

https://www.cnblogs.com/xuwenjin/p/8976696.html
可以参考

5.关于引用

import com..annotation.JsonList;
import com..utils.JsonUtil;
import com..utils.ObjectMapperFactoryBean;
import org.codehaus.jackson.map.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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.BufferedReader;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;

spring理解 -参数处理