问题备忘:Cannot generate variable name for non-typed Collection parameter type

Love The Way You Lie 2022-05-16 14:06 164阅读 0赞

在spring mvc中，定义如下RequestMapping方法

@RequestMapping(value="queryList",method = RequestMethod.POST)
    @ResponseBody
    public String queryList(HttpSession httpSession,@RequestBody(required = false) List<String> taskIds){
            String rtn = "";
            …
           return rtn;
     }

以上方法在本地环境(window)和测试环境 (redhat)是可以正常被请求，但是发布到生产环境(debian8.8)被请求时，却抛出以下异常:

2018-08-14 16:40:33.157 [https-jsse-nio-8443-exec-10] ERROR o.a.c.c.C.[.[.[.[dispatcherServlet] - Servlet.service() for servlet [dispatcherServlet] in context with path [/icc-interface] threw exception [Request processing failed; nested exception is java.lang.IllegalArgumentException: Cannot generate variable name for non-typed Collection parameter type] with root cause
    java.lang.IllegalArgumentException: Cannot generate variable name for non-typed Collection parameter type
            at org.springframework.core.Conventions.getVariableNameForParameter(Conventions.java:119)
            at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:129)
            at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)

定位到源码：抛出异常的原因是程序无法解析出集合中实际的类型，不知道什么原因集合中的真正类型丢失了，程序无法根据集合真正元素的类型生成对象实例

public static String getVariableNameForParameter(MethodParameter parameter) {
        Assert.notNull(parameter, "MethodParameter must not be null");
        Class<?> valueClass;
        boolean pluralize = false;
    
        if (parameter.getParameterType().isArray()) {
            valueClass = parameter.getParameterType().getComponentType();
            pluralize = true;
        }
        else if (Collection.class.isAssignableFrom(parameter.getParameterType())) {
                  // 看源码是程序无法解析出集合中实际的类型
            valueClass = ResolvableType.forMethodParameter(parameter).asCollection().resolveGeneric();
            if (valueClass == null) {
                throw new IllegalArgumentException(
                    "Cannot generate variable name for non-typed Collection parameter type");
            }
            pluralize = true;
        }
        else {
        …
              }
        …
        }

尝试将JDK8升级到最新版本，但是问题还是存在，最后在网上找到如下的解决方法：  
重新定义StringList 类，直接带上集合的类型

public class StringList extends ArrayList<String> { 
    }

修改方法：使用StringList替换List

@RequestMapping(value="queryList",method = RequestMethod.POST)
    @ResponseBody
    public String queryList(HttpSession httpSession,@RequestBody(required = false)StringList  taskIds){
            String rtn = "";
            …
           return rtn;
     }

修正问题成功