HttpServletRequest的getAttributeNames()方法没有全部Attribute属性

在Struts的Action中遍历Attribute没有想要的属性名,但是如果精确的用getAttribute(key)就能获取,不知道怎么回事.

private String arg;
private String htmlId;

@Override
public String execute()
{

    HttpServletRequest req = ServletActionContext.getRequest();

    // Attribute
    Enumeration attrNames = req.getAttributeNames();
    for (int i=0;attrNames.hasMoreElements();i++)
    {
        Object obj = attrNames.nextElement();
        System.out.println((String)obj);
    }
    String str1 = (String) req.getAttribute("arg");
    System.out.println("Attribute 1==== " + str1);
    String str2 = (String) req.getAttribute("htmlId");
    System.out.println("Attribute 2==== " + str2);

    return "ok";
}

用ajax发送的json格式的数据

        xhr.setRequestHeader("Content-type", "application/json");
        str1={"arg":"ab","htmlId":"ac"};
        xhr.send(JSON.stringify(str1));

结果是

struts.actionMapping

__cleanup_recursion_counter

struts.valueStack

Attribute 1==== ab

Attribute 2==== ac

奇了怪了.

从你贴出的结果来看，req.getAttributeNames() 打印出来的是对象，这个里面的内容应该是比页面上的参数多一些的。