why jsp fires a PropertyNotFound?

问题

Writing in a JSP:

${a.b.c} 

throws 'c' PropertyNotFound, but writing

<s:property value="#a.b.c"/> 

works fine.

I'd appreciate if someone can explain why ${a.b.c} doesn't work?

UPDATED:

In the same JSP, accessing to another bean f such as ${a.f.d} it finds d correctly.

I have checked that property c in ${a.b.c} exists.

回答1:

Nice Question.If you have not specified getter setters for property c in b then this error will occur Propertynotfound for

 ${a.b.c}

But

  <s:property value="#a.b.c"/> 

will not cause an error. The difference is ${} works on getter setters as it is OGNL it reads using getter setter from valuestack.

Simply write getter setter in class b. ${a.b.c} will start working. For example if c is public String c then,

public String getC() {
    return c;
}
public void setC(String c) {
    this.c = c;
}

来源：https://stackoverflow.com/questions/21874470/why-jsp-fires-a-propertynotfound