EL expression-1, el expression

EL expression-1, el expression

EL provides the. and [] operators to navigate data. The two represent the same:

$ {SessionScope. user. sex}

Equal

$ {SessionScope. user ["sex"]}

. And [] can also be used together, as follows:

$ {SessionScope. shoppingCart [0]. price}

The returned result is the price of the first item in shoppingCart.

However, there are two differences between the two:

(1) When the attribute name to be accessed contains some special characters, such. or-is not a letter or number, you must use [], for example: $ {user. my-Name}

The preceding method is incorrect and should be changed to: $ {user ["My-Name"]}.

(2) Let's consider the following situations:

$ {SessionScope. user [data]}

In this case, data is a variable. If the value of data is "sex", the above example is equivalent to $ {sessionScope. user. sex };

If the value of data is "name", it is equivalent to $ {sessionScope. user. name }. Therefore, if you want to dynamically set the value, you can use the above method, but you cannot set the dynamic value.