jsp的class和beanName属性之间的区别：useBean

• class="package.class" type="package.class"

  Instantiates a bean from the class named in class and assigns the bean the data type you specify in type. The value of type can be the same as class, a superclass of class, or an interface implemented by class.

  The class you specify in class must not be abstract and must have a public, no-argument constructor. The package and class names you use with both class and type are case sensitive.

• beanName="{package.class | <%= expression %>}" type="package.class"

  Instantiates a bean from a class, a serialized template, or an expression that evaluates to a class or serialized template. When you use beanName, the bean is instantiated by the java.beans.Beans.instantiate method. The Beans.instantiate method checks whether the package and class you specify represents a class or a serialized template. If they represent a serialized template, Beans.instantiate reads the serialized form (which has a name like package.class.ser) using a class loader.

  The value of type can be the same as beanName, a superclass of beanName, or an interface implemented by beanName. The package and class names you use with both beanName and type are case sensitive.