JavaBean and JSP standard action __ Large data

I. JavaBean
1. Understanding: Java classes that can be reused
2. Classification
1 beans that encapsulate data (equivalent to entity classes)
2 encapsulation of the business bean (generally is the implementation of additions and deletions to check)
3. Note:
1 The bean that encapsulates the data generally satisfies the following two conditions
1.implements Serializable: Implementing the Serialization interface
2. Have a parameterless public constructor: easy to use with JSP actions
4. Two ways to create and use:
1) Use Scriptlet code to implement.
2 JSP standard action to achieve.


Two. Standard action
1. Understanding: Label to create and use JavaBean, which is conducive to the development of JSP Application Division, improve the maintainability of JSP applications
2. Categories:
1) Usebean: Creating and using Beans
2) SetProperty: Assigning values to the Bean's properties
3) GetProperty: Remove the value of the Bean's properties
4) Forward: Jump, equivalent forwarding
5) include: dynamic inclusion
3. Usage:
1) Usebean
Example:
<jsp:usebean id= "Emp1" class= "Com.entity.Employee" scope= "Session"/>
Attention:
1 The corresponding class must have a parameterless public constructor
2 If there is no emp1 in the corresponding scope, the object is created, otherwise the object is obtained.


2) SetProperty
Example:
<jsp:setproperty name= "Emp1" property= "EmpNo" value= "001"/>
Attention:
1 at this point, the corresponding class must have: Setempno () method
2) value can only assign static value, param may be dynamically assigned value;
3) value and Param cannot be used simultaneously
4 when the property attribute value is "*", the value of all parameters in the request requests are assigned to the bean in the same name as the parameter.


3) GetProperty
Example:
<jsp:getproperty name= "Emp1" property= "EmpNo"/>
Attention:
1 at this point, the corresponding class must have: Getempno () method




4) Forward
Format:
<jsp:forward page= "url"/>
Example: <jsp:forward page= "index2.jsp"/>
Note: the equivalent of forwarding, and bring return


5) include
Format: <jsp:include page= "Weburl" flush= "true"/>
Attention:
1 Action is dynamic inclusion
2 The difference between <jsp:include> and <% @include >:
Instructions are static include: merge first, then compile
Actions are dynamic include: Compile separately, then merge after compilation