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Using JavaBeans Components in JSP Documents
Contents
1. Why using beans?2. What are beans?3. Using Beans: Basic Tasks4. Sharing Beans 5. Practice exercise
1. Why Use Beans?
- Separate class are easier to write, compile, test, debug and reuse.
- No Java syntax - Simpler object sharing - Convenient correspondence
between request parameters and object properties.
- (Part II, chapter 14)
2. What Are Beans?
A bean class must have a zero-argument (default) constructor
A bean class should have no public instance variables (fields)
Persistent values should be accessed through methods calledget Xxx and setXxx
3. Using Beans: Basic Tasks jsp:useBean <jsp:useBean id="beanName"
class="package.Class" /> jsp:getProperty <jsp:getProperty name="beanName"
property="propertyName" /> jsp:setProperty <jsp:setProperty name="beanName"
property="propertyName" value="propertyValue" />
<jsp:useBean id="book1" class="coreservlets.Book" />
<% coreservlets.Book book1 = new coreservlets.Book(); %>
Accessing Bean Properties: jsp:getProperty
<jsp:getProperty name="book1" property="title" /> <%= book1.getTitle() %>
<jsp:setProperty name="book1" property="title" value="Core Servlets and JavaServer Pages" /> <% book1.setTitle("Core Servlets and JavaServer Pages"); %>
4. Sharing Beans
<jsp:useBean ... scope="page" /> <jsp:useBean ...
scope="request" /> <jsp:useBean ...
scope="session" /> <jsp:useBean ...
scope="application" />
5. Practice Exercise
Develop a WebApp to manage product information. The WebApp allow use add and update a product. Each product has name, description, price, producer name.
Create JSP to add new Product using Product bean
<jsp:useBean id=“product" class=“mylib.Product" scope="page"/>
<jsp:setProperty name=“product" property="*" />
productType.insert(conn)