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)