JavaBean in JSP documents form the application of (14.1)

Sep 19 posted in OS (RSS), comments.

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Build bean: jsp: useBean

<jsp:useBean />
Phrase generally means "an instance of the class specified by the class, and instantiated objects bound to _jspService variables, the variable name specified by id." Note, however, be sure to use the fully qualified class name - including the application class name. Whether you use <% @ page import ...%> enter the package, must meet this requirement.

jsp: useBean class attribute must use the fully qualified class name.

For example, the general JSP actions can be
<jsp:useBean />
That is below the equivalent of this scriptlet
<% Coreservlets.Book book1 = new coreservlets.Book ();%>

installation of the bean class

All are placed in the bean package. Installation is usually used to store the java code in the directory: a single class on WEB-INF/classes/subdirectory, JAR file in the WEB-INF/lib

jsp: useBean options
scope, beanName and type jsp: useBean provides several options to provide more features, described as follows: scope: bean's scope (application, page, session, request) beanName: bean name, both can point to the corresponding bean The class name can point to an object containing the serialized bean file name, beanName attribute values are passed to the javabeansBean.instantiate method type: bean type of statement used to define a bean to a super class or the actual bean implementation interface, if the type is not compatible with the situation will throw a ClassCastException exception if the Bean is already there, eliminating the need for the class attribute directly with the type attribute.

As follows <jsp:useBean type="java.lang.Runnable" /> converted into a servlet, the code is as follows:
java.lang.Runnable thread1 = new mypackage.MyClass ();
jsp: useBean only in the absence of the same id and scope of the time will instantiate a new bean.

Access bean properties: jsp: getProperty

In the jsp: useBean in, bean name given by the id attribute. In the jsp: getProperty and jsp: setProperty, by the name attribute is given.

Like if you like the above code creates a book1 object, then we can use the following code to get book1 of the title attribute value.
<jsp:getProperty name="book1" property="title" />
<% = Book1.getTitle ()%>
Best to use the first method, and so the same method used above to create a.

[Color = blue simple bean properties are set: jsp: setProperty [/ color]
<Jsp: setProperty name = "book1"
property = "title"
value = "Core Servlets and JavaServer Pages" />
<% Book1.setTitle ("Core Servlets and JavaServer Pages");%>