Java / Java EE：从JSP调用getter方法

Question

I want to invoke a getter method (returns String value) of a Java class from JSP by using "jsp:usebean", but it returns a null value. What I don't understand is why it can't return the updated value.

1. Can someone shed some light on this?

2. Should I use a Cookie to get the value from JSP?

Answer 1

I'm not sure what you're using (Struts, plain Servlets, etc.) but essentially you need to add an attribute to the ServletRequest like:

class Person {
    private String firstName;
    // other fields, getters, setters
}

public void method(HttpServletRequest httpServletRequest) {
    Person p = new Person();
    p.setFirstName("Obama");
    httpServletRequest.setAttribute("person", p);
}

and in your JSP:

<jsp:getProperty object="person" property="firstName" />

or if you use JSTL :

<c:out value="${person.firstName}"/>

Answer 2

It is simple.

In java file:

package loga;
class bean{

String name;
public void setName(String Uname)
{
this.name=Uname;
}
public void getName()
{
return name;
}

In jsp file, call this method as:

<jsp:useBean id="object" class="loga.bean">
<jsp:setproperty name="object" property="Name" Value="XXXX"/>
<jsp:getProperty name="object" property="Name"/>
</jsp:usebean>

Here, the property indicates the method name of the getName() in the java class. To pass value from other controls use param property and give name of the control.