Java – Passing a backing bean instance as parameter for another backing bean method

javajavabeansjsfparameters

After the user fills my backing bean with info through the forms, I want to process the instance in Java code (such as JAXB marshalling).

So at the moment i'm doing this like so:

<% OtherBean.method(myBackingBean); %>

which is – if i'm right – not quite an up to date solution 🙂 So how can I make this happen in a 'better' way?

Thanks in advance,
Daniel.

Best Solution

One solution is to add an action method to the bean - it is possible to have it process itself.

For example, this simple bean:

public class SimpleBean {

  private String forename;
  private String surname;

  public String processData() {
    // TODO: real work
    System.out.println("forename=" + forename);
    System.out.println("surname=" + surname);
    return null; // optional navigation rule
  }

  public String getForename() {
    return forename;
  }

  public void setForename(String forename) {
    this.forename = forename;
  }

  public String getSurname() {
    return surname;
  }

  public void setSurname(String surname) {
    this.surname = surname;
  }

}

...defined in WEB-INF/faces-config.xml:

<managed-bean>
    <managed-bean-name>simpleBean</managed-bean-name>
    <managed-bean-class>simplebean.SimpleBean</managed-bean-class>
    <managed-bean-scope>session</managed-bean-scope>
</managed-bean>

...can be processed using the this JSP:

<?xml version="1.0" encoding="UTF-8" ?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.0"
  xmlns:h="http://java.sun.com/jsf/html"
  xmlns:f="http://java.sun.com/jsf/core">
  <jsp:directive.page language="java"
    contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" />
  <jsp:text>
    <![CDATA[<?xml version="1.0" encoding="UTF-8" ?>]]>
  </jsp:text>
  <jsp:text>
    <![CDATA[<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">]]>
  </jsp:text>
  <html xmlns="http://www.w3.org/1999/xhtml">
  <head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  <title>Enter Name</title>
  </head>
  <body>
  <f:view>
    <h:form>
      <h:panelGrid columns="2">
        <h:outputText value="forename:" />
        <h:inputText id="it1" value="#{simpleBean.forename}" />
        <h:outputText value="surname:" />
        <h:inputText id="it2" value="#{simpleBean.surname}" />
      </h:panelGrid>
      <h:commandButton action="#{simpleBean.processData}"
        value="process" />
    </h:form>
  </f:view>
  </body>
  </html>
</jsp:root>

Note the method binding #{simpleBean.processData}. This must be a public method that takes no arguments and returns a String argument (which can be used for page navigation if desired).

This isn't the only way to go about this, but it is fairly straightforward.

Related Solutions

Java – JSF backing bean structure (best practices)

You might want to check this out: making distinctions between different kinds of JSF managed beans.

Here is a description of the different bean types, as defined in the above article by Neil Griffin:

Model Managed-Bean: Normally session scope. This type of managed-bean participates in the "Model" concern of the MVC design pattern. When you see the word "model" -- think DATA. A JSF model-bean should be a POJO that follows the JavaBean design pattern with getters/setters encapsulating properties. The most common use case for a model bean is to be a database entity, or to simply represent a set of rows from the result set of a database query.
Backing Managed-Bean: Normally request scope. This type of managed-bean participates in the "View" concern of the MVC design pattern. The purpose of a backing-bean is to support UI logic, and has a 1::1 relationship with a JSF view, or a JSF form in a Facelet composition. Although it typically has JavaBean-style properties with associated getters/setters, these are properties of the View -- not of the underlying application data model. JSF backing-beans may also have JSF actionListener and valueChangeListener methods.
Controller Managed-Bean: Normally request scope. This type of managed-bean participates in the "Controller" concern of the MVC design pattern. The purpose of a controller bean is to execute some kind of business logic and return a navigation outcome to the JSF navigation-handler. JSF controller-beans typically have JSF action methods (and not actionListener methods).
Support Managed-Bean: Normally session or application scope. This type of bean "supports" one or more views in the "View" concern of the MVC design pattern. The typical use case is supplying an ArrayList to JSF h:selectOneMenu drop-down lists that appear in more than one JSF view. If the data in the dropdown lists is particular to the user, then the bean would be kept in session scope. However, if the data applies to all users (such as a dropdown lists of provinces), then the bean would be kept in application scope, so that it can be cached for all users.
Utility Managed-Bean: Normally application scope. This type of bean provides some type of "utility" function to one or more JSF views. A good example of this might be a FileUpload bean that can be reused in multiple web applications.

Java – “String args[]”? parameter in main method Java

In Java args contains the supplied command-line arguments as an array of String objects.

In other words, if you run your program as java MyProgram one two then args will contain ["one", "two"].

If you wanted to output the contents of args, you can just loop through them like this...

public class ArgumentExample {
    public static void main(String[] args) {
        for(int i = 0; i < args.length; i++) {
            System.out.println(args[i]);
        }
    }
}

Best Solution

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Java – JSF backing bean structure (best practices)

Java – “String args[]”? parameter in main method Java

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