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POJSF - How does the JSF implementation identify the action?
 

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  1. POJSF - How does the JSF implementation identify the action?
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    <p>I am trying to understand how JSF implementation identifies various possible actions from the user. In the simple application I've put together, I have the following fields configured in the <code>login.xhtml</code> page.</p> <p><code>User name - input field</code></p> <p><code>Password - password field</code></p> <p><code>Login button</code></p> <p><code>Cancel button</code></p> <p><strong>login.xhtml</strong></p> <pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt; &lt;html xmlns="http://www.w3.org/1999/xhtml" xmlns:ui="http://java.sun.com/jsf/facelets" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core"&gt; &lt;h:head id="head_id" &gt;&lt;/h:head&gt; &lt;h:body id="body_id"&gt; &lt;h:form id="loginForm_id"&gt; &lt;h:panelGrid id="loginPanelGrid_id"&gt; &lt;h:outputText id="nameLabel_id" value="Name"&gt;&lt;/h:outputText&gt; &lt;h:inputText id="nameInput_id" value="#{loginBean.name}"&gt;&lt;/h:inputText&gt; &lt;h:outputText id="passwordLabel_id" value="Password"&gt;&lt;/h:outputText&gt; &lt;h:inputSecret id="passwordInput_id" value="#{loginBean.password}"&gt;&lt;/h:inputSecret&gt; &lt;/h:panelGrid&gt; &lt;h:commandButton id="loginBtn_id" value="Do Login" action="#{loginBean.login}"&gt;&lt;/h:commandButton&gt; &lt;h:commandButton id="CancelBtn_id" value="Cancel Login" action="#{loginBean.cancel}"&gt;&lt;/h:commandButton&gt; &lt;/h:form&gt; &lt;/h:body&gt; &lt;/html&gt; </code></pre> <p><strong>LoginBean.java</strong></p> <pre><code>package com.ila; import javax.faces.bean.ManagedBean; import javax.faces.bean.SessionScoped; @ManagedBean @SessionScoped public class LoginBean { private String name; private String password; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String login() { if ("a".equals(name)) return "success"; else return "failure"; } public String cancel() { return "cancel"; } } </code></pre> <p><strong>Generated html code from login.xhtml</strong></p> <pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt; &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt; &lt;head&gt;&lt;/head&gt; &lt;body&gt; &lt;form id="loginForm_id" name="loginForm_id" method="post" action="/JSF2TestProject/faces/simple.xhtml" enctype="application/x-www-form-urlencoded"&gt; &lt;input type="hidden" name="loginForm_id" value="loginForm_id" /&gt; &lt;table id="loginForm_id:loginPanelGrid_id"&gt; &lt;tbody&gt; &lt;tr&gt; &lt;td&gt;&lt;span id="loginForm_id:nameLabel_id"&gt;Name&lt;/span&gt;&lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td&gt;&lt;input id="loginForm_id:nameInput_id" type="text" name="loginForm_id:nameInput_id" value="a" /&gt;&lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td&gt;&lt;span id="loginForm_id:passwordLabel_id"&gt;Password&lt;/span&gt;&lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td&gt;&lt;input id="loginForm_id:passwordInput_id" type="password" name="loginForm_id:passwordInput_id" value="" /&gt;&lt;/td&gt; &lt;/tr&gt; &lt;/tbody&gt; &lt;/table&gt; &lt;input id="loginForm_id:loginBtn_id" type="submit" name="loginForm_id:loginBtn_id" value="Do Login" /&gt; &lt;input id="loginForm_id:CancelBtn_id" type="submit" name="loginForm_id:CancelBtn_id" value="Cancel Login" /&gt; &lt;input type="hidden" name="javax.faces.ViewState" id="javax.faces.ViewState" value="H4sIAAAAAAAAAI1QTUoDMRj9Ou1QW2ztDwouBBduVJgD6MIiWCwqFUQRXWicie2UTBKTzHS6KR7BAwhewEuIawUXbryDHsCVSR2nuij4Qd6XfCHvvbz7d7C5FFDtoQg5ofKJs41kdw9xO//28Dh3/pIFqwlFwpDXRK5iogUF1RVYdhnxYr7RAFPT/SmNFb0sBQuEdXzaZCI48701jqTsM+G1KA+VHoQC6qe7IzmCaMdpX/Swq9Zvno/vKnKZWAAx1zy58AqGkDWM6c7mutJTfihg1fDEziVysXRcFnBGMVXOYasdKi23tC8Yx0INdvBAQlI1rSCgPHawRcPg9yVXYEeIhDgSkIuY78G4Yq5VVyapjv44UdQYL3xz+16a+cjCJmMEI/q0KK5fbz8/LMicJB5inhmah2UFJcJcRI7M9AAraaZV4Nz0Wa5Nz//JnaIAp5n/ZPaPVM2maKBkYMZAzUA90Ula/AXEIFMaOgIAAA==" autocomplete="off" /&gt; &lt;/form&gt; &lt;/body&gt; &lt;/html&gt; </code></pre> <p><strong>faces-config.xml</strong></p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;faces-config xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_1.xsd" version="2.1"&gt; &lt;navigation-rule&gt; &lt;display-name&gt;login.xhtml&lt;/display-name&gt; &lt;from-view-id&gt;/login.xhtml&lt;/from-view-id&gt; &lt;navigation-case&gt; &lt;from-outcome&gt;success&lt;/from-outcome&gt; &lt;to-view-id&gt;/welcome.xhtml&lt;/to-view-id&gt; &lt;/navigation-case&gt; &lt;/navigation-rule&gt; &lt;navigation-rule&gt; &lt;display-name&gt;login.xhtml&lt;/display-name&gt; &lt;from-view-id&gt;/login.xhtml&lt;/from-view-id&gt; &lt;navigation-case&gt; &lt;from-outcome&gt;failure&lt;/from-outcome&gt; &lt;to-view-id&gt;/login.xhtml&lt;/to-view-id&gt; &lt;/navigation-case&gt; &lt;/navigation-rule&gt; &lt;navigation-rule&gt; &lt;display-name&gt;login.xhtml&lt;/display-name&gt; &lt;from-view-id&gt;/login.xhtml&lt;/from-view-id&gt; &lt;navigation-case&gt; &lt;from-outcome&gt;cancel&lt;/from-outcome&gt; &lt;to-view-id&gt;/login.xhtml&lt;/to-view-id&gt; &lt;/navigation-case&gt; &lt;/navigation-rule&gt; &lt;/faces-config&gt; </code></pre> <p><strong>UI rendered (screen shot)</strong></p> <p><img src="https://i.stack.imgur.com/eA81y.jpg" alt="enter image description here"></p> <p><strong>Question 1</strong></p> <p>Given that the generated html does NOT have any parameter sent that identifies which button is clicked (atleast I can't see), how does the JSF implementation determine if the 'Do Login' button is clicked or the 'Cancel Login' button is clicked?</p> <p><strong>Question 2</strong></p> <p>What is the purpose of the two hidden (generated by JSF implementation) fields (shown below)? Are these related to the question 1?</p> <pre><code>&lt;input type="hidden" name="loginForm_id" value="loginForm_id" /&gt; &lt;input type="hidden" name="javax.faces.ViewState" id="javax.faces.ViewState" value="H4sIAAAAAAAAAI1QTUoDMRj9Ou1QW2ztDwouBBduVJgD6MIiWCwqFUQRXWicie2UTBKTzHS6KR7BAwhewEuIawUXbryDHsCVSR2nuij4Qd6XfCHvvbz7d7C5FFDtoQg5ofKJs41kdw9xO//28Dh3/pIFqwlFwpDXRK5iogUF1RVYdhnxYr7RAFPT/SmNFb0sBQuEdXzaZCI48701jqTsM+G1KA+VHoQC6qe7IzmCaMdpX/Swq9Zvno/vKnKZWAAx1zy58AqGkDWM6c7mutJTfihg1fDEziVysXRcFnBGMVXOYasdKi23tC8Yx0INdvBAQlI1rSCgPHawRcPg9yVXYEeIhDgSkIuY78G4Yq5VVyapjv44UdQYL3xz+16a+cjCJmMEI/q0KK5fbz8/LMicJB5inhmah2UFJcJcRI7M9AAraaZV4Nz0Wa5Nz//JnaIAp5n/ZPaPVM2maKBkYMZAzUA90Ula/AXEIFMaOgIAAA==" autocomplete="off" /&gt; </code></pre>
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