This example demonstrates how to integrate log4j to your struts 2 project.

• Add log4j.jar file in your project lib folder
• Create log4j.xml file with loggers and appenders. Here I have added file and console appenders. Each log message will be printed in console and a file. Make sure that log4j.xml file is in the classpath.
• Import org.apache.log4j.Logger in your action class and start using the logger methods. In this example I have used logger.info method.

Lets look at the example code.

1. Action Class

[code lang=”java”]
package javabeat.net.struts2;

import org.apache.log4j.Logger;

public class Struts2HelloWorldAction {
private static final Logger logger = Logger.getLogger(Struts2HelloWorldAction.class);

public String execute(){
logger.info("Executing method");
return "success";
}
}
[/code]

2. Log4j XML Configuration Example – log4j.xml

[code lang=”xml”]
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false">
<appender name="fileAppenderInfo" class="org.apache.log4j.RollingFileAppender">
<param name="File" value="D:/info.log" />
<param name="MaxBackupIndex" value="10"/>
<param name="MaxFileSize" value="5120KB"/>
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d
%-5p [%c{1}][%x] %m %n" />
</layout>
<filter class="org.apache.log4j.varia.LevelRangeFilter">
<param name="LevelMin" value="INFO" />
<param name="LevelMax" value="INFO" />
</filter>
</appender>
<appender name="consoleAppenderInfo" class="org.apache.log4j.ConsoleAppender">
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d
%-5p [%c{1}][%x] %m %n" />
</layout>
<filter class="org.apache.log4j.varia.LevelRangeFilter">
<param name="LevelMin" value="INFO" />
<param name="LevelMax" value="INFO" />
</filter>
</appender>
<logger name="javabeat.net.struts2">
<level value="INFO" />
<appender-ref ref="fileAppenderInfo" />
<appender-ref ref="consoleAppenderInfo" />
</logger>
<logger name="com.opensymphony.xwork2">
<level value="INFO" />
<appender-ref ref="fileAppenderInfo" />
<appender-ref ref="consoleAppenderInfo" />
</logger>
<logger name="org.apache.struts2">
<level value="INFO" />
<appender-ref ref="fileAppenderInfo" />
<appender-ref ref="consoleAppenderInfo" />
</logger>

</log4j:configuration>
[/code]

3. Struts.xml

[code lang=”xml”]
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<constant name="struts.devMode" value="true" />
<package name="struts2demo" extends="struts-default">
<action name="log4jdemo" class="javabeat.net.struts2.Struts2HelloWorldAction"
method="execute">
<result name="success">/</result>
</action>
</package>
</struts>
[/code]

4. Log Messages

[code]
2013-12-16 15:11:59,266 INFO [XmlConfigurationProvider][] Parsing configuration file [struts-default.xml]
2013-12-16 15:11:59,341 INFO [XmlConfigurationProvider][] Unable to locate configuration files of the name struts-plugin.xml, skipping
2013-12-16 15:11:59,342 INFO [XmlConfigurationProvider][] Parsing configuration file [struts-plugin.xml]
2013-12-16 15:11:59,346 INFO [XmlConfigurationProvider][] Parsing configuration file [struts.xml]
2013-12-16 15:11:59,348 INFO [DefaultConfiguration][] Overriding property struts.i18n.reload – old value: false new value: true
2013-12-16 15:11:59,349 INFO [DefaultConfiguration][] Overriding property struts.configuration.xml.reload – old value: false new value: true
2013-12-16 15:09:52,345 INFO [Struts2HelloWorldAction][] Executing method
[/code]

There are two ways to get the servlet response object inside struts 2 action class’s execute method.

• ServletActionContext : Directly accessing the getresponse method from the ServletActionContext class will return the response object.
• ServletResponseAware : If you implement the action class with ServletResponseAware interface, then struts controller will send the response object through setServletResponse method. You are requested to declare a variable for response object and write getter and setter methods.

1. ServletActionContext

[code lang=”java”]
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.ServletActionContext;

public class Struts2HelloWorldAction{
public String execute() {
HttpServletResponse response = ServletActionContext.getResponse();
return "SUCCESS";
}
}
[/code]

2. ServletResponseAware

[code lang=”java”]
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.interceptor.ServletResponseAware;

public class Struts2HelloWorldAction implements ServletResponseAware{

HttpServletResponse response;

public String execute() {
Locale locale = getServletResponse().getLocale();
return "SUCCESS";

}

public void setServletResponse(HttpServletResponse response) {
this.response = response;
}

public HttpServletresponse getServletResponse() {
return this.response;
}
}
[/code]

However, it is recommended to use ServletResponseAware instead of ServletActionContext method.

There are two ways to get the servlet request object inside struts 2 action class’s execute method.

• ServletActionContext : Directly accessing the getRequest method from the ServletActionContext class will return the request object.
• ServletRequestAware : If you implement the action class with ServletRequestAware interface, then struts controller will send the request object through setServletRequest method. You are requested to declare a variable for request object and write getter and setter methods.

1. ServletActionContext

[code lang=”java”]
import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.ServletActionContext;

public class Struts2HelloWorldAction{
public String execute() {
HttpServletRequest request = ServletActionContext.getRequest();
return "SUCCESS";
}
}
[/code]

2. ServletRequestAware

[code lang=”java”]
import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.interceptor.ServletRequestAware;

public class Struts2HelloWorldAction implements ServletRequestAware{

HttpServletRequest request;

public String execute() {
String paramValue = getServletRequest().getParameter("param");
return "SUCCESS";

}

public void setServletRequest(HttpServletRequest request) {
this.request = request;
}

public HttpServletRequest getServletRequest() {
return this.request;
}
}
[/code]

However, it is recommended to use ServletRequestAware instead of ServletActionContext method.

Interceptors are powerful mechanism to control the flow of each request. These are custom and default implementations which can be enforced to work as the callback methods at certain point of time. Struts 2 provides handful of default interceptors behind the scenes. One example is the exception handling at action level. Also we can write our own interceptors and add our own business logic inside the custom interceptors.

1. Action Class

[code lang=”java”]
package javabeat.net.struts2;

public class Struts2HelloWorldAction{
public String execute(){
return "success";
}
}

[/code]

2. Custom Interceptor

[code lang=”java”]
package javabeat.net.struts2;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;

public class LoggingInterceptor implements Interceptor{

@Override
public void destroy() {
System.out.println("Destroying logging interceptor…");

}
@Override
public void init() {
System.out.println("Initializing logging interceptor…");

}
@Override
public String intercept(ActionInvocation invocation) throws Exception {
String className = invocation.getAction().getClass().getName();
long startTime = System.currentTimeMillis();
System.out.println("Before calling action class: " + className);
String result = invocation.invoke();
long endTime = System.currentTimeMillis();
System.out.println("After calling action class: " + className
+ " Time taken: " + (endTime – startTime) + " ms");
return result;
}

}

[/code]

3. Struts.xml

If you look at the interceptor definition, we have used interceptor-stack. It is the collection of interceptors defined in one block. The reason why we are doing is to add the default interceptors to the list, otherwise struts 2 will not invoke the default interceptors. 

[code lang=”xml”]
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts
Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<constant name="struts.devMode" value="true" />
<package name="struts2demo" extends="struts-default">
<interceptors>
<interceptor name="logginginterceptor"
class="javabeat.net.struts2.LoggingInterceptor">
</interceptor>
<interceptor-stack name="loggingStack">
<interceptor-ref name="logginginterceptor" />
<interceptor-ref name="defaultStack" />
</interceptor-stack>
</interceptors>
<action name="InterceptorDemo" class="javabeat.net.struts2.Struts2HelloWorldAction">
<interceptor-ref name="loggingStack" />
<result name="success">Result.jsp</result>
</action>
</package>
</struts>
[/code]

4. Result

If you access the application using URL http://localhost:8080/Struts2App/InterceptorDemo, you would see the following output in the console.

[code]
INFO: Choosing bean (struts) for (com.opensymphony.xwork2.util.TextParser)
Initializing logging interceptor…
15 Dec, 2013 5:52:02 PM org.apache.coyote.http11.Http11Protocol start
INFO: Starting Coyote HTTP/1.1 on http-8080
15 Dec, 2013 5:52:02 PM org.apache.jk.common.ChannelSocket init
INFO: JK: ajp13 listening on /0.0.0.0:8009
15 Dec, 2013 5:52:02 PM org.apache.jk.server.JkMain start
INFO: Jk running ID=0 time=0/56 config=null
15 Dec, 2013 5:52:02 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 1385 ms
Before calling action class: javabeat.net.struts2.Struts2HelloWorldAction
After calling action class: javabeat.net.struts2.Struts2HelloWorldAction Time taken: 64 ms
[/code]

Struts 2 provides struts2-json-plugin.jar for supporting the conversion of result type to JSON strings. Nowadays every framework supports the JSON formats because it is the most preferred format for the REST web services. This example shows how you can integrate Struts 2 and JSON.

1. Get the struts2-json-plugin.jar and add to the lib folder
2. In the struts.xml configuration file, extend the package by json-default
3. Make the result type for action mapping to be json

Lets look at the example code.

1. Action Class

[code lang=”java”]
package javabeat.net.struts2;

import java.util.ArrayList;

import org.apache.struts2.convention.annotation.Action;
import org.apache.struts2.convention.annotation.Namespace;
import org.apache.struts2.convention.annotation.Result;
import org.apache.struts2.convention.annotation.ResultPath;

public class HelloJSONAction{
private ArrayList<String> list;
public ArrayList<String> getList() {
return list;
}
public void setList(ArrayList<String> list) {
this.list = list;
}
public String execute(){
list = new ArrayList<String>();
list.add("Java");
list.add("C++");
list.add("Groovy");
return "success";
}
}

[/code]

2. Struts.xml

[code lang=”xml”]
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts
Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<constant name="struts.devMode" value="true" />
<package name="struts2demo" extends="json-default">
<action name="HelloJSONDemo" class="javabeat.net.struts2.HelloJSONAction" >
<result type="json"/>
</action>
</package>
</struts>
[/code]

3. Struts 2 JSON Integration Demo

If you access the application using URL http://localhost:8080/Struts2App/HelloJSONDemo, you would see the following output.

Struts 2 supports annotations out of the box in its latest release without even a single line of configuration changes. You are not needed to create struts.xml file and there is no need to mention the scanning path anywhere like we mention in the spring framework. You have to add one extra JAR file struts2-convention-plugin.jar which has the API to scan the classes and find the annotations.

1. Struts 2 by default scan the action classes and convert the action class name to action mapping. For example if your action class name is “HelloAction”, the default action mapping would be “hello”. The first letter of the first word will be small.
2. If you add @Action annotation before the execute method, the action mapping will be override the default name.

Lets look at the example code.

1. Action Class

[code lang=”java”]
package javabeat.net.struts2;

import org.apache.struts2.convention.annotation.Action;
import org.apache.struts2.convention.annotation.Namespace;
import org.apache.struts2.convention.annotation.Result;
import org.apache.struts2.convention.annotation.ResultPath;

@Namespace("/")
@ResultPath(value="/")
@Result(name="success",location="Annotation.jsp")
public class HelloAction{
private String msg = "JavaBeat – Struts 2 Annotation Hello World!!";

public String getMsg() {
return msg;
}

public void setMsg(String msg) {
this.msg = msg;
}

@Action(value="/helloannotation")
public String execute(){
return "success";
}
}

[/code]

2. JSP File

Annotation.jsp

[code lang=”xml”]
<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
<body>
<h4>
<s:property value="msg" /><br>
</h4>
</body>
</html>
[/code]

3. Struts 2 Annotation Demo

If you access the application using URL http://localhost:8080/Struts2App/helloannotation, you would see the following output.

It is best practice to have all the labels used in your application in the centralized location. Tradionally these message resources are stored in the property files using the key=value pairs and loaded on demand by the forms. Every framework supports this basic feature to configure the message resources. This example shows how to load property files in your Struts 2 Application and display it in the screen. Lets look at the code.

1. Action Class

[code lang=”java”]package javabeat.net.struts2;

public class Struts2HelloWorldAction{
private String firstName;
private String lastName;

public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String execute(){
return "success";
}
}[/code]

2. Property File

Create a property file in the class path.

form_labels.properties

[code]firstName=First Name
lastName=Last Name
[/code]

3. Struts 2 Configuration File

Add the entry for loading the property files from the class path.

[code lang=”xml”]
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts
Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<constant name="struts.custom.i18n.resources" value="form_labels" />
<constant name="struts.devMode" value="true" />
<package name="uitagsdemo" extends="struts-default">
<action name="PropertyDemo" class="javabeat.net.struts2.Struts2HelloWorldAction" >
<result name="success">Input.jsp</result>
</action>
</package>
</struts>
[/code]

4. JSP File

Input.jsp

[code lang=”xml”]<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
<head>
</head>
<body>
<h2>JavaBeat – Struts 2 Property Labels Demo</h2>
<s:form action="PropertyDemo">
<s:textfield name="firstName" key="firstName" />
<s:textfield name="lastName" key="lastName" />
<s:submit label="Submit" />
</s:form>

</body>
</html>[/code]

5. Resource Bundle Demo

If you access the application using URL http://localhost:8080/Struts2App/PropertyDemo, you would see the following output.

Struts 2 TextArea field is helpful for entering the multiple lines in the input box. It is similar to the textfiled tag, but in the textfield tag only one line can be entered. Lets look at the example.

1. Action Class

[code lang=”java”]
package javabeat.net.struts2;

public class Struts2UITagsAction{
private String description;

public String getDescription() {
return description;
}

public void setDescription(String description) {
this.description = description;
}

public String execute(){
return "success";
}
}
[/code]

2. TextArea Tag Example

TextArea.jsp

[code lang=”xml”]
<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
<head>
</head>
<body>
<h1>JavaBeat – Struts 2 TextArea Tag Demo</h1>
<s:form action="TextAreaDemo">
<s:textarea name="description" label="Description : "
cols="40" rows="10" />
<s:submit label="Submit" />
</s:form>

</body>
</html>
[/code]

Result.jsp

[code lang=”xml”]
<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
<body>
<h2>JavaBeat – Struts 2 TextArea Tag Demo</h2>
<h4>
Description : <s:property value="description" /><br>
</h4>
</body>
</html>
[/code]

3. Struts.xml

[code lang=”xml”]
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts
Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<constant name="struts.devMode" value="true" />
<package name="uitagsdemo" extends="struts-default">
<action name="TextAreaDemo" class="javabeat.net.struts2.Struts2UITagsAction" >
<result name="success">Result.jsp</result>
</action>
</package>
</struts>
[/code]

4. TextArea Tag Demo

If you access the application using URL http://localhost:8080/Struts2App/TextAreaDemo, you would see the following output.

Struts 2 Hidden Tag is helpful for passing the hidden values from one page to another page. In the latest web development there is very less need for using this kind of tags for the functionality. If your framework is not handling the values by default, you need to define the hidden fields and then maintain the values across the pages. These values are not displayed to the user, but hidden from the screen.

1. Action Class

[code lang=”java”]
package javabeat.net.struts2;

public class Struts2UITagsAction{
private String pageId;

public String getPageId() {
return pageId;
}

public void setPageId(String pageId) {
this.pageId = pageId;
}

public String execute(){
return "success";
}
}

[/code]

2. Hidden Tag Example

Hidden.jsp

[code lang=”xml”]
<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
<head>
</head>
<body>
<h2>JavaBeat – Struts 2 Hidden Field Demo</h2>
<s:form action="HiddenDemo">
<s:hidden name="pageId" value="0" />
<s:submit label="Submit" />
</s:form>

</body>
</html>
[/code]

Result.jsp

[code lang=”xml”]
<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
<body>
<h2>JavaBeat – Struts 2 Hidden Tag Demo</h2>
<h4>
Page Id : <s:property value="pageId" /><br>
</h4>
</body>
</html>
[/code]

3. Struts.xml

[code lang=”xml”]
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts
Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<constant name="struts.devMode" value="true" />
<package name="uitagsdemo" extends="struts-default">
<action name="HiddenDemo" class="javabeat.net.struts2.Struts2UITagsAction" >
<result name="success">Result.jsp</result>
</action>
</package>
</struts>
[/code]

4. Hidden Tag Demo

If you access the application using URL http://localhost:8080/Struts2App/HiddenDemo, you would see the following output.