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Struts 2 Merge and Append Tag
In this article, I am going to discuss Struts 2 Merge and Append Tag with Examples. Please read our previous article where we discussed Struts 2 Iterator Tag.
What is Merge Tag in Struts 2?
The merge tag is used to merge two different collections together.
How to Implement Merge Tag in Struts 2?
Step 1: Create a new maven project in Eclipse. We will use Maven to manage the dependencies of struts2. This way, we do not have to import JARs.
Remember to set the packaging to war. This is because we shall be deploying a web application.
Finally, click on the finish button to create the project. The following project directories need to be created:
Step 2: Modify pom.xml to add the required dependencies and the build configuration:
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.dotnet</groupId>
<artifactId>strutex</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>org.apache.struts</groupId>
<artifactId>struts2-core</artifactId>
<version>6.1.2.1</version>
</dependency>
<dependency>
<groupId>org.apache.struts</groupId>
<artifactId>struts-taglib</artifactId>
<version>1.3.10</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.3</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp.jstl</groupId>
<artifactId>jstl-api</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>javax.servlet.jsp-api</artifactId>
<version>2.3.3</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.struts</groupId>
<artifactId>struts2-convention-plugin</artifactId>
<version>6.2.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.11.0</version>
<configuration>
<source>17</source>
<target>17</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
Step 3: In the src/main/webapp directory, create a new file called index.jsp. Add the following content to the file:
<%@ page contentType = "text/html; charset = UTF-8"%>
<%@ taglib prefix = "s" uri = "/struts-tags"%>
<html>
<head>
<title>Students</title>
</head>
<body>
<b>Students and Exchange Students Merged together</b>
<br />
<s:merge id = "allstudents">
<s:param value = "students" />
<s:param value = "exchangeStudents" />
</s:merge>
<s:iterator value = "allstudents">
<s:property value = "name"/>,
<s:property value = "faculty"/><br/>
</s:iterator>
</body>
</html>
In the above example, we are using the merge tag. Alternatively, you may also choose to use the append tag. The append tag can be used as follows:
<%@ page contentType = "text/html; charset = UTF-8"%>
<%@ taglib prefix = "s" uri = "/struts-tags"%>
<html>
<head>
<title>Students</title>
</head>
<body>
<b>Students and Exchange Students Appended together</b><br />
<s:append id = "allstudents">
<s:param value = "students" />
<s:param value = "exchangeStudents" />
</s:append>
<s:iterator value = "allstudents">
<s:property value = "name"/>,
<s:property value = "faculty"/><br/>
</s:iterator>
</body>
</html>
Both the append and merge tags have the same functionality
Step 4: In the src/main/java directory, create a new file called Student.java. The file contains the Java action code. Add the following content to the file:
package com.dotnet;
import java.util.ArrayList;
import java.util.List;
import org.apache.struts2.util.SubsetIteratorFilter.Decider;
import com.opensymphony.xwork2.ActionSupport;
public class Student extends ActionSupport
{
private String name, faculty;
private List<Student> students, exchangeStudents;
public Student()
{}
public Student(String name, String faculty)
{
this.name = name;
this.faculty = faculty;
}
public String execute()
{
students = new ArrayList<Student>();
students.add(new Student("Adams Baker", "Science"));
students.add(new Student("Clark Davis", "Commerce"));
students.add(new Student("Evans Frank", "Arts"));
exchangeStudents = new ArrayList<Student>();
students.add(new Student("Ghosh Hills", "Science"));
students.add(new Student("Irwin Jones", "Commerce"));
students.add(new Student("Klein Lopez", "Arts"));
return SUCCESS;
}
public Decider getScienceStudents ()
{
return new Decider()
{
@Override
public boolean decide(Object element) throws Exception
{
Student s = (Student) element;
return s.getFaculty().equalsIgnoreCase("science");
}
};
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getFaculty() {
return faculty;
}
public void setFaculty(String faculty) {
this.faculty = faculty;
}
public List<Student> getStudents() {
return students;
}
public void setStudents(List<Student> students) {
this.students = students;
}
}
Step 5: In the src/main/java directory, create a new file called FacultyComparator.java. The file contains the Java code to arrange the students by faculty. Add the following content to the file:
package com.dotnet;
import java.util.Comparator;
public class FacultyComporator implements Comparator<Student>
{
@Override
public int compare(Student o1, Student o2)
{
return o1.getFaculty().compareTo(o2.getFaculty());
}
}
Step 6: In the src/main/webapp directory, create a new file called struts.xml. This file is responsible for configuring struts2. Add the following content to the file:
<?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 = "helloworld" extends = "struts-default">
<action name = "Student"
class = "com.dotnet.Student"
method = "execute">
<result name = "success">/index.jsp</result>
</action>
</package>
</struts>
Step 7: In the src/main/webapp directory, create a new directory called WEB-INF. In this directory, create a new file called web.xml. This file is responsible for implementing struts2 in the web application. Add the following content to the file:
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/web-app_3_0.xsd" id="apache-struts-config-example" version="3.0"> <display-name>Struts Config XML</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <filter> <filter-name>struts2</filter-name> <filter-class> org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter </filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
Step 8: Compile and execute the program on the Tomcat server. The following page must open in your default web browser:
Congratulations! You now know how to implement merge tags in struts2!
In the next article, I am going to discuss Struts 2 Generator Tag with Examples. Here, in this article, I try to explain Struts 2 Merge and Append Tag with Examples and I hope you enjoy this Struts 2 Merge and Append Tag article.
About the Author: Pranaya Rout
Pranaya Rout has published more than 3,000 articles in his 11-year career. Pranaya Rout has very good experience with Microsoft Technologies, Including C#, VB, ASP.NET MVC, ASP.NET Web API, EF, EF Core, ADO.NET, LINQ, SQL Server, MYSQL, Oracle, ASP.NET Core, Cloud Computing, Microservices, Design Patterns and still learning new technologies.