JAVA EE: What is Spring’s p namespace in XML configuration

Wednesday, 1 August 2018

What is Spring’s p namespace in XML configuration

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Introduction

In standard Spring XML configurations, setting properties typically requires nested <property name="..." value="..."/> tags. When a bean has many attributes, your XML files can quickly become verbose and difficult to navigate. The p-namespace in Spring provides a streamlined, elegant alternative that allows you to configure property values directly as XML bean tag attributes.

Why Use the 'p' Namespace?

Eliminate Boilerplate: Convert multiple lines of nested <property> elements into compact, clean single-line bean definitions.
Zero Schema Location Overhead: The p namespace does not require a formal XSD schema location declaration in the XML header.
Seamless Setter Injection: Under the hood, Spring continues to use standard setter methods, ensuring full compatibility with your existing Java classes.

Step-by-Step Configuration Example

To start using the p namespace, simply include its namespace declaration in the root <beans> element:

xmlns:p="http://www.springframework.org/schema/p"

1. Traditional Configuration vs. p-namespace

Here is how a bean looks using traditional property tags:

<bean id="user" class="com.ram.model.User">
    <property name="id" value="101"/>
    <property name="name" value="Ram"/>
    <property name="email" value="ram@example.com"/>
</bean>

With the p-namespace, the configuration is concise and clean:

<bean id="user" class="com.ram.model.User"
      p:id="101"
      p:name="Ram"
      p:email="ram@example.com" />

2. Loading the Bean in Java

ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

User user = (User) context.getBean("user");
System.out.println("User ID: " + user.getId() + ", Name: " + user.getName());

Key Takeaway

The p namespace provides an intuitive and compact syntax for XML-based dependency injection. It significantly enhances configuration readability and reduces XML verbosity without sacrificing any dependency injection features.

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What is Spring’s p namespace in XML configuration

pom.xml

<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%20http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ram.core</groupId>

    <artifactId>SpringDemo</artifactId>

    <packaging>jar</packaging>

    <version>1.0-SNAPSHOT</version>

    <name>SpringDemo</name>

    <url>http://maven.apache.org</url>

    <properties>

        <spring.version>5.0.2.RELEASE</spring.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>3.8.1</version>

            <scope>test</scope>

        </dependency>

        <!-- Spring 5 dependencies -->

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-core</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-context</artifactId>

            <version>${spring.version}</version>

        </dependency>

    </dependencies>

</project>

Employee.java

package com.ram.model;

/**

 * Spring bean

 *

 */

public class Employee

{

    private String name;

    public void setName(String name)

    {

        this.name = name;

    }

    public void employeeDetails()

    {

        System.out.println("Employee Name =  " + name);

    }

}

applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 

    xmlns:p="http://www.springframework.org/schema/p"

    xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">

    <bean id="employee" class="com.ram.model.Employee" p:name="Peter">

    </bean>

</beans>

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ram.model.Employee;

public class App

{

    public static void main(String[] args)

    {

        ApplicationContext context = new ClassPathXmlApplicationContext(

                "applicationContext.xml");

        System.out.println("---------------------------------------");

        Employee employee = (Employee) context.getBean("employee");

        System.out.println(

                "Got employee object from the ApplicationContext(Spring Container)");

        employee.employeeDetails();

    }

}

Output

Jul 07, 2018 8:51:06 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Sat Jul 07 08:51:06 IST 2018]; root of context hierarchy

Jul 07, 2018 8:51:06 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [applicationContext.xml]

---------------------------------------

Got employee object from the ApplicationContext(Spring Container)

Employee Name =  Peter