spring-framework/spring-framework-reference/src/new-in-3.xml

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<chapter id="new-in-3">
  <title>New Features and Enhancements in Spring 3.0</title>

  <para>If you have been using the Spring Framework for some time, you will be
  aware that Spring has undergone two major revisions: Spring 2.0, released in
  October 2006, and Spring 2.5, released in November 2007. It is now time for
  a third overhaul resulting in Spring 3.0.</para>

  <sidebar id="new-in-3-intro-java">
    <title>Java SE and Java EE Support</title>

    <para>The Spring Framework is now based on Java 5, and Java 6 is fully
    supported.</para>

    <para>Furthermore, Spring is compatible with J2EE 1.4 and Java EE 5, while
    at the same time introducing some early support for Java EE 6.</para>
  </sidebar>

  <section id="new-in-3-intro">
    <title>Java 5</title>

    <para>The entire framework code has been revised to take advantage of Java
    5 features like generics, varargs and other language improvements. We have
    done our best to still keep the code backwards compatible. We now have
    consistent use of generic Collections and Maps, consistent use of generic
    FactoryBeans, and also consistent resolution of bridge methods in the
    Spring AOP API. Generic ApplicationListeners automatically receive
    specific event types only. All callback interfaces such as
    TransactionCallback and HibernateCallback declare a generic result value
    now. Overall, the Spring core codebase is now freshly revised and
    optimized for Java 5.</para>

    <para>Spring's TaskExecutor abstraction has been updated for close
    integration with Java 5's java.util.concurrent facilities. We provide
    first-class support for Callables and Futures now, as well as
    ExecutorService adapters, ThreadFactory integration, etc. This has been
    aligned with JSR-236 (Concurrency Utilities for Java EE 6) as far as
    possible. Furthermore, we provide support for asynchronous method
    invocations through the use of the new @Async annotation (or EJB 3.1's
    @Asynchronous annotation).</para>
  </section>

  <section id="new-in-3-improved-docs">
    <title>Improved documentation</title>

    <para>The Spring reference documentation has also substantially been
    updated to reflect all of the changes and new features for Spring 3.0.
    While every effort has been made to ensure that there are no errors in
    this documentation, some errors may nevertheless have crept in. If you do
    spot any typos or even more serious errors, and you can spare a few cycles
    during lunch, please do bring the error to the attention of the Spring
    team by <ulink url="http://jira.springframework.org/">raising an
    issue</ulink>.</para>
  </section>

  <section id="new-in-3-new-tutorial">
    <title>New articles and tutorials</title>

    <para>
		There are many excellent articles and tutorials that show how to get started with Spring 3 features.
		Read them at the <ulink url="http://www.springsource.org/documentation">Spring Documentation</ulink> page.
	  </para>
	  <para id="new-in-3-samples">
	  The samples have been improved and updated to take advantage of the new features in Spring 3.
	  Additionally, the samples have been moved out of the source tree into a dedicated SVN 
	  <ulink url="https://anonsvn.springframework.org/svn/spring-samples/">repository</ulink> available at:</para>
	  
    <para>
	  <literal>https://anonsvn.springframework.org/svn/spring-samples/</literal>
	  </para>
	  
	  <para>As such, the samples are no longer distributed alongside Spring 3 and need to be downloaded separately from the repository mentioned above. However, this documentation
	  will continue to refer to some samples (in particular Petclinic) to illustrate various features.</para>
	  
	  <note>For more information on Subversion (or in short SVN), see the project homepage at:
      <literal>http://subversion.apache.org/</literal>
	  </note>

  </section>

  <section id="new-in-3-modules-build">
    <title>New module organization and build system</title>

    <para>The framework modules have been revised and are now managed
    separately with one source-tree per module jar:</para>

    <itemizedlist>
      <listitem>
        <para>org.springframework.aop</para>
      </listitem>

      <listitem>
        <para>org.springframework.beans</para>
      </listitem>

      <listitem>
        <para>org.springframework.context</para>
      </listitem>

      <listitem>
        <para>org.springframework.context.support</para>
      </listitem>

      <listitem>
        <para>org.springframework.expression</para>
      </listitem>

      <listitem>
        <para>org.springframework.instrument</para>
      </listitem>

      <listitem>
        <para>org.springframework.jdbc</para>
      </listitem>

      <listitem>
        <para>org.springframework.jms</para>
      </listitem>

      <listitem>
        <para>org.springframework.orm</para>
      </listitem>

      <listitem>
        <para>org.springframework.oxm</para>
      </listitem>

      <listitem>
        <para>org.springframework.test</para>
      </listitem>

      <listitem>
        <para>org.springframework.transaction</para>
      </listitem>

      <listitem>
        <para>org.springframework.web</para>
      </listitem>

      <listitem>
        <para>org.springframework.web.portlet</para>
      </listitem>

      <listitem>
        <para>org.springframework.web.servlet</para>
      </listitem>

      <listitem>
        <para>org.springframework.web.struts</para>
      </listitem>
    </itemizedlist>

    <sidebar id="new-in-3-intro-spring-jar">
      <title>Note:</title>

      <para>The spring.jar artifact that contained almost the entire framework
      is no longer provided.</para>
    </sidebar>

    <para>We are now using a new Spring build system as known from Spring Web
    Flow 2.0. This gives us:</para>

    <itemizedlist>
      <listitem>
        <para>Ivy-based "Spring Build" system</para>
      </listitem>

      <listitem>
        <para>consistent deployment procedure</para>
      </listitem>

      <listitem>
        <para>consistent dependency management</para>
      </listitem>

      <listitem>
        <para>consistent generation of OSGi manifests</para>
      </listitem>
    </itemizedlist>
  </section>

  <section id="new-in-3-features-overview">
    <title>Overview of new features</title>

    <para>This is a list of new features for Spring 3.0. We will cover these
    features in more detail later in this section.</para>

    <itemizedlist>
      <listitem>
        <para>Spring Expression Language</para>
      </listitem>

      <listitem>
        <para>IoC enhancements/Java based bean metadata</para>
      </listitem>

      <listitem>
        <para>General-purpose type conversion system and field formatting
        system</para>
      </listitem>

      <listitem>
        <para>Object to XML mapping functionality (OXM) moved from Spring Web
        Services project</para>
      </listitem>

      <listitem>
        <para>Comprehensive REST support</para>
      </listitem>

      <listitem>
        <para>@MVC additions</para>
      </listitem>

      <listitem>
        <para>Declarative model validation</para>
      </listitem>

      <listitem>
        <para>Early support for Java EE 6</para>
      </listitem>

      <listitem>
        <para>Embedded database support</para>
      </listitem>
    </itemizedlist>

    <section id="new-feature-java5">
      <title>Core APIs updated for Java 5</title>

      <para>BeanFactory interface returns typed bean instances as far as
      possible: <itemizedlist>
          <listitem>
            <para>T getBean(Class&lt;T&gt; requiredType)</para>
          </listitem>

          <listitem>
            <para>T getBean(String name, Class&lt;T&gt; requiredType)</para>
          </listitem>

          <listitem>
            <para>Map&lt;String, T&gt; getBeansOfType(Class&lt;T&gt;
            type)</para>
          </listitem>
        </itemizedlist></para>

      <para>Spring's TaskExecutor interface now extends
      <classname>java.util.concurrent.Executor</classname>: <itemizedlist>
          <listitem>
            <para>extended AsyncTaskExecutor supports standard Callables with
            Futures</para>
          </listitem>
        </itemizedlist></para>

      <para>New Java 5 based converter API and SPI: <itemizedlist>
          <listitem>
            <para>stateless ConversionService and Converters</para>
          </listitem>

          <listitem>
            <para>superseding standard JDK PropertyEditors</para>
          </listitem>
        </itemizedlist></para>

      <para>Typed ApplicationListener&lt;E&gt;</para>
    </section>

    <section id="new-feature-el">
      <title>Spring Expression Language</title>

      <para>Spring introduces an expression language which is similar to
      Unified EL in its syntax but offers significantly more features. The
      expression language can be used when defining XML and Annotation based
      bean definitions and also serves as the foundation for expression
      language support across the Spring portfolio. Details of this new
      functionality can be found in the chapter <link
      linkend="expressions">Spring Expression Language (SpEL).</link></para>

      <para>The Spring Expression Language was created to provide the Spring
      community a single, well supported expression language that can be used
      across all the products in the Spring portfolio. Its language features
      are driven by the requirements of the projects in the Spring portfolio,
      including tooling requirements for code completion support within the
      Eclipse based <ulink url="http://www.springsource.com/products/sts">SpringSource
      Tool Suite</ulink>.</para>

      <para>The following is an example of how the Expression Language can be
      used to configure some properties of a database setup <programlisting
      language="xml">&lt;bean class="mycompany.RewardsTestDatabase"&gt;
    &lt;property name="databaseName"
        value="#{systemProperties.databaseName}"/&gt;
    &lt;property name="keyGenerator"
        value="#{strategyBean.databaseKeyGenerator}"/&gt;
&lt;/bean&gt;
</programlisting></para>

      <para>This functionality is also available if you prefer to configure
      your components using annotations: <programlisting language="java">@Repository 
public class RewardsTestDatabase {

    @Value("#{systemProperties.databaseName}")
    public void setDatabaseName(String dbName) { … }

    @Value("#{strategyBean.databaseKeyGenerator}")
    public void setKeyGenerator(KeyGenerator kg) { … }
}
</programlisting></para>
    </section>

    <section id="new-feature-java-config">
      <title>The Inversion of Control (IoC) container</title>

      <section id="new-java-configuration">
        <title>Java based bean metadata</title>

        <para>Some core features from the <ulink
        url="http://www.springsource.org/javaconfig">JavaConfig</ulink>
        project have been added to the Spring Framework now. This means that
        the following annotations are now directly supported: <itemizedlist>
            <listitem>
              <para>@Configuration</para>
            </listitem>

            <listitem>
              <para>@Bean</para>
            </listitem>

            <listitem>
              <para>@DependsOn</para>
            </listitem>

            <listitem>
              <para>@Primary</para>
            </listitem>

            <listitem>
              <para>@Lazy</para>
            </listitem>

            <listitem>
              <para>@Import</para>
            </listitem>

            <listitem>
              <para>@ImportResource</para>
            </listitem>

            <listitem>
              <para>@Value</para>
            </listitem>
          </itemizedlist></para>

        <para>Here is an example of a Java class providing basic configuration
        using the new JavaConfig features: <programlisting language="java">package org.example.config;

@Configuration
public class AppConfig {
    private @Value("#{jdbcProperties.url}") String jdbcUrl;
    private @Value("#{jdbcProperties.username}") String username;
    private @Value("#{jdbcProperties.password}") String password;

    @Bean
    public FooService fooService() {
        return new FooServiceImpl(fooRepository());
    }

    @Bean
    public FooRepository fooRepository() {
        return new HibernateFooRepository(sessionFactory());
    }

    @Bean
    public SessionFactory sessionFactory() {
        // wire up a session factory
        AnnotationSessionFactoryBean asFactoryBean = 
            new AnnotationSessionFactoryBean();
        asFactoryBean.setDataSource(dataSource());
        // additional config
        return asFactoryBean.getObject();
    }

    @Bean
    public DataSource dataSource() { 
        return new DriverManagerDataSource(jdbcUrl, username, password);
    }
}
</programlisting> To get this to work you need to add the following component
        scanning entry in your minimal application context XML file.
        <programlisting language="xml">&lt;context:component-scan base-package="org.example.config"/&gt;
&lt;util:properties id="jdbcProperties" location="classpath:org/example/config/jdbc.properties"/&gt;
        </programlisting>
        Or you can bootstrap a <literal>@Configuration</literal> class directly using
        <literal>AnnotationConfigApplicationContext</literal>:
        <programlisting language="java">public static void main(String[] args) {
    ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
    FooService fooService = ctx.getBean(FooService.class);
    fooService.doStuff();
}</programlisting>
        See <xref linkend="beans-java-instantiating-container"/> for full information on
        <literal>AnnotationConfigApplicationContext</literal>.</para>
      </section>

      <section>
        <title>Defining bean metadata within components</title>

        <para><literal>@Bean</literal> annotated methods are also supported
        inside Spring components. They contribute a factory bean definition to
        the container. See <link
        linkend="beans-factorybeans-annotations">Defining bean metadata within
        components</link> for more information</para>
      </section>
    </section>

    <section id="new-feature-convert-and-format">
      <title>General purpose type conversion system and field formatting
      system</title>

      <para>A general purpose <link linkend="core-convert">type conversion
      system</link> has been introduced. The system is currently used by SpEL
      for type conversion, and may also be used by a Spring Container and DataBinder when
      binding bean property values.</para>

      <para>In addition, a <link linkend="format">formatter</link> SPI
      has been introduced for formatting field values. This SPI provides
      a simpler and more robust alternative to JavaBean PropertyEditors for use in client
      environments such as Spring MVC.</para>
    </section>

    <section id="new-feature-oxm">
      <title>The Data Tier</title>

      <para>Object to XML mapping functionality (OXM) from the Spring Web
      Services project has been moved to the core Spring Framework now. The
      functionality is found in the <literal>org.springframework.oxm</literal>
      package. More information on the use of the <literal>OXM</literal>
      module can be found in the <link linkend="oxm">Marshalling XML using O/X
      Mappers</link> chapter.</para>
    </section>

    <section id="new-feature-rest">
      <title>The Web Tier</title>

      <para>The most exciting new feature for the Web Tier is the support for
      building RESTful web services and web applications. There are also some
      new annotations that can be used in any web application.</para>

      <section>
        <title>Comprehensive REST support</title>

        <para>Server-side support for building RESTful applications has been
        provided as an extension of the existing annotation driven MVC web
        framework. Client-side support is provided by the
        <classname>RestTemplate</classname> class in the spirit of other
        template classes such as <classname>JdbcTemplate</classname> and
        <classname>JmsTemplate</classname>. Both server and client side REST
        functionality make use of
        <interfacename>HttpConverter</interfacename>s to facilitate the
        conversion between objects and their representation in HTTP requests
        and responses.</para>

        <para>The <classname>MarshallingHttpMessageConverter</classname> uses
        the <emphasis>Object to XML mapping</emphasis> functionality mentioned
        earlier.</para>

        <para>Refer to the sections on <link linkend="mvc">MVC</link> and <link
        linkend="rest-resttemplate">the RestTemplate</link> for more
        information.</para>
      </section>

      <section>
        <title>@MVC additions</title>

        <para>A <literal>mvc</literal> namespace has been introduced that greatly simplifies Spring MVC configuration.</para>

        <para>Additional annotations such as
        <classname>@CookieValue</classname> and
        <classname>@RequestHeaders</classname> have been added. See <link
        linkend="mvc-ann-cookievalue">Mapping cookie values with the
        @CookieValue annotation</link> and <link
        linkend="mvc-ann-requestheader">Mapping request header attributes with
        the @RequestHeader annotation</link> for more information.</para>
      </section>
    </section>

    <section id="new-feature-validation">
      <title>Declarative model validation</title>

      <para>Several <link linkend="validation-beanvalidation">validation enhancements</link>,
      including JSR 303 support that uses Hibernate Validator as the default provider.</para>
    </section>

    <section id="new-feature-jee-6">
      <title>Early support for Java EE 6</title>

      <para>We provide support for asynchronous method invocations through the
      use of the new @Async annotation (or EJB 3.1's @Asynchronous
      annotation).</para>

      <para>JSR 303, JSF 2.0, JPA 2.0, etc</para>

    </section>

    <section id="new-feature-embedded-databases">
      <title>Support for embedded databases</title>

      <para>Convenient support for <link
      linkend="jdbc-embedded-database-support">embedded Java database
      engines</link>, including HSQL, H2, and Derby, is now provided.</para>
    </section>
  </section>
</chapter>