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Monday, January 29, 2007

Integrating Struts 2.0 with Spring

In the past, I posted an example on how to use Displaytag with Struts and Spring, using Spring JDBC for data access(1, 2). In this post, I will describe how to do the same using Struts 2.0. The only major step that needs to be done here is to override the default Struts 2.0 OjbectFactory. Changing the ObjectFactory to Spring give control to Spring framework to instantiate action instances etc. Most of the code is from the previous post, but I will list only the additional changes here.
  1. Changing the default Object factory: In order to change the Ojbect factory to Spring, you have to add a declaration in the struts.properties file.
    struts.objectFactory = spring
    struts.devMode = true
    struts.enable.DynamicMethodInvocation = false
    src/struts.properties
  2. The Action class: Here is the code for the action class
    package actions;

    import java.util.List;

    import business.BusinessInterface;

    import com.opensymphony.xwork2.ActionSupport;

    public class SearchAction extends ActionSupport {
    private BusinessInterface businessInterface;

    private String minSalary;

    private String submit;

    private List data;

    public String getSubmit() {
    return submit;
    }

    public void setSubmit(String submit) {
    this.submit = submit;
    }

    public BusinessInterface getBusinessInterface() {
    return businessInterface;
    }

    public String execute() throws Exception {
    try {
    long minSal = Long.parseLong(getMinSalary());
    System.out.println("Business Interface: " + businessInterface + "Minimum salary : " + minSal);
    data = businessInterface.getData(minSal);
    System.out.println("Data : " + data);

    } catch (Exception e) {
    e.printStackTrace();
    }

    return SUCCESS;
    }

    public void setBusinessInterface(BusinessInterface bi) {
    businessInterface = bi;
    }

    public String getMinSalary() {
    return minSalary;
    }

    public void setMinSalary(String minSalary) {
    this.minSalary = minSalary;
    }

    public List getData() {
    return data;
    }

    public void setData(List data) {
    this.data = data;
    }
    }
    SearchAction.java
    • The Action class here does not have access to the HttpServetRequest and HttpServletResponse. Hence the action class itself was changed to the session scope for this example (see below)
    • In order for the action class to be aware of the Http Session, the action class has to implement the ServletRequestAware interface, and define a setServletRequest method, which will be used to inject the ServletRequest into the action class.
    • The BusinessInterface property is injected by Spring framework.
  3. The struts Configuration:
    <!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">
    <struts>
    <package name="Struts2Spring" namespace="/actions" extends="struts-default">
    <action name="search" class="actions.SearchAction">
    <result>/search.jsp</result>
    </action>
    </package>
    </struts>
    src/struts.xml
    • The action's class attribute has to map the id attribute of the bean defined in the spring bean factory definition.
  4. The Spring bean factory definition
    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd"
    default-autowire="autodetect">
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
    <property name="driverClassName">
    <value>oracle.jdbc.driver.OracleDriver</value>
    </property>
    <property name="url">
    <value>jdbc:oracle:thin:@localhost:1521:orcl</value>
    </property>
    <property name="username">
    <value>scott</value>
    </property>
    <property name="password">
    <value>tiger</value>
    </property>
    </bean>

    <!-- Configure DAO -->
    <bean id="empDao" class="data.DAO">
    <property name="dataSource">
    <ref bean="dataSource"></ref>
    </property>
    </bean>
    <!-- Configure Business Service -->
    <bean id="businessInterface" class="business.BusinessInterface">
    <property name="dao">
    <ref bean="empDao"></ref>
    </property>
    </bean>
    <bean id="actions.SearchAction" name="search" class="actions.SearchAction" scope="session">
    <property name="businessInterface" ref="businessInterface" />
    </bean>
    </beans>
    WEB-INF/applicationContext.xml
    • The bean definition for the action class contains the id attribute which matches the class attribute of the action in struts.xml
    • Spring 2's bean scope feature can be used to scope an Action instance to the session, application, or a custom scope, providing advanced customization above the default per-request scoping.

  5. The web deployment descriptor
    <?xml version="1.0" encoding="UTF-8"?>
    <web-app id="WebApp_9" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

    <display-name>Struts2Spring</display-name>

    <filter>
    <filter-name>struts2</filter-name>
    <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
    </filter>

    <filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
    </filter-mapping>

    <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <listener>
    <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
    </listener>
    <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    </welcome-file-list>
    </web-app>
    web.xml
    The only significant addition here is that of the RequestContextListener. This listener allows Spring framework, access to the HTTP session information.
  6. The JSP file: The JSP file is shown below. The only change here is that the action class, instead of the Data list is accessed from the session.
    <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
    <%@ taglib uri="http://displaytag.sf.net" prefix="display"%>
    <%@ taglib prefix="s" uri="/struts-tags"%>
    <%@ page import="actions.SearchAction,beans.Employee,business.Sorter,java.util.List,org.displaytag.tags.TableTagParameters,org.displaytag.util.ParamEncoder"%>
    <html>
    <head>
    <title>Search page</title>
    <link rel="stylesheet" type="text/css" href="/StrutsPaging/css/screen.css" />
    </head>
    <body bgcolor="white">
    <s:form action="/actions/search.action">
    <table>
    <tr>
    <td>Minimum Salary:</td>
    <td><s:textfield label="minSalary" name="minSalary" /></td>
    </tr>
    <tr>
    <td colspan="2"><s:submit name="submit" /></td>
    </tr>
    </table>
    </s:form>
    <jsp:scriptlet>

    SearchAction action = (SearchAction)session.getAttribute("actions.SearchAction");
    session.setAttribute("empList", action.getData());
    if (session.getAttribute("empList") != null) {
    String sortBy = request.getParameter((new ParamEncoder("empTable")).encodeParameterName(TableTagParameters.PARAMETER_SORT));
    Sorter.sort((List) session.getAttribute("empList"), sortBy);

    </jsp:scriptlet>

    <display:table name="sessionScope.empList" pagesize="4" id="empTable" sort="external" defaultsort="1" defaultorder="ascending" requestURI="">
    <display:column property="empId" title="ID" sortable="true" sortName="empId" headerClass="sortable" />
    <display:column property="empName" title="Name" sortName="empName" sortable="true" headerClass="sortable" />
    <display:column property="empJob" title="Job" sortable="true" sortName="empJob" headerClass="sortable" />
    <display:column property="empSal" title="Salary" sortable="true" headerClass="sortable" sortName="empSal" />
    </display:table>
    <jsp:scriptlet>
    }
    </jsp:scriptlet>

    </body>
    </html:html>
    search.jsp
  7. The Other required classes: The following other classes have been used for the example, and they can be obtained from the previous posts (1, 2).
    • Employee.java
    • BusinessInterface.java
    • Sorter.java
    • DAO.java
    • EmpMapper.java

10 comments:

  1. Big help!
    I did not know that we must set 2 listener for using web scopes like request and session.
    Your post sovled one of my big problems in using Struts 2 + Spring.

    ReplyDelete
  2. scriptlets are no good. u have to change yor strategy

    ReplyDelete
  3. This is a great article. I have been trying to integrate Struts2 ,Spring and DAO for last week when I came across this article. Step by step approach is really nice.
    BTW, it works alright with DriverManagerDatasource configuration but did not work for me when I added connection pool in my applicationContext.xml. Any suggestion?
    My connection pool is defined in context.xml of my web app.

    ReplyDelete
  4. I am working with struts 2.0.8 and I can't use spring IoC container.

    I have writen this in my web deployment descriptor:



    < listener >
    < listener-class > org.springframework.web.context.ContextLoaderListener < /listener-class >
    < /listener >



    but it seems like there was not any ContextLoaderListener. I can't find it in any struts2 jar library.



    11-jul-2007 8:35:07 org.apache.catalina.core.StandardContext listenerStart
    GRAVE: Error configurando escuchador de aplicación de clase org.springframework.web.context.ContextLoaderListener
    java.lang.ClassNotFoundException: org.springframework.web.context.ContextLoaderListener
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1355)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1201)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3711)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4211)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1013)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1013)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
    at org.apache.catalina.core.StandardService.start(StandardService.java:450)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:709)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:551)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:585)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:432)
    11-jul-2007 8:35:07 org.apache.catalina.core.StandardContext listenerStart




    Anybody knows what's happenning?

    ReplyDelete
  5. did you add spring-core.jar to your classpath?

    ReplyDelete
  6. you can find ContextLoaderListener class in spring.jar.

    Visit

    http://j2eeworld.weebly.com

    It contains some good material.

    ReplyDelete
  7. this is crap.. stop making fool out pple.. just mapping in xml no implementation.. there is no spring usage in the entire example..

    ReplyDelete
  8. Great tutorial, thanks.
    I've integrated spring with struts2, and what i need was session scope actions. Now there is only one problem left. If a validation error occurs and you once add an error to actionErrors collection e.g. addActionError(..), then when you attempt the resubmit page again, it directly fails, since the scope is session, errors are also stored at session :( Is there a way to make action errors stateless?

    ReplyDelete
  9. I found a simple solution below. In the view layer aftet I show the errors, I clean the actionErrors collection. I'll write my own error displayer tag for this purpose, e.g:

    <he:statelessactionerror action='myAction'/>

    :)

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

    <s:actionerror />

    <%
    MyAction myAction = (MyAction) session.getAttribute("myAction");
    if(myAction != null) {
    myAction.setActionErrors(null);
    }
    %>

    ReplyDelete