方式一：Action 由 Struts2 自身创建

在 Action 中我们会调用业务层代码，如果按照传统方式，我们要获取到业务类实例，需要通过 Spring 工厂来手动获取，如下：

// com.zze.web.action.UserAction
package com.zze.web.action;

import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;
import com.zze.domain.User;
import com.zze.service.UserService;
import org.apache.struts2.ServletActionContext;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

public class UserAction extends ActionSupport implements ModelDriven<User> {
    private User user = new User();

    @Override
    public User getModel() {
        return user;
    }

    public String save() {
        //传统方式获取 Service
        WebApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(ServletActionContext.getServletContext());
        UserService userService = (UserService) applicationContext.getBean("userService");
        System.out.println(userService);
        /*
        访问 http://localhost:8080/customer_save，输出结果如下：
            com.zze.service.impl.UserServiceImpl@4b65044b
         */
        return NONE;
    }
}

而这种方式的代码显然过于复杂，Struts2 在与 Spring 整合时 Struts2 还为我们提供了更简易的方式哦。

Spring 整合 Struts2 需要引入一个 jar 包 struts2-spring-plugin.jar，这个 jar 包在上述准备工作中就已经引入，查看该 jar 中的 struts-plugin.xml：

<!-- struts2-spring-plugin-2.3.37.jar!/struts-plugin.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<!--
/*
 * $Id$
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
-->
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
    "http://struts.apache.org/dtds/struts-2.3.dtd">
    
<struts>
    <bean type="com.opensymphony.xwork2.ObjectFactory" name="spring" class="org.apache.struts2.spring.StrutsSpringObjectFactory" />
    
    <!--  Make the Spring object factory the automatic default -->
    <constant name="struts.objectFactory" value="spring" />

    <constant name="struts.class.reloading.watchList" value="" />
    <constant name="struts.class.reloading.acceptClasses" value="" />
    <constant name="struts.class.reloading.reloadConfig" value="false" />
    <constant name="xwork.disallowProxyMemberAccess" value="true" />

    <package name="spring-default">
        <interceptors>
            <interceptor name="autowiring" class="com.opensymphony.xwork2.spring.interceptor.ActionAutowiringInterceptor"/>
        </interceptors>
    </package>    
</struts>

可以看到在该文件中配置了如下常量：

<constant name="struts.objectFactory" value="spring" />

查看 Struts2 的默认配置：

# struts2-core-2.3.37.jar!/org/apache/struts2/default.properties
# $Id$
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#  http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
#
### START SNIPPET: complete_file

### Struts default properties
###(can be overridden by a struts.properties file in the root of the classpath)
###

### This can be used to set your default locale and encoding scheme
# struts.locale=en_US
struts.i18n.encoding=UTF-8

### if specified, the default object factory can be overridden here
### Note: short-hand notation is supported in some cases, such as "spring"
###       Alternatively, you can provide a com.opensymphony.xwork2.ObjectFactory subclass name here
# struts.objectFactory = spring

### specifies the autoWiring logic when using the SpringObjectFactory.
### valid values are: name, type, auto, and constructor (name is the default)
struts.objectFactory.spring.autoWire = name

### indicates to the struts-spring integration if Class instances should be cached
### this should, until a future Spring release makes it possible, be left as true
### unless you know exactly what you are doing!
### valid values are: true, false (true is the default)
struts.objectFactory.spring.useClassCache = true

### ensures the autowire strategy is always respected.
### valid values are: true, false (false is the default)
struts.objectFactory.spring.autoWire.alwaysRespect = false

### By default SpringObjectFactory doesn't support AOP
### This flag was added just temporally to check if nothing is broken
### See https://issues.apache.org/jira/browse/WW-4110
struts.objectFactory.spring.enableAopSupport = false

### if specified, the default object type determiner can be overridden here
### Note: short-hand notation is supported in some cases, such as "tiger" or "notiger"
###       Alternatively, you can provide a com.opensymphony.xwork2.util.ObjectTypeDeterminer implementation name here
### Note: By default, com.opensymphony.xwork2.util.DefaultObjectTypeDeterminer is used which handles type detection
###       using generics. com.opensymphony.xwork2.util.GenericsObjectTypeDeterminer was deprecated since XWork 2, it's
###       functions are integrated in DefaultObjectTypeDeterminer now.
###       To disable tiger support use the "notiger" property value here.
#struts.objectTypeDeterminer = tiger
#struts.objectTypeDeterminer = notiger

### Parser to handle HTTP POST requests, encoded using the MIME-type multipart/form-data
# struts.multipart.parser=cos
# struts.multipart.parser=pell
# struts.multipart.parser=jakarta-stream
struts.multipart.parser=jakarta
# uses javax.servlet.context.tempdir by default
struts.multipart.saveDir=
struts.multipart.maxSize=2097152

### Load custom property files (does not override struts.properties!)
# struts.custom.properties=application,org/apache/struts2/extension/custom

### How request URLs are mapped to and from actions
#struts.mapper.class=org.apache.struts2.dispatcher.mapper.DefaultActionMapper

### Used by the DefaultActionMapper
### You may provide a comma separated list, e.g. struts.action.extension=action,jnlp,do
### The blank extension allows you to match directory listings as well as pure action names
### without interfering with static resources, which can be specified as an empty string
### prior to a comma e.g. struts.action.extension=, or struts.action.extension=x,y,z,,
struts.action.extension=action,,

### Used by FilterDispatcher
### If true then Struts serves static content from inside its jar.
### If false then the static content must be available at <context_path>/struts
struts.serve.static=true

### Used by FilterDispatcher
### This is good for development where one wants changes to the static content be
### fetch on each request.
### NOTE: This will only have effect if struts.serve.static=true
### If true -> Struts will write out header for static contents such that they will
###             be cached by web browsers (using Date, Cache-Content, Pragma, Expires)
###             headers).
### If false -> Struts will write out header for static contents such that they are
###            NOT to be cached by web browser (using Cache-Content, Pragma, Expires
###            headers)
struts.serve.static.browserCache=true

### Set this to false if you wish to disable implicit dynamic method invocation
### via the URL request. This includes URLs like foo!bar.action, as well as params
### like method:bar (but not action:foo).
### An alternative to implicit dynamic method invocation is to use wildcard
### mappings, such as <action name="*/*" method="{2}" class="actions.{1}">
struts.enable.DynamicMethodInvocation = false

### Set this to true if you wish to allow slashes in your action names.  If false,
### Actions names cannot have slashes, and will be accessible via any directory
### prefix.  This is the traditional behavior expected of WebWork applications.
### Setting to true is useful when you want to use wildcards and store values
### in the URL, to be extracted by wildcard patterns, such as
### <action name="*/*" method="{2}" class="actions.{1}"> to match "/foo/edit" or
### "/foo/save".
struts.enable.SlashesInActionNames = false

### Disables support for action: prefix
struts.mapper.action.prefix.enabled = false

### Blocks access to actions in other namespace than current with action: prefix
struts.mapper.action.prefix.crossNamespaces = false

### use alternative syntax that requires %{} in most places
### to evaluate expressions for String attributes for tags
struts.tag.altSyntax=true

### when set to true, Struts will act much more friendly for developers. This
### includes:
### - struts.i18n.reload = true
### - struts.configuration.xml.reload = true
### - raising various debug or ignorable problems to errors
###   For example: normally a request to foo.action?someUnknownField=true should
###                be ignored (given that any value can come from the web and it
###                should not be trusted). However, during development, it may be
###                useful to know when these errors are happening and be told of
###                them right away.
struts.devMode = false

### when set to true, resource bundles will be reloaded on _every_ request.
### this is good during development, but should never be used in production
### struts.i18n.reload=false

### Standard UI theme
### Change this to reflect which path should be used for JSP control tag templates by default
struts.ui.theme=xhtml
struts.ui.templateDir=template
### Change this to use a different token to indicate template theme expansion
struts.ui.theme.expansion.token=~~~
#sets the default template type. Either ftl, vm, or jsp
struts.ui.templateSuffix=ftl

### Configuration reloading
### This will cause the configuration to reload struts.xml when it is changed
### struts.configuration.xml.reload=false

### Location of velocity.properties file.  defaults to velocity.properties
struts.velocity.configfile = velocity.properties

### Comma separated list of VelocityContext classnames to chain to the StrutsVelocityContext
struts.velocity.contexts =

### Location of the velocity toolbox
struts.velocity.toolboxlocation=

### used to build URLs, such as the UrlTag
struts.url.http.port = 80
struts.url.https.port = 443
### possible values are: none, get or all
struts.url.includeParams = none

### Load custom default resource bundles
# struts.custom.i18n.resources=testmessages,testmessages2

### workaround for some app servers that don't handle HttpServletRequest.getParameterMap()
### often used for WebLogic, Orion, and OC4J
struts.dispatcher.parametersWorkaround = false

### configure the Freemarker Manager class to be used
### Allows user to plug-in customised Freemarker Manager if necessary
### MUST extends off org.apache.struts2.views.freemarker.FreemarkerManager
#struts.freemarker.manager.classname=org.apache.struts2.views.freemarker.FreemarkerManager

### Enables caching of FreeMarker templates
### Has the same effect as copying the templates under WEB_APP/templates
### struts.freemarker.templatesCache=false

### Enables caching of models on the BeanWrapper
struts.freemarker.beanwrapperCache=false

### See the StrutsBeanWrapper javadocs for more information
struts.freemarker.wrapper.altMap=true

### maxStrongSize for MruCacheStorage for freemarker, when set to 0 SoftCacheStorage which performs better in heavy loaded application
### check WW-3766 for more details
struts.freemarker.mru.max.strong.size=0

### configure the XSLTResult class to use stylesheet caching.
### Set to true for developers and false for production.
struts.xslt.nocache=false

### Whether to always select the namespace to be everything before the last slash or not
struts.mapper.alwaysSelectFullNamespace=false

### Whether to allow static method access in OGNL expressions or not
struts.ognl.allowStaticMethodAccess=false

### Whether to throw a RuntimeException when a property is not found
### in an expression, or when the expression evaluation fails
struts.el.throwExceptionOnFailure=false

### Logs as Warnings properties that are not found (very verbose)
struts.ognl.logMissingProperties=false

### Caches parsed OGNL expressions, but can lead to memory leaks
### if the application generates a lot of different expressions
struts.ognl.enableExpressionCache=true

### Indicates if Dispatcher should handle unexpected exceptions by calling sendError()
### or simply rethrow it as a ServletException to allow future processing by other frameworks like Spring Security
struts.handle.exception=true
### END SNIPPET: complete_file

可以看到，该常量默认是关闭的，而该常量只要开启，另一个常量 struts.objectFactory.spring.autoWire 就会生效：

### specifies the autoWiring logic when using the SpringObjectFactory.
### valid values are: name, type, auto, and constructor (name is the default)
struts.objectFactory.spring.autoWire = name

而该配置的作用就是让 Action 可以按照变量名称自动注入 Spring 工厂中管理的实例，所以业务类实例还可通过如下方式获取：

// com.zze.web.action.UserAction
package com.zze.web.action;

import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;
import com.zze.domain.User;
import com.zze.service.UserService;

public class UserAction extends ActionSupport implements ModelDriven<User> {
    private User user = new User();

    @Override
    public User getModel() {
        return user;
    }

    private UserService userService;

    public void setUserService(UserService userService) {
        this.userService = userService;
    }

    public String save() {
        System.out.println(userService);
        /*
        访问 http://localhost:8080/customer_save，输出结果如下：
            com.zze.service.impl.UserServiceImpl@389b9f55
         */
        return NONE;
    }
}

方式二：Action 由 Spring 创建

修改配置：

<!-- applicationContext.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!--
    让 Spring 来创建 Action 实例
        注意，Action 类要配置为多例
    -->
    <bean name="userAction" class="com.zze.web.action.UserAction" scope="prototype">
        <property name="userService" ref="userService"/>
    </bean>

    <bean name="userService" class="com.zze.service.impl.UserServiceImpl">
        <property name="userDao" ref="userDao"/>
    </bean>

    <bean name="userDao" class="com.zze.dao.impl.UserDaoImpl">
    </bean>
</beans>

<!-- struts.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
        "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
        "http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
    <package name="test" extends="struts-default" namespace="/">
        <!--
        修改 class 对应 applicationContext.xml 中 bean 的名称 (id/name)
        -->
        <action name="customer_*" class="userAction" method="{1}">
        </action>
    </package>
</struts>

测试：

// com.zze.web.action.UserAction
package com.zze.web.action;

import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;
import com.zze.domain.User;
import com.zze.service.UserService;

public class UserAction extends ActionSupport implements ModelDriven<User> {
    private User user = new User();

    @Override
    public User getModel() {
        return user;
    }

    private UserService userService;

    public void setUserService(UserService userService) {
        this.userService = userService;
    }

    public String save() {
        System.out.println(userService);
        /*
        访问 http://localhost:8080/customer_save，输出结果如下：
            com.zze.service.impl.UserServiceImpl@4f543a20
         */
        return NONE;
    }
}

目录CONTENT

SSH整合(2)之整合Struts2

方式一：Action 由 Struts2 自身创建

方式二：Action 由 Spring 创建

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