在 WEB 開發中,擷取到由 Spring 進行管理的某些 Bean,通常采用下面方式來擷取
1、通過set注入方式
private ProjectStageHandler projectStageHandler;
public void setProjectStageHandler(ProjectStageHandler projectStageHandler) {
this.projectStageHandler = projectStageHandler;
}
2、通過注解方式
@Resource
private ProjectStageHandler projectStageHandler;
今天遇到 需要顯示的獲得 ApplicationContext 來得到由 Spring 進行管理的某些 Bean,在這裡和大家分享一下,WEB 開發中,怎麼擷取 ApplicationContext ( 如有不正确之處還請指點)
查找工程有沒有這種實作,功夫沒有白費還真找到了大緻實作方式如下:
3、首先web.xml配置
<listener>
<listener-class>org.common.xxxServletContextListener</listener-class>
</listener>
接着xxxServletContextListener.java
public class xxxServletContextListener implements ServletContextListener {
//ServletContext建立時調用該方法
public void contextInitialized(ServletContextEvent arg0){
ServletContext context= arg0.getServletContext();
System.out.println("監聽器啟動。。。。。。。。。。。。。。。。。。。。。。。。。。。。");
ApplicationCtx.init(context);
}
//ServletContext銷毀時調用該方法
public void contextDestroyed(ServletContextEvent sce){
System.out.println("ServletContext銷毀");
}
}
ApplicationCtx .java
public class ApplicationCtx {
public static ApplicationContext ctx;
public static ApplicationContext getCtx(){
return ctx;
}
public static void init(ServletContext sc){
if(ctx==null){
ctx = WebApplicationContextUtils.getRequiredWebApplicationContext(sc);
}
}
}
通過 ApplicationCtx.getCtx().getBean("xxx"); 就可以獲到想要的bean啦
想想這種方式有點太羅嗦和麻煩,還有沒有更簡單的方式哪?有當然有。
4、首先要在spring.xml中加上
<bean id="applicationContext" class="org.wy.util.AppliactionContextHelper"/>
當對AppliactionContextHelper執行個體時就自動設定applicationContext,以便後來可直接用applicationContext
public class AppliactionContextHelper implements ApplicationContextAware {
private static ApplicationContext applicationContext; //Spring應用上下文環境
/**
* 實作ApplicationContextAware接口的回調方法,設定上下文環境
* @param applicationContext
* @throws BeansException
*/
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
AppliactionContextHelper.applicationContext = applicationContext;
}
/**
* @return ApplicationContext
*/
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
/**
* 擷取對象
* @param name
* @return Object 一個以所給名字注冊的bean的執行個體
* @throws BeansException
*/
public static Object getBean(String name) throws BeansException {
return applicationContext.getBean(name);
}
/**
* 擷取類型為requiredType的對象
* 如果bean不能被類型轉換,相應的異常将會被抛出(BeanNotOfRequiredTypeException)
* @param name bean注冊名
* @param requiredType 傳回對象類型
* @return Object 傳回requiredType類型對象
* @throws BeansException
*/
public static Object getBean(String name, Class requiredType) throws BeansException {
return applicationContext.getBean(name, requiredType);
}
/**
* 如果BeanFactory包含一個與所給名稱比對的bean定義,則傳回true
* @param name
* @return boolean
*/
public static boolean containsBean(String name) {
return applicationContext.containsBean(name);
}
/**
* 判斷以給定名字注冊的bean定義是一個singleton還是一個prototype。
* 如果與給定名字相應的bean定義沒有被找到,将會抛出一個異常(NoSuchBeanDefinitionException)
* @param name
* @return boolean
* @throws NoSuchBeanDefinitionException
*/
public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
return applicationContext.isSingleton(name);
}
/**
* @param name
* @return Class 注冊對象的類型
* @throws NoSuchBeanDefinitionException
*/
public static Class getType(String name) throws NoSuchBeanDefinitionException {
return applicationContext.getType(name);
}
/**
* 如果給定的bean名字在bean定義中有别名,則傳回這些别名
* @param name
* @return
* @throws NoSuchBeanDefinitionException
*/
public static String[] getAliases(String name) throws NoSuchBeanDefinitionException {
return applicationContext.getAliases(name);
}
}
通過AppliactionContextHelper.getBean("xxx");就可以獲到想要的bean啦
5、
利用ClassPathXmlApplicationContext
可以從classpath中讀取XML檔案
(1) ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
UserDao userDao = (UserDao)context.getBean("userDao");
(2) ClassPathXmlApplicationContext resource = new ClassPathXmlApplicationContext(new String[]{"applicationContext-ibatis-oracle.xml","applicationContext.xml","applicationContext-data-oracle.xml"});
BeanFactory factory = resource;
factory.getBean("xxx");
這種方式隻适合非web中的應用程式中。
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轉載:
獲得spring裡注冊Bean的四種方法,特别是第三種方法,簡單:
一:方法一(多在struts架構中)繼承BaseDispatchAction
Java代碼
import com.mas.wawacommunity.wap.service.UserManager;
public class BaseDispatchAction extends DispatchAction {
/**
* web應用上下文環境變量
*/
protected WebApplicationContext ctx;
protected UserManager userMgr;
/**
* 獲得注冊Bean
* @param beanName String 注冊Bean的名稱
* @return
*/
protected final Object getBean(String beanName) {
return ctx.getBean(beanName);
}
protected ActionForward unspecified(ActionMapping mapping, ActionForm form,
javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response) {
return mapping.findForward("index");
}
public void setServlet(ActionServlet servlet) {
this.servlet = servlet;
this.ctx = WebApplicationContextUtils.getWebApplicationContext(servlet.getServletContext());
this.userMgr = (UserManager) getBean("userManager");
}
}
二:方法二實作BeanFactoryAware
一定要在spring.xml中加上:
Xml代碼
<bean id="serviceLocator" class="com.am.oa.commons.service.ServiceLocator" singleton="true" />
當對serviceLocator執行個體時就自動設定BeanFactory,以便後來可直接用 beanFactory
Java代碼
public class UserAction extends BaseAction implements Action,ModelDriven{
private Users user = new Users();
protected ServiceLocator service = ServiceLocator.getInstance();
UserService userService = (UserService)service.getService("userService");
public String execute() throws Exception {
return SUCCESS;
}
public Object getModel() {
return user;
}
public String getAllUser(){
HttpServletRequest request = ServletActionContext.getRequest();
List ls=userService.LoadAllObject( Users.class );
request.setAttribute("user",ls);
this.setUrl("/yonghu.jsp");
return SUCCESS;
}
}
三:方法三實作ApplicationContextAware,一定要在spring.xml中加上:
Xml代碼
<bean id="SpringContextUtil " class="com.am.oa.commons.service.SpringContextUtil " singleton="true" />
當對SpringContextUtil 執行個體時就自動設定applicationContext,以便後來可直接用applicationContext
Java代碼
public class SpringContextUtil implements ApplicationContextAware {
private static ApplicationContext applicationContext; //Spring應用上下文環境
/**
* 實作ApplicationContextAware接口的回調方法,設定上下文環境
* @param applicationContext
* @throws BeansException
*/
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
SpringContextUtil.applicationContext = applicationContext;
}
/**
* @return ApplicationContext
*/
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
/**
* 擷取對象
* @param name
* @return Object 一個以所給名字注冊的bean的執行個體
* @throws BeansException
*/
public static Object getBean(String name) throws BeansException {
return applicationContext.getBean(name);
}
/**
* 擷取類型為requiredType的對象
* 如果bean不能被類型轉換,相應的異常将會被抛出(BeanNotOfRequiredTypeException)
* @param name bean注冊名
* @param requiredType 傳回對象類型
* @return Object 傳回requiredType類型對象
* @throws BeansException
*/
public static Object getBean(String name, Class requiredType) throws BeansException {
return applicationContext.getBean(name, requiredType);
}
/**
* 如果BeanFactory包含一個與所給名稱比對的bean定義,則傳回true
* @param name
* @return boolean
*/
public static boolean containsBean(String name) {
return applicationContext.containsBean(name);
}
/**
* 判斷以給定名字注冊的bean定義是一個singleton還是一個prototype。
* 如果與給定名字相應的bean定義沒有被找到,将會抛出一個異常(NoSuchBeanDefinitionException)
* @param name
* @return boolean
* @throws NoSuchBeanDefinitionException
*/
public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
return applicationContext.isSingleton(name);
}
/**
* @param name
* @return Class 注冊對象的類型
* @throws NoSuchBeanDefinitionException
*/
public static Class getType(String name) throws NoSuchBeanDefinitionException {
return applicationContext.getType(name);
}
/**
* 如果給定的bean名字在bean定義中有别名,則傳回這些别名
* @param name
* @return
* @throws NoSuchBeanDefinitionException
*/
public static String[] getAliases(String name) throws NoSuchBeanDefinitionException {
return applicationContext.getAliases(name);
}
}
action調用:
Java代碼
package com.anymusic.oa.webwork;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import com.anymusic.oa.commons.service.ServiceLocator;
import com.anymusic.oa.hibernate.pojo.Role;
import com.anymusic.oa.hibernate.pojo.Users;
import com.anymusic.oa.spring.IUserService;
import com.opensymphony.webwork.ServletActionContext;
import com.opensymphony.xwork.Action;
import com.opensymphony.xwork.ActionContext;
import com.opensymphony.xwork.ModelDriven;
public class UserAction extends BaseAction implements Action,ModelDriven{
private Users user = new Users();
//不用再加載springContext.xml 檔案,因為在web.xml中配置了,在程式中啟動是就有了.
UserService userService = (UserService) SpringContextUtil.getBean("userService");
public String execute() throws Exception {
return SUCCESS;
}
public Object getModel() {
return user;
}
public String getAllUser(){
HttpServletRequest request = ServletActionContext.getRequest();
List ls=userService.LoadAllObject( Users.class );
request.setAttribute("user",ls);
this.setUrl("/yonghu.jsp");
return SUCCESS;
}
}
四.通過servlet 或listener設定spring的 ApplicationContext,以便後來引用.
注意分别extends ContextLoaderListener和ContextLoaderServlet .然後就可用SpringContext 來getBean.
覆寫原來在web.xml中配置的listener或servlet.
public class SpringContext {
private static ApplicationContext applicationContext; //Spring應用上下文環境
*/
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
SpringContextUtil.applicationContext = applicationContext;
}
/**
* @return ApplicationContext
*/
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
*/
public static Object getBean(String name) throws BeansException {
return applicationContext.getBean(name);
}
}
public class SpringContextLoaderListener extends ContextLoaderListener{ //
public void contextInitialized(ServletContextEvent event) {
super.contextInitialized(event);
SpringContext.setApplicationContext(
WebApplicationContextUtils.getWebApplicationContext(event.getServletContext())
);
}
}
public class SpringContextLoaderServlet extends ContextLoaderServlet {
private ContextLoader contextLoader;
public void init() throws ServletException {
this.contextLoader = createContextLoader();
SpringContext.setApplicationContext(this.contextLoader.initWebApplicationContext(getServletContext()));
}
}