Spring-程序中获取注册bean的方式

时间:2021-02-03 08:31:48

获得spring里注册Bean的四种方法,特别是第三种方法,简单: 
一:方法一(多在struts框架中)继承BaseDispatchAction 

import com.mas.wawacommunity.wap.service.UserManager; 

public class BaseDispatchAction extends DispatchAction {
  /**
   * web应用上下文环境变量
   */
  protected WebApplicationContext ctx;   protected UserManager userMgr;   /**
   * 获得注册Bean
   * @param beanName String 注册Bean的名称
   * @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:方法二实现BeanFactoryAware 
一定要在spring.xml中加上:

<bean id="serviceLocator" class="com.am.oa.commons.service.ServiceLocator" singleton="true" /> 

当对serviceLocator实例时就自动设置BeanFactory,以便后来可直接用beanFactory

public class ServiceLocator implements BeanFactoryAware {
  private static BeanFactory beanFactory = null;   private static ServiceLocator servlocator = null;   public void setBeanFactory(BeanFactory factory) throws BeansException {
    this.beanFactory = factory;
  }   public BeanFactory getBeanFactory() {
    return beanFactory;
  }   public static ServiceLocator getInstance() {
    if (servlocator == null)
      servlocator = (ServiceLocator) beanFactory.getBean("serviceLocator");
    return servlocator;
  }   /**
  * 根据提供的bean名称得到相应的服务类
  * @param servName bean名称
  */
  public static Object getService(String servName) {
    return beanFactory.getBean(servName);
  }   /**
  * 根据提供的bean名称得到对应于指定类型的服务类
  * @param servName bean名称
  * @param clazz 返回的bean类型,若类型不匹配,将抛出异常
  */
  public static Object getService(String servName, Class clazz) {
    return beanFactory.getBean(servName, clazz);
  }
}

action调用: 

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:方法三实现ApplicationContextAware 
一定要在spring.xml中加上:

<bean id="SpringContextUtil " class="com.am.oa.commons.service.SpringContextUtil " singleton="true" /> 

当对SpringContextUtil 实例时就自动设置applicationContext,以便后来可直接用applicationContext

public class SpringContextUtil implements ApplicationContextAware {
private static ApplicationContext applicationContext; //Spring应用上下文环境 /**
* 实现ApplicationContextAware接口的回调方法,设置上下文环境
* @param applicationContext
* @throws BeansException
*/
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
  SpringContextUtil.applicationContext = applicationContext;
} /**
* @return ApplicationContext
*/
public static ApplicationContext getApplicationContext() {
return applicationContext;
} /**
* 获取对象
* @param name
* @return Object 一个以所给名字注册的bean的实例
* @throws BeansException
*/
public static Object getBean(String name) throws BeansException {
return applicationContext.getBean(name);
} /**
* 获取类型为requiredType的对象
* 如果bean不能被类型转换,相应的异常将会被抛出(BeanNotOfRequiredTypeException)
* @param name bean注册名
* @param requiredType 返回对象类型
* @return Object 返回requiredType类型对象
* @throws BeansException
*/
public static Object getBean(String name, Class requiredType) throws BeansException {
return applicationContext.getBean(name, requiredType);
} /**
* 如果BeanFactory包含一个与所给名称匹配的bean定义,则返回true
* @param name
* @return boolean
*/
public static boolean containsBean(String name) {
return applicationContext.containsBean(name);
} /**
* 判断以给定名字注册的bean定义是一个singleton还是一个prototype。
* 如果与给定名字相应的bean定义没有被找到,将会抛出一个异常(NoSuchBeanDefinitionException)
* @param name
* @return boolean
* @throws NoSuchBeanDefinitionException
*/
public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
return applicationContext.isSingleton(name);
} /**
* @param name
* @return Class 注册对象的类型
* @throws NoSuchBeanDefinitionException
*/
public static Class getType(String name) throws NoSuchBeanDefinitionException {
return applicationContext.getType(name);
} /**
* 如果给定的bean名字在bean定义中有别名,则返回这些别名
* @param name
* @return
* @throws NoSuchBeanDefinitionException
*/
public static String[] getAliases(String name) throws NoSuchBeanDefinitionException {
return applicationContext.getAliases(name);
}
}

action调用:

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();
//不用再加载springContext.xml文件,因为在web.xml中配置了,在程序中启动是就有了.
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.通过servlet 或listener设置spring的ApplicationContext,以便后来引用. 
注意分别extends ContextLoaderListener和ContextLoaderServlet .

然后就可用SpringContext来getBean. 覆盖原来在web.xml中配置的listener或servlet.

public class SpringContext {
private static ApplicationContext applicationContext; //Spring应用上下文环境 */
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()));
}
}