Java_web開發_SSH spring中取得Bean實例的方法

時間 2019-12-07

標籤 java web 開發 ssh spring 取得 bean 實例方法欄目 Java 简体版

原文原文鏈接

得到spring裏註冊Bean的四種方法，特別是第三種方法，簡單：
一：方法一（多在struts框架中）繼承BaseDispatchAction java

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;
 
    /**
    * 得到註冊Bean     
    * @param beanName String 註冊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：方法二實現BeanFactoryAware
必定要在spring.xml中加上:
<bean id="serviceLocator" class="項目中ServiceLocator的類路徑好比：com.am.oa.commons.service.SpringContextUtil " singleton="true" />
當對serviceLocator實例時就自動設置BeanFactory,以便後來可直接用beanFactoryweb

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;
    }
 
    /**
    * 根據提供的bean名稱獲得相應的服務類     
    * @param servName bean名稱     
    */
    public static Object getService(String servName) {
        return beanFactory.getBean(servName);
    }
 
    /**
    * 根據提供的bean名稱獲得對應於指定類型的服務類
    * @param servName bean名稱
    * @param clazz 返回的bean類型,若類型不匹配,將拋出異常
    */
    public static Object getService(String servName, Class clazz) {
        return beanFactory.getBean(servName, clazz);
    }
}

action調用: spring

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：方法三實現ApplicationContextAware
必定要在spring.xml中加上:
<bean id="SpringContextUtil " class="項目中applicationContext的類路徑好比：com.am.oa.commons.service.SpringContextUtil " singleton="true" />
當對SpringContextUtil 實例時就自動設置applicationContext,以便後來可直接用applicationContext

app

public class SpringContextUtil implements ApplicationContextAware {
  private static ApplicationContext applicationContext;     //Spring應用上下文環境
 
  /**
  * 實現ApplicationContextAware接口的回調方法，設置上下文環境   
  * @param applicationContext
  * @throws BeansException
  */
  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    SpringContextUtil.applicationContext = applicationContext;
  }
 
  /**
  * @return ApplicationContext
  */
  public static ApplicationContext getApplicationContext() {
    return applicationContext;
  }
 
  /**
  * 獲取對象   
  * @param name
  * @return Object 一個以所給名字註冊的bean的實例
  * @throws BeansException
  */
  public static Object getBean(String name) throws BeansException {
    return applicationContext.getBean(name);
  }
 
  /**
  * 獲取類型爲requiredType的對象
  * 若是bean不能被類型轉換，相應的異常將會被拋出（BeanNotOfRequiredTypeException）
  * @param name       bean註冊名
  * @param requiredType 返回對象類型
  * @return Object 返回requiredType類型對象
  * @throws BeansException
  */
  public static Object getBean(String name, Class requiredType) throws BeansException {
    return applicationContext.getBean(name, requiredType);
  }
 
  /**
  * 若是BeanFactory包含一個與所給名稱匹配的bean定義，則返回true 
  * @param name
  * @return boolean
  */
  public static boolean containsBean(String name) {
    return applicationContext.containsBean(name);
  }
 
  /**
  * 判斷以給定名字註冊的bean定義是一個singleton仍是一個prototype。
  * 若是與給定名字相應的bean定義沒有被找到，將會拋出一個異常（NoSuchBeanDefinitionException）   
  * @param name
  * @return boolean
  * @throws NoSuchBeanDefinitionException
  */
  public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
    return applicationContext.isSingleton(name);
  }
 
  /**
  * @param name
  * @return Class 註冊對象的類型
  * @throws NoSuchBeanDefinitionException
  */
  public static Class getType(String name) throws NoSuchBeanDefinitionException {
    return applicationContext.getType(name);
  }
 
  /**
  * 若是給定的bean名字在bean定義中有別名，則返回這些別名   
  * @param name
  * @return
  * @throws NoSuchBeanDefinitionException
  */
  public static String[] getAliases(String name) throws NoSuchBeanDefinitionException {
    return applicationContext.getAliases(name);
  }
}

action調用：框架

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文件,由於在web.xml中配置了,在程序中啓動是就有了.    
    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.經過servlet 或listener設置spring的ApplicationContext,以便後來引用.
注意分別extends ContextLoaderListener和ContextLoaderServlet .而後就可用SpringContext來getBean.
覆蓋原來在web.xml中配置的listener或servlet.jsp

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()));
    }
}

本身使用：ui

1.若是applicationContext文件是在src的根目錄下：this

ApplicationContext apt= new FileSystemXmlApplicationContext("src/applicationContext.xml");spa

apt.getBean("ID");hibernate

能夠取得

2.若是文件是在WebRoot/WEB-INF下能夠用

ApplicationContext applicationContext= new FileSystemXmlApplicationContext("../applicationContext.xml");

取得

3.若是是在servlet中取可用

ServletContext application = this.getServletContext(); //獲取spring上下文信息爲servlet使用 WebApplicationContext wac = WebApplicationContextUtils.getWebApplicationContext(application); IDicService dicService = (IDicService)wac.getBean("dicService");