在程序中如何获取serverhttprequest

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mob64ca1411a6fc 2024-12-26 06:38:04

文章标签 web.xml java xml spring 文章分类 架构后端开发

在 WEB 开发中，获取到由 Spring 进行管理的某些 Bean，通常采用下面方式来获取

1、通过set注入方式

private ProjectStageHandler projectStageHandler;

public void setProjectStageHandler(ProjectStageHandler projectStageHandler) {
  this.projectStageHandler = projectStageHandler;
 }

2、通过注解方式

@Resource

private ProjectStageHandler projectStageHandler;

今天遇到需要显示的获得 ApplicationContext 来得到由 Spring 进行管理的某些 Bean，在这里和大家分享一下，WEB 开发中，怎么获取 ApplicationContext ( 如有不正确之处还请指点)

查找工程有没有这种实现，功夫没有白费还真找到了大致实现方式如下：

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创建时调用该方法 
	public void contextInitialized(ServletContextEvent arg0){
		ServletContext context= arg0.getServletContext();   
		System.out.println("监听器启动。。。。。。。。。。。。。。。。。。。。。。。。。。。。");
		ApplicationCtx.init(context);
	}  
    //ServletContext销毁时调用该方法    
    public void contextDestroyed(ServletContextEvent sce){    
         System.out.println("ServletContext销毁");    
     }
	  
}

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);
		}
	}
}

通过 ApplicationCtx.getCtx().getBean("xxx"); 就可以获到想要的bean啦

想想这种方式有点太罗嗦和麻烦，还有没有更简单的方式哪？有当然有。

4、首先要在spring.xml中加上

<bean id="applicationContext" class="org.wy.util.AppliactionContextHelper"/>

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

public class AppliactionContextHelper 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 {
    AppliactionContextHelper.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);
  }
}

通过AppliactionContextHelper.getBean("xxx");就可以获到想要的bean啦

5、

利用ClassPathXmlApplicationContext

可以从classpath中读取XML文件

(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");

这种方式只适合非web中的应用程序中。

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

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

Java代码

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:

Xml代码

<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

Java代码

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:

Xml代码

<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

Java代码

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：

Java代码

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()));   
    }   
}

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