Get spring context - applicationContext

Foreword

　　spring context is an implementation of the abstract spring containers. You will need to spring to help you manage objects placed in a container objects, ApplicationContext Bean definition and maintenance is a collaboration between objects off the first high-level interface.

Gets spring of context ApplicationContext way

A), obtained by WebApplicationUtils tools.

　　WebApplicationUtils class is the Spring framework based packet spring-web-3.2.0. RELEASE.jar classes. Using this method must rely Servlet container. Use as follows: 

// the Spring acquired ServletContext object, this general category can be acquired 
ServletContext SC = ContextLoader.getCurrentWebApplicationContext () GetServletContext ();.
 // the servlet may be obtained in this manner, the method more 
ServletContext SC = request.getServletContext ():
SC the ServletContext = servletConfig.getServletContext ();   // ServletConfig can be acquired in the servlet init (ServletConfig config) obtained in the method
 
/ * Need to pass a parameter ServletContext object method for obtaining the above * / 
// This method throws an exception acquisition failure 
ApplicationContext ac = WebApplicationContextUtils.getRequiredWebApplicationContext (SC);
 // returns null acquisition failure this method 
ApplicationContext ac = WebApplicationContextUtils.getWebApplicationContext (sc);

B) by loading configuration files or annotations configuration class acquired

① ClassPathXmlApplicationContext: loaded from the one or more context definition xml configuration file in the class path, applicable to the embodiment xml configuration;  such conventional test

ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

② FileSystemXmlApplicationContext: loaded from the one or more context definition xml configuration file in the file system, that is loaded in the xml configuration file system drive;

③ XmlWebApplicationContext: a load context definitions from the web application or more xml configuration file for xml configuration.

④AnnotationConfigApplicationContext: load context defined java class based on the configuration of one or more suitable manner java annotations;

⑤ AnnotationConfigWebApplicationContext: specifically for web application prepared for annotation mode;

 Three), create your own tools (SpringContextHolder) to achieve the Spring ApplicationContextAware interface.

 ① registration tools in the configuration file

<bean id="springContextHolder" class="com.fubo.utils.spring.SpringContextHolder" lazy-init="false"/>

② Tools

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

/**
 * To achieve spring context management
 */
@Component("applicationContextHelper")
public class ApplicationContextHelper implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext context) throws BeansException {
        applicationContext = context;
    }
　　// Get the type of bean
     public  static <T> T popBean (Class <T> clazz) {
        checkApplicationContext ();
        return applicationContext.getBean(clazz);
    }
　　 // Get the name of The bean
      public  static <T> T popBean (String name) {
        checkApplicationContext ();
        return applicationContext.getBean(clazz);
    }
　　 The bean // Get the name and type of
     public  static <T> T popBean (String name, Class <T> clazz) {
        checkApplicationContext ();
        return applicationContext.getBean(name, clazz);
    }

    // Check whether the empty applicationContext 
    Private  static  void checkApplicationContext () {
         IF (applicationContext == null ) {
             the throw  new new IllegalStateException ( "applicaitonContext not injected, define in the applicationContext.xml SpringContextHolder" );
        }
    }
}