SpringContextHolder 工具类

/**
 * Copyright (c) 2005-2009 springside.org.cn
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * <p>
 * $Id: SpringContextHolder.java,v 1.2 2015/10/28 03:56:19 guobin Exp $
 */

import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候中取出ApplicaitonContext.
 */
@Component
@Lazy(value = false)
public class SpringContextHolder implements ApplicationContextAware {

    /**
     * 用的时候记得初始化，现在这个地方是错的
     * <p>
     * eg： private static ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-mvc.xml");
     * </p>
     */
    private static ApplicationContext applicationContext;

    // private static ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-mvc.xml");

    /**
     * 取得存储在静态变量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext() {
        checkApplicationContext();
        return applicationContext;
    }

    /**
     * 实现ApplicationContextAware接口的context注入函数, 将其存入静态变量.
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        SpringContextHolder.applicationContext = applicationContext; // NOSONAR
    }

    /**
     * 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) {
        checkApplicationContext();
        return (T) applicationContext.getBean(name);
    }

    /**
     * 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型. 如果有多个Bean符合Class, 取出第一个.
     */
    public static <T> T getBean(Class<T> requiredType) {
        checkApplicationContext();
        return applicationContext.getBean(requiredType);
    }

    /**
     * 清除applicationContext静态变量.
     */
    public static void cleanApplicationContext() {
        applicationContext = null;
    }

    private static void checkApplicationContext() {
        if (applicationContext == null) {
            throw new IllegalStateException("applicaitonContext未注入,请在applicationContext.xml中定义SpringContextHolder");
        }
    }
}