ApplicationContext 获取Bean

介绍一种常用的通过SpringBeanUtil工具类获取Bean的方法

• 后台代码
• Spring配置文件
• 使用说明

后台代码

@Component
public class SpringBeanUtil implements ApplicationContextAware {
    private static Logger logger = Logger.getLogger(SpringBeanUtil.class);
    private static ApplicationContext applicationContext = null;

    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException
    {
        logger.info("------SpringBeanUtil setApplicationContext-------");
        SpringBeanUtil.applicationContext = applicationContext;
    }

    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    /**
     * 注意 bean name默认 = 类名(首字母小写)
     * 例如: A8sClusterDao = getBean("k8sClusterDao")
     * @param name
     * @return
     * @throws BeansException
     */
    public static Object getBean(String name) throws BeansException {
        if (applicationContext==nul)
        {
            return new NullPointerException("applicationContext is null");
        }
        return applicationContext.getBean(name);
    }

Spring配置文件

?xml version="1.0" encoding="UTF-8"?>  
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"  
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:p="http://www.springframework.org/schema/p" xmlns:util="http://www.springframework.org/schema/util" xmlns:jdbc="http://www.springframework.org/schema/jdbc"  
    xmlns:cache="http://www.springframework.org/schema/cache"  
    xsi:schemaLocation="  
    http://www.springframework.org/schema/context  
    http://www.springframework.org/schema/context/spring-context.xsd  
    http://www.springframework.org/schema/beans  
    http://www.springframework.org/schema/beans/spring-beans.xsd  
    http://www.springframework.org/schema/tx  
    http://www.springframework.org/schema/tx/spring-tx.xsd  
    http://www.springframework.org/schema/jdbc  
    http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd  
    http://www.springframework.org/schema/cache  
    http://www.springframework.org/schema/cache/spring-cache-3.1.xsd  
    http://www.springframework.org/schema/aop  
    http://www.springframework.org/schema/aop/spring-aop.xsd  
    http://www.springframework.org/schema/util  
    http://www.springframework.org/schema/util/spring-util.xsd">  
  
    <!-- 自动扫描web包 ,将带有注解的类 纳入spring容器管理 -->  
    <context:component-scan base-package="com.eduoinfo.finances.bank.web"></context:component-scan>  
  
    <!-- 引入jdbc配置文件 -->  
    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">  
        <property name="locations">  
            <list>  
                <value>classpath*:jdbc.properties</value>  
            </list>  
        </property>  
    </bean>  
  
    <!-- dataSource 配置 -->  
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">  
        <!-- 基本属性 url、user、password -->  
        <property name="url" value="${jdbc.url}" />  
        <property name="username" value="${jdbc.username}" />  
        <property name="password" value="${jdbc.password}" />  
  
        <!-- 配置初始化大小、最小、最大 -->  
        <property name="initialSize" value="1" />  
        <property name="minIdle" value="1" />  
        <property name="maxActive" value="20" />  
  
        <!-- 配置获取连接等待超时的时间 -->  
        <property name="maxWait" value="60000" />  
  
        <!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->  
        <property name="timeBetweenEvictionRunsMillis" value="60000" />  
  
        <!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->  
        <property name="minEvictableIdleTimeMillis" value="300000" />  
  
        <property name="validationQuery" value="SELECT 'x'" />  
        <property name="testWhileIdle" value="true" />  
        <property name="testOnBorrow" value="false" />  
        <property name="testOnReturn" value="false" />  
  
        <!-- 打开PSCache，并且指定每个连接上PSCache的大小 -->  
        <property name="poolPreparedStatements" value="false" />  
        <property name="maxPoolPreparedStatementPerConnectionSize" value="20" />  
  
        <!-- 配置监控统计拦截的filters -->  
        <property name="filters" value="stat" />  
    </bean>  
  
    <!-- mybatis文件配置，扫描所有mapper文件 -->  
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean" p:dataSource-ref="dataSource" p:configLocation="classpath:mybatis-config.xml" p:mapperLocations="classpath:com/eduoinfo/finances/bank/web/dao/*.xml" />  
  
    <!-- spring与mybatis整合配置，扫描所有dao -->  
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer" p:basePackage="com.eduoinfo.finances.bank.web.dao" p:sqlSessionFactoryBeanName="sqlSessionFactory" />  
  
    <!-- 对dataSource 数据源进行事务管理 -->  
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" p:dataSource-ref="dataSource" />  
  
    <!-- 配置使Spring采用CGLIB代理 -->  
    <aop:aspectj-autoproxy proxy-target-class="true" />  
  
    <!-- 启用对事务注解的支持 -->  
    <tx:annotation-driven transaction-manager="transactionManager" />  
  
    <!-- Cache配置 -->  
    <cache:annotation-driven cache-manager="cacheManager" />  
    <bean id="ehCacheManagerFactory" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean" p:configLocation="classpath:ehcache.xml" />  
    <bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheCacheManager" p:cacheManager-ref="ehCacheManagerFactory" />  
  
</beans> 

需要注意的一点：我们需要注入的Bean必须能被扫描到，即上面的--component-scan base-package--里所填写的路径应包含我们需要注入的Bean

使用说明

在任意类中直接通过下述方式调用即可

LoginService loginService = (LoginService)SpringBeanUtil.getBean("loginService");

其中getBean()中填写的名称在我的演示Demo里是通过@Service注解注入Spring中的。 简单来说就是一个很常用的工具类，希望对大家有所帮助。