Spring 中FactoryBean getObject获得空值

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我是靠谱客的博主勤恳薯片，最近开发中收集的这篇文章主要介绍Spring 中FactoryBean getObject获得空值，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

这里的JobDetail返回为null

 @Bean
public JobDetail printTimeJobDetail(){
JobDetailFactoryBean jobDetailFactoryBean = new JobDetailFactoryBean();
// durability 表示任务完成之后是否依然保留到数据库，默认falses
jobDetailFactoryBean.setDurability(true);
//当Quartz服务被中止后，再次启动或集群中其他机器接手任务时会尝试恢复执行之前未完成的所有任务
jobDetailFactoryBean.setRequestsRecovery(true);
jobDetailFactoryBean.setJobClass(MyDetailQuartzJobBean.class);
jobDetailFactoryBean.setDescription("打印时间定时器2");
Map<String,String> jobDataAsMap = new HashMap<>();
jobDataAsMap.put("targetObject","printTimeQuartz"); //spring 中bean的名字
jobDataAsMap.put("targetMethod","execute");
//执行方法名
jobDetailFactoryBean.setJobDataAsMap(jobDataAsMap);
return
jobDetailFactoryBean.getObject();
}

我们从JobDetailFactoryBean源码入手，实现了InitializingBean接口，会实现afterPropertiesSet()接口，会在初始化bean的时候执行。

观察源码JobDetail在afterPropertiesSet()方法中产生。之所以上面JobDetail返回空，因为afterPropertiesSet()的执行在上面@Bean 注解的方法后执行。

 public void afterPropertiesSet() {
Assert.notNull(this.jobClass, "Property 'jobClass' is required");
if (this.name == null) {
this.name = this.beanName;
}
if (this.group == null) {
this.group = "DEFAULT";
}
if (this.applicationContextJobDataKey != null) {
if (this.applicationContext == null) {
throw new IllegalStateException("JobDetailBean needs to be set up in an ApplicationContext to be able to handle an 'applicationContextJobDataKey'");
}
this.getJobDataMap().put(this.applicationContextJobDataKey, this.applicationContext);
}
JobDetailImpl jdi = new JobDetailImpl();
jdi.setName(this.name != null ? this.name : this.toString());
jdi.setGroup(this.group);
jdi.setJobClass(this.jobClass);
jdi.setJobDataMap(this.jobDataMap);
jdi.setDurability(this.durability);
jdi.setRequestsRecovery(this.requestsRecovery);
jdi.setDescription(this.description);
this.jobDetail = jdi;
}

我们可以这样写，并且能够在spring容器中找到JobDetail。这是FactortBean接口帮我们做到的

@Bean
public JobDetailFactoryBean printTimeJobDetail(){
JobDetailFactoryBean jobDetailFactoryBean = new JobDetailFactoryBean();
// durability 表示任务完成之后是否依然保留到数据库，默认falses
jobDetailFactoryBean.setDurability(true);
//当Quartz服务被中止后，再次启动或集群中其他机器接手任务时会尝试恢复执行之前未完成的所有任务
jobDetailFactoryBean.setRequestsRecovery(true);
jobDetailFactoryBean.setJobClass(MyDetailQuartzJobBean.class);
jobDetailFactoryBean.setDescription("打印时间定时器2");
Map<String,String> jobDataAsMap = new HashMap<>();
jobDataAsMap.put("targetObject","printTimeQuartz"); //spring 中bean的名字
jobDataAsMap.put("targetMethod","execute");
//执行方法名
jobDetailFactoryBean.setJobDataAsMap(jobDataAsMap);
return
jobDetailFactoryBean;
}