问题
Spring中多线程注入userThreadService注不进去,显示userThreadService为null异常
代码如下:
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public class UserThreadTask implements Runnable { @Autowired private UserThreadService userThreadService; @Override public void run() { AdeUser user = userThreadService.get( "0" ); System.out.println(user); } } |
解决方案一
把要注入的Service,通过构造传过去,代码如下:
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public class UserThreadTask implements Runnable { private UserThreadService userThreadService; public UserThreadTask(UserThreadService userThreadService) { this .userThreadService = userThreadService; } @Override public void run() { AdeUser user = userThreadService.get( "0" ); System.out.println(user); } } |
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Thread t = new Thread( new UserThreadTask(userThreadService)); t.start(); |
解决方案二
通过ApplicationContext中获取需要使用的Service
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import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; public class ApplicationContextHolder implements ApplicationContextAware { private static ApplicationContext context; @Override public void setApplicationContext(ApplicationContext context) throws BeansException { ApplicationContextHolder.context = context; } //根据bean name 获取实例 public static Object getBeanByName(String beanName) { if (beanName == null || context == null ) { return null ; } return context.getBean(beanName); } //只适合一个class只被定义一次的bean(也就是说,根据class不能匹配出多个该class的实例) public static Object getBeanByType(Class clazz) { if (clazz == null || context == null ) { return null ; } return context.getBean(clazz); } public static String[] getBeanDefinitionNames() { return context.getBeanDefinitionNames(); } } |
Spring 加载自己定义的ApplicationContextHolder类
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< bean class = "cn.com.infcn.applicationcontext.ApplicationContextHolder" ></ bean > |
根据 bean 的名称获取实例
复制代码代码如下:
UserService user = (UserService) ApplicationContextHolder.getBeanByName("userService");
根据 bean 的Class 获取实例(如果该Class存在多个实例,会报错的)
复制代码代码如下:
UserService user = (UserService) ApplicationContextHolder.getBeanByType(UserService.class);
这种方式,不管是否多线程,还是普通的不收spring管理的类,都可以使用该方法获得spring管理的bean。