問題
Spring中多線程注入userThreadService注不進去,顯示userThreadService爲null異常 代碼如下:
public class UserThreadTask implements Runnable {
@Autowired
private UserThreadService userThreadService;
@Override
public void run() {
AdeUser user = userThreadService.get("0");
System.out.println(user);
}
}
解決方案一
把要注入的Service,通過構造傳過去,代碼如下:
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);
}
}
Thread t = new Thread(new UserThreadTask(userThreadService));
t.start();
解決方案二
通過ApplicationContext中獲取需要使用的Service
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;
}
//根據bean name 獲取實例
public static Object getBeanByName(String beanName) {
if (beanName == null || context == null) {
return null;
}
return context.getBean(beanName);
}
//只適合一個class只被定義一次的bean(也就是說,根據class不能匹配出多個該class的實例)
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 加載自己定義的ApplicationContextHolder類
<bean class = "cn.com.infcn.applicationcontext.ApplicationContextHolder"></bean>
根據 bean 的名稱獲取實例
UserService user = (UserService) ApplicationContextHolder.getBeanByName("userService");
根據 bean 的Class 獲取實例(如果該Class存在多個實例,會報錯的)
UserService user = (UserService) ApplicationContextHolder.getBeanByType(UserService.class);
這種方式,不管是否多線程,還是普通的不收spring管理的類,都可以使用該方法獲得spring管理的bean。
作者:jijs
鏈接:http://www.jianshu.com/p/c8a43d26bc0f
來源:簡書
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