原文地址: http://blog.csdn.net/chen1403876161/article/details/53644024
Spring静态注入的三种方式:
(说明:MongoFileOperationUtil是自己封装的一个Mongodb文件读写工具类,里面需要依赖AdvancedDatastore对象实例,dsForRW用来获取Mongodb数据源)
在springframework里,我们不能@Autowired一个静态变量,使之成为一个spring bean,例如下面这种方式:
- @Autowired
- private static AdvancedDatastore dsForRW;
但是自己比较喜欢封装工具类,并通过@Component注解成功能组件,但是功能组件中的方法一般都是静态方法,静态方法只能调用静态成员变量,于是就有了下面的问题。封有的时候封装功能组件会需要底层的service注入,怎么办呢?
去网上搜了下解决办法,简单总结一下几种实现方式;
1.xml方式实现;
- <bean id="mongoFileOperationUtil" class="com.*.*.MongoFileOperationUtil" init-method="init">
- <property name="dsForRW" ref="dsForRW"/>
- </bean>
- public class MongoFileOperationUtil {
- private static AdvancedDatastore dsForRW;
- private static MongoFileOperationUtil mongoFileOperationUtil;
- public void init() {
- mongoFileOperationUtil = this;
- mongoFileOperationUtil.dsForRW = this.dsForRW;
- }
- }
2.@PostConstruct方式实现;
- import org.mongodb.morphia.AdvancedDatastore;
- import org.springframework.beans.factory.annotation.Autowired;
- @Component
- public class MongoFileOperationUtil {
- @Autowired
- private static AdvancedDatastore dsForRW;
- private static MongoFileOperationUtil mongoFileOperationUtil;
- @PostConstruct
- public void init() {
- mongoFileOperationUtil = this;
- mongoFileOperationUtil.dsForRW = this.dsForRW;
- }
- }
这种方式和在xml中配置 init-method和 destory-method方法差不多,定义spring 容器在初始化bean 和容器销毁之前的所做的操作;
3.set方法上添加@Autowired注解,类定义上添加@Component注解;
- import org.mongodb.morphia.AdvancedDatastore;
- import org.springframework.beans.factory.annotation.Autowired;
- import org.springframework.stereotype.Component;
- @Component
- public class MongoFileOperationUtil {
- private static AdvancedDatastore dsForRW;
- @Autowired
- public void setDatastore(AdvancedDatastore dsForRW) {
- MongoFileOperationUtil.dsForRW = dsForRW;
- }
- }
首先Spring要能扫描到AdvancedDatastore的bean,然后通过setter方法注入;
然后注意:成员变量上不需要再添加@Autowired注解;