Spring Boot @Autowired 注入静态变量或静态方法

女爷i 2022-12-17 07:08 291阅读 0赞

注：用static去定义一个注入的方法或者配置文件值变量，编译时不会有任何异常，运行时会报空指针。

Spring官方不推荐此种方法。

原理：

[https://www.cnblogs.com/chenfeng1122/p/6270217.html][https_www.cnblogs.com_chenfeng1122_p_6270217.html]

## 解决办法 ##

利用spring的set注入方法，通过非静态的setter方法注入静态变量 ，我们可以改成这样就静态变量可以获取到你配置的信息了。

把get,set方法的static 修饰符去掉，然后在set方法上面加@Autowired即可

/** 阿里云OSS配置查询 */
    private static OSSConfMapper ossConfMapper;
    /** 阿里云OSS图片上传 */
    private static UploadImgOSS uploadImgOSS;
    
    public  OSSConfMapper getOssConfMapper() {
        return ossConfMapper;
    }
    @Autowired
    public  void setOssConfMapper(OSSConfMapper ossConfMapper) {
        UploadUtil.ossConfMapper = ossConfMapper;
    }
    public  UploadImgOSS getUploadImgOSS() {
        return uploadImgOSS;
    }
    @Autowired
    public  void setUploadImgOSS(UploadImgOSS uploadImgOSS) {
        UploadUtil.uploadImgOSS = uploadImgOSS;
    }

参考文档

[https://blog.csdn.net/kongrun12/article/details/76246369][https_blog.csdn.net_kongrun12_article_details_76246369]

[https://blog.csdn.net/zxl646801924/article/details/81738231][https_blog.csdn.net_zxl646801924_article_details_81738231]

[https://blog.csdn.net/u014079773/article/details/66973830][https_blog.csdn.net_u014079773_article_details_66973830]

经过尝试，有两种实现方式

方式一：声明一个静态的变量或方法，再相应的注入一个对应的变量和方法，最后PostConstruct注解在init时实现。

代码如下

import lombok.extern.slf4j.Slf4j;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.mail.SimpleMailMessage;
    import org.springframework.mail.javamail.JavaMailSender;
    import org.springframework.stereotype.Component;
    import tylin.paas.transfers.util.DateUtil;
    
    import javax.annotation.PostConstruct;
    import java.text.SimpleDateFormat;
    import java.util.Date;
    import java.util.LinkedList;
    import java.util.List;
    
    @Slf4j
    @Component
    public class ErrorHandler {
    
    
        @Value("${customer.mail.bankMail.sender}")
        private String configSender;
    
        private static String sender;
    
        @Value("${customer.mail.bankMail.receiver}")
        private String configReceiver;
    
        private static String receiver;
    
        public static ErrorHandler errorHandler;
    
        @Autowired
        JavaMailSender autoJavaMailSender;
    
        private static JavaMailSender javaMailSender;
    
    
        @PostConstruct
        public void init() {
            sender = configSender;
            receiver = configReceiver;
            javaMailSender = autoJavaMailSender;
            errorHandler = this;
        }
    
    
        public static void sendMail() {
            
            SimpleMailMessage message = new SimpleMailMessage();
            message.setFrom(sender);
            message.setTo(receiver.split(";"));
            message.setSubject("your subject");
            message.setText("your content text");
    
            try {
                javaMailSender.send(message);
                log.info("发送邮件成功！");
            } catch (Exception e) {
                log.error("发送邮件时发生异常！", e);
            }
            
        }
    
    }

方式二：**(亲测可行)**

在set时注入

import lombok.extern.slf4j.Slf4j;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.mail.SimpleMailMessage;
    import org.springframework.mail.javamail.JavaMailSender;
    import org.springframework.stereotype.Component;
    import org.springframework.test.context.junit4.SpringRunner;
    import org.tylin.TylinERPApplication;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    
    
    @Slf4j
    @Component
    @SpringBootTest(classes = TylinERPApplication.class)
    @RunWith(SpringRunner.class)
    public class MailAutoSendTest {
        private static String sender;
    
        //可以不要
        public  String getSender() {
            return sender;
        }
        @Value("${customer.mail.bankMail.sender}")
        public void setSender(String sender) {
            MailAutoSendTest.sender = sender;
        }
    
        private static String receiver;
    
        //可以不要
        public  String getReceiver() {
            return receiver;
        }
    
        @Value("${customer.mail.bankMail.receiver}")
        public void setReceiver(String receiver) {
            MailAutoSendTest.receiver = receiver;
        }
    
    
        private static JavaMailSender javaMailSender;
    
        public JavaMailSender getJavaMailSender(){
            return javaMailSender;
        }
    
        @Autowired
        public void setJavaMailSender(JavaMailSender javaMailSender){
            MailAutoSendTest.javaMailSender = javaMailSender;
        }
    
    
        @Test
        public void sendMail() {
            SimpleMailMessage message = new SimpleMailMessage();
            message.setFrom(sender);
            log.info(sender);
            log.info(receiver);
            message.setTo(receiver.split(";"));
            message.setSubject("xxxx");
    
            Date date = new Date();
            SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd  HH:mm:ss");
    
            message.setText("xxxx"+dateFormat.format(date));
    
            try {
                javaMailSender.send(message);
                log.info("简单邮件已经发送。");
            } catch (Exception e) {
                log.error("发送简单邮件时发生异常！", e);
            }
        }
    
    }

亲测示例：

@Component
    public class NetEleUtil {
    
        private static WirelessResourceProperties resProps;
    
        public WirelessResourceProperties getResProps() {
            return resProps;
        }
    
    //    @Autowired
        public void setResProps(WirelessResourceProperties resProps) {
            NetEleUtil.resProps = resProps;
        }
    
        /**
         * 根据网元英文简称获取网元中文名称
         *
         * @param obj
         * @return java.util.Map<java.lang.String,java.lang.Object>
         * @author liangzhaolin
         * @date 2020/10/22 11:00
         */
        public static String getNetEleTableCnName(String netEleType) {
            Map<String, String> tableMap = resProps.getTableCnName();
            String netEleTableCnName = tableMap.get(netEleType);
    
            return netEleTableCnName;
        }
    }

[https_www.cnblogs.com_chenfeng1122_p_6270217.html]: https://www.cnblogs.com/chenfeng1122/p/6270217.html
[https_blog.csdn.net_kongrun12_article_details_76246369]: https://blog.csdn.net/kongrun12/article/details/76246369
[https_blog.csdn.net_zxl646801924_article_details_81738231]: https://blog.csdn.net/zxl646801924/article/details/81738231
[https_blog.csdn.net_u014079773_article_details_66973830]: https://blog.csdn.net/u014079773/article/details/66973830