// Field Injection
@Service("uploadService")
public class UploadServiceImpl extends ServiceImpl<UploadDao, UploadEntity> implements UploadService {
@Autowired
private UploadDao uploadDao;
}
// Constructor Injection
@Service("uploadService")
public class UploadServiceImpl extends ServiceImpl<UploadDao, UploadEntity> implements UploadService {
private UploadDao uploadDao;
UploadServiceImpl(UploadDao uploadDao){
this.uploadDao = uploadDao;
}
}
// Setter Injection
@Service("uploadService")
public class UploadServiceImpl extends ServiceImpl<UploadDao, UploadEntity> implements UploadService {
private UploadDao uploadDao;
@Autowired
public void setUploadDao(UploadDao uploadDao){
this.uploadDao =uploadDao
}
}
1.是否进行循环依赖检测
循环依赖报错: 当服务A需要用到服务B时，并且服务B又需要用到服务A时，Spring在初始化创建Bean时，不知道应该先创建哪一个，就会出现该报错。
This is often the result of over-eager type matching - consider using 'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example
class ServerA{
@Autowired
private ServerB b;
}
class ServerB{
@Autowired
private ServerA a;
}
如果使用构造方式注入，能够精准的提醒你是哪两个类产生了循环依赖 .异常报错信息能够迅速定位问题:
循环报错解决办法是使用 @Lazy注解 ，对任意一个需要被注入Bean添加该注解，表示延迟创建即可。
class ServerA{
@Autowired
@Lazy
private ServerB b;
}
class ServerB{
@Autowired
@Lazy
private ServerA a;
}
