Spring Boot自定义注解扫描器
这个还挺实用的,会将指定包下的相应的类加载至Spring容器中,刚好我这边也有一个独立抽取出来的权限模块也想实现这样的功能(当然可以使用@EnableXX的方式,但是注入的组件太多了,直接包扫描直接点),而不是使用@ComponentScan或者是scanBasePackages必须指定某个包,这样显得太low了,使用注解自动扫描多好。
先来看看@MapperScan是怎么实现的:
没有什么特别的,引入了MapperScannerRegistrar:
中间有很多其他的代码都不用管,直接看最关键的:
定义了一个Mapper的Scanner:
然后调用doScan()方法即可:
而doScan()方法实际上就是Spring的核心扫描器ClassPathBeanDefinitionScanner的方法,而tkMybatis中定义了一个ClassPathMapperScanner继承了ClassPathBeanDefinitionScanne重写了doScan()方法,我们就可以照葫芦画瓢了。
自定义注解
自定义Registrar
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import lombok.extern.slf4j.Slf4j;
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import org.springframework.beans.factory.support.BeanDefinitionRegistry;
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import org.springframework.context.EnvironmentAware;
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import org.springframework.context.ResourceLoaderAware;
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import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
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import org.springframework.core.annotation.AnnotationAttributes;
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import org.springframework.core.env.Environment;
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import org.springframework.core.io.ResourceLoader;
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import org.springframework.core.type.AnnotationMetadata;
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import org.springframework.util.StringUtils;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* @author Dongguabai
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* @date 2018/8/15 13:36
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*/
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@Slf4j
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public
class DgbSecurityScannerRegistrar implements ImportBeanDefinitionRegistrar, ResourceLoaderAware, EnvironmentAware {
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private ResourceLoader resourceLoader;
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private Environment environment;
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@Override
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public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
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AnnotationAttributes annoAttrs = AnnotationAttributes.fromMap(importingClassMetadata.getAnnotationAttributes(DgbSecurityScan.class.getName()));
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ClassPathDgbSecurityScanner scanner =
new ClassPathDgbSecurityScanner(registry);
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// this check is needed in Spring 3.1
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if (resourceLoader !=
null) {
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scanner.setResourceLoader(resourceLoader);
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}
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List<String> basePackages =
new ArrayList<String>();
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for (String pkg : annoAttrs.getStringArray(
"basePackages")) {
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if (StringUtils.hasText(pkg)) {
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basePackages.add(pkg);
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}
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}
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scanner.doScan(StringUtils.toStringArray(basePackages));
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}
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@Override
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public void setEnvironment(Environment environment) {
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this.environment = environment;
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}
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@Override
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public void setResourceLoader(ResourceLoader resourceLoader) {
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this.resourceLoader = resourceLoader;
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}
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}
自定义Scanner
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import org.springframework.beans.factory.config.BeanDefinitionHolder;
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import org.springframework.beans.factory.support.BeanDefinitionRegistry;
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import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
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import org.springframework.core.env.Environment;
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import org.springframework.core.io.ResourceLoader;
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import org.springframework.lang.Nullable;
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import java.util.Arrays;
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import java.util.Set;
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/**
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* @author Dongguabai
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* @date 2018/8/15 13:40
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*/
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public
class ClassPathDgbSecurityScanner extends ClassPathBeanDefinitionScanner {
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public ClassPathDgbSecurityScanner(BeanDefinitionRegistry registry) {
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super(registry);
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}
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public ClassPathDgbSecurityScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters) {
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super(registry, useDefaultFilters);
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}
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public ClassPathDgbSecurityScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters, Environment environment) {
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super(registry, useDefaultFilters, environment);
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}
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public ClassPathDgbSecurityScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters, Environment environment, @Nullable ResourceLoader resourceLoader) {
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super(registry, useDefaultFilters, environment, resourceLoader);
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}
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/**
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* Calls the parent search that will search and register all the candidates.
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* Then the registered objects are post processed to set them as
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* MapperFactoryBeans
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*/
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@Override
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public Set<BeanDefinitionHolder> doScan(String... basePackages) {
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Set<BeanDefinitionHolder> beanDefinitions =
super.doScan(basePackages);
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if (beanDefinitions.isEmpty()) {
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logger.warn(
"No DgbSecurity Spring Componet was found in '" + Arrays.toString(basePackages) +
"' package. Please check your configuration.");
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}
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return beanDefinitions;
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}
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}
最后将注解放到Spring Boot启动类上即可。
因为是临时突然想到这个,代码应该有不少可以优化的地方,以后再看吧。
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使用这个方式用在基于Spring Security的权限模块是可以的,但是用在基于Quartz的调度模块一直出问题,经过debug发现是可以扫描成功并且是可以注册的,但是启动过程中执行调度任务的时候一直出问题,异常显示为create Bean找不到那个Bean,一直无法理解。但是在别的模块是可以正常使用的。
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