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自定义starter相当于自己根据配置信息生成了一个默认的bean导入依赖?xml version
0 encodingUTF-8?projectxmlnshttp://maven.apache.org/POM/
4.
0xmlns:xsihttp://www.w
org/2001/XMLSchema-instancexsi:schemaLocationhttp://maven.apache.org/POM/
4.
0 https://maven.apache.org/xsd/maven-
4.
0.
xsdmodelVersion
4.
0/modelVersionparentgroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-parent/artifactIdversion
3.
10/versionrelativePath/!-- lookup parent from repository --/parentgroupIdcom.cj/groupIdartifactIdhello-spring-boot-starter/artifactIdversion
0.
1-SNAPSHOT/versionnamehello-spring-boot-starter/namedescriptionhello-spring-boot-starter/descriptionurl/licenseslicense//licensesdevelopersdeveloper//developersscmconnection/developerConnection/tag/url//scmpropertiesjava.version17/java.version/propertiesdependenciesdependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter/artifactId/dependencydependencygroupIdorg.projectlombok/groupIdartifactIdlombok/artifactIdoptionaltrue/optional/dependency/dependenciesbuildpluginsplugingroupIdorg.apache.maven.plugins/groupIdartifactIdmaven-compiler-plugin/artifactIdconfigurationannotationProcessorPathspathgroupIdorg.springframework.boot/groupIdartifactIdspring-boot-configuration-processor/artifactId/pathpathgroupIdorg.projectlombok/groupIdartifactIdlombok/artifactId/path/annotationProcessorPaths/configuration/plugin/plugins/build/project将springboot启动类测试类删掉将maven打包成jar的配置删掉
自定义一个配置类来定义配置packagecom.cj.hellospringbootstarter;importlombok.Data;importorg.springframework.boot.context.properties.ConfigurationProperties;ConfigurationProperties(prefixmytest)DatapublicclassHelloProperties{privateStringid;privateStringname;privateStringaddress;}通过这个配置加载一个默认的 BeanDataNoArgsConstructorpublicclassHelloService{privateStringname;privateStringaddress;publicHelloService(Stringname,Stringaddress){this.namename;this.addressaddress;}}ConfigurationComponentScanEnableConfigurationProperties(HelloProperties.class)publicclassHelloServiceAutoConfiguration{AutowiredprivateHelloPropertieshelloProperties;BeanpublicHelloServicehelloService(){returnnewHelloService(helloProperties.getName(),helloProperties.getAddress());}}容器中就有这个默认的 HelloService的bean设置自动装配springboot3是在META-INF/spring文件夹下创建org.springframework.boot.autoconfigure.AutoConfiguration.imports这个文件填入自动配置类的全限定类名springboot2是在META-INF下面创建spring.factories打包使用dependencygroupIdcom.cj/groupIdartifactIdhello-spring-boot-starter/artifactIdversion
0.
1-SNAPSHOT/version/dependencyRestControllerLogpublicclassHelloController{AutowiredHelloServicehelloService;GetMapping(/hello)publicHelloServicegetHelloService(){returnhelloService;}}自定义一个注解写在starter里面动态的增强被标注这个注解的类可以用spring中BeanPostProcessor: spring完成 实例化配置 在初始化bean的前后可以实现一些自定义的配置有两个方法postProcessBeforeInitialization bean初始化之前调用postProcessAfterInitialization: bean初始化之后调用如果想增强指定的注解标注的类就可以写在BeanPostProcessor中拦截指定注解增强Target(ElementType.TYPE)Retention(RetentionPolicy.RUNTIME)publicinterfaceLog{/** * 是否打印参数 * return */booleanprintArgs()defaulttrue;booleanprintResult()defaulttrue;/** * 是否打印方法耗时 * return */booleanprintCostTime()defaulttrue;}packagecom.cj.hellospringbootstarter.annotation;importorg.springframework.beans.BeansException;importorg.springframework.beans.factory.config.BeanPostProcessor;importorg.springframework.cglib.proxy.Callback;importorg.springframework.cglib.proxy.Enhancer;importorg.springframework.cglib.proxy.MethodInterceptor;importorg.springframework.cglib.proxy.MethodProxy;importorg.springframework.stereotype.Component;importjava.lang.reflect.Method;importjava.util.Arrays;/** * 对Log 标注的 bean进行统一的 增强 * * * BeanPostProcessor spring完成实例化配置初始化一个bean之后可以实现一些自定义的逻辑 * - postProcessBeforeInitialization bean初始化之前调用 * - postProcessAfterInitialization bean初始化之后调用 */ComponentpublicclassLogBeanPostProcessorimplementsBeanPostProcessor{OverridepublicObjectpostProcessAfterInitialization(Objectbean,StringbeanName)throwsBeansException{Class?beanClassgetTargetClass(bean);// 是否标记了 Log注解if(beanClass.isAnnotationPresent(Log.class)){LoglogAnnotationbeanClass.getAnnotation(Log.class);ObjectenhanceBeancreateLogEnhanceProxy(bean,beanClass,logAnnotation);returnenhanceBean;}returnbean;}privateObjectcreateLogEnhanceProxy(ObjecttargetBean,Class?targetClass,LoglogAnnotation){EnhancerenhancernewEnhancer();enhancer.setSuperclass(targetClass);// MethodInterceptor : cglib的方法拦截器当你调任何方法的时候都会执行这个enhancer.setCallback(newMethodInterceptor(){OverridepublicObjectintercept(Objectobj,Methodmethod,Object[]args,MethodProxyproxy)throwsThrowable{// 跳过Object的基础方法if(isObjectBaseMethod(method)){returnproxy.invokeSuper(obj,args);}try{if(logAnnotation.printArgs()){System.out.printf([日志增强]%s.%s()入参%s%n,targetClass.getSimpleName(),method.getName(),Arrays.toString(args));}longstartTimeSystem.currentTimeMillis();Objectresultproxy.invokeSuper(obj,args);if(logAnnotation.printCostTime()){longendTimeSystem.currentTimeMillis();System.out.printf([日志耗时]%s.%s() 耗时%s,targetClass.getSimpleName(),method.getName(),startTime-endTime);}returnresult;}catch(Throwablee){System.out.printf(日志增强失败 %s.%s() 异常为:%s,targetClass.getSimpleName(),method.getName(),e.getMessage());throwe;}};});ObjectenhancedBeanenhancer.create();System.out.println(增强完成targetClass.getName());returnenhancedBean;}/** * 获取bean的真实类型 * param bean * return */privateClass?getTargetClass(Objectbean){Class?clazzbean.getClass();// 如果是CGLIB代理类获取父类if(clazz.getName().contains($$EnhancerByCGLIB$$)){returnclazz.getSuperclass();}returnclazz;}privatebooleanisObjectBaseMethod(Methodmethod){// 获取声明该方法的类Class?declaringClassmethod.getDeclaringClass();// method.getDeclaringClass()returndeclaringClassObject.class(method.getName().equals(toString)||method.getName().equals(hashCode)||method.getName().equals(equals));}}
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