一、starter的实现方法

1、新建一个工程命名为aspectlog-spring-boot-starter

下图为工程目录结构：

2、pom依赖

写starter时，在pom中配置spring-boot-autoconfigure-processor，在编译时会自动收集配置类的条件，写到一个META-INF/spring-autoconfigure-metadata.properties中。

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.3.3.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.example</groupId><artifactId>aspectlog-spring-boot-starter</artifactId><version>0.0.1-SNAPSHOT</version><name>aspectlog-spring-boot-starter</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-autoconfigure</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-aop</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional></dependency></dependencies>
</project>

3、写自动配置逻辑

各种condition

本次就选用@ConditionalOnProperty。即配置文件中有aspectLog.enable=true,才加载我们的配置。

4、定义AspectLog注解，该注解用于标注需要打印执行时间的方法。代码如下：

package com.example.autoconfiguration.aspetlog;import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;/*** @author chengpan* @date 2020/9/4 下午4:48*/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface AspectLog {
}

5、定义配置文件对应的类

package com.example.autoconfiguration.aspetlog;import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;/*** 定义配置文件对应类* @author chengpan* @date 2020/9/4 下午4:50*/
@ConditionalOnProperty("aspectLog")
public class AspectLogProperties {private boolean enable;public boolean isEnable() {return enable;}public void setEnable(boolean enable) {this.enable = enable;}
}

6、定义自动配置类

当配置文件有aspectLog.enable=true时开启，如果配置文件没有设置aspectLog.enable也开启。

package com.example.autoconfiguration.aspetlog;import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.core.PriorityOrdered;/*** 定义自动配置类* 当配置文件有aspectLog.enable=true时开启，如果配置文件没有设置aspectLog.enable也开启。* @author chengpan* @date 2020/9/4 下午4:53*/
@Aspect
@EnableAspectJAutoProxy(exposeProxy = true, proxyTargetClass = true)
@Configuration
@ConditionalOnProperty(prefix = "aspectLog",name = "enable",havingValue = "true",matchIfMissing = true)
public class AspectLogAutoConfiguration implements PriorityOrdered {protected Logger logger = LoggerFactory.getLogger(getClass());@Around("@annotation(com.example.autoconfiguration.aspetlog.AspectLog)")public Object isOpen(ProceedingJoinPoint joinPoint) throws Throwable{//执行方法名称String taskName = joinPoint.getSignature().toString().substring(joinPoint.getSignature().toString().indexOf(" "),joinPoint.getSignature().toString().indexOf("("));taskName = taskName.trim();long time = System.currentTimeMillis();Object result = joinPoint.proceed();logger.info("method:{} run:{} ms", taskName, (System.currentTimeMillis() - time));return result;}@Overridepublic int getOrder() {//保证事务等切面先执行return Integer.MAX_VALUE;}
}

7、创建spring.factories

META-INF/spring.factories是spring的工厂机制，在这个文件中定义的类，都会被自动加载。多个配置使用逗号分隔，换行用\

在resources文件夹下，新建META-INF文件夹，然后创建spring.factories文件，如下图：

在该文件中加入如下配置，该配置指定上步骤中定义的配置类为自动装配的配置。

#-------starter自动装配---------
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.example.autoconfiguration.aspetlog.AspectLogAutoConfiguration

7、测试

在aspectlog-spring-boot-starter工程中执行mvn clean install,一个自定义的starter就好了。

新建测试工程

引入starter依赖

<dependency><groupId>com.example</groupId><artifactId>aspectlog-spring-boot-starter</artifactId><version>0.0.1-SNAPSHOT</version>
</dependency>

然后写个测试类。内容如下：

package com.example.demo.controller;import com.example.autoconfiguration.aspetlog.AspectLog;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;/*** @author chengpan* @date 2020/9/4 下午5:19*/
@RequestMapping("/hello")
@RestController
@CrossOrigin
public class HelloController {@RequestMapping("/hello")@ResponseBody@AspectLogpublic RespResult sayHello(){RespResult respResult = new RespResult();respResult.setCode(200);respResult.setContent("hello word");respResult.setTimeStamp();return respResult;}
}

测试，效果如下图：