1,自动配置项目—代替xml
META-INF/spring.factories 做好配置类指定，此时可以不需要配置属性文件，用业务中的即可
@ConfigurationProperties 没有属性配置就是空—相当于懒加载配置，@value没有配置就是异常
2,自动依赖项目，依赖自动装配项目，集成一个小功能的所有依赖（会使用到自动装配）—例如切面记录日志
3,业务项目，依赖自动依赖项目，上层的配置文件会被底层依赖的包配置全局使用
实际的做法的1,2都合并为starter 所以会出现一旦引入starter就需要，属性中配置，不配置会出现为空的情况
程序中的1 @Configuration框架可以自动识别加载，依赖包中的需要spring-factories中指定
示例：
1. 创建自己的Starter
一个完整的Spring Boot Starter可能包含以下组件：
- autoconfigure模块：包含自动配置的代码
- starter模块：提供对autoconfigure模块的依赖，以及一些其它的依赖
（PS：如果你不需要区分这两个概念的话，也可以将自动配置代码模块与依赖管理模块合并成一个模块）
简而言之，starter应该提供使用该库所需的一切
1.1. 命名
- 模块名称不能以spring-boot开头
- 如果你的starter提供了配置keys，那么请确保它们有唯一的命名空间。而且，不要用Spring Boot用到的命名空间（比如：server， management， spring 等等）
举个例子，假设你为“acme”创建了一个starter，那么你的auto-configure模块可以命名为acme-spring-boot-autoconfigure，starter模块可以命名为acme-spring-boot-starter。如果你只有一个模块包含这两部分，那么你可以命名为acme-spring-boot-starter。
1.2. autoconfigure模块
建议在autoconfigure模块中包含下列依赖：
1 <dependency> 2 <groupId>org.springframework.boot</groupId> 3 <artifactId>spring-boot-autoconfigure-processor</artifactId> 4 <optional>true</optional> 5 </dependency>
1.3. starter模块
事实上，starter是一个空jar。它唯一的目的是提供这个库所必须的依赖。
你的starter必须直接或间接引用核心的Spring Boot starter（spring-boot-starter）
2. Hello Starter
接下来，作为入门，写一个Spring Boot版的Hello World
2.1. hello-spring-boot-starter-autoconfigure
新建一个Maven项目命名为hello-spring-boot-starter-autoconfigure
pom.xml
1 <?xml version="1.0" encoding="UTF-8"?> 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 3 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 4 <modelVersion>4.0.0</modelVersion> 5 <parent> 6 <groupId>org.springframework.boot</groupId> 7 <artifactId>spring-boot-starter-parent</artifactId> 8 <version>2.1.5.RELEASE</version> 9 <relativePath/> <!-- lookup parent from repository --> 10 </parent> 11 <groupId>com.example</groupId> 12 <artifactId>hello-spring-boot-starter-autoconfigure</artifactId> 13 <version>0.0.1-SNAPSHOT</version> 14 <name>hello-spring-boot-starter-autoconfigure</name> 15 <description>Demo project for Spring Boot</description> 16 17 <properties> 18 <java.version>1.8</java.version> 19 </properties> 20 21 <dependencies> 22 <dependency> 23 <groupId>org.springframework.boot</groupId> 24 <artifactId>spring-boot-starter</artifactId> 25 </dependency> 26 <dependency> 27 <groupId>org.springframework.boot</groupId> 28 <artifactId>spring-boot-autoconfigure</artifactId> 29 </dependency> 30 31 <dependency> 32 <groupId>org.springframework.boot</groupId> 33 <artifactId>spring-boot-configuration-processor</artifactId> 34 <optional>true</optional> 35 </dependency> 36 </dependencies> 37 38 </project>
HelloProperties.java
1 package com.example.hello;
2
3 import org.springframework.boot.context.properties.ConfigurationProperties;
4
5 /**
6 * @author ChengJianSheng
7 * @date 2019-05-26
8 */
9 @ConfigurationProperties("my.hello")
10 public class HelloProperties {
11
12 /**
13 * 姓名
14 */
15 private String name;
16
17 /**
18 * 年龄
19 */
20 private Integer age;
21
22 /**
23 * 家乡
24 */
25 private String hometown;
26
27 public String getName() {
28 return name;
29 }
30
31 public void setName(String name) {
32 this.name = name;
33 }
34
35 public Integer getAge() {
36 return age;
37 }
38
39 public void setAge(Integer age) {
40 this.age = age;
41 }
42
43 public String getHometown() {
44 return hometown;
45 }
46
47 public void setHometown(String hometown) {
48 this.hometown = hometown;
49 }
50
51 @Override
52 public String toString() {
53 return "HelloProperties{" +
54 "name='" + name + '\'' +
55 ", age=" + age +
56 ", hometown='" + hometown + '\'' +
57 '}';
58 }
59 }
HelloService.java
1 package com.example.hello;
2
3 /**
4 * @author ChengJianSheng
5 * @date 2019-05-26
6 */
7 public class HelloService {
8
9 /**
10 * 姓名
11 */
12 private String name;
13
14 /**
15 * 年龄
16 */
17 private Integer age;
18
19 /**
20 * 家乡
21 */
22 private String hometown;
23
24 public HelloService(String name, Integer age, String hometown) {
25 this.name = name;
26 this.age = age;
27 this.hometown = hometown;
28 }
29
30 public String sayHello(String name) {
31 return "Hello, " + name;
32 }
33
34 public String helloWorld() {
35 return String.format("[name=%s, age=%d, hometown=%s]", this.name, this.age, this.hometown);
36 }
37
38 }
HelloServiceAutoConfiguration.java
1 package com.example.hello;
2
3 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
4 import org.springframework.boot.context.properties.EnableConfigurationProperties;
5 import org.springframework.context.annotation.Bean;
6 import org.springframework.context.annotation.Configuration;
7
8 /**
9 * @author ChengJianSheng
10 * @date 2019-05-26
11 */
12 @Configuration
13 @EnableConfigurationProperties(HelloProperties.class)
14 public class HelloServiceAutoConfiguration {
15
16 private final HelloProperties helloProperties;
17
18 public HelloServiceAutoConfiguration(HelloProperties helloProperties) {
19 this.helloProperties = helloProperties;
20 }
21
22 @Bean
23 @ConditionalOnMissingBean
24 public HelloService helloService() {
25 return new HelloService(this.helloProperties.getName(),
26 this.helloProperties.getAge(),
27 this.helloProperties.getHometown());
28 }
29 }
META-INF/spring.factories
1 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ 2 com.example.hello.HelloServiceAutoConfiguration
mvn clean install
2.2. hello-spring-boot-starter
在hello-spring-boot-starter中引用该autoconfigure模块
1 <?xml version="1.0" encoding="UTF-8"?> 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 3 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 4 <modelVersion>4.0.0</modelVersion> 5 <groupId>com.example</groupId> 6 <artifactId>hello-spring-boot-starter</artifactId> 7 <version>0.0.1-SNAPSHOT</version> 8 <name>hello-spring-boot-starter</name> 9 10 <properties> 11 <java.version>1.8</java.version> 12 </properties> 13 14 <dependencies> 15 <dependency> 16 <groupId>com.example</groupId> 17 <artifactId>hello-spring-boot-starter-autoconfigure</artifactId> 18 <version>0.0.1-SNAPSHOT</version> 19 </dependency> 20 </dependencies> 21 22 </project>
至此，我们的hello-spring-boot-starter开发完了
接下来，我们在demo中引用它
2.3. demo
1 <?xml version="1.0" encoding="UTF-8"?> 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 3 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 4 <modelVersion>4.0.0</modelVersion> 5 <parent> 6 <groupId>org.springframework.boot</groupId> 7 <artifactId>spring-boot-starter-parent</artifactId> 8 <version>2.1.5.RELEASE</version> 9 <relativePath/> <!-- lookup parent from repository --> 10 </parent> 11 <groupId>com.example</groupId> 12 <artifactId>demo</artifactId> 13 <version>0.0.1-SNAPSHOT</version> 14 <name>demo</name> 15 16 <properties> 17 <java.version>1.8</java.version> 18 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 19 </properties> 20 21 <dependencies> 22 <dependency> 23 <groupId>org.springframework.boot</groupId> 24 <artifactId>spring-boot-starter-web</artifactId> 25 </dependency> 26 27 <dependency> 28 <groupId>com.example</groupId> 29 <artifactId>hello-spring-boot-starter</artifactId> 30 <version>0.0.1-SNAPSHOT</version> 31 </dependency> 32 33 <dependency> 34 <groupId>org.springframework.boot</groupId> 35 <artifactId>spring-boot-starter-test</artifactId> 36 <scope>test</scope> 37 </dependency> 38 </dependencies> 39 40 <build> 41 <plugins> 42 <plugin> 43 <groupId>org.springframework.boot</groupId> 44 <artifactId>spring-boot-maven-plugin</artifactId> 45 </plugin> 46 </plugins> 47 </build> 48 49 </project>
application.properties
1 my.hello.name=程同学 2 my.hello.age=28 3 my.hello.hometown=湖北省随州市
DemoController.java
1 package com.example.demo.controller;
2
3 import com.example.hello.HelloService;
4 import org.springframework.web.bind.annotation.GetMapping;
5 import org.springframework.web.bind.annotation.PathVariable;
6 import org.springframework.web.bind.annotation.RequestMapping;
7 import org.springframework.web.bind.annotation.RestController;
8
9 import javax.annotation.Resource;
10
11 /**
12 * @author ChengJianSheng
13 * @date 2019-05-26
14 */
15 @RestController
16 @RequestMapping("/demo")
17 public class DemoController {
18
19 @Resource
20 private HelloService helloService;
21
22 @GetMapping("/hello/{name}")
23 public String hello(@PathVariable("name") String name) {
24 return helloService.sayHello(name);
25 }
26
27 @GetMapping("/info")
28 public String info() {
29 return helloService.helloWorld();
30 }
31
32 }
3. 升级版的Hello World
上面的例子中演示了我们引入自定义的starter，然后调用其提供的HelloService服务。感觉好像并没有什么用，下面在此基础上做个升级，再写一个记录日志的服务。
3.1. hello-spring-boot-starter-autoconfigure
pom.xml
1 <?xml version="1.0" encoding="UTF-8"?> 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 3 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 4 <modelVersion>4.0.0</modelVersion> 5 <parent> 6 <groupId>org.springframework.boot</groupId> 7 <artifactId>spring-boot-starter-parent</artifactId> 8 <version>2.1.5.RELEASE</version> 9 <relativePath/> <!-- lookup parent from repository --> 10 </parent> 11 <groupId>com.example</groupId> 12 <artifactId>hello-spring-boot-starter-autoconfigure</artifactId> 13 <version>0.0.1-SNAPSHOT</version> 14 <name>hello-spring-boot-starter-autoconfigure</name> 15 <description>Demo project for Spring Boot</description> 16 17 <properties> 18 <java.version>1.8</java.version> 19 </properties> 20 21 <dependencies> 22 <dependency> 23 <groupId>org.springframework.boot</groupId> 24 <artifactId>spring-boot-starter</artifactId> 25 </dependency> 26 <dependency> 27 <groupId>org.springframework.boot</groupId> 28 <artifactId>spring-boot-autoconfigure</artifactId> 29 </dependency> 30 <dependency> 31 <groupId>org.springframework.boot</groupId> 32 <artifactId>spring-boot-starter-web</artifactId> 33 <optional>true</optional> 34 </dependency> 35 <dependency> 36 <groupId>org.projectlombok</groupId> 37 <artifactId>lombok</artifactId> 38 <optional>true</optional> 39 </dependency> 40 <dependency> 41 <groupId>com.alibaba</groupId> 42 <artifactId>fastjson</artifactId> 43 <version>1.2.58</version> 44 <optional>true</optional> 45 </dependency> 46 <dependency> 47 <groupId>org.springframework.boot</groupId> 48 <artifactId>spring-boot-configuration-processor</artifactId> 49 <optional>true</optional> 50 </dependency> 51 </dependencies> 52 53 </project>
MyLog.java
1 package com.example.log;
2
3 import java.lang.annotation.ElementType;
4 import java.lang.annotation.Retention;
5 import java.lang.annotation.RetentionPolicy;
6 import java.lang.annotation.Target;
7
8 /**
9 * @author ChengJianSheng
10 * @date 2019-05-26
11 */
12 @Target(ElementType.METHOD)
13 @Retention(RetentionPolicy.RUNTIME)
14 public @interface MyLog {
15
16 /**
17 * 方法描述
18 */
19 String desc() default "";
20 }
MyLogInterceptor.java
1 package com.example.log;
2
3 import com.alibaba.fastjson.JSON;
4 import lombok.extern.slf4j.Slf4j;
5 import org.springframework.web.method.HandlerMethod;
6 import org.springframework.web.servlet.ModelAndView;
7 import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
8
9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 import java.lang.reflect.Method;
12
13 /**
14 * @author ChengJianSheng
15 * @date 2019-05-26
16 */
17 @Slf4j
18 public class MyLogInterceptor extends HandlerInterceptorAdapter {
19
20 private static final ThreadLocal<Long> startTimeThreadLocal = new ThreadLocal<>();
21
22 @Override
23 public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
24 HandlerMethod handlerMethod = (HandlerMethod) handler;
25 Method method = handlerMethod.getMethod();
26 MyLog myLog = method.getAnnotation(MyLog.class);
27 if (null != myLog) {
28 // 设置开始时间
29 long startTime = System.currentTimeMillis();
30 startTimeThreadLocal.set(startTime);
31 }
32 return true;
33 }
34
35 @Override
36 public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
37 HandlerMethod handlerMethod = (HandlerMethod) handler;
38 Method method = handlerMethod.getMethod();
39 MyLog myLog = method.getAnnotation(MyLog.class);
40 if (null != myLog) {
41 // 获取开始时间
42 long startTime = startTimeThreadLocal.get();
43 long endTime = System.currentTimeMillis();
44 long expendTime = endTime - startTime;
45
46 // 打印参数
47 String requestUri = request.getRequestURI();
48 String methodName = method.getDeclaringClass().getName() + "#" + method.getName();
49 String methodDesc = myLog.desc();
50 String parameters = JSON.toJSONString(request.getParameterMap());
51
52 log.info("\n描述：{}\n路径: {}\n方法: {}\n参数：{}\n耗时：{}", methodDesc, requestUri, methodName, parameters, expendTime);
53 }
54 }
55 }
MyLogAutoConfiguration.java
1 package com.example.log;
2
3 import org.springframework.context.annotation.Configuration;
4 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
5 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
6
7 /**
8 * @author ChengJianSheng
9 * @date 2019-05-26
10 */
11 @Configuration
12 public class MyLogAutoConfiguration implements WebMvcConfigurer {
13
14 @Override
15 public void addInterceptors(InterceptorRegistry registry) {
16 registry.addInterceptor(new MyLogInterceptor());
17 }
18 }
META-INF/spring.factories
1 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ 2 com.example.hello.HelloServiceAutoConfiguration,\ 3 com.example.log.MyLogAutoConfiguration
3.2. demo
ProductController.java
1 package com.example.demo.controller;
2
3 import com.example.demo.domain.ProductVO;
4 import com.example.log.MyLog;
5 import org.springframework.web.bind.annotation.*;
6
7 /**
8 * @author ChengJianSheng
9 * @date 2019-05-26
10 */
11 @RestController
12 @RequestMapping("/product")
13 public class ProductController {
14
15 @MyLog(desc = "查询商品")
16 @GetMapping("/list")
17 public String list() {
18 System.out.println("查询商品");
19 return "ok";
20 }
21
22 @MyLog(desc = "添加商品")
23 @PostMapping("/save")
24 public String save(@RequestBody ProductVO productVO) {
25 System.out.println("添加商品");
26 return "ok";
27 }
28
29 @MyLog(desc = "删除商品")
30 @GetMapping("/delete")
31 public String delete(@RequestParam("productId") Long productId) {
32 System.out.println("删除商品");
33 return "ok";
34 }
35
36 @MyLog(desc = "获取商品详情")
37 @GetMapping("/detail/{productId}")
38 public String detail(@PathVariable("productId") Long productId) {
39 System.out.println("商品详情");
40 return "ok";
41 }
42
43 }
查看控制台
（PS：这里就打印日志这个功能没有使用AOP，因为这意味着在自动配置的代码中就要定义切面、切点这些东西，而且在项目启动的时候还要扫描切面，感觉比较麻烦）
4. 工程结构
5. 源码
chengjiansheng (chengjiansheng) / Repositories · GitHub
https://github.com/chengjiansheng/hello-spring-boot-starter-autoconfigure.git
https://github.com/chengjiansheng/starter-demo.git