1 什么是Spring Starter
摘自官网
Starters are a set of convenient dependency descriptors that you can include in your application. You get a one-stop shop for all the Spring and related technologies that you need without having to hunt through sample code and copy-paste loads of dependency descriptors. For example, if you want to get started using Spring and JPA for database access, include the spring-boot-starter-data-jpa dependency in your project.
翻译下：
启动器是一组方便的依赖项描述符，您可以在应用程序中包含它们。您可以获得所需的所有Spring和相关技术的一站式服务，而无需查找示例代码和复制-粘贴大量依赖描述符。例如，如果您想开始使用Spring和JPA进行数据库访问，请在您的项目中包含Spring -boot-starter-data- JPA依赖项。
2 自定义Starter的Hello World
2.1 自定义Spring Starter的一般流程
（1）新建Spring Boot项目
（2）添加依赖
（3）调整项目结构
（4）自定义Configuration配置类
（5）增加spring.factories文件，指定自动配置类
（6）maven install安装到本地仓库
（7）其他项目引入使用
下面我们就来一一的实现下：
2.2 具体流程
2.2.1 新建Spring Boot项目
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.4.RELEASE</version> <relativePath/> </parent> <groupId>org.ymx</groupId> <artifactId>go-kafka-log-spring-starter</artifactId> <version>0.0.1-RELEASE</version> 复制代码
2.2.2 添加依赖
<!--引入web依赖，下文自定义拦截器使用--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!--自定义starter需要的依赖 autoconfigure--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-autoconfigure</artifactId> </dependency> <!--自定义starter需要的依赖 configuration-processor--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional>true</optional> </dependency> <!-- lombok--> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> 复制代码
2.2.3 调整项目结构
一般就是：
- 删除主启动类
- 删除test包
- 删除主配置文件
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2.2.4 自定义Configuration配置类
LogAutoConfig.java
@Configuration @EnableConfigurationProperties({ConfigProperties.class}) @ConditionalOnProperty(prefix = "go.kafka.log", name = "enable", havingValue = "true") public class LogAutoConfig { @Autowired private ConfigProperties configProperties; @Bean(name = "logService") public LogService getLogService() { LogService logService = new LogService(); logService.setConfigProperties(configProperties); return logService; } } 复制代码
ConfigProperties.java
@Component @ConfigurationProperties("go.kafka.log") public class ConfigProperties { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } } 复制代码
LogService.java
public class LogService { private ConfigProperties configProperties; public String getName() { return configProperties.getName(); } public void setConfigProperties(ConfigProperties configProperties) { this.configProperties = configProperties; } public String hello() { return "Hello " + getName() + "!"; } } 复制代码
2.2.5 增加spring.factories文件，指定自动配置类
spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ org.ymx.log.config.LogAutoConfig 复制代码
2.2.6 maven install安装到本地仓库
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2.2.7 测试
新建Spring Boot项目
<dependency> <groupId>org.ymx</groupId> <artifactId>go-kafka-log-spring-starter</artifactId> <version>0.0.1-RELEASE</version> </dependency> 复制代码
application.properties
server.port=8888 go.kafka.log.name=Spring Starter go.kafka.log.enable=true 复制代码
HelloController.java
@RestController public class HelloController { @Resource private LogService logService; @GetMapping("/hello") public String hello() { return logService.hello(); } } 复制代码
测试:
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3 自定义Starter实现拦截器
3.1 编写自定义拦截器
@Component public class LogInterceptor implements HandlerInterceptor { @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println("----------------------"+request.getMethod()+"----------------------"); return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println("----------------------"+request.getMethod()+"----------------------"); HandlerInterceptor.super.postHandle(request, response, handler, modelAndView); } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { HandlerInterceptor.super.afterCompletion(request, response, handler, ex); } } 复制代码
3.2 starter增加配置类
@Configuration @ConditionalOnProperty(prefix = "go.kafka.log.interception", name = "enable", havingValue = "true") public class LogInterceptorConfig implements WebMvcConfigurer { @Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(new LogInterceptor()) .addPathPatterns("/**") ; } } 复制代码
3.3 调用方增加配置文件内容，主启动类增加注解
配置文件：
go.kafka.log.enable=true 复制代码
主启动类：
@SpringBootApplication @ComponentScans(value = {@ComponentScan("org.ymx.log"),@ComponentScan("com.example.demo")}) public class DemoApplication { public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); } } 复制代码
3.4 测试
访问任意url
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4 自定义Starter实现全局异常处理
4.1 编写starter全局异常处理类
@RestControllerAdvice public class LogAdviceHandler { @ExceptionHandler(value = NullPointerException.class) public String exceptionHandlerJwt(NullPointerException e) { e.printStackTrace(); return "error----NullPointerException"; } @ExceptionHandler(value = Exception.class) public String exceptionHandler(Exception e) { e.printStackTrace(); return "error----Exception"; } } 复制代码
4.2 调用方制造异常测试
@GetMapping("/ex") public String ex() { String str = null; str.equals("2"); return "22"; } 复制代码
测试结果：
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5 总结几个重要的注解
- @ConditionalOnProperty(prefix = “go.kafka.log”, name = “enable”, havingValue = “true”)
prefix为配置文件中的前缀,
name为配置的名字
havingValue是与配置的值对比值,当两个值相同返回true,配置类生效. - @EnableConfigurationProperties({ConfigProperties.class})
使@ConfigurationProperties()注解生效 - @ConfigurationProperties(“go.kafka.log”)
见文章：blog.csdn.net/Mr_YanMingX… - @ComponentScans(value = {@ComponentScan(“org.ymx.log”),@ComponentScan(“com.example.demo”)})
扫描的bean的路径，这里是扫描starter的路径加上本项目的路径
