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
代码语言：javascript复制<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>
2.2.2 添加依赖
代码语言：javascript复制<!--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>
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
2.2.4 自定义Configuration配置类
LogAutoConfig.java
代码语言：javascript复制@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;
}
}
ConfigProperties.java
代码语言：javascript复制@Component
@ConfigurationProperties("go.kafka.log")
public class ConfigProperties {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
LogService.java
代码语言：javascript复制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() "!";
}
}
2.2.5 增加spring.factories文件，指定自动配置类
spring.factories
代码语言：javascript复制org.springframework.boot.autoconfigure.EnableAutoConfiguration=
org.ymx.log.config.LogAutoConfig
2.2.6 maven install安装到本地仓库
2.2.7 测试
新建Spring Boot项目
代码语言：javascript复制<dependency>
<groupId>org.ymx</groupId>
<artifactId>go-kafka-log-spring-starter</artifactId>
<version>0.0.1-RELEASE</version>
</dependency>
application.properties
代码语言：javascript复制server.port=8888
go.kafka.log.name=Spring Starter
go.kafka.log.enable=true
HelloController.java
代码语言：javascript复制@RestController
public class HelloController {
@Resource
private LogService logService;
@GetMapping("/hello")
public String hello() {
return logService.hello();
}
}
测试:
3 自定义Starter实现拦截器
3.1 编写自定义拦截器
代码语言：javascript复制@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);
}
}
3.2 starter增加配置类
代码语言：javascript复制@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("/**") ;
}
}
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：
代码语言：javascript复制go.kafka.log.enable=true
主启动类：
代码语言：javascript复制@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);
}
}
3.4 测试
访问任意url
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
代码语言：javascript复制@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";
}
}
4.2 调用方制造异常测试
代码语言：javascript复制@GetMapping("/ex")
public String ex() {
String str = null;
str.equals("2");
return "22";
}
测试结果：
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：https://blog.csdn.net/Mr_YanMingXin/article/details/119249740
- @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
