SpringBoot 使用文档

时间：2018/7/18 11:02:37

参考：

1.Spring Boot Reference Guide

SpringBoot 使用文档¶

注：完整代码可参考 https://github.com/LanSeTianYe/DemoContainer/tree/master/springboot

使用基础¶

特性¶

创建独立的Spring应用项目。
内嵌Tomcat、Jetty和Undertoe容器，不需要把项目打成 war 包，直接运行 jar 包即可。
提供第三方框架或者工具 starter 依赖，简化构造应用程序。
尽可能自动配置Spring和第三方类库。
提供指标、健康状况和外部配置等生产环境需要的功能。
完全不需要代码生成和 Xml 配置文件。

系统要求¶

基本环境要求：

Java8/Java9
Spring 5.0.7 或以上版本
Maven3.2+ 或 Gradle 4

内嵌容器版本：Tomcat8.5、Jetty 9.4 Undertow 1.4等，可以运行再任何实现 Servlet 3.1 规范的容器上。

第一个项目¶

当前可用版本是 2.0.3 ，下面引入parent依赖、Web模块儿依赖和构建插件。

<!--父项目，管理依赖的版本-->
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.3.RELEASE</version>
</parent>

<!--Web模块依赖-->
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

<!--插件-->
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

项目入口¶

@RestController
@EnableAutoConfiguration
public class Example {

    @RequestMapping("/")
    String home() {
        return "Hello World!";
    }

    public static void main(String[] args) throws Exception {
        SpringApplication.run(Example.class, args);
    }

}

@RestController：标识 ResetController
@EnableAutoConfiguration：自动扫描配置类
@RequestMapping：请求路径
main方法是项目的启动入口

使用进阶¶

CommandLineRunner¶

实现 CommandLineRunner 接口的 Bean 会在 SpringApplication 开始之后运行。同一个项目可以有多个 CommandLineRunner 的实现，可以通过 Order注解指定执行顺寻。多个 CommandLineRunner 会按照顺序同步执行。

@Order(1)
@Component
public class TestCommandLineRunner implements CommandLineRunner {

    private final static Logger logger = LogManager.getLogger(TestCommandLineRunner.class);

    private final PersonService personService;

    @Autowired
    public TestCommandLineRunner(TestAsyncMethod testAsyncMethod, PersonService personService) {
        this.testAsyncMethod = testAsyncMethod;
        this.personService = personService;
    }

    @Override
    public void run(String... args) throws Exception {
        ArrayList<Person> personList = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Person person = new Person();
            person.setName("name" + i);
            personList.add(person);
        }
        personService.addAll(personList);
    }
}

HandlerMethodArgumentResolver¶

Handler 方法参数注入，使用示例：

@Component
public class PersonParameterHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver {

    private final PersonService personService;

    @Autowired
    public PersonParameterHandlerMethodArgumentResolver(PersonService personService) {
        this.personService = personService;
    }

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        if(parameter.getParameterType().equals(Person.class)) {
            return true;
        }
        return false;
    }

    @Nullable
    @Override
    public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer, NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
        String personId = webRequest.getParameter("personId");
        if (null == personId || "".equals(personId)) {
            return Person.NULL;
        }
        Optional<Person> personOptional = personService.findByPersonId(Long.valueOf(personId));
        return personOptional.orElse(Person.NULL);
    }
}

配置使用参数注入工具：

@Configuration
public class AppConfig implements WebMvcConfigurer {

    private final PersonParameterHandlerMethodArgumentResolver personParameterHandlerMethodArgumentResolver;

    public AppConfig(PersonParameterHandlerMethodArgumentResolver personParameterHandlerMethodArgumentResolver) {
        this.personParameterHandlerMethodArgumentResolver = personParameterHandlerMethodArgumentResolver;
    }

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
        resolvers.add(personParameterHandlerMethodArgumentResolver);
    }
}

Filter 过滤器¶

过滤器需要实现 Filter 接口，然后添加 @WebFilter 注解即可。

@WebFilter
public class MyFilter implements Filter {

    private final static Logger logger = LogManager.getLogger(MyFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        logger.info("Filter init");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        logger.info("Filter do filter: " + servletRequest.getRemoteAddr());
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {
        logger.info("Filter destroy...");
    }
}

Interceptor 拦截器¶

拦截器需要继承 HandlerInterceptorAdapter，并再 Configuration 类里面添加到容器的拦截器集合里面。

拦截器实现：

@Component
public class MyIntercepter extends HandlerInterceptorAdapter {

    private final static Logger logger = LogManager.getLogger(MyIntercepter.class);

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        logger.debug("HandlerInterceptorAdapter_preHandle: " + request.getRequestURI());
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
        logger.debug("HandlerInterceptorAdapter_postHandle: " + request.getRequestURI());
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
        logger.debug("HandlerInterceptorAdapter_afterCompletion: " + request.getRequestURI());
    }
}

添加拦截器到容器：

@Configuration
public class AppConfig implements WebMvcConfigurer {

    private final MyIntercepter filterIntercepter;


    public AppConfig(MyIntercepter filterIntercepter) {
        this.filterIntercepter = filterIntercepter;

    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(filterIntercepter);

    }
}

Async 异步方法¶

在方法上添加 @Async 注解，让类通过容器进行管理，调用方法的时候会异步执行。在项目启动类添加 @EnableAsync 注解。

@Component
public class TestAsyncMethod {

    private final static Logger logger = LogManager.getLogger(TestAsyncMethod.class);

    @Async
    public void run() {
        try {
            TimeUnit.SECONDS.sleep(5);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        logger.info("TestAsyncMethod run finished after 5 second ...");
    }
}

EventListener 事件监听器¶

ServletContextListener¶

Servlet容器初始化和销毁事件监听器，容器初始化和销毁的时候会发送事件到监听器。

@WebListener
public class MyServletContextListener implements ServletContextListener {

    private final static Logger logger = LogManager.getLogger(MyServletContextListener.class);

    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        logger.info("contextInitialized ...");
    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
        System.err.println("contextDestroyed");
    }
}

HttpSessionListener¶

监听Session创建和关闭事件

@WebListener
public class MyHttpSessionListener implements HttpSessionListener {

    private final static Logger logger = LogManager.getLogger(MyHttpSessionListener.class);

    @Override
    public void sessionCreated(HttpSessionEvent httpSessionEvent) {
        logger.info("sessionCreated");
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
        logger.info("sessionDestroyed");
    }
}

整合 mybatis¶

引入依赖
```
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.2</version>
 </dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>
```
- 增加数据库配置文件
  
  spring.datasource.url=jdbc:mysql://127.0.0.1:3306/spring_demo?useUnicode=true&characterEncoding=UTF-8 spring.datasource.username=root spring.datasource.password=000000 spring.datasource.driver-class-name=com.mysql.jdbc.Driver * 启动类添加Mapper文件扫描注解
  
  @MapperScan("com.sun.xiaotian.demo.mybatis.mapper")

写Mapper文件

@Mapper
public interface CityMapper {

    @Select("SELECT id, name, state, country FROM city WHERE state = #{state}")
    List<City> findByState(String state);
}

开始使用

@Autowired
private final CityMapper cityMapper;