Spring零配置环境记录

比眉伴天荒 2021-10-01 11:48 252阅读 0赞

# 实现Spring零配置搭建 #

最近在为去除配置文件做了一些研究,基于Spring 4 的一些特性将原来有配置的地方全部转化成了基于注解的形式,发现Spring的强大不是一点点.

以下是对Spring的改造做了一些记录:

## Spring ##

### 注解介绍 ###

*  `@Configuration`，用于表示这个类是一个配置类，用于配置Spring的相关信息
 *  `@EnableAspectJAutoProxy`，启用切面自动代理，用于AOP

等价于

<aop:aspectj-autoproxy></aop:aspectj-autoproxy>

*  `@EnableTransactionManagement`，启用注解事务，即可以使用@Transactional注解来控制事务,具体实现

**TransactionManagementConfigurer** \-> 等价于

<tx:annotation-driven transaction-manager="transactionManager"
                              proxy-target-class="true"></tx:annotation-driven>

*  `@EnableCaching`:启用缓存实现,这里是针对于Spring定义的缓存实现,具体实现类:**CachingConfigurerSupport**等价于

<cache:annotation-driven error-handler="defaultErrorCacheHandle" key-generator="defaultCacheKeyGenerator"/>

*  `@ComponentScan`，组件扫描，在basePackages指定的目录下扫描被@**Controller**、@**Service**、@**Component**等注解注册的组件
 *  `@Import`，引入指定的配置类，我们引入了Spring容器配置类和数据源事务配置类
 *  `@PropertySource`，加载指定的配置文件，配置文件内容会加载入Environment中等待调用

#### 去除配置中的AOP动态代理 ####

1.  xml

<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
         
        <bean id="manyDataSourceAspect" class="com.elab.core.aop.DataSourceAspect"/>
        
        <aop:config proxy-target-class="true">
        
        <aop:aspect ref="manyDataSourceAspect">
          <aop:before method="before" pointcut="execution(* com.elab.ecrm.services..*.*(..))">        </aop:before>
          <aop:after-returning pointcut="execution(* com.elab.ecrm.services..*.*(..))"
          arg-names="point,retValue" returning="retValue" method="after"/>
          </aop:aspect>
    </aop:config>

1.  注解

@Aspect
    @EnableAspectJAutoProxy
    @Configuration
    public class DataSourceAopConfigBean { 
        @Bean
        public DataSourceAspect getDataSourceAspect() {
            DataSourceAspect catAspect = new DataSourceAspect();
            return catAspect;
        }
    
        @Before(value = "execution(* com.elab.ecrm.services..*.*(..))")
        public void dataSourceBefor(JoinPoint pjp) throws CoreException {
            getDataSourceAspect().before(pjp);
        }
    
    }

#### 去除配置中的数据源 ####

其实这里就和普通的bean定义没什么差别

@EnableWebMvc
    @PropertySource({"classpath:database.properties"})
    @Configuration
    public class DataSourceConfigBean {
     
        @Autowired
        private Environment env;
    
        @Bean(name = "default")
        public DataSource getDefaultDataSource() throws SQLException {
            DruidDataSource dataSource = new DruidDataSource();
            dataSource.setDriverClassName(env.getProperty("default.driverClassName"));
            dataSource.setUrl(env.getProperty("default.url"));
            dataSource.setUsername(env.getProperty("default.username"));
            dataSource.setPassword(env.getProperty("default.password"));
            dataSource.setFilters(env.getProperty("default.filters"));
            dataSource.setInitialSize(Integer.parseInt(env.getProperty("default.initialSize")));
            dataSource.setMinIdle(Integer.parseInt(env.getProperty("default.minIdle")));
            dataSource.setMaxActive(Integer.parseInt(env.getProperty("default.maxActive")));
            return dataSource;
        }
     
    }

#### 配置中的事务 ####

@EnableTransactionManagement
    @Configuration
    public class TransactionConfigBean implements TransactionManagementConfigurer {
    
        @Qualifier("default")
        @Autowired
        private DataSource dataSource;
    
        @Override
        public PlatformTransactionManager annotationDrivenTransactionManager() {
            return getDataSourceTransactionManager();
        } 
        @Bean
        public DataSourceTransactionManager getDataSourceTransactionManager() {
            DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
            transactionManager.setDataSource(dataSource);
            return transactionManager;
        }
    
        @Bean
        public JdbcTemplate getJDBCTemplate() {
            JDBCTemplate jdbcTemplate = new JDBCTemplate(); 
            return jdbcTemplate;
        }
    
    }

#### 普通的Bean定义 ####

@Configuration
    // 这里默认只扫Spring相关的,去除Controller相关的
    @ComponentScan(basePackages = {"com.*.*.*"}, excludeFilters = {
            @ComponentScan.Filter(type = FilterType.ANNOTATION, value = {Controller.class})
    })
    public class BeanConfig {
    
        @Bean
        public ClientHttpRequestFactory getClientHttpRequestFactory() {
            SimpleClientHttpRequestFactory simpleClientHttpRequestFactory = new SimpleClientHttpRequestFactory();
            simpleClientHttpRequestFactory.setConnectTimeout(120000);
            simpleClientHttpRequestFactory.setReadTimeout(120000);
            return simpleClientHttpRequestFactory;
        }
    
        @Bean
        public RestTemplate getRestTemplate() {
            RestTemplate restTemplate = new RestTemplate(getClientHttpRequestFactory());
            return restTemplate;
        }
    }

#### 缓存替代 ####

基于Spring的缓存接口做替换

<cache:annotation-driven error-handler="defaultErrorCacheHandle" key-generator="defaultCacheKeyGenerator"/>

@EnableCaching
    @Configuration
    public class RedisBeanConfig extends CachingConfigurerSupport {
    
        @Value("${domain}")
        private String domain; 
      
        @Autowired
        private org.springframework.core.env.Environment env;
    
        @Override
        public KeyGenerator keyGenerator() {
            return getDefaultCacheKeyGenerator();
        }
    
        @Override
        public CacheErrorHandler errorHandler() {
            return getErrorCacheHandle();
        }
    
        @Override
        public CacheManager cacheManager() {
            return getCompositeCacheManager();
        }
    }

## SpringMVC ##

### 注解介绍 ###

*  `@EnableWebMvc` : 开启SpringMVC的支持，注册了这个方法并且实现了WebMvcConfigurerAdapter类的话,就拥有相当SpingMVC配置文件中的所有属性了

![6370985-29d13355fdfb3afb.png][]

image.png

将这个类注册到容器时,会触发一个`DelegatingWebMvcConfiguration`委托类的注册的`setConfigurers`方法

@Autowired(required = false)
    public void setConfigurers(List<WebMvcConfigurer> configurers) {
       if (configurers == null || configurers.isEmpty()) {
          return;
       }
       this.configurers.addWebMvcConfigurers(configurers);
    }

这个方法会将所有实现WebMvcConfigurer接口的方法全部注册进来,WebMvcConfigurerAdapter已经实现了接口

![6370985-b329a6d55b470fef.png][]

image.png

所以重写过的所有方法都会被触发注册

#### 拦截器 ####

<mvc:interceptors>
            
      <mvc:interceptor>
        <mvc:mapping path="/**"/>
        
        <mvc:exclude-mapping path="/"/>
        
        <bean class="com.demo.log.asepct.TimeInterceptor"/>
      </mvc:interceptor>
    </mvc:interceptors>

这里只需要根据业务实现从**WebMvcConfigurerAdapter**重写自己需要的方法即可

@Configuration
    @EnableWebMvc
    // 这里只扫描和MVC相关的注解,为了和Spring容器区分开
    @ComponentScan(basePackages = {"com.elab.ecrm.controllers"}, includeFilters = {
            @ComponentScan.Filter(type = FilterType.ANNOTATION, value = {Controller.class})
    })
    public class MvcConfigBean extends WebMvcConfigurerAdapter {
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(getTimeHandlerInterceptor())
            .addPathPatterns("/**")
             .excludePathPatterns("/");
        }
      
      public HandlerInterceptor getTimeHandlerInterceptor() {
            return new TimeInterceptor();
        }
    }

## web.xml ##

**从前Spring和SpringMVC的启动入口** , 由于Spring 4是基于Servlet 3.0以上实现的 , 所以Spring提供了SpringServletContainerInitializer这个类可以做为一个入口类.

[参考][Link 1]

<context-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>
        classpath:applicationContext-datasource.xml
      </param-value>
    </context-param>
    <listener>
      <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <servlet>
      <servlet-name>appServlet</servlet-name>
      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
      <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring-mvc.xml</param-value>
      </init-param>
      <load-on-startup>1</load-on-startup>=
    </servlet>

改成编程方式

public class WebInitializer implements WebApplicationInitializer {
        private Logger logger = LoggerFactory.getLogger(WebInitializer.class);
    
        @Override
        public void onStartup(ServletContext servletContext) throws ServletException {
            logger.info("begin init web application.");
            long startTime = System.currentTimeMillis();
            CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
            characterEncodingFilter.setEncoding("UTF-8");
            //配置Spring
            AnnotationConfigWebApplicationContext springContext = new AnnotationConfigWebApplicationContext();
            // 这里一般配置扫描类
            springContext.register(BeanConfig.class);
    
            //添加linstener
            servletContext.addListener(new ContextLoaderListener(springContext));
    
            //添加servlet
            ServletRegistration.Dynamic dispatcher = servletContext.addServlet(
                    "dispatcher", new DispatcherServlet(springContext));
            dispatcher.setLoadOnStartup(1);
            dispatcher.addMapping("/");
            //添加filter
    //        LoggerFilter loggerFilter = new LoggerFilter();
    //        FilterRegistration.Dynamic logFilterRegistration=container.addFilter("requestResponseLogFilter", loggerFilter);
    //        logFilterRegistration.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST, DispatcherType.ASYNC), false, "/*");
            javax.servlet.FilterRegistration.Dynamic filter = servletContext.addFilter("encoding", characterEncodingFilter);
            long time = System.currentTimeMillis() - startTime;
            logger.info("init web application success. start count time : " + time);
        } 
    }

以上代码可以总结出来:

1.  spring 将配置文件和编程方式做了共同的实现,稍微复杂的配置例如

<cache:annotation-driven />
    <aop:aspectj-autoproxy />
    <tx:annotation-driven />

Spring也通过编程方式去指定了具体的实现类,这个可以从注解类中的注释了解到

1.  启动方面基于Servlet 3去实现的,也能通过接口方式启动应用

由于代码中贴入的时候有一些去除,可能会导致阅读收到影响,这只是提供一些更改思路,可以照着这个来.基本上应该是OK的。

项目可以部署到tomcat中,无需纠结..

[6370985-29d13355fdfb3afb.png]: /images/20210811/dfc68b897cbc428bb5f27066ecdd2797.png
[6370985-b329a6d55b470fef.png]: /images/20210811/c6f6d544f2784173ba16cfb524d3c339.png
[Link 1]: https://link.jianshu.com?t=http%3A%2F%2Ftramp-zzy.iteye.com%2Fblog%2F2319916