SpringBoot：进阶使用

SpringBoot的web开发

Web开发的自动配置类：“org.springframework.boot.autoconfigure.web”包中：“WebMvcAutoConfiguration.class”类；（SpringMVC的自动配置）

自动配置：ViewResolver

“WebMvcAutoConfiguration.class”中：（一般不需要自行配置）

@Configuration
@ConditionalOnWebApplication
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurerAdapter.class })
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {
   ...
   @Configuration
	@Import(EnableWebMvcConfiguration.class)
	@EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })
	public static class WebMvcAutoConfigurationAdapter extends WebMvcConfigurerAdapter {
      ...
      private final WebMvcProperties mvcProperties;
      ...
		@Bean
		@ConditionalOnMissingBean
		public InternalResourceViewResolver defaultViewResolver() {
			InternalResourceViewResolver resolver = new InternalResourceViewResolver();
			resolver.setPrefix(this.mvcProperties.getView().getPrefix());
			resolver.setSuffix(this.mvcProperties.getView().getSuffix());
			return resolver;
		}

		@Bean
		@ConditionalOnBean(View.class)
		@ConditionalOnMissingBean
		public BeanNameViewResolver beanNameViewResolver() {
			BeanNameViewResolver resolver = new BeanNameViewResolver();
			resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
			return resolver;
		}
      ...
   }
   ...
}

“WebMvcProperties”（“org.springframework.boot.autoconfigure.web”包中）：

@ConfigurationProperties(prefix = "spring.mvc")
public class WebMvcProperties {
   ...
   public static class View {

		/**
		 * Spring MVC view prefix.
		 */
		private String prefix;

		/**
		 * Spring MVC view suffix.
		 */
		private String suffix;  
      ...
   }
}

自动配置：静态资源位置

全局变量中配置springMVC解析规则：

server.port=8088
server.servlet-path=/
...

1. “/”：Spring Boot的默认静态资源的路径为：“spring.resources.static-locations=classpath:/resources/”；
   • 可以指定为“classpath:/META-INF/resources/,classpath:/resources/,classpath:/static/,classpath:/public/”等；

   

2. “*.xxx”：（或，不指定静态文件路径时）将静态资源放置到“webapp”下的“static”目录中即可通过地址访问；

   

自定义消息转化器

自定义消息转化器：只需要在“@Configuration”注解的类中，添加“@bean”注解的消息转化器方法，就会被Spring Boot自动加入到容器中：

@Controller
@SpringBootApplication(exclude = { RedisAutoConfiguration.class })
@Configuration
public class HelloApplication {
   ...
   @Bean
    public StringHttpMessageConverter stringHttpMessageConverter() {
        StringHttpMessageConverter converter = new StringHttpMessageConverter(Charset.forName("ISO-8859-1"));
        return converter;
    }

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

系统中已有默认配置：（一般不需自行定义）

• “org.springframework.boot.autoconfigure.web”包中“HttpMessageConvertersAutoConfiguration.class”类；

@Configuration
@ConditionalOnClass(HttpMessageConverter.class)
@AutoConfigureAfter({ GsonAutoConfiguration.class, JacksonAutoConfiguration.class })
@Import({ JacksonHttpMessageConvertersConfiguration.class, GsonHttpMessageConvertersConfiguration.class })
public class HttpMessageConvertersAutoConfiguration {
   ...
   @Configuration
	@ConditionalOnClass(StringHttpMessageConverter.class)
	@EnableConfigurationProperties(HttpEncodingProperties.class)
	protected static class StringHttpMessageConverterConfiguration {
      
		private final HttpEncodingProperties encodingProperties;

		protected StringHttpMessageConverterConfiguration(
				HttpEncodingProperties encodingProperties) {
			this.encodingProperties = encodingProperties;
		}

		@Bean
		@ConditionalOnMissingBean
		public StringHttpMessageConverter stringHttpMessageConverter() {
			StringHttpMessageConverter converter = new StringHttpMessageConverter(
					this.encodingProperties.getCharset());
			converter.setWriteAcceptCharset(false);
			return converter;
		}
	}
}

重写SpringMVC的配置

有些时候需要自已配置SpringMVC而不是采用默认；

比如说增加一个拦截器，这个时候就得通过继承“WebMvcConfigurerAdapter.class”（“org.springframework.web.servlet.config.annotation”包）然后重写父类中的方法进行扩展：

import ...

@Configuration
public class MySrpingMVCConfig extends WebMvcConfigurerAdapter{

    // 自定义拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        HandlerInterceptor handlerInterceptor = new HandlerInterceptor() {
            @Override
            public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
                System.out.println("自定义拦截器............");
                return true;
            }
            
            @Override
            public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
                    ModelAndView modelAndView) throws Exception {
            }
            
            @Override
            public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
                    Exception ex) throws Exception {
            }
        };
        registry.addInterceptor(handlerInterceptor).addPathPatterns("/**");
    }

    // 自定义消息转化器的第二种方法
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        StringHttpMessageConverter converter  = new StringHttpMessageConverter(Charset.forName("UTF-8"));
        converters.add(converter);
    }
}