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本篇文章将在将介绍如何使用slf4j。
Slf4J是Simple Logging Facade for Java的缩写，从其全称即可清晰地看出其定位为日志系统的Facade，其实它就是在不同的日志系统之上封装的门面，便于移植和更换，降低了日志和系统的直接耦合。
使用前提
为了使用slf4j，一般需要import的主要有slf4j的Logger和LoggerFactory。
import org.slf4j.Logger;import org.slf4j.LoggerFactory;
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LoggerFactory就是一个普通的工厂模式的实现，可以追到其源码的主要实现部分如下：
public static ILoggerFactory getILoggerFactory() { if(INITIALIZATION_STATE == 0) { Class var0 = LoggerFactory.class; synchronized(LoggerFactory.class) { if(INITIALIZATION_STATE == 0) { INITIALIZATION_STATE = 1; performInitialization(); } } } switch(INITIALIZATION_STATE) { case 1: return SUBST_FACTORY; case 2: throw new IllegalStateException("org.slf4j.LoggerFactory could not be successfully initialized. See also http://www.slf4j.org/codes.html#unsuccessfulInit"); case 3: return StaticLoggerBinder.getSingleton().getLoggerFactory(); case 4: return NOP_FALLBACK_FACTORY; default: throw new IllegalStateException("Unreachable code"); } }
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使用方式
取得
private final Logger logger = LoggerFactory.getLogger(this.getClass());
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使用
logger.info("## Info Information ##: {}", name); logger.warn("## Warn Information ##: {}", name); logger.error("## Error Information ##: {}", name);
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修改DemoApplication
package com.example;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;import java.util.concurrent.atomic.AtomicLong;@RestController@SpringBootApplicationpublic class DemoApplication { private final Logger logger = LoggerFactory.getLogger(this.getClass()); private final AtomicLong counter = new AtomicLong(); private final String templateStr="Hello, %s, Welcome to Spring Boot ..."; @RequestMapping("/greeting") public User greeting(@RequestParam(value="name",defaultValue = "World") String name){ logger.info("## Info Information ##: {}", name); logger.warn("## Warn Information ##: {}", name); logger.error("## Error Information ##: {}", name); return new User(counter.incrementAndGet(),String.format(templateStr,name)); } public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); }}
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Console输出
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v1.4.2.RELEASE)2016-12-08 21:13:36.786 INFO 3096 --- [ main] com.example.DemoApplication : Starting DemoApplication on vcc-PC with PID 3096 (C:\Users\Administrator\IdeaProjects\demo\target\classes started by Administrator in C:\Users\Administrator\IdeaProjects\demo)2016-12-08 21:13:36.786 INFO 3096 --- [ main] com.example.DemoApplication : No active profile set, falling back to default profiles: default2016-12-08 21:13:36.848 INFO 3096 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@30ee2816: startup date [Thu Dec 08 21:13:36 CST 2016]; root of context hierarchy2016-12-08 21:13:38.411 INFO 3096 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)2016-12-08 21:13:38.426 INFO 3096 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat2016-12-08 21:13:38.426 INFO 3096 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.62016-12-08 21:13:38.536 INFO 3096 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2016-12-08 21:13:38.536 INFO 3096 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1688 ms2016-12-08 21:13:38.676 INFO 3096 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]2016-12-08 21:13:38.692 INFO 3096 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]2016-12-08 21:13:38.692 INFO 3096 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]2016-12-08 21:13:38.692 INFO 3096 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]2016-12-08 21:13:38.692 INFO 3096 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]2016-12-08 21:13:38.972 INFO 3096 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@30ee2816: startup date [Thu Dec 08 21:13:36 CST 2016]; root of context hierarchy2016-12-08 21:13:39.050 INFO 3096 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/greeting]}" onto public com.example.User com.example.DemoApplication.greeting(java.lang.String)2016-12-08 21:13:39.050 INFO 3096 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)2016-12-08 21:13:39.050 INFO 3096 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)2016-12-08 21:13:39.082 INFO 3096 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2016-12-08 21:13:39.082 INFO 3096 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2016-12-08 21:13:39.113 INFO 3096 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2016-12-08 21:13:39.253 INFO 3096 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup2016-12-08 21:13:39.316 INFO 3096 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)2016-12-08 21:13:39.316 INFO 3096 --- [ main] com.example.DemoApplication : Started DemoApplication in 3.109 seconds (JVM running for 3.645)
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结果确认
画面刷新
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log输出确认
参数绑定刷新
log输出确认
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