SpringBoot——日志系统解析

日志介绍

日志作用：记录程序的运行轨迹，方便查找关键信息以及快速定位解决问题

日志实现框架

• 具体的日志功能实现
• 日志实现框架有：JUL、Log4j、Logback、Log4j2

日志门面框架

• 具体实现的抽象层，定义log.info、log.error等方法
• 日志的门面框架主要有两个：JCL和SLF4J
• 日志门面框架是避免日志实现中代码的改动影响用户的使用，抽象日志的实现接口，使得上层用户只需要调用接口而不用感知接口内部的实现

日志发展历程

• JDK1.3及以前，通过System.out|err.println打印，存在巨大缺陷
• 为了解决系统打印缺陷问题，出现了log4j，但2015年8月停止更新
• 受到log4j影响，SUN公司推出java.util.logging即JUL
• 由于存在两个系统的实现，为了解决兼容性问题，Apache推出了门面框架commons-logging即JCL，可以使用它兼容不同的日志实现框架，但是它对log4f和JUL的配置兼容问题处理的不是很好，存在一定的缺陷
• 随后log4j的作者推出了slf4j，功能完善兼容性好，成为业界主流
• log4j的作者在推出log4j后进行了新的思考，改进后推出了logback
• log4j2是对log4j的重大升级，修复已知缺陷，极大提升性能
• 最佳组合：slf4j+logback(SpringBoot使用)或者slf4j+log4j2

日志实现寻址解析

@RunWith(SpringRunner.class)
@SpringBootTest
public class ApplicationTest {

    private Logger logger = LoggerFactory.getLogger(ApplicationTest.class);

    ......
}

• 通过debug模式会进入到getLogger方法中

public static Logger getLogger(Class clazz) {
    Logger logger = getLogger(clazz.getName());
    if (DETECT_LOGGER_NAME_MISMATCH) {
        Class autoComputedCallingClass = Util.getCallingClass();
        if (autoComputedCallingClass != null && nonMatchingClasses(clazz, autoComputedCallingClass)) {
            Util.report(String.format("Detected logger name mismatch. Given name: \"%s\"; computed name: \"%s\".", logger.getName(), autoComputedCallingClass.getName()));
            Util.report("See http://www.slf4j.org/codes.html#loggerNameMismatch for an explanation");
        }
    }

    return logger;
}

public static Logger getLogger(String name) {
    ILoggerFactory iLoggerFactory = getILoggerFactory();
    return iLoggerFactory.getLogger(name);
}

• 跟进getILoggerFactory()方法

static final int UNINITIALIZED = 0;
static final int ONGOING_INITIALIZATION = 1;
static final int FAILED_INITIALIZATION = 2;
static final int SUCCESSFUL_INITIALIZATION = 3;
static final int NOP_FALLBACK_INITIALIZATION = 4;
public static ILoggerFactory getILoggerFactory() {
    //判断当前的日志启动状态是否是未启动
    if (INITIALIZATION_STATE == UNINITIALIZED) {
        synchronized (LoggerFactory.class) {
            //duble check
            if (INITIALIZATION_STATE == UNINITIALIZED) {
                INITIALIZATION_STATE = ONGOING_INITIALIZATION;
                //实现寻址
                performInitialization();
            }
        }
    }
    switch (INITIALIZATION_STATE) {
    case SUCCESSFUL_INITIALIZATION:
        //通过StaticLoggerBinder获取获取LoggerFactory
        return StaticLoggerBinder.getSingleton().getLoggerFactory();
    case NOP_FALLBACK_INITIALIZATION:
        return NOP_FALLBACK_FACTORY;
    case FAILED_INITIALIZATION:
        throw new IllegalStateException(UNSUCCESSFUL_INIT_MSG);
    case ONGOING_INITIALIZATION:
        // support re-entrant behavior.
        // See also http://jira.qos.ch/browse/SLF4J-97
        return SUBST_FACTORY;
    }
    throw new IllegalStateException("Unreachable code");
}

• 通过performInitialization()方法实现寻址

private final static void performInitialization() {
    bind();
    if (INITIALIZATION_STATE == SUCCESSFUL_INITIALIZATION) {
        versionSanityCheck();
    }
}

• 点击跟进bind方法

private final static void bind() {
    try {
        Set staticLoggerBinderPathSet = null;
        // skip check under android, see also
        // http://jira.qos.ch/browse/SLF4J-328
        //如果不是安卓环境
        if (!isAndroid()) {
            staticLoggerBinderPathSet = findPossibleStaticLoggerBinderPathSet();
            reportMultipleBindingAmbiguity(staticLoggerBinderPathSet);
        }
        // the next line does the binding
        StaticLoggerBinder.getSingleton();
        INITIALIZATION_STATE = SUCCESSFUL_INITIALIZATION;
        reportActualBinding(staticLoggerBinderPathSet);
        fixSubstituteLoggers();
        replayEvents();
        // release all resources in SUBST_FACTORY
        SUBST_FACTORY.clear();
    } catch (NoClassDefFoundError ncde) {
        String msg = ncde.getMessage();
        if (messageContainsOrgSlf4jImplStaticLoggerBinder(msg)) {
            INITIALIZATION_STATE = NOP_FALLBACK_INITIALIZATION;
            Util.report("Failed to load class \"org.slf4j.impl.StaticLoggerBinder\".");
            Util.report("Defaulting to no-operation (NOP) logger implementation");
            Util.report("See " + NO_STATICLOGGERBINDER_URL + " for further details.");
        } else {
            failedBinding(ncde);
            throw ncde;
        }
    } catch (java.lang.NoSuchMethodError nsme) {
        String msg = nsme.getMessage();
        if (msg != null && msg.contains("org.slf4j.impl.StaticLoggerBinder.getSingleton()")) {
            INITIALIZATION_STATE = FAILED_INITIALIZATION;
            Util.report("slf4j-api 1.6.x (or later) is incompatible with this binding.");
            Util.report("Your binding is version 1.5.5 or earlier.");
            Util.report("Upgrade your binding to version 1.6.x.");
        }
        throw nsme;
    } catch (Exception e) {
        failedBinding(e);
        throw new IllegalStateException("Unexpected initialization failure", e);
    }
}

• 跟进findPossibleStaticLoggerBinderPathSet方法

private static String STATIC_LOGGER_BINDER_PATH = "org/slf4j/impl/StaticLoggerBinder.class";
static Set findPossibleStaticLoggerBinderPathSet() {
    // use Set instead of list in order to deal with bug #138
    // LinkedHashSet appropriate here because it preserves insertion order
    // during iteration
    Set staticLoggerBinderPathSet = new LinkedHashSet();
    try {
        //获取loggerFactoryClassLoader便于加载资源
        ClassLoader loggerFactoryClassLoader = LoggerFactory.class.getClassLoader();
        Enumeration paths;
        if (loggerFactoryClassLoader == null) {
            paths = ClassLoader.getSystemResources(STATIC_LOGGER_BINDER_PATH);
        } else {
            //加载资源
            paths = loggerFactoryClassLoader.getResources(STATIC_LOGGER_BINDER_PATH);
        }
        while (paths.hasMoreElements()) {
            URL path = paths.nextElement();
            //将StaticLoggerBinder.class添加到集合当中，如果存在多个的话，会依次添加
            staticLoggerBinderPathSet.add(path);
        }
    } catch (IOException ioe) {
        Util.report("Error getting resources from path", ioe);
    }
    return staticLoggerBinderPathSet;
}

• 接着跟进reportMultipleBindingAmbiguity方法，主要判断binderPathSet集合的数量是否大于1，如果存在多个日志实现框架的话，会打印日志提示

private static void reportMultipleBindingAmbiguity(Set binderPathSet) {
    if (isAmbiguousStaticLoggerBinderPathSet(binderPathSet)) {
        Util.report("Class path contains multiple SLF4J bindings.");
        for (URL path : binderPathSet) {
            Util.report("Found binding in [" + path + "]");
        }
        Util.report("See " + MULTIPLE_BINDINGS_URL + " for an explanation.");
    }
}

private static boolean isAmbiguousStaticLoggerBinderPathSet(Set binderPathSet) {
    return binderPathSet.size() > 1;
}

• 接着跟进getSingleton方法，如果StaticLoggerBinder不存在，则会抛异常

private static StaticLoggerBinder SINGLETON = new StaticLoggerBinder();
public static StaticLoggerBinder getSingleton() {
    return SINGLETON;
}

• 跟进reportActualBinding(staticLoggerBinderPathSet)方法，如果binderPathSet集合不为null，并且集合数量为多个的话，那么就会输出一行日志提醒

private static void reportActualBinding(Set binderPathSet) {
    // binderPathSet can be null under Android
    if (binderPathSet != null && isAmbiguousStaticLoggerBinderPathSet(binderPathSet)) {
        Util.report("Actual binding is of type [" + StaticLoggerBinder.getSingleton().getLoggerFactoryClassStr() + "]");
    }
}

日志配置

在spring-boot-starter里面引入了spring-boot-starter-logging，而spring-boot-starter-logging里面又引入了logback-classic、log4j-to-slf4j、jul-to-slf4j，其关系图如下所示：

日志使用方式

• Logger log = LoggerFactory.getLogger(xxx.class);
• 如果添加了lombok依赖可以使用@Slf4j
• log.level("xyz {} is {}",i ,j)，比如log.info()，log.error()等

日志level如下所示：

日志配置

• scan：当此属性设置为true时，配置文档如果发生改变，将会被重新加载，默认值为true
• scanPeriod：设置监测配置文档是否有修改的时间间隔，如果没有给出时间单位，默认单位是毫秒。当scan为true时，此属性生效。默认的时间间隔为1分钟。
• debug：当此属性设置为true时，将打印出logback内部日志信息，实时查看logback运行状态。默认值为false。

configuration子节点：

contextName：上下文名称
用来区分不同应用程序的记录，默认为default

logback

property：属性配置
name的值是变量的名称，value的值时变量定义的值。通过定义的值会被插入到logger上下文中。定义后，可以使“${}”来使用变量

还可以通过加载配置的属性

appender：格式化日志输出

    
    ${log.path}/xundu_info.log
    
    
        %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
        UTF-8
    
    
    
        
        ${log.path}/xundu-info-%d{yyyy-MM-dd}.%i.log
        
        100MB
        
        20GB
        
        15
    
    
    
        info
        ACCEPT
        DENY
    

常用的pattern介绍

• logger{length}：输出日志的logger名，可有一个整型参数，功能是缩短logger名
• contextName|cn：上下文名称
• date {pattern}：输出日志的打印信息，模式语法与java.test.SimpleDateFormat兼容
• p/le/level：日志级别
• M/method：输出日志的方法名
• r/relative：从程序启动到创建日志记录的时间
• m/msg/message：程序提供的信息
• n：换行符

root：全局日志输出设置

logger：具体包或子类输出设置

• 用来设置某一个包或者具体的某一个类的日志打印级别、以及指定。
• 仅有一个name属性，一个可选的level和一个可选的addtivity属性。
• name:用来指定受此logger约束的某一个包或者具体的某一个类。
• level:用来设置打印级别，大小写无关：TRACE, DEBUG, INFO, WARN, ERROR, ALL 和 OFF，还有一个特俗值INHERITED或者同义词NULL，代表强制执行上级的级别。如果未设置此属性，那么当前logger将会继承上级的级别。
• addtivity:是否向上级logger传递打印信息。默认是true。

日志实战

在工作开发当中，日志通常都是和切面结合使用，也就是说会在项目中建一个异常切面来捕获程序中抛出的错误，捕获之后会记录异常的基本信息，以及根据异常的级别来分别使用不同的日志级别来记录，例如，业务异常使用警告级别就可以了，对于系统级别的异常则需要使用error来记录，

引入aop starter

    org.springframework.boot
    spring-boot-starter-aop

logback-spring.xml文件

    logback

    
    
    
    

    
    
    
    
    
    
    
    


    
    
        
        
            INFO
        
        
            ${CONSOLE_LOG_PATTERN}
            
            UTF-8
        
    

    
        
        ${LOG_FILE}
        
        
            %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
            UTF-8
        
        
        
            
            ${LOG_FILE}.%d{yyyy-MM-dd}.%i.log
            
            100MB
            
            20GB
            
            15
        
    

    
    
    
        
    

    
        
        
    

    

创建业务异常和系统异常类

public class BusinessException extends RuntimeException {

    public BusinessException() {
    }

    public BusinessException(String message) {
        super(message);
    }

    public BusinessException(String message, Throwable cause) {
        super(message, cause);
    }

    public BusinessException(Throwable cause) {
        super(cause);
    }

    public BusinessException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
    }
}

public class SystemException extends RuntimeException {

    public SystemException() {
    }

    public SystemException(String message) {
        super(message);
    }

    public SystemException(String message, Throwable cause) {
        super(message, cause);
    }

    public SystemException(Throwable cause) {
        super(cause);
    }

    public SystemException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
    }
}

创建异常切面

@Component
@Aspect
public class ExceptionAspect {

    private static final Logger logger = LoggerFactory.getLogger(ExceptionAspect.class);

    @AfterThrowing(pointcut = "within(com.yibo.controller.*)", throwing = "ex")
    public void handlerException(JoinPoint joinPoint,Exception ex)throws Exception{
        //出错的类
        Class declaringType = joinPoint.getSignature().getDeclaringType();
        //获取全类名
        String clazz = declaringType.getCanonicalName();
        //获取具体出错的方法
        String name = joinPoint.getSignature().getName();
        if(ex instanceof BusinessException){
            logger.warn("clazz:{},name:{}",clazz,name,ex);
        }else if(ex instanceof SystemException){
            logger.error("clazz:{},name:{}",clazz,name,ex);
        }
        throw ex;
    }
}

演示异常抛出

@Component
public class DemoHandler {

    @Autowired
    private PersonService personService;

    public Mono queryPerson(ServerRequest request){
        Integer id = Integer.valueOf(request.pathVariable("id"));
        //日志切面演示
        if(id == 1){
            throw new BusinessException("can not use this id " + id);
        }else if(id == 2){
            throw new SystemException("can not use this id " + id);
        }
        return ok().contentType(MediaType.APPLICATION_JSON_UTF8)
                .body(Mono.just(personService.getPersonById(id)), Person.class);
    }
}

在启动内上添加开启切面功能的注解

@SpringBootApplication
@MapperScan("com.yibo.mapper")
@EnableAspectJAutoProxy//开启切面功能
public class Application {

    public static void main(String[] args) {

        SpringApplication.run(Application.class,args);
    }
}

Siftingappender

logback 按照业务主键分文件输出日志，使用SiftingAppender结合MDC

修改logback-spring.xml文件

    logback

    
    
    
    

    
    
    
    
    
    
    
    


    
    
        
        
            INFO
        
        
            ${CONSOLE_LOG_PATTERN}
            
            UTF-8
        
    

    
            
                
                ${BIZ_FILE}
                
                
                    %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
                    UTF-8
                
                
                
                    
                    ${BIZ_FILE}.%d{yyyy-MM-dd}.%i.log
                    
                    100MB
                    
                    20GB
                    
                    15
                
            
        
    

    
    
    
        
    

    
        
        
    

    

修改异常抛出

@Component
public class DemoHandler {

    @Autowired
    private PersonService personService;

    public Mono queryPerson(ServerRequest request){
        Integer id = Integer.valueOf(request.pathVariable("id"));
        //日志切面演示
        if(id == 1){
            MDC.put("bizType","MONEY");
            throw new BusinessException("can not use this id " + id);
        }else if(id == 2){
            MDC.put("bizType","HOUSE");
            throw new SystemException("can not use this id " + id);
        }
        return ok().contentType(MediaType.APPLICATION_JSON_UTF8)
                .body(Mono.just(personService.getPersonById(id)), Person.class);
    }
}

日志结合切面的步骤

业务日志分类

详细的日志文件

    logback

    
    

    
    
    
    
    
    
    
    


    
    
        
        
            INFO
        
        
            ${CONSOLE_LOG_PATTERN}
            
            UTF-8
        
    

    
    
    
        
        ${log.path}/xundu_debug.log
        
        
            %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
            UTF-8 
        
        
        
            
            ${log.path}/xundu-debug-%d{yyyy-MM-dd}.%i.log
            
                100MB
            
            
            15
            20GB
        
        
        
            debug
            ACCEPT
            DENY
        
    

    
    
        
        ${log.path}/xundu_info.log
        
        
            %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
            UTF-8
        
        
        
            
            ${log.path}/xundu-info-%d{yyyy-MM-dd}.%i.log
            
            100MB
            
            20GB
            
            15
        
        
        
            info
            ACCEPT
            DENY
        
    

    
    
        
        ${log.path}/xundu_warn.log
        
        
            %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
            UTF-8 
        
        
        
            ${log.path}/xundu-warn-%d{yyyy-MM-dd}.%i.log
            
                100MB
            
            
            15
            20GB
        
        
        
            warn
            ACCEPT
            DENY
        
    

    
    
        
        ${log.path}/xundu_error.log
        
        
            %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
            UTF-8 
        
        
        
            ${log.path}/xundu-error-%d{yyyy-MM-dd}.%i.log
            
                100MB
            
            
            15
            20GB
        
        
        
            ERROR
            ACCEPT
            DENY
        
    

    

    

    

    
    
    
        
    

    
        
        
        
        
        
    

    

    
    
    
    
    
    
        
        
            #s_logger#%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %highlight(%-5level) %cyan(%logger{50}-%line) %msg #e_logger#%n
            UTF-8 
        
    
    
    
    
        
            
            ${log.base}/normal/normal.%d{yyyy-MM-dd}.log
            30
        
        
            #s_logger#%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %highlight(%-5level) %cyan(%logger{50}-%line) %msg #e_logger#%n
            UTF-8 
        
        
            ERROR
            DENY
            ACCEPT
        
    
    
    
        
            ${log.base}/sql/sql.%d{yyyy-MM-dd}.log
            30
        
        
            #s_logger#%d{yyyy-MM-dd HH:mm:ss.SSS}%n%msg #e_logger#%n
            UTF-8 
        
        
            ERROR
            ACCEPT
            DENY
        
    

    
        
            ${log.base}/error/error.%d{yyyy-MM-dd}.log
            30
        
        
            #s_logger#%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %highlight(%-5level) %cyan(%logger{50}-%line) %msg #e_logger#%n
            UTF-8 
        
        
            ERROR
            ACCEPT
            DENY
        
    

    
        
    

    
        
        
        
    

logging:
  level:
    com.netflix.discovery: 'OFF'
    org.springframework.cloud: 'INFO'
    com.xundu.service.mapper: 'WARN'

参考：
https://www.cnblogs.com/zhangjianbing/p/8992897.html

https://www.cnblogs.com/jpfss/p/11090550.html

https://www.cnblogs.com/liufei96/p/16069903.html

https://www.cnblogs.com/flyingrun/p/16631090.html

https://www.dandelioncloud.cn/article/details/1510720395119546369