解锁新技能《logback packagingData属性配置作用及源码分析》

开源SDK:

<dependency>
  <groupId>io.github.mingyang66groupId>
  <artifactId>oceansky-loggerartifactId>
  <version>4.3.6version>
dependency>  

<dependency>
    <groupId>io.github.mingyang66groupId>
    <artifactId>emily-spring-boot-loggerartifactId>
    <version>4.3.6version>
dependency>

在logback日志的xml配置文件中经常可以看到如下配置：

<configuration scan="true" scanPeriod="60000" debug="false" packagingData="false">

其中packagingData的默认值是false，这个属性会有何作用，对日志打印有何影戏？

一、logback-classic包中的ConfigurationAction类对Configuration配置属性进行读取

    static final String INTERNAL_DEBUG_ATTR = "debug";
    static final String PACKAGING_DATA_ATTR = "packagingData";
    static final String SCAN_ATTR = "scan";
    static final String SCAN_PERIOD_ATTR = "scanPeriod";
    static final String DEBUG_SYSTEM_PROPERTY_KEY = "logback.debug";

    long threshold = 0;

    public void begin(InterpretationContext ic, String name, Attributes attributes) {
        ...
        LoggerContext lc = (LoggerContext) context;
       //读取packagingData属性配置
        boolean packagingData = OptionHelper.toBoolean(ic.subst(attributes.getValue(PACKAGING_DATA_ATTR)), LoggerContext.DEFAULT_PACKAGING_DATA);
       //设置属性
        lc.setPackagingDataEnabled(packagingData);

        if (EnvUtil.isGroovyAvailable()) {
            ContextUtil contextUtil = new ContextUtil(context);
            contextUtil.addGroovyPackages(lc.getFrameworkPackages());
        }

        // the context is turbo filter attachable, so it is pushed on top of the
        // stack
        ic.pushObject(getContext());
    }

此处会将从配置文件中读取到的属性值设置到Context上下文之中；而setPackagingDataEnabled方法又是LoggerContext类中的一个方法，LoggerContext类中还存在一个读取packingData属性的方法isPackagingDataEnabled；

二、isPackagingDataEnabled方法调用处理类

经追踪可以发现isPackagingDataEnabled方法会被EnsureExceptionHandling类的process方法调用

    public void process(Context context, Converter<ILoggingEvent> head) {
        if (head == null) {
            // this should never happen
            throw new IllegalArgumentException("cannot process empty chain");
        }
        if (!chainHandlesThrowable(head)) {
            Converter<ILoggingEvent> tail = ConverterUtil.findTail(head);
            Converter<ILoggingEvent> exConverter = null;
            LoggerContext loggerContext = (LoggerContext) context;
            if (loggerContext.isPackagingDataEnabled()) {
                exConverter = new ExtendedThrowableProxyConverter();
            } else {
                exConverter = new ThrowableProxyConverter();
            }
            tail.setNext(exConverter);
        }
    }

我们会发现如果packingData属性被设置为true的时候会new一个ExtendedThrowableProxyConverter类的实例对象，否则就是ThrowableProxyConverter类的实例对象；

三、ExtendedThrowableProxyConverter和ThrowableProxyConverter的区别

public class ExtendedThrowableProxyConverter extends ThrowableProxyConverter {

    @Override
    protected void extraData(StringBuilder builder, StackTraceElementProxy step) {
        ThrowableProxyUtil.subjoinPackagingData(builder, step);
    }

    protected void prepareLoggingEvent(ILoggingEvent event) {

    }

}

看过ExtendedThrowableProxyConverter的源码后你会清楚的了解到ExtendedThrowableProxyConverter类是ThrowableProxyConverter的子类；其唯一不同点就是实现了extraData方法的实现；

ThrowableProxyConverter类中extraData方法调用入口：

    private void printStackLine(StringBuilder buf, int ignoredCount, StackTraceElementProxy element) {
        buf.append(element);
        extraData(buf, element); // allow other data to be added
        if (ignoredCount > 0) {
            printIgnoredCount(buf, ignoredCount);
        }
    }

看到这里清除ExtendedThrowableProxyConverter类实现方法的不同点了吗？它会在每一行打印的堆栈后面添加上自己指定的字符串，具体添加什么字符串后面我们接着看。

四、ExtendedThrowableProxyConverter类在每行堆栈后面添加了哪些内容

public class ExtendedThrowableProxyConverter extends ThrowableProxyConverter {

    @Override
    protected void extraData(StringBuilder builder, StackTraceElementProxy step) {
        ThrowableProxyUtil.subjoinPackagingData(builder, step);
    }

    protected void prepareLoggingEvent(ILoggingEvent event) {

    }

}

在每行堆栈后面添加额外信息的实现是在ThrowableProxyUtil.subjoinPackagingData方法中实现；

    public static void subjoinPackagingData(StringBuilder builder, StackTraceElementProxy step) {
        if (step != null) {
            ClassPackagingData cpd = step.getClassPackagingData();
            if (cpd != null) {
                if (!cpd.isExact()) {
                    builder.append(" ~[");
                } else {
                    builder.append(" [");
                }

                builder.append(cpd.getCodeLocation()).append(':').append(cpd.getVersion()).append(']');
            }
        }
    }

看到这段代码就明白了了吧，会在堆栈每一行后面添加一个左中括号和右中括号，内部填充类所属的包；

五、打印案例

• packingData为true

2023-07-17 13:17:04.483 ERROR default --- [tp-nio-8080-exec-2] c.e.i.t.controller.LogbackController:35   : -----error test---- 
java.lang.NullPointerException: Cannot invoke "String.length()" because "s" is null
	at com.emily.infrastructure.test.controller.LogbackController.debug(LogbackController.java:33) ~[classes/:na]
	at com.emily.infrastructure.test.controller.LogbackController$$FastClassBySpringCGLIB$$2de19373.invoke(<generated>) ~[classes/:na]
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.3.28.jar:5.3.28]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:793) ~[spring-aop-5.3.28.jar:5.3.28]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.3.28.jar:5.3.28]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-5.3.28.jar:5.3.28]
	at com.alibaba.druid.support.spring.stat.DruidStatInterceptor.invoke(DruidStatInterceptor.java:70) ~[druid-1.2.18.jar:na]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.28.jar:5.3.28]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-5.3.28.jar:5.3.28]
	at com.emily.infrastructure.autoconfigure.request.interceptor.DefaultRequestMethodInterceptor.invoke(DefaultRequestMethodInterceptor.java:64) ~[classes/:na]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:175) ~[spring-aop-5.3.28.jar:5.3.28]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-5.3.28.jar:5.3.28]
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) ~[spring-aop-5.3.28.jar:5.3.28]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.28.jar:5.3.28]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-5.3.28.jar:5.3.28]
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708) ~[spring-aop-5.3.28.jar:5.3.28]
	at com.emily.infrastructure.test.controller.LogbackController$$EnhancerBySpringCGLIB$$5379665.debug(<generated>) ~[classes/:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.28.jar:5.3.28]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.28.jar:5.3.28]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.28.jar:5.3.28]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.28.jar:5.3.28]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.28.jar:5.3.28]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.28.jar:5.3.28]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1072) ~[spring-webmvc-5.3.28.jar:5.3.28]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:965) ~[spring-webmvc-5.3.28.jar:5.3.28]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.28.jar:5.3.28]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.28.jar:5.3.28]

• packingData为false

java.lang.NullPointerException: Cannot invoke "String.length()" because "s" is null
	at com.emily.infrastructure.test.controller.LogbackController.debug(LogbackController.java:33)
	at com.emily.infrastructure.test.controller.LogbackController$$FastClassBySpringCGLIB$$2de19373.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:793)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
	at com.alibaba.druid.support.spring.stat.DruidStatInterceptor.invoke(DruidStatInterceptor.java:70)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
	at com.emily.infrastructure.autoconfigure.request.interceptor.DefaultRequestMethodInterceptor.invoke(DefaultRequestMethodInterceptor.java:64)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:175)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708)
	at com.emily.infrastructure.test.controller.LogbackController$$EnhancerBySpringCGLIB$$3879bcba.debug(<generated>)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1072)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:965)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:529)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:209)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at com.alibaba.druid.support.http.WebStatFilter.doFilter(WebStatFilter.java:114)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at com.emily.infrastructure.core.servlet.filter.RequestChannelFilter.doFilter(RequestChannelFilter.java:26)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:130)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:390)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:926)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1791)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:833)

GitHub源码：https://github.com/mingyang66/spring-parent