SpringBoot集成日志系统logback的问题解决

问题 ：java.lang.IllegalStateException: java.io.FileNotFoundException: class path resource [/logback-spring.xml] cannot be resolved to URL because it does not exist

配置内容

logging.config=classpath:/logback-spring.xml

报错日志：

14:18:06.707 [main] DEBUG org.springframework.core.env.MutablePropertySources - Adding PropertySource 'inline' with highest search precedence
14:18:06.713 [main] DEBUG org.springframework.test.context.support.TestPropertySourceUtils - Adding inlined properties to environment: {
     spring.jmx.enabled=false, org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true, server.port=-1}
14:18:06.713 [main] DEBUG org.springframework.core.env.StandardEnvironment - Adding PropertySource 'Inlined Test Properties' with highest search precedence
Logging system failed to initialize using configuration from 'classpath:/logback-spring.xml'
java.io.FileNotFoundException: class path resource [/logback-spring.xml] cannot be resolved to URL because it does not exist
	at org.springframework.util.ResourceUtils.getURL(ResourceUtils.java:135)
	at org.springframework.boot.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:307)
	at org.springframework.boot.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:276)
	at org.springframework.boot.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:239)
	at org.springframework.boot.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:212)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:122)
	at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:74)
	at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:54)
	at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:325)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:296)
	at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:120)
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:98)
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:116)
	at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:83)
	at org.springframework.test.context.web.ServletTestExecutionListener.setUpRequestContextIfNecessary(ServletTestExecutionListener.java:189)
	at org.springframework.test.context.web.ServletTestExecutionListener.prepareTestInstance(ServletTestExecutionListener.java:131)
	at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:230)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:228)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:287)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:289)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:247)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
14:18:07.350 [main] DEBUG org.springframework.boot.logging.ClasspathLoggingApplicationListener - Application failed to start with classpath: unknown

原因分析

在网上查找了解决方案，了解到问题出在“涉及报错的源码在org.springframework.util.ResourceUtils”

    /**
     * Resolve the given resource location to a {@code java.net.URL}.
     * 
Does not check whether the URL actually exists; simply returns
     * the URL that the given location would correspond to.
     * @param resourceLocation the resource location to resolve: either a
     * "classpath:" pseudo URL, a "file:" URL, or a plain file path
     * @return a corresponding URL object
     * @throws FileNotFoundException if the resource cannot be resolved to a URL
     */
    public static URL getURL(String resourceLocation) throws FileNotFoundException {
     
        Assert.notNull(resourceLocation, "Resource location must not be null");
        if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) {
     
            String path = resourceLocation.substring(CLASSPATH_URL_PREFIX.length());
            ClassLoader cl = ClassUtils.getDefaultClassLoader();
            URL url = (cl != null ? cl.getResource(path) : ClassLoader.getSystemResource(path));
            if (url == null) {
     
                String description = "class path resource [" + path + "]";
                throw new FileNotFoundException(description +
                        " cannot be resolved to URL because it does not exist");
            }
            return url;
        }
        try {
     
            // try URL
            return new URL(resourceLocation);
        }
        catch (MalformedURLException ex) {
     
            // no URL -> treat as file path
            try {
     
                return new File(resourceLocation).toURI().toURL();
            }
            catch (MalformedURLException ex2) {
     
                throw new FileNotFoundException("Resource location [" + resourceLocation +
                        "] is neither a URL not a well-formed file path");
            }
        }
    }

通过源码，我们可以看出spring配置文件里这个locations是uri表示，也就是说我们写的logback-spring.xml是当前相对路径。

解决方案

spring配置文件里这个locations是相对路径，要访问classpath，要使用相对路径：

logging.config=classpath:logback-spring.xml