最近将一个旧系统的日志框架从 Log4j 升级至 Log4j 2，发现部分在 Log4j 2 中未配置的日志信息（DEBUG / INFO）打印在控制台上，本文介绍屏蔽这些额外日志打印的方法。
Spring 框架打印日志
...
2019-02-25 10:10:02,605 DEBUG [org.springframework.core.env.StandardEnvironment] - Adding [systemProperties] PropertySource with lowest search precedence
2019-02-25 10:10:02,607 DEBUG [org.springframework.core.env.StandardEnvironment] - Adding [systemEnvironment] PropertySource with lowest search precedence
2019-02-25 10:10:02,608 DEBUG [org.springframework.core.env.StandardEnvironment] - Initialized StandardEnvironment with PropertySources [systemProperties,systemEnvironment]
2019-02-25 10:10:02,609 INFO [org.springframework.context.support.ClassPathXmlApplicationContext] - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@6b927fb: startup date [Mon Feb 25 10:10:02 GMT+08:00 2019]; root of context hierarchy
2019-02-25 10:10:02,663 DEBUG [org.springframework.core.env.StandardEnvironment] - Adding [systemProperties] PropertySource with lowest search precedence
2019-02-25 10:10:02,663 DEBUG [org.springframework.core.env.StandardEnvironment] - Adding [systemEnvironment] PropertySource with lowest search precedence
2019-02-25 10:10:02,663 DEBUG [org.springframework.core.env.StandardEnvironment] - Initialized StandardEnvironment with PropertySources [systemProperties,systemEnvironment]
2019-02-25 10:10:02,717 INFO [org.springframework.beans.factory.xml.XmlBeanDefinitionReader] - Loading XML bean definitions from class path resource [xxx.xml]
2019-02-25 10:10:02,782 DEBUG [org.springframework.beans.factory.xml.DefaultDocumentLoader] - Using JAXP provider [com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl]
...
解决思路：
- 首先选取一条日志信息，定位源码所在包，如
org.springframework.beans.factory.xml.XmlBeanDefinitionReader在spring-beans中。 - 查看
XmlBeanDefinitionReader源码，定位日志Loading XML bean definitions from class path resource所在位置。
public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {
Assert.notNull(encodedResource, "EncodedResource must not be null");
if (this.logger.isInfoEnabled()) {
this.logger.info("Loading XML bean definitions from " + encodedResource.getResource());
}
......
- 定位
logger对象所属 API
package org.springframework.beans.factory.support;
import java.io.IOException;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.core.env.Environment;
import org.springframework.core.env.EnvironmentCapable;
import org.springframework.core.env.StandardEnvironment;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.util.Assert;
public abstract class AbstractBeanDefinitionReader implements EnvironmentCapable, BeanDefinitionReader {
protected final Log logger = LogFactory.getLog(this.getClass());
......
发现这段日志是通过 Apache Commons Logging（原名：Jakarta Commons Logging，JCL）打印出来的。JCL 只提供 log 接口，具体实现在运行时动态寻找。但是当程序规模越来越大后，JCL 的动态绑定不是总能成功，所有 SLF4J 诞生了，与 JCL 的不同之处在于 SLF4J 在程序部署时静态绑定指定的日志工具。
因为此次升级也同时使用了 SLF4J，因此需要一个桥接器组件将 JCL 的日志输出重定向到 SLF4J。如果使用 Maven 则添加以下依赖，或者直接下载 jcl-over-slf4j.jar 放入工程 CLASSPATH。
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>1.7.25</version>
</dependency>
Hibernate 框架打印日志
...
2019-02-25 16:27:54,602 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration boolean -> org.hibernate.type.BooleanType@4832f03b
2019-02-25 16:27:54,602 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration boolean -> org.hibernate.type.BooleanType@4832f03b
2019-02-25 16:27:54,603 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration java.lang.Boolean -> org.hibernate.type.BooleanType@4832f03b
2019-02-25 16:27:54,604 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration numeric_boolean -> org.hibernate.type.NumericBooleanType@5115f590
2019-02-25 16:27:54,606 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration true_false -> org.hibernate.type.TrueFalseType@2ff7a73
2019-02-25 16:27:54,607 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration yes_no -> org.hibernate.type.YesNoType@3a790e40
2019-02-25 16:27:54,617 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration byte -> org.hibernate.type.ByteType@60c73e58
2019-02-25 16:27:54,617 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration byte -> org.hibernate.type.ByteType@60c73e58
2019-02-25 16:27:54,617 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration java.lang.Byte -> org.hibernate.type.ByteType@60c73e58
2019-02-25 16:27:54,620 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration character -> org.hibernate.type.CharacterType@4483d35
2019-02-25 16:27:54,621 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration char -> org.hibernate.type.CharacterType@4483d35
2019-02-25 16:27:54,621 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration java.lang.Character -> org.hibernate.type.CharacterType@4483d35
2019-02-25 16:27:54,623 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration short -> org.hibernate.type.ShortType@3762c4fc
2019-02-25 16:27:54,623 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration short -> org.hibernate.type.ShortType@3762c4fc
2019-02-25 16:27:54,624 DEBUG [org.hibernate.type.BasicTypeRegistry] - Adding type registration java.lang.Short -> org.hibernate.type.ShortType@3762c4fc
...
解决思路和 Spring 框架日志定位思路类似：
- 首先选取一条日志信息，定位源码所在包，如
org.hibernate.type.BasicTypeRegistry在hibernate-core中。 - 查看
BasicTypeRegistry源码，定位日志Adding type registration所在位置。
public void register(BasicType type) {
if (this.locked) {
throw new HibernateException("Can not alter TypeRegistry at this time");
} else if (type == null) {
throw new HibernateException("Type to register cannot be null");
} else {
if (type.getRegistrationKeys() == null || type.getRegistrationKeys().length == 0) {
LOG.typeDefinedNoRegistrationKeys(type);
}
String[] arr$ = type.getRegistrationKeys();
int len$ = arr$.length;
for(int i$ = 0; i$ < len$; ++i$) {
String key = arr$[i$];
if (key != null) {
LOG.debugf("Adding type registration %s -> %s", key, type);
Type old = (Type)this.registry.put(key, type);
if (old != null && old != type) {
LOG.typeRegistrationOverridesPrevious(key, old);
}
}
}
}
}
- 定位
LOG对象所属 API。
import java.io.Serializable;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.hibernate.HibernateException;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.usertype.CompositeUserType;
import org.hibernate.usertype.UserType;
import org.jboss.logging.Logger;
public class BasicTypeRegistry implements Serializable {
private static final CoreMessageLogger LOG = (CoreMessageLogger)Logger.getMessageLogger(CoreMessageLogger.class, BasicTypeRegistry.class.getName());
发现这段日志是通过 JBoss Logging 打印出来的。
Hibernate 日志加载顺序：
JBoss 日志实现 -> Log4j 2 -> Log4j -> SLF4J -> java.util.logging
为了让 Hibernate 使用 Log4j 2 输出日志，有两种解决方案：
- 将
jboss-logging依赖升级到3.2以上版本，如：
<dependency>
<groupId>org.jboss.logging</groupId>
<artifactId>jboss-logging</artifactId>
<version>3.3.2.Final</version>
</dependency>
- 配置系统属性：
jboss.logging.provider=slf4j
