SLF4j解决多个绑定

Question

在我的应用程序中，我将SLF4j用作日志门面，并且存在多个绑定，如下所示：

1. slf4j-simple-1.6.2.jar
2. logback-classic-1.0.4.jar

这两个都在pom.xml中定义为

    **<!--MANDATORY -->**
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.6.2</version>
    </dependency>

    **<!--SIMPLY DUMPS THE MESSAGE TO ERROR STREAM -->**
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>1.6.2</version>
    </dependency>

    **<!--logback : further configuration in logback.xml -->**
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-core</artifactId>
        <version>1.0.4</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.0.4</version>
    </dependency> 

一个简单的测试程序，可以在本地运行

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class TimePass {
    private Logger log = LoggerFactory.getLogger(getClass());
    public static void main(String[] args) {
        new TimePass().run();
    }

    private void run() {
        System.out.println(log);
        log.info("WE ARE RUNNING");
        System.out.println("HIHIHIHI");
    }

}

此项目/ webapp部署在2个位置。 但是，当我同时在两者上运行时，结果却截然不同。

On 1 instance, output is

    SLF4J: Class path contains multiple SLF4J bindings.
    SLF4J: Found binding in [jar:file:/home/hemant/.m2/repository/org/slf4j/slf4j-simple/1.6.2/slf4j-simple-1.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
    SLF4J: Found binding in [jar:file:/home/hemant/.m2/repository/ch/qos/logback/logback-classic/1.0.4/logback-classic-1.0.4.jar!/org/slf4j/impl/StaticLoggerBinder.class]
    SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
    0 [main] INFO com.expertly.bin.TimePass - WE ARE RUNNING
    org.slf4j.impl.SimpleLogger(com.expertly.bin.TimePass)
    HIHIHIHI

另一方面，它的

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/hemant/.m2/repository/ch/qos/logback/logback-classic/1.0.4/logback-classic-1.0.4.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/hemant/.m2/repository/org/slf4j/slf4j-simple/1.6.2/slf4j-simple-1.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
14:58:18,760 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback.groovy]
14:58:18,760 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback-test.xml]
14:58:18,760 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Found resource [logback.xml] at [file:/home/hemant/Project/Expertly/ee/workspace/branches/integration/target/ROOT/WEB-INF/classes/logback.xml]
14:58:18,823 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - debug attribute not set
14:58:18,827 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.classic.sift.SiftingAppender]
14:58:18,831 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [SIFT]
14:58:18,853 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.sift.MDCBasedDiscriminator] for [discriminator] property
14:58:18,859 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.core.rolling.RollingFileAppender]
14:58:18,862 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [FILE-HIBERNATE]
14:58:18,868 |-ERROR in ch.qos.logback.core.joran.spi.Interpreter@59:13 - no applicable action for [Encoding], current pattern is [[configuration][appender][Encoding]]
14:58:18,897 |-WARN in ch.qos.logback.core.rolling.RollingFileAppender[FILE-HIBERNATE] - This appender no longer admits a layout as a sub-component, set an encoder instead.
14:58:18,897 |-WARN in ch.qos.logback.core.rolling.RollingFileAppender[FILE-HIBERNATE] - To ensure compatibility, wrapping your layout in LayoutWrappingEncoder.
14:58:18,897 |-WARN in ch.qos.logback.core.rolling.RollingFileAppender[FILE-HIBERNATE] - See also http://logback.qos.ch/codes.html#layoutInsteadOfEncoder for details
14:58:18,905 |-INFO in ch.qos.logback.core.rolling.FixedWindowRollingPolicy@1fc6e42 - Will use zip compression
14:58:18,910 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILE-HIBERNATE] - Active log file name: catalina.base_IS_UNDEFINED/logs/hibernate.log
14:58:18,910 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILE-HIBERNATE] - File property is set to [catalina.base_IS_UNDEFINED/logs/hibernate.log]
14:58:18,911 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.classic.net.SMTPAppender]
14:58:18,918 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [EMAIL]
14:58:18,937 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to ERROR
14:58:18,937 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [EMAIL] to Logger[ROOT]
14:58:18,937 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting level of logger [org.hibernate.type] to INFO
14:58:18,937 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting additivity of logger [org.hibernate.type] to false
14:58:18,937 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE-HIBERNATE] to Logger[org.hibernate.type]
14:58:18,937 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting level of logger [org.hibernate] to INFO
14:58:18,938 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting additivity of logger [org.hibernate] to false
14:58:18,938 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE-HIBERNATE] to Logger[org.hibernate]
14:58:18,938 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to DEBUG
14:58:18,938 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [SIFT] to Logger[ROOT]
14:58:18,938 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - End of configuration.
14:58:18,939 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@1aaf0b3 - Registering current configuration as safe fallback point

Logger[com.expertly.bin.TimePass]
HIHIHIHI

在这两种情况下似乎都存在问题，征用了多个绑定，但是顺序不同。

**在情况1中：它记录的位置：1. slf4j-simple-1.6.2.jar 2. logback-classic-1.0.4.jar并使用了第一次绑定来记录日志

在案例2中：它没有记录日志，其顺序相反，因此它去寻找logback.xml并且无法解析web容器特定的变量（$ {catalina.home}）**

我不知道这种逆转的原因。

我需要两个绑定。 以防万一，当我本机运行Java文件时，我希望slf4j-simple绑定位于logback绑定之前。

提前致谢。

Answer 1

如错误消息中指出的页面中所述 ，这不是一个好主意。 引用该页面上的注释：

SLF4J发出的警告就是警告。 即使存在多个绑定，SLF4J也会选择一个日志记录框架/实现并与其绑定。 SLF4J选择绑定的方式由JVM确定，出于所有实际目的，应将其视为随机的。 从1.6.6版开始，SLF4J将命名其实际绑定到的框架/实现类。