Logback & profiles

发表于 | 分类于

在不同环境使用不同的日志记录方式是常见的需求，而在 Spring 下可以使用 profiles 区分环境。但网上大多数教程是基于 Spring-boot 的，SpringMvc 似乎不支持 logback-spring.xml 的配置方式。好在还有其他方式来支持 logback-extensions

  1. 添加依赖 
    1
    2
    3
    4
    5
    <dependency>
    <groupId>org.logback-extensions</groupId>
    <artifactId>logback-ext-spring</artifactId>
    <version>${version}</version>
</dependency>
  2. 启动Logback 
    1
    2
    3
    4
    5
    6
    7
    8
    9
    public class Initializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        super.onStartup(servletContext);
        servletContext.addListener(LogbackConfigListener.class);
    }
...
}
  3. 配置Logback.xml 
    1
    2
    3
    4
    5
    6
    <configuration>
    <appender name="appender" class="ch.qos.logback.ext.spring.DelegatingLogbackAppender"/>
    <root level="INFO">
        <appender-ref ref="appender"/>
    </root>
</configuration>

    配置非常简单，仅仅是作为占位符，真正的配置在 Java 代码中，这也方便使用 Spring 的 profiles 功能

  4. Spring 配置 
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    @Configuration
public class LogbackConfig {

    @Bean 
    public static ApplicationContextHolder applicationContextHolder() {
        return new ApplicationContextHolder ();
    }

    @Bean 
    public static LoggerContext loggerContext() {
        return (LoggerContext) LoggerFactory.getILoggerFactory();
    }

    @Bean (initMethod = "start", destroyMethod = "stop")
    public static PatternLayoutEncoder encoder (LoggerContext ctx) {
        PatternLayoutEncoder encoder = new PatternLayoutEncoder();
        encoder.setContext(ctx);
        encoder.setPattern("%date %-5level \[%thread\] %logger{36} %m%n");
        return encoder;
    }

    @Bean (initMethod = "start", destroyMethod = "stop")
    public static ConsoleAppender appender (LoggerContext ctx, PatternLayoutEncoder encoder) {
        ConsoleAppender appender = new ConsoleAppender();
        appender.setContext(ctx);
        appender.setEncoder(encoder);
        return appender;
    }
}

    代码来自官方示例，需要注意的是配置 Appender 的 方法名必须和 logback.xml 中的引用相同。要使用 profiles 只需要配置多个 Appender ，但又必须同名，我的作法是拆分到不同类中。

  5. profiles 配置 
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    @Configuration
@Profile("prod")
public class LogbackConfigProd { 
    @Bean(initMethod = "start", destroyMethod = "stop")
    public static FileAppender appender(LoggerContext ctx, PatternLayoutEncoder encoder) {
    ... 
    }
}

@Configuration
@Profile("dev")
public class LogbackConfigDev {

    @Bean(initMethod = "start", destroyMethod = "stop")
    public static ConsoleAppender appender(LoggerContext ctx, PatternLayoutEncoder encoder) {
    ...
    }
}

@Configuration
@Import({LogbackConfigProd.class,LogbackConfigDev.class})
public class LogbackConfig {
...
}

2018-04-30 更新

需要和 logback.xml 中引用名相同的实际是 bean 的名字，所以可以通过指定 bean 名字来将多个 pattern 配置放在同一个类中：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
public class LogbackConfig {

    @Profile("dev")
    @Bean(initMethod = "start", destroyMethod = "stop", name = "appender")
    public static Appender<ILoggingEvent> consoleAppender(LoggerContext ctx, PatternLayoutEncoder encoder) {
        ...
    }

    @Profile("!dev")
    @Bean(initMethod = "start", destroyMethod = "stop", name = "appender")
    public static Appender<ILoggingEvent> fileAppender(LoggerContext ctx, PatternLayoutEncoder encoder{
        ...
    }

}

注意此时的方法名反而不能相同，否则构成方法重载，Spring 将忽略 @profile 注解而选择其中一个重载方法

NOTE: With {@code @Profile} on {@code @Bean} methods, a special scenario may apply: In the case of overloaded {@code @Bean} methods of the same Java method name (analogous to constructor overloading), an {@code @Profile} condition needs to be consistently declared on all overloaded methods. If the conditions are inconsistent, only the condition on the first declaration among the overloaded methods will matter. {@code @Profile} can therefore not be used to select an overloaded method with a particular argument signature over another; resolution between all factory methods for the same bean follows Spring’s constructor resolution algorithm at creation time. Use distinct Java method names pointing to the same {@link Bean#name bean name} if you’d like to define alternative beans with different profile conditions

参考链接：https://github.com/qos-ch/logback-extensions/wiki/Spring