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整合日志
========

将Spring与日志框架整合，通过控制台输出Spring运行过程中的重要信息，便于调试和纠错：

- Spring1/2/3
  - commons-logging
- Spring4/5
  - 默认logback/log4j2
  - log4j

1 添加依赖

/pom.xml：

...
<dependency>                               \
    <groupId>org.slf4j</groupId>           | 日志门面
    <artifactId>slf4j-log4j12</artifactId> | 屏蔽默认的
    <version>1.7.25</version>              | logback/log4j2
</dependency>                              /
<dependency>                               \
    <groupId>log4j</groupId>               |
    <artifactId>log4j</artifactId>         | log4j
    <version>1.2.17</version>              |
</dependency>                              /
...

2 添加配置

/src/main/resources/log4j.properties：

log4j.rootLogger = debug,console

log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss} %-5p %l - %m%n
                                                       |  |  |  |  |  |   |    |    |  |
                                                      年 月 日 时 分 秒 级别 位置 消息 换行

3 打印日志

/src/test/java/cn/tedu/log/StudentTest.java：

class StudentTest {
    private Logger logger = Logger.getLogger(StudentTest.class);

    @org.junit.jupiter.api.Test
    void test() {
        ApplicationContext applicationContext =
            new ClassPathXmlApplicationContext("/applicationContext.xml");
        Student student = applicationContext.getBean("student", Student.class);
        logger.debug(student);
    }
}

2022-04-20 15:01:43 DEBUG org.springframework.context.support.AbstractApplicationContext.prepareRefresh(AbstractApplicationContext.java:590) - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7ff95560
2022-04-20 15:01:43 DEBUG org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:395) - Loaded 1 bean definitions from class path resource [applicationContext.xml]
2022-04-20 15:01:43 DEBUG org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:213) - Creating shared instance of singleton bean 'student'
2022-04-20 15:01:43 DEBUG cn.tedu.log.StudentTest.test(StudentTest.java:15) - cn.tedu.log.Student@7770f470

例程：Log