Java Web 学习笔记(6)

JavaWeb Spring SpringMVC log4j

本节讲述使用log4j2，其实和.net下的使用log4net用法差不多，只是要注意下配置文件位置。
配置寻找原则如下

首先在test\resources下添加log4j2-test.xml

内容如下

<?xml version="1.0" encoding="UTF-8"?>
<configuration status="WARN">
    <appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout
                    pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
        </Console>
    </appenders>
    <loggers>
        <root level="debug">
            <appender-ref ref="Console"/>
        </root>
    </loggers>
</configuration>

在GreetServlet中添加日志，代码如下

public class GreetServlet extends HttpServlet {
    private static final Logger log = LogManager.getLogger();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        log.warn("Action GreetServlet not supported.");
        log.error("Action GreetServlet Error.");
        req.getRequestDispatcher("/WEB-INF/jsp/Greet.jsp")
                .forward(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().println("Hello Post From GreetServlet");
    }
}

运行程序，在浏览器输入localhost:8080\greet，会在Console输出看到如下日志，因为配置中leve是debug，所以只看到Error的日志输出，看不到info的日志输出

PS:添加配置到test/resources注意，文件夹要设置成Test Resources而不是Resources,不然会覆盖掉production/resources下面的配置。如下

添加log4j2.xml配置

添加log4j2.xml到src\production\resources下，内容如下，可以输出到tomcat的log的目录下。配置和之前使用的log4net差别不大，不在赘述。

<?xml version="1.0" encoding="UTF-8"?>
<configuration status="WARN">
    <appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout
                    pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
        </Console>
        <RollingFile name="WroxFileAppender" fileName="../logs/application.log"
                     filePattern="../logs/application-%d{MM-dd-yyyy}-%i.log">
            <PatternLayout>
                <pattern>%d{HH:mm:ss.SSS} [%t] %X{id} %X{username} %-5level %c{36} %l: %msg%n</pattern>
            </PatternLayout>
            <Policies>
                <SizeBasedTriggeringPolicy size="10 MB" />
            </Policies>
            <DefaultRolloverStrategy min="1" max="4" />
        </RollingFile>
    </appenders>
    <loggers>
        <root level="warn">
            <appender-ref ref="Console" />
        </root>
        <logger name="com.liuyb" level="info" additivity="false">
            <appender-ref ref="WroxFileAppender" />
            <appender-ref ref="Console">
            </appender-ref>
        </logger>
        <logger name="org.apache" level="info">
            <appender-ref ref="WroxFileAppender" />
        </logger>
    </loggers>
</configuration>