Place the log4j configuration file outside the project

Why the profile is placed outside the project

在项目开发阶段，我们使用的是测试区的数据库，FTP 等等 资源。在项目上线时，自然要切换到正式区。 如果配置文件写在项目里面，那么发布时就要变更代码，修改链接地址。所以讲配置文件放在项目之外，就可以解决这个问题了。

Why to dynamically configure the path of log4j.properties

因为目前我的项目要给多个外包厂用，部署到多个服务器上。 因外包厂服务器安装目录不同，各自的命令规范也无法统一。

Therefore, the client needs to make the log path location.

Basic ideas

* 在tomcat的context.xml中 新增一个变量，维护log4j的位置.* 在项目启动加载时，根据路径读取log4j的文件，重新定义log4j配置文件.

Configuring Tomcat's Context.xml

• Context.xml New Line

<br /><Environment name="myLog4jPath" override="false" type="java.lang.String" value="/opt/conf/log4j.properties"/> <br />

Create a MAVEN project

• Pom.xml

  Note: log4j if 1.2.17 or above, otherwise not supported

  <dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>3.8.1</version>      <scope>test</scope>    </dependency>    <dependency>        <groupId>log4j</groupId>        <artifactId>log4j</artifactId>        <version>1.2.17</version>    </dependency>    <dependency>        <groupId>javax.servlet</groupId>        <artifactId>servlet-api</artifactId>        <version>2.5</version>        <scope>provided</scope>    </dependency></dependencies><build>    <finalName>MyLogger</finalName>  </build>

New servlet

Package Com;import Java.io.file;import Java.io.fileinputstream;import java.io.ioexception;import Java.io.inputstream;import Java.io.printwriter;import Javax.naming.context;import Javax.naming.InitialContext; Import Javax.naming.namingexception;import Javax.servlet.servletexception;import Javax.servlet.http.HttpServlet; Import Javax.servlet.http.httpservletrequest;import Javax.servlet.http.httpservletresponse;import Org.apache.log4j.logger;import Org.apache.log4j.propertyconfigurator;public class Myloggerservlet extends HttpServlet {private static final long Serialversionuid = 1l;private Logger Logger = Logger.getlogger (myloggerservlet.cla    SS);/** * @see httpservlet#httpservlet () */public Myloggerservlet () {Context initctx = null;    String config = null;    InputStream is = null;    Context envctx = null;        try {initctx = new InitialContext ();        Envctx = (Context) initctx.lookup ("java:comp/env");        Config = (String) envctx.lookup ("Mylog4jpath"); is = new FileInputStream (The new File (config));        Propertyconfigurator.configure (IS);    Logger.info ("========================config file path=============" + config);    } catch (Exception ex) {Logger.error (ex.tostring ());            } finally {if (envctx! = null) {try {envctx.close ();            } catch (Namingexception e) {e.printstacktrace ();            }} if (Initctx! = null) {try {initctx.close ();            } catch (Namingexception e) {e.printstacktrace (); }}}}/** * @see httpservlet#doget (httpservletrequest request, HttpServletResponse * response) */protected void Doget (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {prin    Twriter pw = Response.getwriter ();    Logger.info ("Hello servlet, Hello log4j");    Pw.write ("Okok"); Pw.flush ();} /** * @see Httpservlet#dopost (httpservletrEquest request, HttpServletResponse * response) */protected void DoPost (HttpServletRequest request, Httpservle Tresponse response) throws Servletexception, IOException {doget (request, response);}

}

`

Xml

<servlet>    <servlet-name>MyLoggerServlet</servlet-name>    <display-name>MyLoggerServlet</display-name>    <description></description>    <servlet-class>com.MyLoggerServlet</servlet-class></servlet><servlet-mapping>    <servlet-name>MyLoggerServlet</servlet-name>    <url-pattern>/MyLoggerServlet</url-pattern></servlet-mapping>

Test

The servlet loads the/opt/conf/log4j.properties file at the first call and prints the log to the specified directory
Http://localhost:8080/MyLogger/MyLoggerServlet

Place the log4j configuration file outside the project