log4j 的配置文件以及在代碼中的使用 log4j.properties

1、先引入相關的jar包依賴
只引入下面的兩個也可以，源代碼如下：

        <dependency>
		   <groupId>org.slf4j</groupId>
		   <artifactId>slf4j-api</artifactId>
		   <version>1.7.7</version>
		</dependency>
		<!-- For log4j -->
	    <dependency>
	        <groupId>org.slf4j</groupId>
	        <artifactId>slf4j-log4j12</artifactId>
	        <version>1.7.7</version>
	    </dependency>
	    <dependency>
	        <groupId>log4j</groupId>
	        <artifactId>log4j</artifactId>
	        <version>1.2.17</version>
	    </dependency>

2、編寫log4j配置文件log4j.properties

代碼如下：

### \u8bbe\u7f6e###
log4j.rootLogger = debug,D,E

### \u8f93\u51fa\u4fe1\u606f\u5230\u63a7\u5236\u62ac ###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

### \u8f93\u51faDEBUG \u7ea7\u522b\u4ee5\u4e0a\u7684\u65e5\u5fd7\u5230=E://logs/error.log ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = F:/logs/log.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = INFO
log4j.appender.D.ImmediateFlush = true
log4j.appender.D.DatePattern='.'yyyy-MM-dd
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

### \u8f93\u51faERROR \u7ea7\u522b\u4ee5\u4e0a\u7684\u65e5\u5fd7\u5230=E://logs/error.log ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =F:/logs/error.log
log4j.appender.E.Append = true
log4j.appender.E.Threshold = ERROR
log4j.appender.E.ImmediateFlush = true
log4j.appender.E.DatePattern='.'yyyy-MM-dd
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

3、在程序中的使用
在控制器類中先定義 log，在每個方法中使用它。


代碼如下：

private static Logger log = LogManager.getLogger(SysUserController.class);

public AjaxResult addUser(HttpServletRequest request,HttpServletResponse response,SysUserDto userDto){
		try{
			SysUser user = userDto.convertUser();
			user.setId(GenerateID.getIdByUUID());
			
			userService.addUser(user);
		}catch(Exception e){
			AjaxResult ajaxResult = AjaxResult.error();
			e.printStackTrace();
			log.error("添加用戶:", e);  //這一句就是生成錯誤日誌信息
			return ajaxResult;
		}
		
		return AjaxResult.success();
	}

最後在 定義的日誌文件輸出路徑下可以看到日誌，比如上面配置文件中我定義的是 F:/logs/log.log F:/logs/error.log