Java 记录日志

 1 package test;
 2 
 3 import java.io.IOException;
 4 import java.util.logging.FileHandler;
 5 import java.util.logging.Level;
 6 import java.util.logging.Logger;
 7 
 8 public class Test{
 9        public static void main(String[] args) throws IOException {
10               //设置使用a.xml文件保存日志,会在项目的根目录下生成一个a.xml文件来保存日志。也可指定其他目录。
11               // "fkjava"是特定的字符串。
12               Logger.getLogger("fkjava").addHandler(new FileHandler("a.xml"));
13               //设置日志级别为WARNING，低于WARNING的日志都会被忽略
14               Logger.getLogger("fkjava").setLevel(Level.WARNING);
15               //使用System的静态方法获取System.Logger对象，用于输出日志
16               System.Logger logger=System.getLogger("fkjava");
17               //输出一条日志，第一个参数设置此条日志的级别，第二个参数为String，设置要输出的日志信息。
18               // 由于DEBUG低于设置的WARNING,所以此条日志会被忽略（不会被输出到a.xml文件）
19               logger.log(System.Logger.Level.DEBUG,"debug信息");
20               //debug、run时，会在控制台输出此条日志，“警告：warning信息"，冒号后面是第二个参数的内容
21               //同时会输出此条日志到a.xml文件中
22               logger.log(System.Logger.Level.WARNING,"warning信息");
23               logger.log(System.Logger.Level.ERROR,"error信息");
24        }
25 }

D:\jdk-12.0.1\bin\java.exe -agentlib:jdwp=transport=dt_socket,address=127.0.0.1:52275,suspend=y,server=n -javaagent:C:\Users\chy\.IntelliJIdea2019.1\system\captureAgent\debugger-agent.jar -Dfile.encoding=UTF-8 -classpath "D:\疯狂Java讲义\untitled\out\production\untitled;C:\Program Files\JetBrains\IntelliJ IDEA 2019.1.1\lib\idea_rt.jar" test.Test
Connected to the target VM, address: '127.0.0.1:52275', transport: 'socket'
Java HotSpot(TM) 64-Bit Server VM warning: Sharing is only supported for boot loader classes because bootstrap classpath has been appended
5月 14, 2019 2:20:35 上午 test.Test main
警告: warning信息
5月 14, 2019 2:20:35 上午 test.Test main
严重: error信息
Disconnected from the target VM, address: '127.0.0.1:52275', transport: 'socket'

Process finished with exit code 0

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE log SYSTEM "logger.dtd">
<log>
<record>
  <date>2019-05-13T18:20:35.025273100Z</date>
  <millis>1557771635025</millis>
  <nanos>273100</nanos>
  <sequence>0</sequence>
  <logger>fkjava</logger>
  <level>WARNING</level>
  <class>test.Test</class>
  <method>main</method>
  <thread>1</thread>
  <message>warning信息</message>
</record>
<record>
  <date>2019-05-13T18:20:35.164415700Z</date>
  <millis>1557771635164</millis>
  <nanos>415700</nanos>
  <sequence>1</sequence>
  <logger>fkjava</logger>
  <level>SEVERE</level>
  <class>test.Test</class>
  <method>main</method>
  <thread>1</thread>
  <message>error信息</message>
</record>
</log>