查看“JUL 配置文件入门”的源代码

https://www.bilibili.com/video/BV1iJ411H74S?p=8

=== 默认配置文件调用 ===
Logger.getLogger(String name) ->

Logger.demandLogger(String name, String resourceBundleName, Class<?> caller) ->

LogManager.getLogManager() ->

manager.ensureLogManagerInitialized() ->

owner.readPrimordialConfiguration()->

readConfiguration()->

f = new File(f, "logging.properties")

I:\Java\jdk1.8.0_101\jre\lib\logging.properties





=== 加载自定义配置文件 ===

==== src/main/resources/logging.properties ====
<syntaxhighlight lang="properties">
handlers= java.util.logging.ConsoleHandler


.level= ALL



# default file output is in user's home directory.
java.util.logging.FileHandler.pattern = %h/java%u.log
java.util.logging.FileHandler.limit = 50000
java.util.logging.FileHandler.count = 1
java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter

# Limit the message that are printed on the console to INFO and above.
java.util.logging.ConsoleHandler.level = ALL
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
</syntaxhighlight>

==== JULTest.java ====
<syntaxhighlight lang="java">
    //加载自定义配置文件
    @Test
    public void testLogProperties() throws IOException {
        // 读取配置文件，通过类加载器
        InputStream resourceAsStream = JULTest.class.getClassLoader().getResourceAsStream("logging.properties");
        // 创建 LogManager
        LogManager logManager = LogManager.getLogManager();
        // 通过 LogManager 加载配置文件
        logManager.readConfiguration(resourceAsStream);

        // 创建日志记录器
        Logger logger = Logger.getLogger("io.github.jihch");

        logger.severe("severe");
        logger.warning("warning");
        logger.info("info");
        logger.config("config");
        logger.fine("fine");
        logger.finer("finer");
        logger.finest("finest");
    }
</syntaxhighlight><syntaxhighlight lang="console">
二月 23, 2023 8:58:36 上午 io.github.jihch.JULTest test01
严重: severe
二月 23, 2023 8:58:36 上午 io.github.jihch.JULTest test01
警告: warning
二月 23, 2023 8:58:36 上午 io.github.jihch.JULTest test01
信息: info
二月 23, 2023 8:58:36 上午 io.github.jihch.JULTest test01
配置: config
二月 23, 2023 8:58:36 上午 io.github.jihch.JULTest test01
详细: fine
二月 23, 2023 8:58:36 上午 io.github.jihch.JULTest test01
较详细: finer
二月 23, 2023 8:58:36 上午 io.github.jihch.JULTest test01
非常详细: finest
</syntaxhighlight>




=== 添加 Handler ===
logging.properties<syntaxhighlight lang="properties">
handlers= java.util.logging.ConsoleHandler,java.util.logging.FileHandler


.level= ALL



# default file output is in user's home directory.
java.util.logging.FileHandler.pattern = java%u.log
java.util.logging.FileHandler.limit = 50000
java.util.logging.FileHandler.count = 1
java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter

# Limit the message that are printed on the console to INFO and above.
java.util.logging.ConsoleHandler.level = ALL
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
</syntaxhighlight>这样将在项目根目录下增加日志文件的输出

关键点是在 handlers 后面追加了下面的 FileHandler