JUL默认的配置文件 在我们没有手动配置的情况下读取的都是JDK的配置文件image.png
我们目前有两种方式给logger进行相应的配置:
1.通过代码进行配置
2.读取配置文件:
a. 如果没有指明配置文件 则默认按jdk的配置文件去配置
b. 手动添加logging.properties配置文件

怎么样让logger去读指明的配置文件呢?

首先先把jdk的logging.properties配置文件复制一份到我们的项目里
放在resources中 image.png

  1. public void testProperties() throws Exception {
  2.     // 读取自定义配置文件
  3.     InputStream in =
  4.  JULTest.class.getClassLoader().getResourceAsStream("logging.properties");
  5.     // 获取日志管理器对象
  6.     LogManager logManager = LogManager.getLogManager();
  7.     // 通过日志管理器加载配置文件
  8.     logManager.readConfiguration(in);
  9.     Logger logger = Logger.getLogger("com.ydlclass.log.JULTest");
  10.     logger.severe("severe");
  11.     logger.warning("warning");
  12.     logger.info("info");
  13.     logger.config("config");
  14.     logger.fine("fine");
  15.     logger.finer("finer");
  16.     logger.finest("finest");
  17. }
  1.  // 读取自定义配置文件  读取properties文件的留
  2.     InputStream in =
  3.         JULTest.class.getClassLoader().getResourceAsStream("logging.properties");
  4.     // 获取日志管理器对象
  5.     LogManager logManager = LogManager.getLogManager();
  6.     // 通过日志管理器加载配置文件  将流文件传进去
  7.     logManager.readConfiguration(in);

从这行下面的代码 只要获取logger的代码都会默认从我们的配置文件去读取配置
记得更改输出方式ConsoleHandler和FileHandlerimage.png
然后还要进一步配置流, 文件存储位置
//查看FileHandler发现是已占位符的形式存储
image.png
//进一步可以设置 输出文件 和 输出的格式image.png

———————————————————————————————————————
我们不妨看看一个文件处理器的源码是怎么读配置项的：

  1. private void configure() {
  2.         LogManager manager = LogManager.getLogManager();
  4.         String cname = getClass().getName();
  6.         pattern = manager.getStringProperty(cname + ".pattern", "%h/java%u.log");
  7.         limit = manager.getLongProperty(cname + ".limit", 0);
  8.         if (limit < 0) {
  9.             limit = 0;
  10.         }
  11.         count = manager.getIntProperty(cname + ".count", 1);
  12.         if (count <= 0) {
  13.             count = 1;
  14.         }
  15.         append = manager.getBooleanProperty(cname + ".append", false);
  16.         setLevel(manager.getLevelProperty(cname + ".level", Level.ALL));
  17.         setFilter(manager.getFilterProperty(cname + ".filter", null));
  18.         setFormatter(manager.getFormatterProperty(cname + ".formatter", new XMLFormatter()));
  19.         // Initialize maxLocks from the logging.properties file.
  20.         // If invalid/no property is provided 100 will be used as a default value.
  21.         maxLocks = manager.getIntProperty(cname + ".maxLocks", MAX_LOCKS);
  22.         if(maxLocks <= 0) {
  23.             maxLocks = MAX_LOCKS;
  24.         }
  25.         try {
  26.             setEncoding(manager.getStringProperty(cname +".encoding", null));
  27.         } catch (Exception ex) {
  28.             try {
  29.                 setEncoding(null);
  30.             } catch (Exception ex2) {
  31.                 // doing a setEncoding with null should always work.
  32.                 // assert false;
  33.             }
  34.         }
  35.     }

可以从以下源码中看到配置项：

  1. public class FileHandler extends StreamHandler {
  2.     private MeteredStream meter;
  3.     private boolean append;
  4.     // 限制文件大小
  5.     private long limit;       // zero => no limit.
  6.     // 控制日志文件的数量
  7.     private int count;
  8.     // 日志文件的格式化方式
  9.     private String pattern;
  10.     private String lockFileName;
  11.     private FileChannel lockFileChannel;
  12.     private File files[];
  13.     private static final int MAX_LOCKS = 100;
  14.     // 可以理解为同时可以有多少个线程打开文件，源码中有介绍
  15.     private int maxLocks = MAX_LOCKS;
  16.     private static final Set<String> locks = new HashSet<>();
  17. }

我们已经知道系统默认的配置文件的位置，那我们能不能自定义呢？当然可以了，我们从jdk中赋值一个配置文件过来：

  1. .level= INFO
  3. # default file output is in user's home directory.
  4. java.util.logging.FileHandler.pattern = %h/java%u.log
  5. java.util.logging.FileHandler.limit = 50000
  6. java.util.logging.FileHandler.count = 1
  8. # Default number of locks FileHandler can obtain synchronously.
  9. # This specifies maximum number of attempts to obtain lock file by FileHandler
  10. # implemented by incrementing the unique field %u as per FileHandler API documentation.
  11. java.util.logging.FileHandler.maxLocks = 100
  12. java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter
  14. # Limit the message that are printed on the console to INFO and above.
  15. java.util.logging.ConsoleHandler.level = INFO
  16. java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
  18. # java.util.logging.SimpleFormatter.format=%4$s: %5$s [%1$tc]%n
  1. pattern = manager.getStringProperty(cname + ".pattern", "%h/java%u.log");
  1. static File generate(String pat, int count, int generation, int unique)
  2.             throws IOException
  3. {
  4.     Path path = Paths.get(pat);
  5.     Path result = null;
  6.     boolean sawg = false;
  7.     boolean sawu = false;
  8.     StringBuilder word = new StringBuilder();
  9.     Path prev = null;
  10.     for (Path elem : path) {
  11.         if (prev != null) {
  12.             prev = prev.resolveSibling(word.toString());
  13.             result = result == null ? prev : result.resolve(prev);
  14.         }
  15.         String pattern = elem.toString();
  16.         int ix = 0;
  17.         word.setLength(0);
  18.         while (ix < pattern.length()) {
  19.             char ch = pattern.charAt(ix);
  20.             ix++;
  21.             char ch2 = 0;
  22.             if (ix < pattern.length()) {
  23.                 ch2 = Character.toLowerCase(pattern.charAt(ix));
  24.             }
  25.             if (ch == '%') {
  26.                 if (ch2 == 't') {
  27.                     String tmpDir = System.getProperty("java.io.tmpdir");
  28.                     if (tmpDir == null) {
  29.                         tmpDir = System.getProperty("user.home");
  30.                     }
  31.                     result = Paths.get(tmpDir);
  32.                     ix++;
  33.                     word.setLength(0);
  34.                     continue;
  35.                 } else if (ch2 == 'h') {
  36.                     result = Paths.get(System.getProperty("user.home"));
  37.                     if (jdk.internal.misc.VM.isSetUID()) {
  38.                         // Ok, we are in a set UID program.  For safety's sake
  39.                         // we disallow attempts to open files relative to %h.
  40.                         throw new IOException("can't use %h in set UID program");
  41.                     }
  42.                     ix++;
  43.                     word.setLength(0);
  44.                     continue;
  45.                 } else if (ch2 == 'g') {
  46.                     word = word.append(generation);
  47.                     sawg = true;
  48.                     ix++;
  49.                     continue;
  50.                 } else if (ch2 == 'u') {
  51.                     word = word.append(unique);
  52.                     sawu = true;
  53.                     ix++;
  54.                     continue;
  55.                 } else if (ch2 == '%') {
  56.                     word = word.append('%');
  57.                     ix++;
  58.                     continue;
  59.                 }
  60.             }
  61.             word = word.append(ch);
  62.         }
  63.         prev = elem;
  64.     }
  66.     if (count > 1 && !sawg) {
  67.         word = word.append('.').append(generation);
  68.     }
  69.     if (unique > 0 && !sawu) {
  70.         word = word.append('.').append(unique);
  71.     }
  72.     if (word.length() > 0) {
  73.         String n = word.toString();
  74.         Path p = prev == null ? Paths.get(n) : prev.resolveSibling(n);
  75.         result = result == null ? p : result.resolve(p);
  76.     } else if (result == null) {
  77.         result = Paths.get("");
  78.     }
  80.     if (path.getRoot() == null) {
  81.         return result.toFile();
  82.     } else {
  83.         return path.getRoot().resolve(result).toFile();
  84.     }
  85. }

System.out.println(System.getProperty(“user.home”) );
输出内容:C:\Users\zn\java0.log
我们将拷贝的文件稍作修改：

  1. .level= INFO
  3. # default file output is in user's home directory.
  4. java.util.logging.FileHandler.pattern = D:/log/java%u.log
  5. java.util.logging.FileHandler.limit = 50000
  6. java.util.logging.FileHandler.count = 1
  7. java.util.logging.FileHandler.maxLocks = 100
  8. java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter
  10. # Limit the message that are printed on the console to INFO and above.
  11. java.util.logging.ConsoleHandler.level = INFO
  12. java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
  14. # java.util.logging.SimpleFormatter.format=%4$s: %5$s [%1$tc]%n
  1. public void testProperties() throws Exception {
  2.     // 读取自定义配置文件
  3.     InputStream in =
  4.         JULTest.class.getClassLoader().getResourceAsStream("logging.properties");
  5.     // 获取日志管理器对象
  6.     LogManager logManager = LogManager.getLogManager();
  7.     // 通过日志管理器加载配置文件
  8.     logManager.readConfiguration(in);
  9.     Logger logger = Logger.getLogger("com.ydlclass.log.JULTest");
  10.     logger.severe("severe");
  11.     logger.warning("warning");
  12.     logger.info("info");
  13.     logger.config("config");
  14.     logger.fine("fine");
  15.     logger.finer("finer");
  16.     logger.finest("finest");

image.png
文件中也出现了：image.png
打开日志发现是xml，因为这里用的就是XMLFormatter：
image.png
上边我们配置了两个handler给根Logger，我们还可以给其他的Logger做独立的配置：

  1. handlers = java.util.logging.ConsoleHandler
  2. .level = INFO
  3. # 对这个logger独立配置
  4. com.ydlclass.handlers = java.util.logging.FileHandler
  5. com.ydlclass.level = ALL
  6. com.ydlclass.useParentHandlers = false
  8. # 修改了名字
  9. java.util.logging.FileHandler.pattern = D:/logs/ydl-java%u.log
  10. java.util.logging.FileHandler.limit = 50000
  11. java.util.logging.FileHandler.count = 1
  12. java.util.logging.FileHandler.maxLocks = 100
  13. java.util.logging.FileHandler.formatter = java.util.logging.SimpleFormatter
  14. # 文件使用追加方式
  15. java.util.logging.FileHandler.append = true
  17. # Limit the message that are printed on the console to INFO and above.
  18. java.util.logging.ConsoleHandler.level = INFO
  19. java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
  21. # 修改日志格式
  22. java.util.logging.SimpleFormatter.format=%4$s: %5$s [%1$tc]%n

执行发现控制台没有内容，文件中有了，说明没有问题OK了：image.pngimage.png