探究JDK-logging

测试 Apache-common-logging 的使用：

调试程序：

1、Log log = LogFactory.getLog(LogTest.class);

2、log.error()

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程序执行到 1 时， F5

调用 LogFactory中的： 创建一个指定clazz（名字）的Log

public static Log getLog(Class clazz)
throws LogConfigurationException {

return (getFactory().getInstance(clazz));

}

执行到 2 时： F5

程序进入 public class Jdk14Logger implements Log, Serializable 中的

public void error(Object message) {
log(Level.SEVERE, String.valueOf(message), null);
}

其中 Logger 为 java.util.logging.Logger

private void log( Level level, String msg, Throwable ex ) {

Logger logger = getLogger();
if (logger.isLoggable(level)) {
// Hack (?) to get the stack trace.

Throwable dummyException=new Throwable();
StackTraceElement locations[]=dummyException.getStackTrace();
// Caller will be the third element
String cname="unknown";
String method="unknown";
if( locations!=null && locations.length >2 ) {
StackTraceElement caller=locations[2];
cname=caller.getClassName();
method=caller.getMethodName();
}
if( ex==null ) {
logger.logp( level, cname, method, msg );
} else {
logger.logp( level, cname, method, msg, ex );
}
}

}

public Logger getLogger() {
if (logger == null) {
logger = Logger.getLogger(name);
}
return (logger);
}