使用方法：
private static final Logger LOGGER = Logger.getLogger(TestNG.class);
方法详解：
1.首先定义静态变量，static静态代码块，构造方法
2.1 getLogger-> initialize-> checkProperties
源码如下：
package TestNGlog;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.Map.Entry;
import org.testng.Assert;
import org.testng.collections.Maps;
public class Logger1 {
private static int i = 0;
private static final int TRACE;
private static final int DEBUG;
private static final int INFO;
private static final int WARN;
private static final int ERROR;
private static final int FATAL;
private static final int LEVEL_COUNT;
private static final String PREFIX = "log4testng.";
private static final String LOGGER_PREFIX = "log4testng.logger.";
private static final String ROOT_LOGGER = "log4testng.rootLogger";
private static final String DEBUG_PROPERTY = "log4testng.debug";
private static PrintStream err;
private static PrintStream out;
private static final String[] levelNames;
private static final Map<String, Integer> levelMap;
private static boolean initialized;
private static final Map<String, Integer> loggerLevels;
private static final Map <Class, Logger1> loggers;
private static int rootLoggerLevel;
private static boolean debug;
private final int level;
private final Class klass;
private final String m_className;
//构造方法，初始化类和日志级别
private Logger1(Class pClass, int pLevel) {
this.level = pLevel;
this.klass = pClass;
this.m_className = pClass.getName().substring(pClass.getName().lastIndexOf(46) + 1);
}
static {
TRACE = i++;
DEBUG = i++;
INFO = i++;
WARN = i++;
ERROR = i++;
FATAL = i++;
LEVEL_COUNT = i;
//默认为NULL
err = System.err;
//默认为NULL
out = System.out;
levelNames = new String[LEVEL_COUNT];
levelNames[TRACE] = "TRACE";
levelNames[DEBUG] = "DEBUG";
levelNames[INFO] = "INFO";
levelNames[WARN] = "WARN";
levelNames[ERROR] = "ERROR";
levelNames[FATAL] = "FATAL";
//初始化级别Map，<级别，级别ID>
levelMap = Maps.newHashMap();
for(i = 0; i < LEVEL_COUNT; ++i) {
levelMap.put(levelNames[i], i);
}
//<空的>
loggerLevels = Maps.newHashMap();
//定义一个空的MAP
loggers = Maps.newHashMap();
//默认的日志级别
rootLoggerLevel = WARN;
//debug是否开启
debug = false;
}
public static synchronized Logger1 getLogger(Class pClass) {
initialize();
Logger1 logger = loggers.get(pClass);
if (logger != null) {
return logger;
} else {
int level = getLevel(pClass);
logger = new Logger1(pClass, level);
loggers.put(pClass, logger);
return logger;
}
}
public boolean isTraceEnabled() {
return this.isLevelEnabled(TRACE);
}
public void trace(Object message) {
this.log(TRACE, message, (Throwable)null);
}
public void trace(Object message, Throwable t) {
this.log(TRACE, message, t);
}
public boolean isDebugEnabled() {
return this.isLevelEnabled(DEBUG);
}
public void debug(Object message) {
this.log(DEBUG, message, (Throwable)null);
}
public void debug(Object message, Throwable t) {
this.log(DEBUG, message, t);
}
public boolean isInfoEnabled() {
return this.isLevelEnabled(INFO);
}
public void info(Object message) {
this.log(INFO, message, (Throwable)null);
}
public void info(Object message, Throwable t) {
this.log(INFO, message, t);
}
public void warn(Object message) {
this.log(WARN, message, (Throwable)null);
}
public void warn(Object message, Throwable t) {
this.log(WARN, message, t);
}
public void error(Object message) {
this.log(ERROR, message, (Throwable)null);
}
public void error(Object message, Throwable t) {
this.log(ERROR, message, t);
}
public void fatal(Object message) {
this.log(FATAL, message, (Throwable)null);
}
public void fatal(Object message, Throwable t) {
this.log(FATAL, message, t);
}
private static synchronized void initialize() {
//initialized默认为false
if (!initialized) {
initialized = true;
//读取ClassPath路径下的配置文件log4testng.properties
InputStream is = Thread.currentThread().getContextClassLoader().getResourceAsStream("log4testng.properties");
//如果文件存在
if (is != null) {
Properties properties = new Properties();
try {
properties.load(is);
} catch (IOException var3) {
throw new RuntimeException(var3);
}
checkProperties(properties);
}
}
}
private static void checkProperties(Properties pProperties) {
//从配置文件里读key：log4testng.debug
String rootLevelStr = pProperties.getProperty("log4testng.debug");
//如有key：log4testng.debug
if (rootLevelStr != null) {
//判断如果值=true
if (rootLevelStr.equalsIgnoreCase("true")) {
//给debug赋值
debug = true;
} else {
//如果不等于true&&不等于false
if (!rootLevelStr.equalsIgnoreCase("false")) {
//抛出异常
throw new IllegalArgumentException("Unknown log4testng.debug value " + rootLevelStr);
}
//给debug赋值
debug = false;
}
}
//打印debug日志，前提是debug=true;
loglog4testng("log4testng.debug set to " + debug);
//获取log4testng.rootLogger配置的日志级别
rootLevelStr = pProperties.getProperty("log4testng.rootLogger");
//不等于空
if (rootLevelStr != null) {
// 取出来赋值给ilevel
Integer ilevel = (Integer)levelMap.get(rootLevelStr.toUpperCase());
//赋值失败
if (ilevel == null) {
throw new IllegalArgumentException("Unknown level for log4testng.rootLogger " + rootLevelStr + " in log4testng.properties");
}
//如果有值将值赋给rootLoggerLevel，默认WARN
rootLoggerLevel = ilevel;
loglog4testng("Root level logger set to " + rootLevelStr + " level.");
}
//定义了一个集合，将配置文件里的值放到集合里
Iterator it = pProperties.entrySet().iterator();
while(it.hasNext()) {
Entry entry = (Entry)it.next();
String logger = (String)entry.getKey();
String level = (String)entry.getValue();
if (!logger.startsWith("log4testng.")) {
throw new IllegalArgumentException("Illegal property value: " + logger);
}
//如果没有debug和root相关的配置信息，抛出异常
if (!logger.equals("log4testng.debug") && !logger.equals("log4testng.rootLogger")) {
if (!logger.startsWith("log4testng.logger.")) {
throw new IllegalArgumentException("Illegal property value: " + logger);
}
Integer ilevel = (Integer)levelMap.get(level.toUpperCase());
if (ilevel == null) {
throw new IllegalArgumentException("Unknown level " + level + " for logger " + logger + " in log4testng.properties");
}
//配置日志级别默认为WARN，如果配置文件有配置，配置优先
loggerLevels.put(logger.substring("log4testng.logger.".length()), ilevel);
loglog4testng("logger " + logger + " set to " + ilevel + " level.");
}
}
}
private static int getLevel(Class pClass) {
//获取类名
String name = pClass.getName();
loglog4testng("Getting level for logger " + name);
while(true) {
//根据类名取日志级别
Integer level = (Integer)loggerLevels.get(name);
//如果级别不为null
if (level != null) {
loglog4testng("Found level " + level + " for logger " + name);
return level;
}
// 返回指定字符在此字符串中最后一次出现处的索引，如果此字符串中没有这样的字符，则返回 -1。
int dot = name.lastIndexOf(46);
//没找到，返回默认配置的日志级别：WARN
if (dot == -1) {
loglog4testng("Found level " + rootLoggerLevel + " for root logger");
return rootLoggerLevel;
}
//截取正确的名字
name = name.substring(0, dot);
}
}
private boolean isLevelEnabled(int pLevel) {
return this.level <= pLevel;
}
private void log(int pLevel, Object pMessage, Throwable pT) {
if (this.isLevelEnabled(pLevel)) {
PrintStream ps = pLevel >= ERROR ? err : out;
if (null != pT) {
synchronized(ps) {
ps.println("[" + this.m_className + "] [" + levelNames[pLevel] + "] " + pMessage);
pT.printStackTrace(ps);
}
} else {
ps.println("[" + this.m_className + "] [" + levelNames[pLevel] + "] " + pMessage);
}
}
}
private static void loglog4testng(String pmessage) {
if (debug) {
out.println("[log4testng] [debug] " + pmessage);
}
}
private static synchronized void testInitialize(Properties pProperties, PrintStream pOut, PrintStream pErr) {
initialized = true;
loggers.clear();
rootLoggerLevel = WARN;
debug = false;
out = pOut;
err = pErr;
checkProperties(pProperties);
}
private static void testDebugDefault() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.rootLogger", "WARN");
testInitialize(props, out2, err2);
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
}
private static void testDebugOn() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.debug", "true");
props.put("log4testng.rootLogger", "WARN");
testInitialize(props, out2, err2);
System.out.println(out1.toString());
Assert.assertTrue(out1.toString().startsWith("[log4testng] [debug]"));
Assert.assertEquals(err1.toString(), "");
}
private static void testDebugOff() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.debug", "false");
props.put("log4testng.rootLogger", "WARN");
testInitialize(props, out2, err2);
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
}
private static void testDebugError() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.debug", "unknown");
props.put("log4testng.rootLogger", "WARN");
try {
testInitialize(props, out2, err2);
throw new RuntimeException("failure");
} catch (IllegalArgumentException var6) {
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
}
}
private static void testRootLoggerDefault() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
testInitialize(props, out2, err2);
Logger1 strLogger = getLogger(String.class);
strLogger.trace("trace should not appear");
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
strLogger.debug("debug should not appear");
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
strLogger.info("info should not appear");
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
strLogger.warn("warn should appear");
int outlength = out1.toString().length();
System.out.println(out1);
Assert.assertTrue(out1.toString().indexOf("String] [WARN] warn should appear")!=-1);
Assert.assertEquals(err1.toString(), "");
strLogger.error("error should appear");
Assert.assertEquals(out1.toString().length(), outlength);
Assert.assertTrue(err1.toString().startsWith("[String] [ERROR] error should appear"));
strLogger.fatal("fatal should appear");
Assert.assertEquals(out1.toString().length(), outlength);
Assert.assertTrue(err1.toString().contains("[String] [FATAL] fatal should appear"));
}
private static void testRootLoggerSet() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.rootLogger", "DEBUG");
testInitialize(props, out2, err2);
Logger1 strLogger = getLogger(String.class);
strLogger.trace("trace should appear");
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
strLogger.debug("debug should appear");
Assert.assertTrue(out1.toString().startsWith("[String] [DEBUG] debug should appear"));
Assert.assertEquals(err1.toString(), "");
}
private static void testRootLoggerSetError() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.rootLogger", "unknown");
try {
testInitialize(props, out2, err2);
throw new RuntimeException("failure");
} catch (IllegalArgumentException var6) {
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
}
}
private static void testUserLoggerSet() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.logger.java.lang.String", "DEBUG");
testInitialize(props, out2, err2);
Logger1 strLogger = getLogger(String.class);
strLogger.trace("trace should not appear");
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
strLogger.debug("debug should appear");
int outLength = out1.toString().length();
Assert.assertTrue(out1.toString().startsWith("[String] [DEBUG] debug should appear"));
Assert.assertEquals(err1.toString(), "");
Logger1 classLogger = getLogger(Class.class);
classLogger.debug("debug should not appear");
Assert.assertEquals(out1.toString().length(), outLength);
Assert.assertEquals(err1.toString(), "");
classLogger.warn("warn should appear");
System.out.println(out1);
Assert.assertTrue(out1.toString().contains("[Class] [WARN] warn should appear"));
Assert.assertEquals(err1.toString(), "");
}
private static void testUserLoggerSetError() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.logger.java.lang.String", "unknown");
try {
testInitialize(props, out2, err2);
throw new RuntimeException("failure");
} catch (IllegalArgumentException var6) {
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
}
}
private static void testUserLoggerSetHierarchy() {
Properties props = new Properties();
ByteArrayOutputStream out1 = new ByteArrayOutputStream();
ByteArrayOutputStream err1 = new ByteArrayOutputStream();
PrintStream out2 = new PrintStream(out1);
PrintStream err2 = new PrintStream(err1);
props.put("log4testng.logger.java.lang", "DEBUG");
testInitialize(props, out2, err2);
Logger1 strLogger = getLogger(String.class);
strLogger.trace("trace should not appear");
Assert.assertEquals(out1.toString(), "");
Assert.assertEquals(err1.toString(), "");
strLogger.debug("debug should appear");
Assert.assertTrue(out1.toString().startsWith("[String] [DEBUG] debug should appear"));
Assert.assertEquals(err1.toString(), "");
}
public static void main(String[] pArgs) {
// testDebugDefault();
// testDebugOn();
// testDebugOff();
// testDebugError();
// testRootLoggerDefault();
// testRootLoggerSet();
// testRootLoggerSetError();
// testUserLoggerSet();
// testUserLoggerSetError();
// testUserLoggerSetHierarchy();
Logger1 logger=Logger1.getLogger(Logger1.class);
System.out.println(logger);
}
}
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