JConsole:
1) java -Dcom.sun.management.jmxremote MainClass
2) JDK\bin\jconsole {java pid}
在jconsole的界面可以看到简单的内存使用情况

Hat:
1) java -Xrunhprof:file=dump.hprof,format=b MainClass
2) hat dump.hprof
3) Browse http://localhost:7000
dump.hprof是java程序产生的dump文件名

如何用netbeans5.5 profiler 调试 memory Leak (JDK1.5)
1) 下载如下包，
netbeans-5_5-windows.exe -- netbeans 5.5
netbeans-profiler-5_5-win.exe -- profiler
profiler-server-55-windows-15.zip -- remote pack. 与profiler是分开的，作remote attach的时候要用
2) netbeans 与profiler 都安装在你本地
3）将profiler-server-55-windows-15.zip解压到你远程的机器
4）运行profiler-server-55-windows-15\bin\calibrate.bat
5) 把下面的参数加到你的JVM启动参数里面：
 -agentpath:<profiler-server-55-windows-15>\lib\deployed\jdk15\windows\profilerinterface.dll=<profiler-server-55-windows-15>\lib,5140
6) 启动你的Java.exe时，java 程序对等待你attach,通过netbeans attach后，你可以看到Objects使用的信息了

记得要选中："Record both object creation and garbage collection (Object Liveness Profiling)"
This option provides additional information about how many objects of each type are still alive, as well as data on live objects. The results are displayed in the Object Liveness Results.