HotSpot SA #4：输出类加载路径

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参考R大的文章，也写了一个SA的小工具，可以输出指定类（使用-Dme.kisimple.just4fun.ClassPathDump=类名指定）是从什么地方加载进来的，

package me.kisimple.just4fun;import sun.jvm.hotspot.oops.*;import sun.jvm.hotspot.runtime.VM;import sun.jvm.hotspot.tools.Tool;public class ClassPathDump extends Tool {    private String className;    public ClassPathDump(String className) {        super();        this.className = className;    }    public static void main(String[] args) {        String className = System.getProperty("me.kisimple.just4fun.ClassPathDump");        if(className != null) {            ClassPathDump dump = new ClassPathDump(className.replace(".", "/"));            dump.start(args);            dump.stop();        }    }    @Override    public void run() {        VM vm = VM.getVM();        final ObjectHeap objectHeap = vm.getObjectHeap();        objectHeap.iteratePerm(new HeapVisitor() {            @Override            public void prologue(long l) {            }            @Override            public boolean doObj(Oop oop) {                if(oop instanceof InstanceKlass) {                    InstanceKlass klass = (InstanceKlass)oop;                    if(klass.getName() != null &&                            className.equals(klass.getName().asString())) {                        Oop protectionDomain = klass.getProtectionDomain();                        if(protectionDomain == null)                            return true;                        Oop codesource = getOopFieldValue(protectionDomain,                                "codesource", "Ljava/security/CodeSource;");                        if(codesource == null)                            return true;                        Oop location = getOopFieldValue(codesource,                                "location", "Ljava/net/URL;");                        if(location == null)                            return true;                        Oop path = getOopFieldValue(location,                                "path", "Ljava/lang/String;");                        if (path == null)                            return true;                        System.out.println("////////////////////////////////////////");                        System.out.println("[LOADED]" + className);                        System.out.println("[FROM]"+ OopUtilities.stringOopToString(path));                        return true;                    }                }                return false;            }            @Override            public void epilogue() {            }        });    }    private Oop getOopFieldValue(Oop oop, String name, String sig) {        InstanceKlass klass = (InstanceKlass) oop.getKlass();        OopField field = (OopField) klass.findField(name, sig);        return field.getValue(oop);    }}

执行以下命令（sa-jdi.jar需要放在classpath上），

> java -Dme.kisimple.just4fun.ClassPathDump=groovy.lang.GroovyClassLoader me.kisimple.just4fun.ClassPathDump 6376

6376是目标进程pid，示例输出如下，

Attaching to process ID 6376, please wait...Debugger attached successfully.Server compiler detected.JVM version is 24.51-b03////////////////////////////////////////[LOADED]groovy/lang/GroovyClassLoader[FROM]/C:/Java/jdk1.7.0_51/jre/lib/ext/groovy-2.4.0.jar

参考资料

http://rednaxelafx.iteye.com/blog/1295944

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