JNI：一个典型的错误——A fatal error has been detected by the Java Runtime Environment

原因：传递给本地函数的对象为null

// string操作
class JNIString
{
	static
	{
		System.loadLibrary("JNIString");
	}
	public static native String strMethod(String s);
}
/*
javac JNIString.java
javah JNIString.java	// get the file JNIString.h
*/

#include "JNIString.h"
#include <string.h>
JNIEXPORT jstring JNICALL Java_JNIString_strMethod(JNIEnv *env, jclass jcls, jstring jstr)
{
	int i;
	char str2[128];	// 变量定义只能在程序开头部分
	//jsize len = env->GetStringLength(jstr);
	const char *str = env->GetStringUTFChars(jstr, NULL);	// must be const
										// const jchar * GetStringChars(JNIEnv *env, jstring string, jboolean *isCopy);
	printf("%s\n", str);
	strcpy(str2,str);
	env->ReleaseStringUTFChars(jstr, str);
	return env->NewStringUTF(str2);
}
/*
set java_inc=E:\FILES\java\jdk1.6.0_29\include
cl -I%java_inc% -I%java_inc%\win32 -LD JNIString.c -FeJNIString.dll
*/


public class Test
{
	public static void main(String[] args)
	{
		String str = "abc123abc";	// 123中国123湖北123武汉123
		String s1 = new String(str);
		String s2 = JNIString.strMethod(s1);
		System.out.println(s2);
		str = null;
		s2 = JNIString.strMethod(str);
	}
}
/* output:
abc123abc
abc123abc
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x6d9332ca, pid=4764, tid=5056
#
# JRE version: 6.0_29-b11
# Java VM: Java HotSpot(TM) Client VM (20.4-b02 mixed mode, sharing windows-x86
)
# Problematic frame:
# V  [jvm.dll+0x932ca]
#
# An error report file with more information is saved as:
# G:\编程\Java\test\hs_err_pid4764.log
#
# If you would like to submit a bug report, please visit:
#   http://java.sun.com/webapps/bugreport/crash.jsp
#
*/