从JNI调用main方法失败 [英] Calling main method from JNI fails
问题描述
我创建了一个C ++类,该类应该通过以下方式调用Main.main
:
I created a C++ class that is supposed to call Main.main
by following: http://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/invocation.html#wp9502.
I didn't get it to work so I followed: http://www.coderanch.com/t/525082/CPP/create-JVM-native-code-call
和:
imp_JNI_Crea> http://www.codeproject.com/Questions/263687/Linker-error-undefined-reference-to- imp _JNI_Crea
imp_JNI_Crea">http://www.codeproject.com/Questions/263687/Linker-error-undefined-reference-to-imp_JNI_Crea
没有一个有效.因此,我将代码改回了oracle的Invocation API文章所说的内容(第一个链接).
None of which worked. So I changed my code back to what the Invocation API article by oracle says (the first link).
我的C ++代码如下:
My C++ code looks like:
在JNI.hpp文件中:
In JNI.hpp file:
#include <jni.h>
#include <windows.h>
#include <iostream>
class Jvm
{
private:
JavaVM* jvm;
JNIEnv* env;
JavaVMInitArgs jvm_args;
JavaVMOption* options;
public:
Jvm();
};
在JNI.cpp文件中:
In JNI.cpp file:
Jvm::Jvm()
{
options = new JavaVMOption[3];
options[0].optionString = "-Djava.compiler=NONE";
options[1].optionString = "-Djava.class.path=C:/Users/Brandon/Documents/NetBeansProjects/Loader/build/classes";
options[2].optionString = "-verbose:class";
jvm_args.version = JNI_VERSION_1_6;
jvm_args.nOptions = 3;
jvm_args.options = options;
jvm_args.ignoreUnrecognized = false;
//JNI_GetDefaultJavaVMInitArgs(&jvm_args);
JNI_CreateJavaVM(&jvm, reinterpret_cast<void**>(&env), &jvm_args);
jclass MainClass = env->FindClass("loader.Main");
//Crashes on the next line:
jmethodID MainMethod = env->GetStaticMethodID(MainClass, "main", "([Ljava/lang/String;)V");
MessageBox(NULL, "", "", 0);
Sleep(1000);
jvm->DestroyJavaVM();
delete[] options;
}
我的Java代码如下:
My java code looks like:
package loader;
public class Main {
public static void main(String[] args) {
//JavaProcess.exec(ClientApplet.class);
System.out.println("Hello!");
}
}
详细打印:
[Loaded loader.Main from file:/C:/Users/Brandon/Documents/NetBeansProjects/Loader/build/classes/]
Process returned -1073741571 (0xC00000FD) execution time : 1.730 s
Press any key to continue.
我做错了什么?为什么无法调用该方法?
我加载的JNI.dll
来自:C:\Program Files\Java\jdk1.7.0_21\jre\bin\server\jvm.dll
,因为最新的Java 7u25
没有bin\client\jvm.dll
.
What am I doing wrong? Why does it fail to call the method?
The JNI.dll
that I loaded is from: C:\Program Files\Java\jdk1.7.0_21\jre\bin\server\jvm.dll
because the latest Java 7u25
doesn't have a bin\client\jvm.dll
.
我什至静态链接到jvm.lib:C:\Program Files\Java\jdk1.7.0_21\lib\jvm.lib
.
I even statically linked to the jvm.lib: C:\Program Files\Java\jdk1.7.0_21\lib\jvm.lib
.
推荐答案
jclass MainClass = env->FindClass("loader.Main");
这是错误的.就像在方法签名中一样,使用JNI函数时必须使用斜杠而不是点.
This is wrong. You have to use slashes instead of dots when using JNI functions, just like in method signatures.
正确的代码是:
jclass MainClass = env->FindClass("loader/Main");
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