Java程序在JNI方法调用后终止 [英] Java Program terminates after JNI method call

问题描述

我正在使用JNI调用本机C方法，但是我的java程序在第一个方法调用后终止(退出代码0)，并且没有到达其余代码.

I'm using JNI to call native C methods, but my java program terminates (Exit code 0) after the first method call and doesn't reach the rest of the code.

这是我的出处:

Exec.java:

Exec.java:

package libs;

public class Exec {

    static {
        System.load(System.getProperty("user.dir")+"/bin/"+"libexec.so");
    }

    public static native int execv(String pExecPath, String[] pArgs);
}

Exec.c:

#include <jni.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>


JNIEXPORT jint JNICALL
Java_libs_Exec_execv(JNIEnv * env, jclass clazz, jstring pExecPath, jobjectArray array) {
const char* execPath = (*env)->GetStringUTFChars(env, pExecPath, NULL); 
(*env)->ReleaseStringUTFChars(env, pExecPath, NULL);

printf("Execution path: %s\n", execPath);

int stringCount = (int) (*env)->GetArrayLength(env, array);
char * args[stringCount+1];
args[stringCount] = NULL;

for (int i=0; i<stringCount; i++) {
    jstring string = (jstring) (*env)->GetObjectArrayElement(env, array, i);
    char * arg = (*env)->GetStringUTFChars(env, string, 0);

    printf("Argument %i:\t%s\n", (i+1), arg);

    args[i] = arg;

    (*env)->ReleaseStringUTFChars(env, string, 0);
}



int result = execv(execPath, args);

printf("Exit code: %i\n", result);
perror(NULL);

return result;
}

TestExec.java:

TestExec.java:

package test;

import libs.Exec;


public class TestExec extends Exec {

    public static void main(String[] args) {

        execv("/bin/ps", new String[]{"ps", "ax"});
        execv("/bin/ls", new String[]{"ls", "-la", "/home"});
}
}

控制台输出:

PID TTY      STAT   TIME COMMAND
1 ?        Ss     0:00 /sbin/init
[...]
5532 ?        R      0:00 ps ax

我还缺少我的c方法的控制台输出，该输出看起来应该像这样:

I'm also missing the console output from my c-method, which should look like this:

Execution path: /bin/ps
Argument 1: ax
Exit code: 0

我希望我能提供足够的信息以获得合格的帮助.

I hope I gave enough information to get qualified help.

推荐答案

当然终止.您正在调用execv().您将用"ps"程序替换JVM，该程序将退出，从而完成操作.

Of course it terminates. You're calling execv(). You're replacing the JVM with the 'ps' program, which exits, so you're done.

当您仍然持有指向chars的指针时，无法调用ReleaseStringUTFChars().

You can't call ReleaseStringUTFChars() while you're still holding a pointer to the chars.

除非有错误，否则调用'execv()'后您将看不到进程的任何输出.

And you won't see any output from a process after calling 'execv()', unless there was an error.

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