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这是本机 C++ 方法。

JNIEXPORT jboolean JNICALL Java_xpnp_XpNamedPipe_readBytes
(JNIEnv* pEnv, jclass cls, jlong pipeHandle, jbyteArray readBufferJava, jint bytestoread, jint timeoutMsecs){

    jbyte* readBuffer = NULL;
    try {
        readBuffer = pEnv->GetByteArrayElements(readBufferJava, NULL);
        if (readBuffer == NULL) {
            throw std::bad_alloc();
        }
        int retval = XPNP_readBytes ((XPNP_PipeHandle)pipeHandle, (char*)readBuffer, bytestoread, timeoutMsecs);

        std::cout<<"this is what I read: " << readBuffer << "\n";
        std::flush(std::cout);

        return (retval <= 0) ? 0 : retval;
    }catch (std::exception& except) {
        // setErrorInfo(except.what());
    }
    return 0;
}

此方法打印readBuffer从 call 读取的正确文本XPNP_readBytes,但将全零数组传递给 Java!知道为什么会这样吗?我在传递指针或将其转换为 Java 时做错了什么?

这是 Java 文件中本地 C++ 方法的声明。

private static native boolean readBytes(long pipeHandle, byte[] buffer, int bytesToRead, int timeoutMsecs);

这是我调用本机方法的地方。

boolean b = readBytes(namedPipeHandle, buffer, bytesToRead, timeoutMsecs);
String a = new String(buffer);

我在调用后读到的buffer都是 0,即使它在本机代码中打印了正确的文本!

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1 回答 1

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抬头看ReleaseByteArrayElements

于 2012-07-13T21:41:48.993 回答