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我正在尝试在 android ndk 项目中使用 canutils。包 canutils 通常编译为可执行文件，但我还没有找到将这些可执行文件包含在 ndk 项目中的方法。所以我现在做的只是像这样加载共享库：

static{
System.loadLibrary("cansend");
}
public native void cansend();

因为我已经更改了 android-mk 来构建共​​享库。

仍然我的 c 代码看起来像这样 cansend.c 作为示例：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>

#include <linux/can.h>
#include <linux/can/raw.h>

#include "lib.h"

int main(int argc, char **argv)
{
int s; /* can raw socket */ 
int required_mtu;
int mtu;
int enable_canfd = 1;
struct sockaddr_can addr;
struct canfd_frame frame;
struct ifreq ifr;

/* check command line options */
if (argc != 3) {
    fprintf(stderr, "Usage: %s <device> <can_frame>.\n", argv[0]);
    return 1;
}

/* parse CAN frame */
required_mtu = parse_canframe(argv[2], &frame);
if (!required_mtu){
    fprintf(stderr, "\nWrong CAN-frame format! Try:\n\n");
    fprintf(stderr, "    <can_id>#{R|data}          for CAN 2.0 frames\n");
    fprintf(stderr, "    <can_id>##<flags>{data}    for CAN FD frames\n\n");
    fprintf(stderr, "<can_id> can have 3 (SFF) or 8 (EFF) hex chars\n");
    fprintf(stderr, "{data} has 0..8 (0..64 CAN FD) ASCII hex-values (optionally");
    fprintf(stderr, " seperated by '.')\n");
    fprintf(stderr, "<flags> a single ASCII Hex value (0 .. F) which defines");
    fprintf(stderr, " canfd_frame.flags\n\n");
    fprintf(stderr, "e.g. 5A1#11.2233.44556677.88 / 123#DEADBEEF / 5AA# / ");
    fprintf(stderr, "123##1 / 213##311\n     1F334455#1122334455667788 / 123#R ");
    fprintf(stderr, "for remote transmission request.\n\n");
    return 1;
}

/* open socket */
if ((s = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0) {
    perror("socket");
    return 1;
}

addr.can_family = AF_CAN;

strcpy(ifr.ifr_name, argv[1]);
if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
    perror("SIOCGIFINDEX");
    return 1;
}
addr.can_ifindex = ifr.ifr_ifindex;

if (required_mtu > CAN_MTU) {

    /* check if the frame fits into the CAN netdevice */
    if (ioctl(s, SIOCGIFMTU, &ifr) < 0) {
        perror("SIOCGIFMTU");
        return 1;
    }
    mtu = ifr.ifr_mtu;

    if (mtu != CANFD_MTU) {
        printf("CAN interface ist not CAN FD capable - sorry.\n");
        return 1;
    }

    /* interface is ok - try to switch the socket into CAN FD mode */
    if (setsockopt(s, SOL_CAN_RAW, CAN_RAW_FD_FRAMES,
               &enable_canfd, sizeof(enable_canfd))){
        printf("error when enabling CAN FD support\n");
        return 1;
    }

    /* ensure discrete CAN FD length values 0..8, 12, 16, 20, 24, 32, 64 */
    frame.len = can_dlc2len(can_len2dlc(frame.len));
}

/* disable default receive filter on this RAW socket */
/* This is obsolete as we do not read from the socket at all, but for */
/* this reason we can remove the receive list in the Kernel to save a */
/* little (really a very little!) CPU usage.                          */
setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, NULL, 0);

if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
    perror("bind");
    return 1;
}

/* send frame */
if (write(s, &frame, required_mtu) != required_mtu) {
    perror("write");
    return 1;
}

close(s);

return 0;
}

我希望能够在我的 android-ndk-project 中使用这个 cansend 方法。我是否需要调整 c 代码并从代码中创建一个共享库，或者我是否需要使用可执行文件并以某种方式调用并将其包含在我的项目中以便能够使用它？

4

1 回答 1

1

重命名您的主要功能或在其周围放置另一个包装器。如果你希望你的原生函数被命名为cansend()，你的包装函数应该是这样的：

#ifdef __cplusplus
extern "C" {
#endif

JNIEXPORT 
void
Java_com_aaa_bbb_ccc_cansend( JNIEnv* env, jobject thiz);

#ifdef __cplusplus
}
#endif

在这里，com_aaa_bbb_ccc 来自您的 java 代码的包名，其中包含public native void cansend();.

例如，如果您的包名称是com.example.test，那么您的函数名称将是：

Java_com_example_test_cansend();
于 2015-03-29T10:05:41.883 回答