android - NewObject 调用的间接引用无效

Question

好的，下面是 native 代码。我试图从中返回一个 FilePermissionInfo 数组，其中填充了 stat() 返回的一些数据。问题是第一次调用 NewObject 时出现以下错误:

06-15 20:25:17.621: W/dalvikvm(2287): Invalid indirect reference 0x40005820 in decodeIndirectRef 06-15 20:25:17.621: E/dalvikvm(2287): VM aborting

这很奇怪，因为我拥有的唯一引用对象是 jclass(用于 FilePermissionInfo)，我将其转换为全局引用。

代码是:

JNIEXPORT jobjectArray JNICALL
Java_com_mn_rootscape_utils_NativeMethods_getFilesPermissions( JNIEnv* env, jobject thizz, jobjectArray filePathsArray ) 
{
jobjectArray result;
int size = (*env)->GetArrayLength(env, filePathsArray);
jboolean isCopy;

jclass filePermInfoCls = (*env)->FindClass(env, kFilePermissionInfoPath);
if(!filePermInfoCls)
{
    LOGE("getFilesPermissions: failed to get class reference.");
    return NULL;
}

gFilePermInfoClass = (jclass)(*env)->NewGlobalRef(env, filePermInfoCls);
LOGI("got gFilePermInfoClass");

jmethodID filePermInfoClsConstructor = (*env)->GetMethodID(env, gFilePermInfoClass, "<init>", kFilePermInfoConstructorSig);
if(!filePermInfoClsConstructor)
{
    LOGE("getFilesPermissions: failed to get method reference.");
    return NULL;
}

struct stat sb;

LOGI("starting...");
result = (jobjectArray)(*env)->NewObjectArray(env, size, gFilePermInfoClass, NULL);
for(int i = 0; i != size; ++i) 
{
    jstring string = (jstring) (*env)->GetObjectArrayElement(env, filePathsArray, i);
const char *rawString = (*env)->GetStringUTFChars(env, string, &isCopy);    

    if(stat(rawString, &sb) == -1) 
    {
        LOGE("stat error for: %s", rawString);
    }

    LOGI("%ld %ld %ld %ld %ld %ld %ld %ld", sb.st_dev, sb.st_mode, sb.st_nlink, sb.st_uid, sb.st_gid, sb.st_atime, sb.st_mtime, sb.st_ctime);

    jobject permInfo = (*env)->NewObject(env, 
                            gFilePermInfoClass, 
                            filePermInfoClsConstructor, 
                            (long)sb.st_dev,
                            (long)sb.st_mode,
                            (long)sb.st_nlink,
                            (long)sb.st_uid,
                            (long)sb.st_gid,
                            (long)sb.st_atime,
                            (long)sb.st_mtime,
                            (long)sb.st_ctime,
                            "",
                            "",
                            1,
                            "");

    LOGI("xxx1");
    (*env)->SetObjectArrayElement(env, result, i, permInfo);
    LOGI("xxx2");
    (*env)->ReleaseStringUTFChars(env, string, rawString);
    LOGI("xxx3");
}

(*env)->DeleteLocalRef(env, filePermInfoCls);

return result;

Java 类构造函数签名和路径为:

const char* kFilePermissionInfoPath = "com/mn/rootscape/utils/FilePermissionInfo";
const char* kFilePermInfoConstructorSig = "(JJJJJJJJLjava/lang/String;Ljava/lang/String;ZLjava/lang/String;)V";

请注意，如果我在默认构造函数上调用 NewObject，那么它工作正常。

Answer 1

好的，找到了。jstring 参数有问题。事实证明，您不能将空字符串(甚至 NULL)作为 jstring 传递。相反，我使用 (*env)->NewStringUTF(env, NULL) 来创建 NULL jstring。

现在似乎工作正常。

---

由于这个问题产生了一些高活跃度，我在下面发布最终解决方案。请注意，nullString 变量在其范围结束时(或当您使用完它时)被释放:

        jstring nullString = (*env)->NewStringUTF(env, NULL);
...
        jobject permInfo = (*env)->NewObject(env, 
                                gFilePermInfoClass, 
                                filePermInfoClsConstructor, 
                                (jbyte)permsOwner,
                                (jbyte)permsGroup,
                                (jbyte)permsOthers,
                                (jlong)sb.st_uid,
                                (jlong)sb.st_gid,
                                (jlong)sb.st_atime,
                                (jlong)sb.st_mtime,
                                (jlong)sb.st_ctime,
                                nullString,
                                nullString,
                                (jboolean)1,
                                nullString);
...
       (*env)->DeleteLocalRef(env, nullString);