RosettaCodeData/Task/Use-another-language-to-cal.../Java/use-another-language-to-cal...

106 lines
2.5 KiB
Java

/* query-jni.c */
#include <stdio.h>
#include <stdlib.h>
#include <jni.h>
static JavaVM *jvm = NULL;
static JNIEnv *jenv = NULL;
static void die(const char *message) {
fprintf(stderr, "%s\n", message);
exit(1);
}
static void oom(void) {
die("Query: out of memory");
}
static void except(void) {
if ((*jenv)->ExceptionCheck(jenv))
die("Query: unexpected Java exception");
}
static void do_at_exit(void) {
(*jvm)->DestroyJavaVM(jvm);
}
static void require_jvm(void) {
JavaVMInitArgs args;
if (jvm)
return;
args.version = JNI_VERSION_1_4;
args.nOptions = 0;
args.options = NULL;
args.ignoreUnrecognized = JNI_FALSE;
if (JNI_CreateJavaVM(&jvm, (void **)&jenv, &args) != JNI_OK)
die("Query: can't create Java VM");
atexit(do_at_exit);
}
int Query(char *data, size_t *length) {
jclass cQuery;
jmethodID mcall;
jintArray jlength;
jint jlength0;
jbyteArray jdata;
jboolean result;
jlength0 = (jint)length[0];
if ((size_t)jlength0 != length[0])
die("Query: length is too large for Java array");
require_jvm();
/* Create a local frame for references to Java objects. */
if ((*jenv)->PushLocalFrame(jenv, 16))
oom();
/* Look for class Query, static boolean call(byte[], int[]) */
cQuery = (*jenv)->FindClass(jenv, "Query");
if (cQuery == NULL)
die("Query: can't find Query.class");
mcall = (*jenv)->GetStaticMethodID(jenv, cQuery, "call", "([B[I)Z");
if (mcall == NULL)
die("Query: missing call() method");
/*
* Make arguments to Query.call(). We can't pass data[] and
* length[] to Java, so we make new Java arrays jdata[] and
* jlength[].
*/
jdata = (*jenv)->NewByteArray(jenv, (jsize)jlength0);
if (jdata == NULL)
oom();
jlength = (*jenv)->NewIntArray(jenv, 1);
if (jlength == NULL)
oom();
/* Set jlength[0] = length[0]. */
(*jenv)->SetIntArrayRegion(jenv, jlength, 0, 1, &jlength0);
except();
/*
* Call our Java method.
*/
result = (*jenv)->CallStaticBooleanMethod
(jenv, cQuery, mcall, jdata, jlength);
except();
/*
* Set length[0] = jlength[0].
* Copy length[0] bytes from jdata[] to data[].
*/
(*jenv)->GetIntArrayRegion(jenv, jlength, 0, 1, &jlength0);
except();
length[0] = (size_t)jlength0;
(*jenv)->GetByteArrayRegion
(jenv, jdata, 0, (jsize)jlength0, (jbyte *)data);
/* Drop our local frame and its references. */
(*jenv)->PopLocalFrame(jenv, NULL);
return (int)result;
}