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/* File : example.i */
%module example
%{
/*
example of a function that returns a value in the char * argument
normally used like:
char buf[bigenough];
f1(buf);
*/
void f1(char *s) {
if(s != NULL) {
sprintf(s, "hello world");
}
}
void f2(char *s) {
f1(s);
}
void f3(char *s) {
f1(s);
}
%}
/* default behaviour is that of input arg, Java cannot return a value in a
* string argument, so any changes made by f1(char*) will not be seen in the Java
* string passed to the f1 function.
*/
void f1(char *s);
%include various.i
/* use the BYTE argout typemap to get around this. Changes in the string by
* f2 can be seen in Java. */
void f2(char *BYTE);
/* Alternative approach uses a StringBuffer typemap for argout */
/* Define the types to use in the generated JNI C code and Java code */
%typemap(jni) char *SBUF "jobject"
%typemap(jtype) char *SBUF "StringBuffer"
%typemap(jstype) char *SBUF "StringBuffer"
/* How to convert Java(JNI) type to requested C type */
%typemap(in) char *SBUF {
$1 = NULL;
if($input != NULL) {
/* Get the String from the StringBuffer */
jmethodID setLengthID;
jclass sbufClass = (*jenv)->GetObjectClass(jenv, $input);
jmethodID toStringID = (*jenv)->GetMethodID(jenv, sbufClass, "toString", "()Ljava/lang/String;");
jstring js = (jstring) (*jenv)->CallObjectMethod(jenv, $input, toStringID);
/* Convert the String to a C string */
const char *pCharStr = (*jenv)->GetStringUTFChars(jenv, js, 0);
/* Take a copy of the C string as the typemap is for a non const C string */
jmethodID capacityID = (*jenv)->GetMethodID(jenv, sbufClass, "capacity", "()I");
jint capacity = (*jenv)->CallIntMethod(jenv, $input, capacityID);
$1 = (char *) malloc(capacity+1);
strcpy($1, pCharStr);
/* Release the UTF string we obtained with GetStringUTFChars */
(*jenv)->ReleaseStringUTFChars(jenv, js, pCharStr);
/* Zero the original StringBuffer, so we can replace it with the result */
setLengthID = (*jenv)->GetMethodID(jenv, sbufClass, "setLength", "(I)V");
(*jenv)->CallVoidMethod(jenv, $input, setLengthID, (jint) 0);
}
}
/* How to convert the C type to the Java(JNI) type */
%typemap(argout) char *SBUF {
if($1 != NULL) {
/* Append the result to the empty StringBuffer */
jstring newString = (*jenv)->NewStringUTF(jenv, $1);
jclass sbufClass = (*jenv)->GetObjectClass(jenv, $input);
jmethodID appendStringID = (*jenv)->GetMethodID(jenv, sbufClass, "append", "(Ljava/lang/String;)Ljava/lang/StringBuffer;");
(*jenv)->CallObjectMethod(jenv, $input, appendStringID, newString);
/* Clean up the string object, no longer needed */
free($1);
$1 = NULL;
}
}
/* Prevent the default freearg typemap from being used */
%typemap(freearg) char *SBUF ""
/* Convert the jstype to jtype typemap type */
%typemap(javain) char *SBUF "$javainput"
/* apply the new typemap to our function */
void f3(char *SBUF);
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