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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);
+