[Backport release/3.10] Java bindings: add byte[] org.gdal.gdal.GetMemFileBuffer(String filename)

swig/include/java/gdal_java.i

@@ -1432,3 +1432,17 @@ import org.gdal.gdalconst.gdalconstConstants;
 %include callback.i
 
 %include typemaps_java.i
+
+
+// Also defined in python/gdal_python.i and csharp/gdal_csharp.i
+
+%rename (GetMemFileBuffer) wrapper_VSIGetMemFileBuffer;
+
+%apply (GByte* outBytes) {GByte*};
+%inline %{
+GByte* wrapper_VSIGetMemFileBuffer(const char *utf8_path, vsi_l_offset *length)
+{
+    return VSIGetMemFileBuffer(utf8_path, length, 0);
+}
+%}
+%clear GByte*;

swig/include/java/typemaps_java.i

@@ -403,6 +403,45 @@ SafeNewStringUTF8(JNIEnv *jenv, const char* pszInput)
   }
 
 
+/***************************************************************
+ * Typemaps for  (const char *utf8_path, vsi_l_offset *length)
+ ***************************************************************/
+
+%typemap(in) (const char *utf8_path, vsi_l_offset *length) (vsi_l_offset length)
+{
+    /* %typemap(in) (const char *utf8_path, vsi_l_offset *length) */
+    if ($input)
+    {
+        $1 = (char *)jenv->GetStringUTFChars($input, 0);
+    }
+    else
+    {
+        SWIG_JavaException(jenv, SWIG_ValueError, "Received a NULL pointer."); return $null;
+    }
+    $2 = &length;
+}
+
+%typemap(argout) (const char *utf8_path, vsi_l_offset *length)
+{
+    /* %typemap(argout) (const char *utf8_path, vsi_l_offset *length) */
+    if ($input)
+    {
+        jenv->ReleaseStringUTFChars($input, (char*)$1);
+    }
+    $result = jenv->NewByteArray((jsize)length$argnum);
+    jenv->SetByteArrayRegion($result, (jsize)0, (jsize)length$argnum, (jbyte*)result);
+    // Do not free result, as it is owned by the /vsimem/ file
+}
+
+%typemap(jni) (const char *utf8_path, vsi_l_offset *length) "jstring"
+%typemap(jtype) (const char *utf8_path, vsi_l_offset *length) "String"
+%typemap(jstype) (const char *utf8_path, vsi_l_offset *length) "String"
+%typemap(javain) (const char *utf8_path, vsi_l_offset *length) "$javainput"
+%typemap(javaout) (const char *utf8_path, vsi_l_offset *length) {
+    return $jnicall;
+  }
+
+
 /***************************************************
  * Typemaps for  (GByte* outBytes )
  ***************************************************/

swig/java/apps/GDALTestIO.java

@@ -23,6 +23,7 @@
 import org.gdal.gdal.Dataset;
 import org.gdal.gdal.Driver;
 import org.gdal.gdalconst.gdalconst;
+import org.gdal.gdal.*;
 
 public class GDALTestIO implements Runnable
 {
@@ -148,7 +149,9 @@ public static void main(String[] args) throws InterruptedException
         gdal.AllRegister();
 
         testInt64();
-
+
+        testGetMemFileBuffer();
+
         int nbIters = 50;
 
         method = METHOD_JAVA_ARRAYS;
@@ -186,12 +189,12 @@ public static void main(String[] args) throws InterruptedException
 
         System.out.println("Success !");
     }
-    
+
     private static void testInt64() {
-        
+
         long[] data1;
         long[] data2;
-        
+
         int xSz = 5;
         int ySz = 2;
         int nBands = 1;
@@ -214,4 +217,17 @@ private static void testInt64() {
                 throw new RuntimeException("int64 write and read values are not the same "+data1[i]+" "+data2[i]);
         }
     }
+
+    private static void testGetMemFileBuffer()
+    {
+        gdal.FileFromMemBuffer("/vsimem/test", new byte[] {1, 2, 3});
+        for(int iter = 0; iter < 2; iter++)
+        {
+            byte[] res = gdal.GetMemFileBuffer("/vsimem/test");
+            if (res.length != 3 )
+                throw new RuntimeException("res.length != 3");
+            if (res[0] != 1 || res[1] != 2 || res[2] != 3)
+                throw new RuntimeException("res != {1, 2, 3}");
+        }
+    }
 }

swig/java/javadoc.java

@@ -239,6 +239,25 @@ public class gdal:public static String EscapeString(byte[] byteArray, int scheme
  */
 public class gdal:public static void FileFromMemBuffer(String fileName, byte[] byteArray)
 
+
+/**
+ * Fetch buffer underlying memory file.
+ *
+ * This function returns a byte[] array with a copy of the content of the memory
+ * buffer underlying a virtual "in memory" file. The original file is unmodified
+ * by this operation, and must be removed with Unlink(fileName) if necessary.
+ *
+ * @param fileName filename (should begin with "/vsimem/")
+ *
+ * @return file content
+ *
+ * @since 3.10.1
+ *
+ * @see #Unlink(String fileName)
+ */
+public class gdal:public static byte[] GetMemFileBuffer(String fileName)
+
+
 /**
  * Delete a file.
  * <p>