Fixes #631: add XmlMapper overloads for parser/generator creation fro…

…m Stax entities (#632)

release-notes/VERSION-2.x

@@ -9,6 +9,8 @@ Project: jackson-dataformat-xml
 #618: `ArrayIndexOutOfBoundsException` thrown for invalid ending XML string
   when using JDK default Stax XML parser
  (reported by Arthur C)
+#631: Add `XmlMapper.createGenerator(XMLStreamWriter)` and
+  `XmlMapper.createParser(XMLStreamReader)` overloads
 * Upgrade Woodstox to 6.6.0 (latest at the time)
 
 2.16.1 (24-Dec-2023)

src/main/java/com/fasterxml/jackson/dataformat/xml/XmlMapper.java

@@ -268,7 +268,7 @@ protected TypeResolverBuilder<?> _constructDefaultTypeResolverBuilder(DefaultTyp
      */
     @Deprecated
     protected void setXMLTextElementName(String name) {
-        ((XmlFactory) _jsonFactory).setXMLTextElementName(name);
+        getFactory().setXMLTextElementName(name);
     }
 
     /**
@@ -292,7 +292,7 @@ public XmlMapper setDefaultUseWrapper(boolean state) {
      * @since 2.14
      */
     public void setXmlNameProcessor(XmlNameProcessor processor) {
-        ((XmlFactory)_jsonFactory).setXmlNameProcessor(processor);
+        getFactory().setXmlNameProcessor(processor);
     }
 
     /*
@@ -342,6 +342,26 @@ public ObjectMapper disable(FromXmlParser.Feature f) {
     /**********************************************************
      */
 
+    /**
+     * Overloaded variant that allows constructing {@link FromXmlParser}
+     * for given Stax {@link XMLStreamReader}.
+     *
+     * @since 2.17
+     */
+    public FromXmlParser createParser(XMLStreamReader r) throws IOException {
+        return getFactory().createParser(r);
+    }
+
+    /**
+     * Overloaded variant that allows constructing {@link ToXmlGenerator}
+     * for given Stax {@link XMLStreamWriter}.
+     *
+     * @since 2.17
+     */
+    public ToXmlGenerator createGenerator(XMLStreamWriter w) throws IOException {
+        return getFactory().createGenerator(w);
+    }
+
     /**
      * Method for reading a single XML value from given XML-specific input
      * source; useful for incremental data-binding, combining traversal using
@@ -374,7 +394,7 @@ public <T> T readValue(XMLStreamReader r, TypeReference<T> valueTypeRef) throws
     @SuppressWarnings("resource")
     public <T> T readValue(XMLStreamReader r, JavaType valueType) throws IOException
     {
-        FromXmlParser p = getFactory().createParser(r);
+        FromXmlParser p = createParser(r);
         return super.readValue(p,  valueType);
     } 
 
@@ -385,9 +405,9 @@ public <T> T readValue(XMLStreamReader r, JavaType valueType) throws IOException
      * 
      * @since 2.4
      */
-    public void writeValue(XMLStreamWriter w0, Object value) throws IOException {
+    public void writeValue(XMLStreamWriter w, Object value) throws IOException {
         @SuppressWarnings("resource")
-        ToXmlGenerator g = getFactory().createGenerator(w0);
+        ToXmlGenerator g = createGenerator(w);
         super.writeValue(g, value);
         // NOTE: above call should do flush(); and we should NOT close here.
         // Finally, 'g' has no buffers to release.

src/test/java/com/fasterxml/jackson/dataformat/xml/incr/IncrementalWritingTest.java

@@ -2,10 +2,12 @@
 
 import java.io.*;
 
+import javax.xml.stream.XMLOutputFactory;
 import javax.xml.stream.XMLStreamWriter;
 
 import com.fasterxml.jackson.dataformat.xml.XmlMapper;
 import com.fasterxml.jackson.dataformat.xml.XmlTestBase;
+import com.fasterxml.jackson.dataformat.xml.ser.ToXmlGenerator;
 
 public class IncrementalWritingTest extends XmlTestBase
 {
@@ -31,4 +33,29 @@ public void testSimple() throws Exception
                 +"<NameBean age=\"17\"><first>Growl</first><last>Tiger</last></NameBean></root>",
                 xml);
     }
+
+    // @since 2.17
+    public void testWriteUsingXMLStreamWriter() throws Exception
+    {
+        XMLOutputFactory staxF = MAPPER.getFactory().getXMLOutputFactory();
+        final Point p = new Point(1, 2);
+
+        // Serialize first using convenience method
+        try (StringWriter w = new StringWriter()) {
+            XMLStreamWriter sw = staxF.createXMLStreamWriter(w);
+            MAPPER.writeValue(sw, p);
+            assertEquals("<Point><x>1</x><y>2</y></Point>", w.toString());
+        }
+
+        // and then by explicit XMLStreamWriter
+        try (StringWriter w = new StringWriter()) {
+            XMLStreamWriter sw = staxF.createXMLStreamWriter(w);
+            sw.writeStartDocument("US-ASCII", "1.1");
+            try (ToXmlGenerator g = MAPPER.createGenerator(sw)) {
+                MAPPER.writeValue(g, p);
+                assertEquals("<?xml version='1.1' encoding='US-ASCII'?>"
+                        +"<Point><x>1</x><y>2</y></Point>", w.toString());
+            }
+        }
+    }
 }

src/test/java/com/fasterxml/jackson/dataformat/xml/incr/PartialReadTest.java

@@ -3,6 +3,7 @@
 import java.io.*;
 import javax.xml.stream.*;
 
+import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.dataformat.xml.XmlMapper;
 import com.fasterxml.jackson.dataformat.xml.XmlTestBase;
 
@@ -43,4 +44,27 @@ public void testSimpleRead() throws Exception
 
         sr.close();
     }
+
+    // @since 2.17
+    public void testReadUsingXMLStreamReader() throws Exception
+    {
+        final String DOC = "<Point><x>1</x><y>2</y></Point>";
+
+        XMLInputFactory staxF = MAPPER.getFactory().getXMLInputFactory();
+
+        // First read using XmlMapper convenience method
+        XMLStreamReader sr = staxF.createXMLStreamReader(new StringReader(DOC));
+        Point p = MAPPER.readValue(sr, Point.class);
+        assertEquals(1, p.x);
+        assertEquals(2, p.y);
+        sr.close();
+
+        // Then read using XmlFactory parser factory method
+        sr = staxF.createXMLStreamReader(new StringReader(DOC));
+        try (JsonParser jp = MAPPER.createParser(sr)) {
+            p = MAPPER.readValue(jp, Point.class);
+            assertEquals(1, p.x);
+            assertEquals(2, p.y);
+        }
+    }
 }