Add a ToXmlGenerator.Feature to use XML Schema-compatible representation for floating-point infinity.

Fixes FasterXML#643.

Author: ahcodedthat

src/main/java/com/fasterxml/jackson/dataformat/xml/ser/ToXmlGenerator.java

@@ -20,6 +20,7 @@
 import com.fasterxml.jackson.core.json.JsonWriteContext;
 import com.fasterxml.jackson.core.util.JacksonFeatureSet;
 import com.fasterxml.jackson.dataformat.xml.XmlPrettyPrinter;
+import com.fasterxml.jackson.dataformat.xml.deser.FromXmlParser;
 import com.fasterxml.jackson.dataformat.xml.util.DefaultXmlPrettyPrinter;
 import com.fasterxml.jackson.dataformat.xml.util.StaxUtil;
 
@@ -106,6 +107,34 @@ public enum Feature implements FormatFeature
          * @since 2.17
          */
         AUTO_DETECT_XSI_TYPE(false),
+
+        /**
+         * Feature that determines how floating-point infinity values are
+         * serialized.
+         *<p>
+         * By default, {@link Float#POSITIVE_INFINITY} and
+         * {@link Double#POSITIVE_INFINITY} are serialized as {@code Infinity},
+         * and {@link Float#NEGATIVE_INFINITY} and
+         * {@link Double#NEGATIVE_INFINITY} are serialized as
+         * {@code -Infinity}. This is the representation that Java normally
+         * uses for these values (see {@link Float#toString(float)} and
+         * {@link Double#toString(double)}), but JAXB and other XML
+         * Schema-conforming readers won't understand it.
+         *<p>
+         * With this feature enabled, these values are instead serialized as
+         * {@code INF} and {@code -INF}, respectively. This is the
+         * representation that XML Schema and JAXB use (see the XML Schema
+         * primitive types
+         * <a href="https://www.w3.org/TR/xmlschema-2/#float"><code>float</code></a>
+         * and
+         * <a href="https://www.w3.org/TR/xmlschema-2/#double"><code>double</code></a>).
+         *<p>
+         * When deserializing, Jackson always understands both representations,
+         * so there is no corresponding {@link FromXmlParser.Feature}.
+         *<p>
+         * Feature is disabled by default for backwards compatibility.
+         */
+        XML_SCHEMA_CONFORMING_FLOATS(false),
         ;
 
         final boolean _defaultState;
@@ -145,7 +174,7 @@ private Feature(boolean defaultState) {
     protected final XMLStreamWriter2 _xmlWriter;
 
     protected final XMLStreamWriter _originalXmlWriter;
-    
+
     /**
      * Marker flag set if the underlying stream writer has to emulate
      * Stax2 API: this is problematic if trying to use {@link #writeRaw} calls.
@@ -184,7 +213,7 @@ private Feature(boolean defaultState) {
 
     /**
      * Marker set when {@link #initGenerator()} has been called or not.
-     * 
+     *
      * @since 2.2
      */
     protected boolean _initialized;
@@ -218,7 +247,7 @@ private Feature(boolean defaultState) {
 
     /**
      * To support proper serialization of arrays it is necessary to keep
-     * stack of element names, so that we can "revert" to earlier 
+     * stack of element names, so that we can "revert" to earlier
      */
     protected LinkedList<QName> _elementNameStack = new LinkedList<QName>();
 
@@ -403,7 +432,7 @@ public boolean inRoot() {
     public XMLStreamWriter getStaxWriter() {
         return _xmlWriter;
     }
-    
+
     /*
     /**********************************************************
     /* Extended API, passing XML specific settings
@@ -424,7 +453,7 @@ public void setNextIsCData(boolean isCData)
     {
         _nextIsCData = isCData;
     }
-    
+
     public final void setNextName(QName name)
     {
         _nextName = name;
@@ -433,7 +462,7 @@ public final void setNextName(QName name)
     /**
      * Method that does same as {@link #setNextName}, unless
      * a name has already been set.
-     * 
+     *
      * @since 2.1.2
      */
     public final boolean setNextNameIfMissing(QName name)
@@ -444,11 +473,11 @@ public final boolean setNextNameIfMissing(QName name)
         }
         return false;
     }
-    
+
     /**
      * Methdod called when a structured (collection, array, map) is being
      * output.
-     * 
+     *
      * @param wrapperName Element used as wrapper around elements, if any (null if none)
      * @param wrappedName Element used around individual content items (can not
      *   be null)
@@ -491,7 +520,7 @@ public void finishWrappedValue(QName wrapperName, QName wrappedName) throws IOEx
 
     /**
      * Trivial helper method called when to add a replicated wrapper name
-     * 
+     *
      * @since 2.2
      */
     public void writeRepeatedFieldName() throws IOException
@@ -500,7 +529,7 @@ public void writeRepeatedFieldName() throws IOException
             _reportError("Can not write a field name, expecting a value");
         }
     }
-    
+
     /*
     /**********************************************************
     /* JsonGenerator method overrides
@@ -582,7 +611,7 @@ public final void writeStartArray() throws IOException
             // nothing to do here; no-operation
         }
     }
-    
+
     @Override
     public final void writeEndArray() throws IOException
     {
@@ -640,7 +669,7 @@ public final void _handleStartObject() throws IOException
             StaxUtil.throwAsGenerationException(e, this);
         }
     }
-    
+
     // note: public just because pretty printer needs to make a callback
     public final void _handleEndObject() throws IOException
     {
@@ -664,7 +693,7 @@ public final void _handleEndObject() throws IOException
             StaxUtil.throwAsGenerationException(e, this);
         }
     }
-    
+
     /*
     /**********************************************************
     /* Output method implementations, textual
@@ -706,12 +735,12 @@ public void writeString(String text) throws IOException
                     _xmlWriter.writeCharacters(text);
                 }
                 _xmlWriter.writeEndElement();
-            } 
+            }
         } catch (XMLStreamException e) {
             StaxUtil.throwAsGenerationException(e, this);
         }
-    }    
-    
+    }
+
     @Override
     public void writeString(char[] text, int offset, int len) throws IOException
     {
@@ -751,7 +780,7 @@ public void writeString(char[] text, int offset, int len) throws IOException
     public void writeString(SerializableString text) throws IOException {
         writeString(text.getValue());
     }
-    
+
     @Override
     public void writeRawUTF8String(byte[] text, int offset, int length) throws IOException
     {
@@ -901,7 +930,7 @@ public void writeRaw(char c) throws IOException
     {
         writeRaw(String.valueOf(c));
     }
-    
+
     /*
     /**********************************************************
     /* Output method implementations, base64-encoded binary
@@ -987,7 +1016,7 @@ public int writeBinary(Base64Variant b64variant, InputStream data, int dataLengt
     }
 
     private void writeStreamAsBinary(org.codehaus.stax2.typed.Base64Variant stax2base64v,
-            InputStream data, int len) throws IOException, XMLStreamException 
+            InputStream data, int len) throws IOException, XMLStreamException
     {
         // base64 encodes up to 3 bytes into a 4 bytes string
         byte[] tmp = new byte[3];
@@ -1024,7 +1053,7 @@ private byte[] toFullBuffer(byte[] data, int offset, int len)
         return result;
     }
 
-    private byte[] toFullBuffer(InputStream data, final int len) throws IOException 
+    private byte[] toFullBuffer(InputStream data, final int len) throws IOException
     {
         byte[] result = new byte[len];
         int offset = 0;
@@ -1174,6 +1203,11 @@ public void writeNumber(long l) throws IOException
     @Override
     public void writeNumber(double d) throws IOException
     {
+        if (Double.isInfinite(d) && isEnabled(Feature.XML_SCHEMA_CONFORMING_FLOATS)) {
+            writeNumber(d > 0d ? "INF" : "-INF");
+            return;
+        }
+
         _verifyValueWrite("write number");
         if (_nextName == null) {
             handleMissingName();
@@ -1202,6 +1236,11 @@ public void writeNumber(double d) throws IOException
     @Override
     public void writeNumber(float f) throws IOException
     {
+        if (Float.isInfinite(f) && isEnabled(Feature.XML_SCHEMA_CONFORMING_FLOATS)) {
+            writeNumber(f > 0f ? "INF" : "-INF");
+            return;
+        }
+
         _verifyValueWrite("write number");
         if (_nextName == null) {
             handleMissingName();
@@ -1418,7 +1457,7 @@ protected boolean checkNextIsUnwrapped()
         }
         return false;
     }
-    
+
     protected void handleMissingName() {
         throw new IllegalStateException("No element/attribute name specified when trying to output element");
     }

src/test/java/com/fasterxml/jackson/dataformat/xml/ser/TestSerialization.java

@@ -26,11 +26,27 @@ static class AttributeBean
     static class AttrAndElem
     {
         public String elem = "whatever";
-        
+
         @JacksonXmlProperty(isAttribute=true, localName="id")
         public int attr = 42;
     }
 
+    static class Floats
+    {
+        public float elem;
+
+        @JacksonXmlProperty(isAttribute=true, localName="attr")
+        public float attr;
+    }
+
+    static class Doubles
+    {
+        public double elem;
+
+        @JacksonXmlProperty(isAttribute=true, localName="attr")
+        public double attr;
+    }
+
     static class WrapperBean<T>
     {
         public T value;
@@ -58,7 +74,7 @@ static class NsElemBean2
         @JsonProperty(namespace="http://foo")
         public String text = "blah";
     }
-    
+
     static class CDataStringBean
     {
         @JacksonXmlCData
@@ -103,7 +119,7 @@ public void testSimpleNsElemWithJsonProp() throws IOException
         // here we assume woodstox automatic prefixes, not very robust but:
         assertEquals("<NsElemBean2><wstxns1:text xmlns:wstxns1=\"http://foo\">blah</wstxns1:text></NsElemBean2>", xml);
     }
-    
+
     public void testSimpleAttrAndElem() throws IOException
     {
         String xml = _xmlMapper.writeValueAsString(new AttrAndElem());
@@ -119,7 +135,7 @@ public void testMap() throws IOException
         map.put("b", 2);
 
         String xml;
-        
+
         xml = _xmlMapper.writeValueAsString(new WrapperBean<Map<?,?>>(map));
         assertEquals("<WrapperBean><value>"
                 +"<a>1</a>"
@@ -138,14 +154,14 @@ public void testMap() throws IOException
 
     public void testNakedMap() throws IOException
     {
-        CustomMap input = new CustomMap();        
+        CustomMap input = new CustomMap();
         input.put("a", 123);
         input.put("b", 456);
         String xml = _xmlMapper.writeValueAsString(input);
 
-        
+
 //        System.err.println("XML = "+xml);
-        
+
         CustomMap result = _xmlMapper.readValue(xml, CustomMap.class);
         assertEquals(2, result.size());
 
@@ -175,4 +191,62 @@ public void testJAXB() throws Exception
         System.out.println("JAXB -> "+sw);
     }
     */
+
+    public void testFloatInfinity() throws IOException
+    {
+        Floats infinite = new Floats();
+        infinite.attr = Float.POSITIVE_INFINITY;
+        infinite.elem = Float.NEGATIVE_INFINITY;
+
+        Floats finite = new Floats();
+        finite.attr = 42.5f;
+        finite.elem = 1337.875f;
+
+        checkFloatInfinity(infinite, false, "<Floats attr=\"Infinity\"><elem>-Infinity</elem></Floats>");
+        checkFloatInfinity(finite, false, "<Floats attr=\"42.5\"><elem>1337.875</elem></Floats>");
+        checkFloatInfinity(infinite, true, "<Floats attr=\"INF\"><elem>-INF</elem></Floats>");
+        checkFloatInfinity(finite, true, "<Floats attr=\"42.5\"><elem>1337.875</elem></Floats>");
+    }
+
+    private void checkFloatInfinity(Floats original, boolean xmlSchemaConforming, String expectedXml) throws IOException
+    {
+        _xmlMapper.configure(ToXmlGenerator.Feature.XML_SCHEMA_CONFORMING_FLOATS, xmlSchemaConforming);
+
+        String xml = _xmlMapper.writeValueAsString(original);
+        xml = removeSjsxpNamespace(xml);
+        assertEquals(expectedXml, xml);
+
+        Floats deserialized = _xmlMapper.readValue(xml, Floats.class);
+        assertEquals(original.attr, deserialized.attr);
+        assertEquals(original.elem, deserialized.elem);
+    }
+
+    public void testDoubleInfinity() throws IOException
+    {
+        Doubles infinite = new Doubles();
+        infinite.attr = Double.POSITIVE_INFINITY;
+        infinite.elem = Double.NEGATIVE_INFINITY;
+
+        Doubles finite = new Doubles();
+        finite.attr = 42.5d;
+        finite.elem = 1337.875d;
+
+        checkDoubleInfinity(infinite, false, "<Doubles attr=\"Infinity\"><elem>-Infinity</elem></Doubles>");
+        checkDoubleInfinity(finite, false, "<Doubles attr=\"42.5\"><elem>1337.875</elem></Doubles>");
+        checkDoubleInfinity(infinite, true, "<Doubles attr=\"INF\"><elem>-INF</elem></Doubles>");
+        checkDoubleInfinity(finite, true, "<Doubles attr=\"42.5\"><elem>1337.875</elem></Doubles>");
+    }
+
+    private void checkDoubleInfinity(Doubles original, boolean xmlSchemaConforming, String expectedXml) throws IOException
+    {
+        _xmlMapper.configure(ToXmlGenerator.Feature.XML_SCHEMA_CONFORMING_FLOATS, xmlSchemaConforming);
+
+        String xml = _xmlMapper.writeValueAsString(original);
+        xml = removeSjsxpNamespace(xml);
+        assertEquals(expectedXml, xml);
+
+        Doubles deserialized = _xmlMapper.readValue(xml, Doubles.class);
+        assertEquals(original.attr, deserialized.attr);
+        assertEquals(original.elem, deserialized.elem);
+    }
 }