double exponent notation to number

src/main/java/com/googlecode/protobuf/format/XmlFormat.java

@@ -31,18 +31,17 @@ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 
 import java.io.IOException;
 import java.math.BigInteger;
+import java.text.DecimalFormat;
+import java.text.Format;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.nio.CharBuffer;
 
-import com.google.protobuf.ByteString;
-import com.google.protobuf.Descriptors;
-import com.google.protobuf.ExtensionRegistry;
-import com.google.protobuf.Message;
-import com.google.protobuf.UnknownFieldSet;
+import com.google.protobuf.*;
 import com.google.protobuf.Descriptors.EnumValueDescriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
 import static com.googlecode.protobuf.format.util.TextUtils.*;
@@ -62,6 +61,7 @@ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  */
 public final class XmlFormat extends AbstractCharBasedFormatter {
 
+    public Map<FieldDescriptor.Type, Format> formatter = new HashMap<FieldDescriptor.Type, Format>();
     /**
      * Outputs a textual representation of the Protocol Message supplied into the parameter output.
      * (This representation is the new version of the classic "ProtocolPrinter" output from the
@@ -164,7 +164,10 @@ private void printFieldValue(FieldDescriptor field, Object value, XmlGenerator g
             case DOUBLE:
             case BOOL:
                 // Good old toString() does what we want for these types.
-                generator.print(value.toString());
+                if(formatter.containsKey(field.getType()))
+                    generator.print(formatter.get(field.getType()).format(value));
+                else
+                    generator.print(value.toString());
                 break;
 
             case UINT32:

src/test/java/com/googlecode/protobuf/format/XmlFormatTest.java

@@ -0,0 +1,37 @@
+package com.googlecode.protobuf.format;
+
+import com.google.protobuf.Descriptors;
+import com.googlecode.protobuf.format.issue23.Issue23;
+import org.testng.annotations.Test;
+import org.testng.reporters.Files;
+
+import java.io.IOException;
+import java.text.DecimalFormat;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+/**
+ * Created by kyakkala on 3/22/2018.
+ */
+public class XmlFormatTest {
+
+    @Test
+    public void testDecimalFormat() throws IOException {
+
+        Issue23.MsgWithUnknownFields msg = Issue23.MsgWithUnknownFields.newBuilder()
+                .setLeaf4(12345670678.01245)
+                .build();
+        XmlFormat xmlFormat = new XmlFormat();
+
+        DecimalFormat decimalFormat = new DecimalFormat("#");
+        decimalFormat.setMaximumFractionDigits(4);
+        xmlFormat.formatter.put(Descriptors.FieldDescriptor.Type.DOUBLE, decimalFormat);
+
+        assertThat(xmlFormat.printToString(msg).toString(),
+                is(Files.readFile(XmlFormatTest.class
+                .getResourceAsStream(
+                "/expectations/xmlFormatTest/xml_format_without_exponent_notation.txt")).trim()));
+
+    }
+}

src/test/resources/expectations/xmlFormatTest/xml_format_without_exponent_notation.txt

@@ -0,0 +1 @@
+<MsgWithUnknownFields><leaf4>12345670678.0124</leaf4></MsgWithUnknownFields>

src/test/resources/proto/issue23.proto

@@ -8,4 +8,5 @@ message MsgWithUnknownFields {
   optional string leaf1 = 1;
   optional int32 leaf2 = 2;
   repeated int32 leaf3 = 3;
+  optional double leaf4 = 4;
 }