fix #305, Java Double type to float64 get error when null value set

double.go

@@ -146,6 +146,9 @@ func (d *Decoder) decDouble(flag int32) (interface{}, error) {
 		var f64 float64
 		err = binary.Read(d.reader, binary.BigEndian, &f64)
 		return f64, perrors.WithStack(err)
+
+	case BC_NULL:
+		return float64(0), nil
 	}
 
 	return nil, perrors.Errorf("decDouble parse double wrong tag:%d-%#x", int(tag), tag)

double_test.go

@@ -18,6 +18,7 @@
 package hessian
 
 import (
+	"reflect"
 	"testing"
 )
 
@@ -69,7 +70,35 @@ func TestIssue181(t *testing.T) {
 	t.Logf("decode(%v) = %v\n", v, res)
 }
 
+func TestDoubleNull(t *testing.T) {
+	var (
+		v   float32
+		err error
+		d   *Decoder
+		res interface{}
+	)
+
+	// Double type with null value
+	d = NewDecoder([]byte{'C', 'N'})
+	res, err = d.Decode()
+	if err != nil {
+		t.Errorf("get error when decode %v", err)
+		return
+	}
+	f, ok := res.(float64)
+	if !ok {
+		t.Errorf("float64 is expected but %v", reflect.TypeOf(res))
+		return
+	}
+	if float32(f) != 0.0 {
+		t.Errorf("expect float32")
+		return
+	}
+	t.Logf("decode(%v) = %v\n", v, res)
+}
+
 func TestDouble(t *testing.T) {
+	testDecodeFramework(t, "replyNull", nil)
 	testDecodeFramework(t, "replyDouble_0_0", 0.0)
 	testDecodeFramework(t, "replyDouble_0_001", 0.001)
 	testDecodeFramework(t, "replyDouble_1_0", 1.0)
@@ -109,3 +138,17 @@ func TestDoublePrtEncode(t *testing.T) {
 	testSimpleEncode(t, &f0)
 	testSimpleEncode(t, &f1)
 }
+
+type score struct {
+	Score float64
+	Name  string
+}
+
+func (s score) JavaClassName() string {
+	return "test.Score"
+}
+
+func TestDecodeDoubleHasNull(t *testing.T) {
+	RegisterPOJO(&score{})
+	testDecodeFramework(t, "customReplyTypedDoubleHasNull", &score{Score: 0, Name: "DoubleWithNull"})
+}

test_hessian/src/main/java/test/TestCustomReply.java

@@ -693,6 +693,35 @@ public void customReplyEnumSet() throws Exception {
         output.writeObject(map);
         output.flush();
     }
+
+    public void customReplyTypedDoubleHasNull() throws Exception {
+
+        Score s = new Score();
+        s.setScore(null);
+        s.setName("DoubleWithNull");
+        output.writeObject(s);
+        output.flush();
+    }
+}
+
+class Score implements Serializable {
+    private Double score;
+    private String name;
+
+    public void setName(String name) {
+        this.name = name;
+    }
+    public String getName() {
+        return this.name;
+    }
+
+    public void setScore(Double score) {
+        this.score = score;
+    }
+
+    public Double getScore() {
+        return this.score;
+    }
 }
 
 interface Leg {