Further improve read performance

Instead of re-encoding the full sheet to change the namespaces
in the encoded bytes, read the sheet again and do the byte
replacements there.

In this case, file access ends up being more performant than
marshaling the sheet back to XML.

In the SharedStrings test, ensure the strings are actually read.

Fix #439

2 files changed, 7 insertions, 3 deletions

diff --git a/excelize_test.go b/excelize_test.go
index 79010b1..4169983 100644
--- a/excelize_test.go
+++ b/excelize_test.go
@@ -1003,7 +1003,11 @@ func TestSharedStrings(t *testing.T) {
 	if !assert.NoError(t, err) {
 		t.FailNow()
 	}
-	f.GetRows("Sheet1")
+	rows, err := f.GetRows("Sheet1")
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+	assert.Equal(t, "A", rows[0][0])
 }
 
 func TestSetSheetRow(t *testing.T) {
diff --git a/rows.go b/rows.go
index cb0e31f..220c233 100644
--- a/rows.go
+++ b/rows.go
@@ -112,8 +112,8 @@ func (f *File) Rows(sheet string) (*Rows, error) {
 		return nil, ErrSheetNotExist{sheet}
 	}
 	if xlsx != nil {
-		output, _ := xml.Marshal(f.Sheet[name])
-		f.saveFileList(name, replaceWorkSheetsRelationshipsNameSpaceBytes(output))
+		data := f.readXML(name)
+		f.saveFileList(name, replaceWorkSheetsRelationshipsNameSpaceBytes(namespaceStrictToTransitional(data)))
 	}
 	return &Rows{
 		f:    f,