内容压缩支持对已压缩内容重新压缩

internal/compressions/writer_encoding.go

@@ -0,0 +1,51 @@
+// Copyright 2021 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
+
+package compressions
+
+import (
+	"bytes"
+	"io"
+)
+
+type EncodingWriter struct {
+	contentEncoding ContentEncoding
+	writer          Writer
+	buf             *bytes.Buffer
+}
+
+func NewEncodingWriter(contentEncoding ContentEncoding, writer Writer) (Writer, error) {
+	return &EncodingWriter{
+		contentEncoding: contentEncoding,
+		writer:          writer,
+		buf:             &bytes.Buffer{},
+	}, nil
+}
+
+func (this *EncodingWriter) Write(p []byte) (int, error) {
+	return this.buf.Write(p)
+}
+
+func (this *EncodingWriter) Flush() error {
+	return this.writer.Flush()
+}
+
+func (this *EncodingWriter) Close() error {
+	reader, err := NewReader(this.buf, this.contentEncoding)
+	if err != nil {
+		_ = this.writer.Close()
+		return err
+	}
+	_, err = io.Copy(this.writer, reader)
+	if err != nil {
+		_ = reader.Close()
+		_ = this.writer.Close()
+		return err
+	}
+
+	_ = reader.Close()
+	return this.writer.Close()
+}
+
+func (this *EncodingWriter) Level() int {
+	return this.writer.Level()
+}