mime/multipart: add NewReader example

Fixes #7888

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/100420043

diff --git a/src/pkg/mime/multipart/example_test.go b/src/pkg/mime/multipart/example_test.go
new file mode 100644 (file)
index 0000000..26135b7
--- /dev/null
+++ b/src/pkg/mime/multipart/example_test.go
@@ -0,0 +1,53 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package multipart_test
+
+import (
+       "fmt"
+       "io"
+       "io/ioutil"
+       "log"
+       "mime"
+       "mime/multipart"
+       "net/mail"
+       "strings"
+)
+
+func ExampleNewReader() {
+       msg := &mail.Message{
+               Header: map[string][]string{
+                       "Content-Type": []string{"multipart/mixed; boundary=foo"},
+               },
+               Body: strings.NewReader(
+                       "--foo\r\nFoo: one\r\n\r\nA section\r\n" +
+                               "--foo\r\nFoo: two\r\n\r\nAnd another\r\n" +
+                               "--foo--\r\n"),
+       }
+       mediaType, params, err := mime.ParseMediaType(msg.Header.Get("Content-Type"))
+       if err != nil {
+               log.Fatal(err)
+       }
+       if strings.HasPrefix(mediaType, "multipart/") {
+               mr := multipart.NewReader(msg.Body, params["boundary"])
+               for {
+                       p, err := mr.NextPart()
+                       if err == io.EOF {
+                               return
+                       }
+                       if err != nil {
+                               log.Fatal(err)
+                       }
+                       slurp, err := ioutil.ReadAll(p)
+                       if err != nil {
+                               log.Fatal(err)
+                       }
+                       fmt.Printf("Part %q: %q\n", p.Header.Get("Foo"), slurp)
+               }
+       }
+
+       // Output:
+       // Part "one": "A section"
+       // Part "two": "And another"
+}

diff --git a/src/pkg/mime/multipart/multipart.go b/src/pkg/mime/multipart/multipart.go
index 2b4f5b433ec51c3b6643349e1268dd7db0f8d0f3..7382efab96723a66a87dadaf73e9a199fa4461c2 100644 (file)
--- a/src/pkg/mime/multipart/multipart.go
+++ b/src/pkg/mime/multipart/multipart.go
@@ -81,12 +81,16 @@ func (p *Part) parseContentDisposition() {
        }
 }
 
-// NewReader creates a new multipart Reader reading from reader using the
+// NewReader creates a new multipart Reader reading from r using the
 // given MIME boundary.
-func NewReader(reader io.Reader, boundary string) *Reader {
+//
+// The boundary is usually obtained from the "boundary" parameter of
+// the message's "Content-Type" header. Use mime.ParseMediaType to
+// parse such headers.
+func NewReader(r io.Reader, boundary string) *Reader {
        b := []byte("\r\n--" + boundary + "--")
        return &Reader{
-               bufReader: bufio.NewReader(reader),
+               bufReader: bufio.NewReader(r),
 
                nl:               b[:2],
                nlDashBoundary:   b[:len(b)-2],