Allow passing a key to the Google Books API

googlebooks.go

@@ -4,6 +4,7 @@ import (
 	"crypto/md5"
 	"encoding/xml"
 	"errors"
+	"flag"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -14,6 +15,8 @@ import (
 	"time"
 )
 
+var googleAPIKey = flag.String("google-api-key", "", "Google API key")
+
 type googleBooksRefiner struct{}
 
 func (r *googleBooksRefiner) Name() string {
@@ -155,6 +158,9 @@ func (r *googleBooksRefiner) Lookup(m *Metadata) ([]*Metadata, error) {
 	}
 	values := make(url.Values)
 	values.Set("q", qstr)
+	if *googleAPIKey != "" {
+		values.Set("key", *googleAPIKey)
+	}
 	uri := "http://books.google.com/books/feeds/volumes?" + values.Encode()
 	resp, err := googleBooksGet(uri)
 	if err != nil {