easyjson是什么呢？ 根据官网介绍，easyjson是提供高效快速且易用的结构体structs<-->json转换包。easyjson并没有使用反射方式实现，所以性能比其他的json包该4-5倍，比golang 自带的json包快2-3倍。 easyjson目标是维持生成去代码简单，以致于它可以轻松地进行优化或固定。

goget-ugithub.com/mailru/easyjson/goinstallgithub.com/mailru/easyjson/easyjsonorgobuild-oeasyjsongithub.com/mailru/easyjson/easyjson

验证是否安装成功。

$easyjsonUsageofD:\Code\go\bin\easyjson.exe:-allgeneratemarshaler/unmarshalersforallstructsinafile-build_tagsstringbuildtagstoaddtogeneratedfile-leave_tempsdonotdeletetemporaryfiles-lower_camel_caseuselowerCamelCasenamesinsteadofCamelCasebydefault-no_std_marshalersdon'tgenerateMarshalJSON/UnmarshalJSONfuncs-noformatdonotrun'gofmt-w'onoutputfile-omit_emptyomitemptyfieldsbydefaultstringspecifythefilenameoftheoutput-pkgprocessthewholepackageinsteadofjustthegivenfile-snake_caseusesnake_casenamesinsteadofCamelCasebydefault-stubsonlygeneratestubsformarshaler/unmarshalerfuncs

其中有几个选项需要注意：

-lower_camel_case:将结构体字段field首字母改为小写。如Name=>name。-build_tagsstring:将指定的string生成到生成的go文件头部。-no_std_marshalers：不为结构体生成MarshalJSON/UnmarshalJSON函数。-omit_empty:没有赋值的field可以不生成到json，否则field为该字段类型的默认值。-output_filename:定义生成的文件名称。-pkg:对包内指定有`//easyjson:json`结构体生成对应的easyjson配置。-snke_case:可以下划线的field如`Name_Student`改为`name_student`。使用

记得在需要使用easyjson的结构体上加上//easyjson:json。 如下：

//easyjson:jsontypeSchoolstruct{Namestring`json:"name"`Addrstring`json:"addr"`}//easyjson:jsontypeStudentstruct{Idint`json:"id"`Namestring`json:"s_name"`SchoolSchool`json:"s_chool"`Birthdaytime.Time`json:"birthday"`}

在结构体包下执行

easyjson-allstudent.go

此时在该目录下出现一个新的文件。

//Codegeneratedbyeasyjsonformarshaling/unmarshaling.DONOTEDIT.packageeasyjsonimport(json"encoding/json"easyjson"github.com/mailru/easyjson"jlexer"github.com/mailru/easyjson/jlexer"jwriter"github.com/mailru/easyjson/jwriter")//suppressunusedpackagewarningvar(_*json.RawMessage_*jlexer.Lexer_*jwriter.Writer_easyjson.Marshaler)funceasyjsonB83d7b77DecodeStudygoEasyjson(in*jlexer.Lexer,out*Student){isTopLevel:=in.IsStart()ifin.IsNull(){ifisTopLevel{in.Consumed()}in.Skip()return}in.Delim('{')for!in.IsDelim('}'){key:=in.UnsafeString()in.WantColon()ifin.IsNull(){in.Skip()in.WantComma()continue}switchkey{case"id":out.Id=int(in.Int())case"s_name":out.Name=string(in.String())case"s_chool":easyjsonB83d7b77DecodeStudygoEasyjson1(in,&out.School)case"birthday":ifdata:=in.Raw();in.Ok(){in.AddError((out.Birthday).UnmarshalJSON(data))}default:in.SkipRecursive()}in.WantComma()}in.Delim('}')ifisTopLevel{in.Consumed()}}funceasyjsonB83d7b77EncodeStudygoEasyjson(out*jwriter.Writer,inStudent){out.RawByte('{')first:=true_=firstif!first{out.RawByte(',')}first=falseout.RawString("\"id\":")out.Int(int(in.Id))if!first{out.RawByte(',')}first=falseout.RawString("\"s_name\":")out.String(string(in.Name))if!first{out.RawByte(',')}first=falseout.RawString("\"s_chool\":")easyjsonB83d7b77EncodeStudygoEasyjson1(out,in.School)if!first{out.RawByte(',')}first=falseout.RawString("\"birthday\":")out.Raw((in.Birthday).MarshalJSON())out.RawByte('}')}//MarshalJSONsupportsjson.Marshalerinterfacefunc(vStudent)MarshalJSON()([]byte,error){w:=jwriter.Writer{}easyjsonB83d7b77EncodeStudygoEasyjson(&w,v)returnw.Buffer.BuildBytes(),w.Error}//MarshalEasyJSONsupportseasyjson.Marshalerinterfacefunc(vStudent)MarshalEasyJSON(w*jwriter.Writer){easyjsonB83d7b77EncodeStudygoEasyjson(w,v)}//UnmarshalJSONsupportsjson.Unmarshalerinterfacefunc(v*Student)UnmarshalJSON(data[]byte)error{r:=jlexer.Lexer{Data:data}easyjsonB83d7b77DecodeStudygoEasyjson(&r,v)returnr.Error()}//UnmarshalEasyJSONsupportseasyjson.Unmarshalerinterfacefunc(v*Student)UnmarshalEasyJSON(l*jlexer.Lexer){easyjsonB83d7b77DecodeStudygoEasyjson(l,v)}funceasyjsonB83d7b77DecodeStudygoEasyjson1(in*jlexer.Lexer,out*School){isTopLevel:=in.IsStart()ifin.IsNull(){ifisTopLevel{in.Consumed()}in.Skip()return}in.Delim('{')for!in.IsDelim('}'){key:=in.UnsafeString()in.WantColon()ifin.IsNull(){in.Skip()in.WantComma()continue}switchkey{case"name":out.Name=string(in.String())case"addr":out.Addr=string(in.String())default:in.SkipRecursive()}in.WantComma()}in.Delim('}')ifisTopLevel{in.Consumed()}}funceasyjsonB83d7b77EncodeStudygoEasyjson1(out*jwriter.Writer,inSchool){out.RawByte('{')first:=true_=firstif!first{out.RawByte(',')}first=falseout.RawString("\"name\":")out.String(string(in.Name))if!first{out.RawByte(',')}first=falseout.RawString("\"addr\":")out.String(string(in.Addr))out.RawByte('}')}

现在可以写一个测试类啦。

packagemainimport("studygo/easyjson""time""fmt")funcmain(){s:=easyjson.Student{Id:11,Name:"qq",School:easyjson.School{Name:"CUMT",Addr:"xz",},Birthday:time.Now(),}bt,err:=s.MarshalJSON()fmt.Println(string(bt),err)json:=`{"id":11,"s_name":"qq","s_chool":{"name":"CUMT","addr":"xz"},"birthday":"2017-08-04T20:58:07.9894603+08:00"}`ss:=easyjson.Student{}ss.UnmarshalJSON([]byte(json))fmt.Println(ss)}

运行结果：

{"id":11,"s_name":"qq","s_chool":{"name":"CUMT","addr":"xz"},"birthday":"2017-08-04T20:58:07.9894603+08:00"}<nil>{121{CwwwwwwwUMTxzwwwww}2017-08-0420:52:03.4066002+0800CST}