Record the Go language mining pit and record the gob serialization pit.

The following is the tutorial column of golang to share with you the Go language mining pit record gob serialization pit. I hope it will be helpful to friends in need!

package mainimport (
	"bytes"
	"encoding/gob"
	"fmt"
	"log"
	"os")func main() {
	/// 序列化编码&写入文件开始 ///
	// 实例化一个学生对象s1
	s1 := &Student{id: 1, name: "jack ma", age: 2, cash: 43242334.35}

	// 实例化一个gob编码对象，并对s1学生对象进行编码
	var buf bytes.Buffer
	encoder := gob.NewEncoder(&buf)
	error2Log("Encode: ", encoder.Encode(s1))

	// 输出序列化后的类容
	fmt.Printf("Serialized: %x\n", buf.Bytes())

	// 创建data.data文件，存放序列化数据
	fs, err := os.Create("./data.data")
	error2Log("Creat File: ", err)
	// 写入数据，并打印写入数据长度
	wlen, err := fs.Write(buf.Bytes())
	error2Log("Write file: ", err)
	fmt.Println("Wirte bytes:", wlen)
	fs.Close()

	/// 序列化编码&写入文件结束 ///

	/// 读入文件&反序列化编码开始 ///

	// 从文件打开写入的序列化数据
	fs, err = os.Open("./data.data")
	error2Log("Open file: ", err)
	// 获取文件信息接口
	finfo, err := fs.Stat()
	error2Log("Get fileinfo: ", err)
	// 根据文件大小创建字节数组，然后将文件中数据读入到字节数组中，并打印读入数据长度
	readBuf := make([]byte, finfo.Size())
	rlen, err := fs.Read(readBuf)
	error2Log("Read file: ", err)
	fmt.Println("Read bytes:", rlen)
	fs.Close()

	// 实例化一个用于接收反序列化数据的学生对象
	s2 := new(Student)

	// 实例化一个gob解码对象
	decoder := gob.NewDecoder(bytes.NewReader(readBuf))
	// 将数据解码到学生对象s2
	error2Log("Decode: ", decoder.Decode(s2))
	// 将反序列化后的数据，s2学生对象打印出来
	fmt.Println("Unserialized：", s2)

	/// 读入文件&反序列化编码结束 ///}func error2Log(m string, e error) {
	if e != nil {
		log.Fatal(m, e)
	}}// Student 学生对象type Student struct {
	id   uint64
	name string
	age  uint
	cash float64}

The running structure after compilation is as follows:

2019/04/17 15:07:46 Encode: gob: type main.Student has no exported fields

It made me depressed Many hours. I checked some information, such as:

https://github.com/golang/go/issues/5819
But this is not the solution to the problem I need. I just want to add one The structure object is written to the file, and there is no intention to embed the structure.
Then a sudden inspiration came to me, and I made a super low-level mistake:

type Student struct {
	id   uint64
	name string
	age  uint
	cash float64}

Nima... Structure members (called fields in Golang) are lowercase..., and suddenly I remembered about package-level variable names and function names, Lowercase is equivalent to private... Is that so?
Immediately changed:

type Student struct {
	ID   uint64
	Name string
	Age  uint
	Cash float64}

The instantiation s1 in line 14 was changed to:

s1 := &Student{ID: 1, Name: "jack ma", Age: 2, Cash: 43242334.35}

Then the compile and run structure was finally correct:

Serialized: 36ff810301010753747564656e7401ff820001040102494401060001044e616d65010c00010341676501060001044361736801080000001aff82010101076a61636b206d61010201f8cdccccf29a9e844100
Wirte bytes: 82
Read bytes: 82
Unserialized： &{1 jack ma 2 4.324233435e+07}

This is equivalent to going back It seems that there are no coding habits developed in golang.
Therefore, when writing structures in the future, you must develop a good habit: field names should use capital letters. (555555555555555~)

package mainimport (
	"bytes"
	"encoding/gob"
	"fmt"
	"log"
	"os")func main() {
	/// 序列化编码&写入文件开始 ///
	// 实例化一个学生对象s1
	s1 := &Student{id: 1, name: "jack ma", age: 2, cash: 43242334.35}

	// 实例化一个gob编码对象，并对s1学生对象进行编码
	var buf bytes.Buffer
	encoder := gob.NewEncoder(&buf)
	error2Log("Encode: ", encoder.Encode(s1))

	// 输出序列化后的类容
	fmt.Printf("Serialized: %x\n", buf.Bytes())

	// 创建data.data文件，存放序列化数据
	fs, err := os.Create("./data.data")
	error2Log("Creat File: ", err)
	// 写入数据，并打印写入数据长度
	wlen, err := fs.Write(buf.Bytes())
	error2Log("Write file: ", err)
	fmt.Println("Wirte bytes:", wlen)
	fs.Close()

	/// 序列化编码&写入文件结束 ///

	/// 读入文件&反序列化编码开始 ///

	// 从文件打开写入的序列化数据
	fs, err = os.Open("./data.data")
	error2Log("Open file: ", err)
	// 获取文件信息接口
	finfo, err := fs.Stat()
	error2Log("Get fileinfo: ", err)
	// 根据文件大小创建字节数组，然后将文件中数据读入到字节数组中，并打印读入数据长度
	readBuf := make([]byte, finfo.Size())
	rlen, err := fs.Read(readBuf)
	error2Log("Read file: ", err)
	fmt.Println("Read bytes:", rlen)
	fs.Close()

	// 实例化一个用于接收反序列化数据的学生对象
	s2 := new(Student)

	// 实例化一个gob解码对象
	decoder := gob.NewDecoder(bytes.NewReader(readBuf))
	// 将数据解码到学生对象s2
	error2Log("Decode: ", decoder.Decode(s2))
	// 将反序列化后的数据，s2学生对象打印出来
	fmt.Println("Unserialized：", s2)

	/// 读入文件&反序列化编码结束 ///}func error2Log(m string, e error) {
	if e != nil {
		log.Fatal(m, e)
	}}// Student 学生对象type Student struct {
	id   uint64
	name string
	age  uint
	cash float64}

The running structure after compilation is as follows:

2019/04/17 15:07:46 Encode: gob: type main.Student has no exported fields

It made me depressed for more than an hour . I queried some information, such as:

https://github.com/golang/go/issues/5819
But this is not the solution to the problem I need. I just want to write a structure object to a file. There is no intention to embed the structure into it.
Then a sudden inspiration came to me, and I made a super low-level mistake:

type Student struct {
	id   uint64
	name string
	age  uint
	cash float64}

Nima... Structure members (called fields in Golang) are lowercase..., and suddenly I remembered about package-level variable names and function names, Lowercase is equivalent to private... Is that so?

Immediately changed:

type Student struct {
	ID   uint64
	Name string
	Age  uint
	Cash float64}

The instantiation s1 in line 14 was changed to:

s1 := &Student{ID: 1, Name: "jack ma", Age: 2, Cash: 43242334.35}

Then the compile and run structure was finally correct:

Serialized: 36ff810301010753747564656e7401ff820001040102494401060001044e616d65010c00010341676501060001044361736801080000001aff82010101076a61636b206d61010201f8cdccccf29a9e844100
Wirte bytes: 82
Read bytes: 82
Unserialized： &{1 jack ma 2 4.324233435e+07}

This is equivalent to going back It seems that there are no coding habits developed in golang.

Therefore, when writing structures in the future, you must develop a good habit: field names should use capital letters. (555555555555555~)

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