json, xml and protobuf encoding and decoding methods of Golang functions

Golang is an open source programming language that is widely used in the development of network applications. In Golang, it not only provides a rich function library, but also provides a variety of encoding and decoding methods, including json, xml and protobuf. This article will introduce the json, xml and protobuf encoding and decoding methods of Golang functions and their use.

1. json encoding and decoding

1.1 Encoding

In Golang, encoding a structure into json format is very simple. Just use the Marshal function in the json package to encode the structure into json data.

For example, we have a structure as follows:

type Student struct {
    Name    string `json:"name"`
    Age     int    `json:"age"`
    Address string `json:"address"`
}

If we want to encode this structure into json format, we can do this:

s := Student{
    Name:    "张三",
    Age:     18,
    Address: "北京市朝阳区",
}
b, err := json.Marshal(s)
if err != nil {
    //错误处理
}
fmt.Println(string(b))

The output json format is as follows ：

{
    "name": "张三",
    "age": 18,
    "address": "北京市朝阳区"
}

1.2 Decoding

Similarly, it is also very simple to use the Unmarshal function in the json package to decode json data into a structure. Just pass the json data into the Unmarshal function.

For example, we have the following json data:

data := `{
    "name": "李四",
    "age": 20,
    "address": "上海市浦东新区"
}`

If we want to decode this json data into a structure, we can do this:

var s Student
err := json.Unmarshal([]byte(data), &s)
if err != nil {
    //错误处理
}
fmt.Println(s.Name, s.Age, s.Address)

The output result is:

李四 20 上海市浦东新区

2. XML encoding and decoding

2.1 Encoding

In Golang, the structure can also be encoded into xml format. Just use the Marshal function in the encoding/xml package.

For example, we have a structure as follows:

type Student struct {
    Name    string `xml:"name"`
    Age     int    `xml:"age"`
    Address string `xml:"address"`
}

If we want to encode this structure into xml format, we can do this:

s := Student{
    Name:    "张三",
    Age:     18,
    Address: "北京市朝阳区",
}
b, err := xml.Marshal(s)
if err != nil {
    //错误处理
}
fmt.Println(string(b))

Output xml format As follows:

<Student>
    <name>张三</name>
    <age>18</age>
    <address>北京市朝阳区</address>
</Student>

2.2 Decoding

Similarly, it is also very simple to use the Unmarshal function in the encoding/xml package to decode xml data into a structure. Just pass the xml data into the Unmarshal function.

For example, we have the following xml data:

data := `
<Student>
    <name>李四</name>
    <age>20</age>
    <address>上海市浦东新区</address>
</Student>`

If we want to decode this xml data into a structure, we can do this:

var s Student
err := xml.Unmarshal([]byte(data), &s)
if err != nil {
    //错误处理
}
fmt.Println(s.Name, s.Age, s.Address)

The output result is:

李四 20 上海市浦东新区

3. protobuf encoding and decoding

3.1 Install protobuf

Before protobuf encoding and decoding, you need to install protobuf first. The installation method is as follows:

1. Download the protobuf installation file. Download address: https://github.com/protocolbuffers/protobuf/releases
2. Extract the installation file and enter the decompressed directory.
3. Execute the following command to install protobuf:

./configure
make
make check
sudo make install
sudo ldconfig

4. Check whether protobuf is installed successfully:

protoc --version

If information similar to the following is output, please indicate protobuf has been installed successfully:

libprotoc 3.6.1

3.2 Write protobuf file

Before protobuf encoding and decoding, you need to write a protobuf file. In the protobuf file, you need to define the Message type and assign a tag to each field.

For example, we write a protobuf file as follows:

syntax = "proto3";
package main;

message Student {
    string name = 1;
    int32 age    = 2;
    string address = 3;
}

In protobuf, tag is an integer value used to identify each field. In this example, the name field is set to 1, the age field is set to 2, and the address field is set to 3.

3.3 Coding

In Golang, coding using protobuf is very simple. Just use the Marshal function in the protobuf package.

For example, we have a structure as follows:

s := &pb.Student{
    Name:    "张三",
    Age:     18,
    Address: "北京市朝阳区",
}
b, err := proto.Marshal(s)
if err != nil {
    //错误处理
}
fmt.Println(string(b))

The output protobuf encoding is as follows:

1:6
2:18
3:"北京市朝阳区"

3.4 Decoding

Similarly, use the protobuf package The Unmarshal function to decode protobuf data into a structure is also very simple. Just pass the protobuf data and Message type into the Unmarshal function.

For example, we have the following protobuf data:

data := []byte{0x0a, 0x06, 0xe5, 0xbc, 0xa0, 0xe4, 0xb8, 0x89, 0x10, 0x12, 0x0f, 0xe5, 0x8c, 0x97, 0xe4, 0xba, 0xac, 0xe5, 0x9b, 0xbd, 0xe5, 0x8c, 0x9d, 0xe5, 0x8c, 0x97, 0xe5, 0x8c, 0x80, 0x1a, 0x0d, 0xe5, 0x8c, 0x97, 0xe4, 0xba, 0xac, 0xe5, 0x9b, 0xbd, 0xe5, 0x8c, 0x9d}

If we want to decode this protobuf data into a structure, we can do this:

var s pb.Student
err := proto.Unmarshal(data, &s)
if err != nil {
    //错误处理
}
fmt.Println(s.Name, s.Age, s.Address)

The output result is:

张三 18 北京市朝阳区

Summary

In Golang, a variety of encoding and decoding methods are provided to meet the needs of different scenarios. json encoding and decoding, xml encoding and decoding, and protobuf encoding and decoding are commonly used encoding and decoding methods and have wide applicability. Mastering these codecs can help us develop network applications more easily.

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