Using the Gin framework to implement blockchain and digital currency payment functions

Today with the popularity of blockchain, more and more people are paying attention to digital currency and its application scenarios. How to use existing technology to quickly implement digital currency payment functions has become a hot topic in the industry. This article will introduce how to use the Gin framework to implement blockchain and digital currency payment functions.

1. What is the Gin framework?

Gin is a lightweight web framework, implemented based on Go language. Compared to other web frameworks, it is very fast, stable, simple, and has good performance. Therefore, using Gin to build web applications is a wise choice.

2. What is blockchain?

Blockchain is a distributed database that can record transaction information and save this information on multiple computers. Its core idea is decentralization, each node has the right to participate in the system, and there is no central control agency. Blockchain is based on cryptography technology so that transaction information can be transmitted and stored securely. The advantages are that it cannot be tampered with, transparent and safe. Therefore, blockchain is widely used in financial transactions, digital currency payments, supply chain management and other fields.

3. How to use the Gin framework to implement blockchain and digital currency payment functions?

1. Install the Gin framework

Use the command line tool to install the Gin framework. Enter the following command in the terminal:

go get -u github.com/gin-gonic/gin

2. Create a blockchain

First you need to define a Block structure to represent a block. Each block contains the following information:

• Index: The index of the block.
• Timestamp: The creation time of the block.
• Data: Block data.
• PreviousHash: The hash value of the previous block.
• Hash: The hash value of the block.

The hash of each block is calculated from the block’s index, timestamp, data, and the hash of the previous block. The purpose of this is to achieve data integrity and data immutability.

type Block struct {
    Index        int
    Timestamp    string
    Data         string
    PreviousHash string
    Hash         string
}

var Blockchain []Block

Define a function GenerateHash to calculate the block hash value. This function uses the SHA256 algorithm.

func GenerateHash(b Block) string {
    record := string(b.Index) + b.Timestamp + b.Data + b.PreviousHash
    h := sha256.New()
    h.Write([]byte(record))
    hash := hex.EncodeToString(h.Sum(nil))
    return hash
}

Function CreateBlock generates a new block. Every time someone transfers money, a new block needs to be created.

func CreateBlock(data string, previousBlockHash string) Block {
    var newBlock Block
    newBlock.Index = len(Blockchain)
    newBlock.Timestamp = time.Now().String()
    newBlock.Data = data
    newBlock.PreviousHash = previousBlockHash
    newBlock.Hash = GenerateHash(newBlock)
    return newBlock
}

The function AddBlock is used to add a new block. It needs to check whether the hash of the new block is legitimate and add the new block to the blockchain.

func AddBlock(data string) Block {
    previousBlock := Blockchain[len(Blockchain)-1]
    newBlock := CreateBlock(data, previousBlock.Hash)
    if newBlock.Hash != GenerateHash(newBlock) {
        log.Fatal("Invalid block")
    }
    Blockchain = append(Blockchain, newBlock)
    return newBlock
}

3. Implement digital currency payment function

Define a structure Transaction, which contains the following information:

• Sender: the number of the payer Wallet address.
• Receiver: The digital wallet address of the payee.
• Amount: The amount paid.

type Transaction struct {
    Sender   string `json:"sender"`
    Receiver string `json:"receiver"`
    Amount   int    `json:"amount"`
}

Define a variable Wallet, which is a dictionary used to store digital wallets and their balances. The digital wallet is a string and the balance is an integer type value.

var Wallet = make(map[string]int)

Define a function Transfer for transferring money. It needs to check whether the balance in the digital wallet is sufficient, and if so, subtract the transfer amount and update its balance to the digital wallet.

func Transfer(t Transaction) {
    balance := Wallet[t.Sender]
    if balance < t.Amount {
        log.Fatal("Insufficient balance")
    }
    Wallet[t.Sender] = balance - t.Amount
    Wallet[t.Receiver] += t.Amount
}

Create web applications using the Gin framework. Define a router that contains two URIs. The first URI is "/block", which is used to add new blocks. The second URI is "/transfer", used for transfers.

func main() {
    r := gin.Default()
    Blockchain = append(Blockchain, CreateBlock("Genesis Block", ""))
    r.POST("/block", func(c *gin.Context) {
        var data string
        if err := c.ShouldBindJSON(&data); err != nil {
            c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
            return
        }
        AddBlock(data)
        c.String(http.StatusOK, "New block created")
    })
    r.POST("/transfer", func(c *gin.Context) {
        var t Transaction
        if err := c.ShouldBindJSON(&t); err != nil {
            c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
            return
        }
        Transfer(t)
        c.JSON(http.StatusOK, Wallet)
    })
    r.Run()
}

4. Summary

This article introduces how to use the Gin framework to implement blockchain and digital currency payment functions. We created a Block structure to implement the blockchain. We also defined a Transaction structure and created a digital wallet. Finally, we implemented a web application using the router functionality provided by the Gin framework and added new blocks and transfer URIs to it. Using Gin framework is very simple and helps in building web applications quickly.

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