# 示例三：數字貨幣發行與管理 ## 簡介 該智能合約實現一個簡單的商業應用案例，即數字貨幣的發行與轉賬。在這之中一共分為三種角色：中央銀行，商業銀行，企業。其中中央銀行可以發行一定數量的貨幣，企業之間可以進行相互的轉賬。主要實現如下的功能： * 初始化中央銀行及其發行的貨幣數量 * 新增商業銀行，同時央行並向其發行一定數量的貨幣 * 新增企業 * 商業銀行向企業轉給一定數量的數字貨幣 * 企業之間進行相互的轉賬 * 查詢企業、銀行、交易信息 ## 主要函數 * `init`：初始化中央銀行，併發行一定數量的貨幣； * `invoke`：調用合約內部的函數； * `query`：查詢相關的信息； * `createBank`：新增商業銀行，同時央行向其發行一定數量的貨幣； * `createCompany`：新增企業； * `issueCoin`：央行再次發行一定數量的貨幣（歸於交易）； * `issueCoinToBank`：央行向商業銀行轉一定數量的數字貨幣（歸於交易）； * `issueCoinToCp`：商業銀行向企業轉一定數量的數字貨幣（歸於交易行為）； * `transfer`：企業之間進行相互轉賬（歸於交易行為）； * `getCompanys`：獲取所有的公司信息，如果企業個數大於10，先訪問前10個； * `getBanks`：獲取所有的商業銀行信息，如果商業銀行個數大於10，先訪問前 10 個 * `getTransactions`：獲取所有的交易記錄 如果交易個數大於10，先訪問前 10 個； * `getCompanyById`：獲取某家公司信息； * `getBankById`：獲取某家銀行信息； * `getTransactionBy`：獲取某筆交易記錄； * `writeCenterBank`：修改央行信息； * `writeBank`：修改商業銀行信息； * `writeCompany`：修改企業信息； * `writeTransaction`：寫入交易信息。 ## 數據結構設計 * centerBank 中央銀行 * Name：名稱 * TotalNumber：發行貨幣總數額 * RestNumber：賬戶餘額 * ID：ID固定為 0 * bank 商業銀行 * Name：名稱 * TotalNumber：收到貨幣總數額 * RestNumber：賬戶餘額 * ID：銀行 ID * company 企業 * Name：名稱 * Number：賬戶餘額 * ID：企業 ID * transaction 交易內容 * FromType：發送方角色 //centerBank:0,Bank:1,Company:2 * FromID：發送方 ID * ToType：接收方角色 //Bank:1,Company:2 * ToID：接收方 ID * Time：交易時間 * Number：交易數額 * ID：交易 ID ## 接口設計 ### `init` request 參數: ``` args[0] 銀行名稱 args[1] 初始化發佈金額 ``` response 參數: ```javascript {"Name":"XXX","TotalNumber":"0","RestNumber":"0","ID":"XX"} ``` ### `createBank` request 參數: ``` args[0] 銀行名稱 ``` response 參數: ```javascript {"Name":"XXX","TotalNumber":"0","RestNumber":"0","ID":"XX"} ``` ### `createCompany` request 參數: ``` args[0] 公司名稱 ``` response 參數: ```javascript {"Name":"XXX","Number":"0","ID":"XX"} ``` ### `issueCoin` request 參數: ``` args[0] 再次發行貨幣數額 ``` response 參數: ```javascript {"FromType":"0","FromID":"0","ToType":"0","ToID":"0","Time":"XX","Number":"XX","ID":"XX"} ``` ### `issueCoinToBank` request 參數: ``` args[0] 商業銀行ID args[1] 轉賬數額 ``` response 參數: ```javascript {"FromType":"0","FromID":"0","ToType":"1","ToID":"XX","Time":"XX","Number":"XX","ID":"XX"} ``` ### `issueCoinToCp` request 參數: ``` args[0] 商業銀行ID args[1] 企業ID args[2] 轉賬數額 ``` response 參數: ```javascript {"FromType":"1","FromID":"XX","ToType":"2","ToID":"XX","Time":"XX","Number":"XX","ID":"XX"} ``` ### `transfer` request 參數: ``` args[0] 轉賬用戶ID args[1] 被轉賬用戶ID args[2] 轉賬餘額 ``` response 參數: ```javascript {"FromType":"2","FromID":"XX","ToType":"2","ToID":"XX","Time":"XX","Number":"XX","ID":"XX"} ``` ### `getBanks` response 參數 ```javascript [{"Name":"XXX","Number":"XX","ID":"XX"},{"Name":"XXX","Number":"XX","ID":"XX"},...] ``` ### `getCompanys` response 參數 ```javascript [{"Name":"XXX","TotalNumber":"XX","RestNumber":"XX","ID":"XX"},{"Name":"XXX","TotalNumber":"XX","RestNumber":"XX","ID":"XX"},...] ``` ### `getTransactions` response 參數 ```javascript [{"FromType":"XX","FromID":"XX","ToType":"XX","ToID":"XX","Time":"XX","Number":"XX","ID":"XX"},{"FromType":"XX","FromID":"XX","ToType":"XX","ToID":"XX","Time":"XX","Number":"XX","ID":"XX"},...] ``` ### `getCenterBank` response 參數 ```javascript [{"Name":"XX","TotalNumber":"XX","RestNumber":"XX","ID":"XX"}] ``` ### `getBankById` request 參數 ``` args[0] 商業銀行ID ``` response 參數 ```javascript [{"Name":"XX","TotalNumber":"XX","RestNumber":"XX","ID":"XX"}] ``` ### `getCompanyById` request 參數 ``` args[0] 企業ID ``` response 參數 ```javascript [{"Name":"XXX","Number":"XX","ID":"XX"}] ``` ### `getTransactionById` request 參數 ``` args[0] 交易ID ``` response 參數 ```javascript {"FromType":"XX","FromID":"XX","ToType":"XX","ToID":"XX","Time":"XX","Number":"XX","ID":"XX"} ``` ### `writeCenterBank` request 參數 ``` CenterBank ``` response 參數 ``` err nil 為成功 ``` ### `writeBank` request 參數 ``` Bank ``` response 參數 ``` err nil 為成功 ``` ### `writeCompany` request 參數 ``` Company ``` response 參數 ``` err nil 為成功 ``` ### `writeTransaction` request 參數 ``` Transaction ``` response 參數 \`\`\` err nil 為成功 ··· ### 其它 查詢時為了兼顧讀速率，將一些信息備份存放在非區塊鏈數據庫上也是一個較好的選擇。