馬蹄鏈佛薩奇/泰山眾籌阿凡達/眾籌互助/智慧合約流動性挖礦分紅系統開發技術案例

　　Smart contract,in short,is a technology that digitizes the contract in our life and can be automatically executed by the program when a condition is met.For example,you made an agreement with me.We decided on reward and punishment measures,and then entered the agreement into the blockchain in the form of code.Once the agreed conditions are triggered,a program will automatically execute it,which is smart contract

　　從部署的智慧合約中讀取資料

　　在我們的合約中，有一個方法getGreeting()可以檢索我們在區塊鏈中新增的問候語。我們將使用web3.py呼叫此方法開啟您的Python IDLE編輯器並使用以下程式碼建立一個新檔案read.py。執行py read.py讀取問候語。

　　import json

　　from web3 importWeb3,HTTPProvider

　　from web3.contract importConciseContract

　　#compile your smart contract with truffle first

　　truffleFile=json.load(open('./build/contracts/greeter.json'))

　　abi=truffleFile['abi']

　　bytecode=truffleFile['bytecode']

　　#web3.py instance

　　w3=Web3(HTTPProvider(" Key here>"))

　　print(w3.isConnected())

　　contract_address=Web3.toChecksumAddress("<Deployed Contract Address here>")

　　#Instantiate and deploy contract

　　contract=w3.eth.contract(abi=abi,bytecode=bytecode)

　　#Contract instance

　　contract_instance=w3.eth.contract(abi=abi,address=contract_address)

　　#Contract instance in concise mode

　　#contract_instance=w3.eth.contract(abi=abi,address=contract_address,ContractFactoryClass=ConciseContract)

　　#Getters+Setters for web3.eth.contract object ConciseContract

　　#print(format(contract_instance.getGreeting()))需求及案例：MrsFu123

　　print('Contract value:{}'.format(contract_instance.functions.getGreeting().call()))

　　匯入的web3庫和所有其他必需的模組

　　透過指向Ropsten Infura節點啟動web3提供程式

　　透過指向abi和contract_Address建立合約例項（來自上一步）

　　呼叫getGreeting()方法並在控制檯列印結果