本文节选自电子书《Netkiller Blockchain 手札》

Netkiller Blockchain 手札

本文作者最近在找工作，有意向致电 13113668890

Mr. Neo Chan, 陈景峯(BG7NYT)

中国广东省深圳市龙华新区民治街道溪山美地
518131
+86 13113668890

<netkiller@msn.com>

文档始创于2018-02-10

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5.5. 实用例子

5.5.1. 数据写入到区块链中

做一笔交易，并写入数据到区块链中

let Web3 = require("web3");
let fs = require("fs");
let web3 = new Web3("http://localhost:8545");

let log = {
    time:(new Date).getTime(),
    type:"info",
    msg:"Web3 Test!!!"
};
let str = JSON.stringify(log);
console.log(str);
let data = Buffer.from(str).toString('hex');
data = '0x'+data;
console.log(data);

//将数据写入到交易中
let coinbase = "0x5c18a33df2cc41a1beddc91133b8422e89f041b7"
console.log(coinbase)
let user1 = "0xc2b9e316f246d35052118e51b55c75bfe99d247e";
web3.eth.personal.unlockAccount(coinbase, "chen1980");
let address = web3.eth.sendTransaction({
    from:coinbase,
    to:user1,
    value:'0x00',
    data:data
},function(error, hash){
    console.log(hash);
});

运行上面程序，会产生一个交易，记下hash值，然后启动挖矿。

> miner.start();
null
# 过一段时间后停止
> miner.stop();
true

然后查看这比交易

let Web3 = require("web3");
let fs = require("fs");
let web3 = new Web3("http://localhost:8545");
let address ="0xb15681eb4bdb6b9670d305fb341ebbc95d45c2ede0ea5034ef432b74f30b1b4f";
//从交易地址获取数据
web3.eth.getTransaction(address).then(console.log);

web3.eth.getTransaction(address,function(error, result){
    //console.log(result);
    inputData = result.input;
    res_str = Buffer.from(inputData.replace('0x',''),'hex').toString();
    res_json = JSON.parse(res_str);
    console.log(res_json);
});

结果输出

{ blockHash: '0x78dacc2af60900d2e4cae90b71e27446e6e883df36c53f21cbc9e071f7a586f4',
  blockNumber: 1258,
  from: '0x5c18a33DF2cc41a1bedDC91133b8422e89f041B7',
  gas: 90000,
  gasPrice: '18000000000',
  hash: '0xb15681eb4bdb6b9670d305fb341ebbc95d45c2ede0ea5034ef432b74f30b1b4f',
  input: '0x7b2274696d65223a313531383933313435323537372c2274797065223a22696e666f222c226d7367223a22576562332054657374212121227d',
  nonce: 4,
  to: '0xc2b9e316F246d35052118E51B55C75BfE99d247e',
  transactionIndex: 0,
  value: '0',
  v: '0x41',
  r: '0x7fcd86c7fd975a0e98bd0e61a99da950b0155cd6c4581fefa4defbdcd404a930',
  s: '0x16f14ce1fbfadb9d59f343f8ac235cdd73dcedec5db1025ef91206b8bb17a827' }
{ time: 1518931452577, type: 'info', msg: 'Web3 Test!!!' }

{ time: 1518931452577, type: 'info', msg: 'Web3 Test!!!' } 就是保存在区块链中的数据。