以太坊物联网区块链（一）

Web3js 与 java 连接区块链可以参考我github上的两个小demo

Ethereum-java

Ethereum-javascript

搭建私有链, 利用以太坊平台完成数据上链

如何搭建？

用Geth搭建一个区块链节点，本地主机就和区块链网络中主机一致了，（可以连接main链，和其它测试链，还有自定义链）。注：可以通过赋予chainid和networkid不同的值让本机成为连接在main链chainid（1），测试链chanid（2-4）或者自定义链chainid（其它，暂设置为666）

chainid 与 networkid 具体用途，建议设置成一样，后面省心

安装geth

一台新机器 Ubuntu 20.04LTS (虚拟机)#新机器需要做以下两步#更换清华的源，参考网上#安装vim，参考网上#执行下列命令sudo apt-get updatesudo apt-get install software-properties-commonsudo add-apt-repository -y ppa:ethereum/ethereumsudo add-apt-repository -y ppa:ethereum/ethereum-devsudo apt-get updatesudo apt-get install ethereum

创世块文件

#在桌面创建 mkdir privateblock && cd privateblock#创建创世块文件genesis.json，并将下列内容放入genesis.json文件中{"config": {"chainId": 666,"homesteadBlock": 0,"eip150Block": 0,"eip150Hash": "0x0000000000000000000000000000000000000000000000000000000000000000","eip155Block": 0,"eip158Block": 0,"byzantiumBlock": 0,"constantinopleBlock": 0,"petersburgBlock": 0,"istanbulBlock": 0,"ethash": {}},"nonce": "0x0","timestamp": "0x5ddf8f3e","extraData": "0x0000000000000000000000000000000000000000000000000000000000000000","gasLimit": "0x47b760","difficulty": "0x00002","mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000","coinbase": "0x0000000000000000000000000000000000000000","alloc": {"bc9a3ece02d7cb31cf63dfdfc48db0b82770d014": {"balance": "8000000000000000000000000000000"}},"number": "0x0","gasUsed": "0x0","parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000"}

#打开geth之前一定要进入privateblock目录，初始化创世块文件，每台主机只需要初始化一次geth --datadir data init genesis.json

打开Geth客户端

Geth版本：Welcome to the Geth JavaScript console!instance: Geth/v1.10.8-stable-26675454/linux-amd64/go1.16.4#下面是我编写的开启geth脚本root@blockchain1:/home/chenhui/privateblock# cat frist_start_2.sh #!/bin/bashnohup geth --datadir data --networkid 666 --http --http.corsdomain="*" --http.port 8545 --http.addr "0.0.0.0" --http.api db,web3,eth,debug,personal,net,miner,admin --allow-insecure-unlock --rpc.allow-unprotected-txs --port 30303 --dev --dev.period 1 2>./console.log &

Geth操作命令

#创建账户 123为账户密码personal.newAccount("12345678")#查看第一个账户eth.accounts[0]#查看用户eth.accounts#查看矿工账户，若节点中有多个账户，默认第一个账户为矿工账户eth.coinbase#查看区块数量eth.blockNumber#通过区块号，查看区块信息eth.getBlock(i)#给账户地址取别名user1=eth.accounts[0]#通过别名获取金额eth.getBalance(user1)#转账之前需要解锁密码，直接回车，默认账号锁定密码为空，返回true成功personal.unlockAccount(user1)#账户之间转账,提交交易，但是还未经区块链网络确认//可以在geth运行期间一直解锁账户personal.unlockAccount(eth.accounts[0],"123",0)"enode://238dec8d985d6959f8b99e94e8d343be4a3d0f6737972531b226ea154212d3cf315b536bd3f4463d29096a6c3853ab783f2e78faeb6a787259e888d782dec88c@115.29.67.40:30303"eth.sendTransaction({from:user1,to:user2,value:web3.toWei(3,"ether")})

挖矿命令

#若本机挖矿成功，矿工地址就会有就会有一笔收益，可以通过eth.coinbase查看eth.coinbase#设置矿工地址miner.setEtherbase(eth.coinbase)#设置矿工miner.setEtherbase(user3)#挖矿,开启1个线程挖矿miner.start(1)#查看是否在挖矿eth.mining#结束挖矿miner.stop()# 挖出新区块后，立马停止miner.start(1);admin.sleepBlocks(1);miner.stop();

查看交易指令

#查看本地交易池，待提交的交易txpool.statuseth.getBlock("pending", true).transactions#查看用户的以太币个数，用以太币表示，而不是Weiweb3.fromWei(eth.getBalance(eth.accounts[1]),'ether')#通过交易链接，查看交易eth.getTransaction("0x9f5e61f3d686f793e2df6378d1633d7a9d1df8ec8c597441e1355112d102a6ce")

将区块链数据同步到其它 peer 节点

当 peer 连接好了的时候，就自动完成同步了#查看其它节点信息admin.peers#查看node信息admin.nodeInfoadmin.nodeInfo.enode区块链中，节点是p2p模式网络#通过admin.addPeer()添加peer节点，添加节点1admin.addPeer("enode://917e60c31d4cac6eb1af97fd971c96f172f386d5de04fadaf01b0e1ff38c49877e4a1fcd3275659e6fd19c9fb09fc5a93a50597ff9b87d261ca216706106923b@192.168.188.133:30303")#查看是否有其它的peernet.peerCount#单位换算web3.fromWei（100000000，'ether'）#跨节点转账： 如果报错可能安装web3的版本太高eth.sendTransaction({from:address1,to:address2,value:web3.toWei(3,"ether")})

如何验证区块链节点，同步了？

可以将BlockChain2和BlockChain3，分别在Geth的控制台下，使用admin.addpeer()连接到Cluster节点（第一个节点）。可以开启一个节点的挖矿程序，在别的系统中，查看区块，发现，另一台主机也在进行同步。

如何通过产生的交易地址，来查看交易内容？

开发框架Truffle

开发框架Truffle介绍

truffle 是一个部署合约的框架，提高效率

安装方式

1 添加 node 源$ curl -sL /setup_14.x | sudo -E bash -2 安装 nodejs$ sudo apt-get install -y nodejs3 安装区块链测试环境$ npm install -g ganache-cli$ ganache-cli --versionGanache CLI v6.12.2 (ganache-core: 2.13.2)$ npm install -g ethereumjs-testrpc4 安装truffle$ sudo npm install -g truffle5 终端创建一个目录mkdir testcd test6 下载初始项目truffle init7 在contract 目录下编写智能合约Say.solpragma solidity ^0.5.0;contract Say {string private content;function set(string memory _msg) public {content=_msg;}function say() public view returns(string memory ){return content;;}}~ 8 增加合约部署文件#在目录migrations下新建2_deploy_contracts.js（1开头的文件不能删除，否则就会报错）var Say = artifacts.require("./Say.sol");module.exports = function(deployer) {deployer.deploy(Say);};9 编译合约 执行命令（应该在truffle目录下）truffle compile //此时执行编译时，✔ Fetching solc version list from solc-bin. Attempt #3卡在这卡了很久？解决办法：见bug10 修改目录下的文件truffle-config.js 如下(host和port要根据自己的配置来定)部署合约到区块链上module.exports = {networks:{development:{host:"localhost",port:8545,network_id:"0821",gas:3000000}}};11 部署前先解锁账号，并启动挖矿>personal.unlockAccount(user1)>miner.start() 12 然后执行部署，应该是在truffle目录下truffle migrate 此处报错，解决见bug5

truffle 开发 ,使用开发模式的前提是，之前一定要安装第三步，区块链测试环境

$ truffle Develop started at http://127.0.0.1:9545/Accounts:(0) 0x55cc26a61e5ed0946aee50e7895f1064ccd01da4(1) 0x17f53146ab4ecb78fa9c9c3795ee84e77b46a7a9(2) 0x37110b76c6951c94ced4b4d46ef99013b60652cf(3) 0xc7910dc26d37ff4cc3b855527c4074ddb36f8942(4) 0x70aac68de9e77ec836f431e048d287a8f9330a55...⚠️ Important ⚠️ : This mnemonic was created for you by Truffle. It is not secure.Ensure you do not use it on production blockchains, or else you risk losing funds.$ truffle(develop)> compileCompiling your contracts...===========================> Everything is up to date, there is nothing to compile.truffle(develop)> truffle migrateCompiling your contracts...===========================> Everything is up to date, there is nothing to compile.Starting migrations...======================> Network name: 'develop'> Network id:5777> Block gas limit: 6721975 (0x6691b7)1_initial_migration.js======================Deploying 'Migrations'----------------------> transaction hash: 0xf6dbd0e3400fc70664a6b60fa922377ee2b5f3ac6bb630ae20d951d05791c442> Blocks: 0 Seconds: 0> contract address: 0xE612CF8f9DDCCfB89D5aED08E9cDeFFb3711ABc6> block number: 1> block timestamp:1630758669> account: 0x55Cc26A61E5eD0946aEe50e7895f1064cCD01dA4> balance: 99.999616114> gas used: 191943 (0x2edc7)> gas price: 2 gwei> value sent:0 ETH> total cost:0.000383886 ETH> Saving migration to chain.> Saving artifacts-------------------------------------> Total cost: 0.000383886 ETH2_deploy_contracts.js=====================Deploying 'Say'---------------> transaction hash: 0x35fed518448b51036dd245c5f180d6af7c3e7050e5c166bff94f9360479e3ce2> Blocks: 0 Seconds: 0> contract address: 0x02db26E5099Ae13ad8282A82A7bD818e3030bC27> block number: 3> block timestamp:1630758669> account: 0x55Cc26A61E5eD0946aEe50e7895f1064cCD01dA4> balance: 99.99908693> gas used: 222254 (0x3642e)> gas price: 2 gwei> value sent:0 ETH> total cost:0.000444508 ETH> Saving migration to chain.> Saving artifacts-------------------------------------> Total cost: 0.000444508 ETHSummary=======> Total deployments: 2> Final cost:0.000828394 ETH- Blocks: 0 Seconds: 0- Saving migration to chain.- Blocks: 0 Seconds: 0- Saving migration to chain.

安装nodejs

//新建一个文件夹，然后初始化$ mkdir nodejs && cd nodejs$ npm init -f //此处的-f会自动给你配好配置文件$ npm install web3@^0.20.0//若想 安装最新版web3 npm install web3安装报错，见bug6

查看，node内嵌web3版本的方式chenhui@ubuntu:~/privateblock/nodejs$ node> web3.version.apiThrown:ReferenceError: web3 is not defined> var Web3 = require('web3')undefined> var web3 = new Web3(new Web.providers.HttpProvider("http://localhost:8545"))Thrown:ReferenceError: Web is not defined> var web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"))undefined> web3.version.api'0.20.7'nodejs 在命令行输入参数var arguments = process.argv.splice(2)arguments[0] arguments[1]

Bug 笔记

1. Fatal: Error starting protocol stack: listen tcp :30303: bind: address already in use

ps ax | grep gethkill -9 <pid>

2.personal.unlockAccount(user1,“12345678”)

解锁失败，报错如下

GoError: Error: could not decrypt key with given password at web3.js:6357:37(47)

at native

at :1:30(4)

解决方案：可能是密码出错了，也可能是尝试新建一个用户eth.newAccount("123")并将这个用户立马使用personal.unlockAccount(eth.accounts[2])输入密码：123

3.Error: etherbase must be explicitly specified

at web3.js:6357:37(47)at get (web3.js:6257:66(14))

可能首次，没有创建用户

4.truffle compile编译这部分，可能需要弄很久

/detail/19-sczhvzvgfkmlgse.html

解决方案：/question/1568

将 compiler 用别的方式下载下来，放到下面的目录~。

修改truffle-config.js中的去掉version注释

5.报错如下

undefined:1

b0VIM 8.1

^

SyntaxError: Unexpected token b in JSON at position 0

at JSON.parse ()

chenhui@ubuntu:~/privateblock/truffle$ truffle migrateCompiling your contracts...===========================> Everything is up to date, there is nothing to compile.Starting migrations...======================> Network name: 'development'> Network id:0821> Block gas limit: 4787948 (0x490eec)1_initial_migration.js======================undefined:1b0VIM 8.1^SyntaxError: Unexpected token b in JSON at position 0at JSON.parse (<anonymous>)at FS.getContractName (/usr/lib/node_modules/truffle/build/webpack:/packages/resolver/dist/lib/sources/fs.js:44:1)at FS.require (/usr/lib/node_modules/truffle/build/webpack:/packages/resolver/dist/lib/sources/fs.js:25:1)at /usr/lib/node_modules/truffle/build/webpack:/packages/resolver/dist/lib/resolver.js:53:1at Array.forEach (<anonymous>)at Resolver.require (/usr/lib/node_modules/truffle/build/webpack:/packages/resolver/dist/lib/resolver.js:52:1)at Object.require (/usr/lib/node_modules/truffle/build/webpack:/packages/migrate/index.js:172:1)at ResolverIntercept.require (/usr/lib/node_modules/truffle/build/webpack:/packages/migrate/ResolverIntercept.js:22:1)at /home/chenhui/privateblock/truffle/migrations/1_initial_migration.js:1:30at Script.runInContext (vm.js:144:12)at Script.runInNewContext (vm.js:149:17)at Object.file (/usr/lib/node_modules/truffle/build/webpack:/packages/require/require.js:94:1)at Migration._load (/usr/lib/node_modules/truffle/build/webpack:/packages/migrate/Migration.js:44:1)at processTicksAndRejections (internal/process/task_queues.js:95:5)at Migration.run (/usr/lib/node_modules/truffle/build/webpack:/packages/migrate/Migration.js:217:1)at Object.runMigrations (/usr/lib/node_modules/truffle/build/webpack:/packages/migrate/index.js:150:1)Truffle v5.4.9 (core: 5.4.9)Node v14.17.6

解决：

1_initial_migration.js 这个文件是重要文件，不能删除，删除就会报上面的错误

6：chenhui@ubuntu:~/privateblock/nodejs$ npm install web3@0.20.0

npm ERR! code ENOENT

npm ERR! syscall spawn git

npm ERR! path git

npm ERR! errno ENOENT

npm ERR! enoent Error while executing:

npm ERR! enoent undefined ls-remote -h -t /frozeman/bignumber.js-nolookahead.git

npm ERR! enoent

npm ERR! enoent

npm ERR! enoent spawn git ENOENT

npm ERR! enoent This is related to npm not being able to find a file.

npm ERR! enoent

npm ERR! A complete log of this run can be found in:

npm ERR! /home/chenhui/.npm/_logs/-09-05T08_29_15_774Z-debug.log

错误原因，没有安装git解决办法： 用管理员权限安装gitsudo apt install git 此错误好了，出现下列错误

chenhui@ubuntu:~/privateblock/nodejs$ npm install web3@0.20.0npm ERR! code 128npm ERR! Command failed: git clone --mirror -q /frozeman/bignumber.js-nolookahead.git /home/chenhui/.npm/_cacache/tmp/git-clone-40a3a4f4/.gitnpm ERR! warning: templates not found in /tmp/pacote-git-template-tmp/git-clone-921abd23npm ERR! fatal: unable to access '/frozeman/bignumber.js-nolookahead.git/': GnuTLS recv error (-54): Error in the pull function.npm ERR! npm ERR! A complete log of this run can be found in:npm ERR!/home/chenhui/.npm/_logs/-09-05T08_33_49_217Z-debug.log

错误原因:尝试

git config --global url.“https://”.insteadOf git://

再进行安装，没有成功，再尝试，报错

npm ERR! Error while executing:npm ERR! /usr/bin/git ls-remote -h -t /frozeman/bignumber.js-nolookahead.gitnpm ERR! npm ERR! fatal: unable to access '/frozeman/bignumber.js-nolookahead.git/': GnuTLS recv error (-54): Error in the pull function.npm ERR! npm ERR! exited with error code: 128npm ERR! A complete log of this run can be found in:npm ERR!/root/.npm/_logs/-09-06T07_09_43_403Z-debug.log执行：git config --global url.git:///.insteadOf /

解决办法

执行：

git config --global url.git:///.insteadOf /

结果

7.连接MetaMask报错

报错问题：无法获取链 IC，您的 RPC URL 地址是正确的么？

原因是少了–http.port 8545 和 --http.addr “0.0.0.0”

下面是我开启geth的命令

#!/bin/bashnohup geth --datadir data --networkid 666 --http --http.corsdomain="*" --http.port 8545 --http.addr "0.0.0.0" --http.api db,web3,eth,debug,personal,net,miner,admin --allow-insecure-unlock --rpc.allow-unprotected-txs --port 30303 --dev --dev.period 1 2>./console.log &

连接成功图：

注意：链id 为genesis.json文件中的chainid ，而不是运行geth时的 networkid

如果上述错误，请确认，通过上述开启的 geth 的参数都没有遗漏

8.remix 部署合约上不了链，或者转账无法数据无法上链

解决方式：

1.将链id 和 网络id更换为相同的

2.把metamask卸载重新安装

3 .增大 gas limit

9.区块链编程，想通过调用区块链上的函数时，出现了跨域问题

test.html:1 Access to XMLHttpRequest at 'http://10.69.177.223:8545/' from origin 'http://localhost:8080' has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.index.js:106 POST http://10.69.177.223:8545/ net::ERR_FAILEDtest.html:1 Access to XMLHttpRequest at 'http://10.69.177.223:8545/' from origin 'http://localhost:8080' has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.index.js:106 POST http://10.69.177.223:8545/ net::ERR_FAILEDerrors.js:43 Uncaught (in promise) Error: Invalid JSON RPC response: ""at Object.InvalidResponse (errors.js:43)at XMLHttpRequest.i.onreadystatechange (index.js:95)

错误原因，跨域的时候，之前只指定了，导致出现跨域问题， 后面将-http.corsdomain="" 改为 “”成功解决

下面是我开启geth的命令行指令

nohup geth --datadir data --networkid 666 --ipcdisable --rpc --rpccorsdomain "*" --port 30303 --rpcport 8545 --rpcaddr "0.0.0.0" --http --http.corsdomain="*" --http.api db,web3,eth,debug,personal,net,miner,admin --vmdebug --rpcapi "db,eth,net,web3,admin,personal,miner" --allow-insecure-unlock 2>./console.log &

10.当使用idea开发java时，使用

E:\Ethereum-java>mvn web3j:generate-sources

出现下列需要等待很久

Solidity version 0.4.25 is not installed. Downloading and installing it to ~/.web3j/solc/0.4.25

解决办法：开启科学上网工具，等待一下就会自己下载完毕

11 . java.lang.RuntimeException: java.lang.RuntimeException: Error processing transaction request: only replay-protected (EIP-155) transactions allowed over RPC

at org.web3j.tx.Contract.deploy(Contract.java:460)at org.web3j.tx.Contract.deploy(Contract.java:506)at org.web3j.tx.Contract.lambda$deployRemoteCall$5(Contract.java:549)at org.web3j.protocol.core.RemoteCall.send(RemoteCall.java:42)at com.nwpu.eth.sol.SaySample.deploy(SaySample.java:42)at com.nwpu.eth.sol.SaySample.main(SaySample.java:30)

解决办法在打geth时，-加入参数--rpc.allow-unprotected-txs