区块链的原理与应用? -2
接着上一篇.上一篇还没有输出,其实加入了index在实体类中. package com.sha256.sha256.bean; import com.sha256.sha256.utils.SHA256Util; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import java.util.Date; @Data @NoArgsConstructor @AllArgsConstructor public class Block { private long index; private String hash; // our signature private String previousHash; // the hash of previous block private String data; //our data will be a simple message. private long timeStamp; //as number of milliseconds since 1/1/1970. //Block Constructor public Block(long index,String data,String previousHash){ this.index = index; this.data = data; this.previousHash = previousHash; this.timeStamp = new Date().getTime(); this.hash = SHA256Util.calculateHash(this); //Making sure we do this after we set the other values. } } 测试类: package com.sha256.sha256.test; import com.alibaba.fastjson.JSONArray; import com.alibaba.fastjson.JSONObject; import com.google.gson.GsonBuilder; import com.sha256.sha256.bean.Block; import com.sha256.sha256.utils.SHA256Util; import java.util.ArrayList; import java.util.Random; public class TestSHA256 { //声明一个区块链,用于添加Block实体 public static ArrayList<Block> blockChain = new ArrayList<>(); public static void main(String[] args) { //test1 测试三个被加密字符串 加密后的hash值的差别 /** * 虽然第三条信息仅仅多一个".",但加密后的数据hash相差极大 */ // String message0 = "我是要被加密的信息"; // String message1 = "我是要被加密的信息"; // String message2 = "我是要被加密的信息."; // String encryptionMessage0 = SHA256Util.applySha256(message0); // String encryptionMessage1 = SHA256Util.applySha256(message1); // String encryptionMessage2 = SHA256Util.applySha256(message2); // System.out.println(encryptionMessage0); // System.out.println(encryptionMessage1); // System.out.println(encryptionMessage2); // // //test2 创建区块链逻辑, 因为第一个块没有上一个块的hash头部值,所以输入0 作为前一个块的previous hash // /** // * 由于在{@link SHA256Util#calculateHash(Block)} // * 中对同时产生的new Date().getTime() (timestamp) // * 也加入进行了hash加密,所以固有的message (data)及 // * previoushash之和进行了加密. // */ // Block genesisBlock = new Block(0,"这是第一个区块中的要被加密的信息和交易信息","0"); // String hash1 = genesisBlock.getHash(); // System.out.println("Hash for block 1 : "+hash1); // // Block secondBlock = new Block(1,"这是第二个区块,以及其中信息!!!它的前区块头部hash我们拿上一个的来使用",hash1); // String hash2 = secondBlock.getHash(); // // System.out.println("Hash for block 2 : "+hash2); // // Block thirdBlock = new Block(2,"这是第三个区块,它的hash应该已经被前两个的信息纳入进来了,它的hash如果对不上,那么说明前面的信息被改动过了",hash2); // String hash3 = thirdBlock.getHash(); // System.out.println("Hash for block 3 : "+hash3); // //// test3 add our blocks to the blockchain ArrayList : // blockChain.add(new Block(0,"区块链上第一小节","0")); // blockChain.add(new Block(1,"区块链第二小节",blockChain.get(blockChain.size()-1).getHash())); // blockChain.add(new Block(2,"区块链第三小节",blockChain.get(blockChain.size()-1).getHash())); int chainNumber = 24; int index = 0; while (chainNumber > 0) { System.out.println("blockChain.size():" + blockChain.size()); if (blockChain.size() == 0) { blockChain.add(new Block(0, "创世块", "0")); } index++; blockChain.add(new Block(index, "区块内容" + blockChainMessage(index), blockChain.get(blockChain.size() - 1).getHash())); chainNumber--; } // JSONArray blockChainJson1 = (JSONArray)JSONArray.toJSON(blockChain); //JSONArray是不排版的 // System.out.println(blockChainJson1); String blockChainJson = new GsonBuilder().setPrettyPrinting().create().toJson(blockChain); System.out.println(blockChainJson); } //模拟一些交易信息 private static String blockChainMessage(int getNumber) { Random random = new Random(getNumber); long l = random.nextLong(); System.out.println("blockChainMessage:" + l); return String.valueOf(l); } }
