用Java模拟一个简单的区块链，至少有一个功能输出整个链，包含链中所有的数据，并实现转账功能

好的，我可以帮你实现这个功能。首先，我们需要定义一个区块的数据结构。每个区块包含以下字段：

- index: 区块在链中的位置
- timestamp: 区块的创建时间戳
- data: 区块中存储的数据，可以是任意类型
- previousHash: 前一个区块的哈希值
- hash: 当前区块的哈希值

下面是Java代码实现区块：

import java.util.Date;
import java.security.MessageDigest;

public class Block {
    private int index;
    private long timestamp;
    private Object data;
    private String previousHash;
    private String hash;

    public Block(int index, Object data, String previousHash) {
        this.index = index;
        this.timestamp = new Date().getTime();
        this.data = data;
        this.previousHash = previousHash;
        this.hash = calculateHash();
    }

    public String calculateHash() {
        String dataString = index + timestamp + data.toString() + previousHash;
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-256");
            byte[] hashBytes = digest.digest(dataString.getBytes("UTF-8"));
            StringBuffer hexString = new StringBuffer();
            for (int i = 0; i < hashBytes.length; i++) {
                String hex = Integer.toHexString(0xff & hashBytes[i]);
                if(hex.length() == 1) hexString.append('0');
                hexString.append(hex);
            }
            return hexString.toString();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public int getIndex() {
        return index;
    }

    public long getTimestamp() {
        return timestamp;
    }

    public Object getData() {
        return data;
    }

    public String getPreviousHash() {
        return previousHash;
    }

    public String getHash() {
        return hash;
    }
}

接下来，我们需要定义一个区块链的数据结构。它包括一个区块列表和一个当前链的哈希值。在添加一个新块时，我们需要计算新块的哈希值，然后将其添加到链的末尾。

下面是Java代码实现区块链：

import java.util.ArrayList;

public class Blockchain {
    private ArrayList<Block> chain;
    private String currentHash;

    public Blockchain() {
        chain = new ArrayList<Block>();
        currentHash = "0";
    }

    public void addBlock(Object data) {
        Block newBlock = new Block(chain.size(), data, currentHash);
        chain.add(newBlock);
        currentHash = newBlock.getHash();
    }

    public ArrayList<Block> getChain() {
        return chain;
    }
}

现在，我们已经实现了区块链的基本功能。为了测试代码，我们可以创建一个简单的转账示例，其中每个块代表一次转账操作。下面是Java代码实现转账：

public class Main {
    public static void main(String[] args) {
        Blockchain blockchain = new Blockchain();

        blockchain.addBlock(new Transaction("A", "B", 10));
        blockchain.addBlock(new Transaction("B", "C", 5));
        blockchain.addBlock(new Transaction("C", "A", 3));

        ArrayList<Block> chain = blockchain.getChain();
        for (Block block : chain) {
            Transaction transaction = (Transaction) block.getData();
            System.out.println("From: " + transaction.getFrom());
            System.out.println("To: " + transaction.getTo());
            System.out.println("Amount: " + transaction.getAmount());
            System.out.println("Hash: " + block.getHash());
            System.out.println();
        }
    }
}

class Transaction {
    private String from;
    private String to;
    private int amount;

    public Transaction(String from, String to, int amount) {
        this.from = from;
        this.to = to;
        this.amount = amount;
    }

    public String getFrom() {
        return from;
    }

    public String getTo() {
        return to;
    }

    public int getAmount() {
        return amount;
    }
}

以上就是一个简单的区块链和转账示例。