整个区块链通过链的循环进行验证，以确保一个区块的哈希仍然与前一个区块的哈希匹配。

这是 SimpleBlockChain.java的 validate（）方法实现。

public 
boolean 
validate() {

String previousHash = 
null
;

for 
(Block<T> block : chain) {

String currentHash = block.getHash();

if 
(!currentHash.equals(previousHash)) {

return 
false
;

}

previousHash = currentHash;

}

return 
true
;

}

下面是模块中的方法。从事务列表中创建Merkle树的java类。

public 
List<String> merkleTree() {        

ArrayList<String> tree = 
new 
ArrayList<>();

// Start by adding all the hashes of the transactions as leaves of the

// tree.

for 
(T t : transactions) {

tree.add(t.hash());

}

int 
levelOffset = 
0
; 
// Offset in the list where the currently processed

// level starts.

// Step through each level, stopping when we reach the root (levelSize

// == 1).

for 
(
int 
levelSize = transactions.size(); levelSize > 
1
; levelSize = (levelSize + 
1
) / 
2
) {

// For each pair of nodes on that level:

for 
(
int 
left = 
0
; left < levelSize; left += 
2
) {

// The right hand node can be the same as the left hand, in the

// case where we don't have enough

// transactions.

int 
right = Math.min(left + 
1
, levelSize - 
1
);

String tleft = tree.get(levelOffset + left);

String tright = tree.get(levelOffset + right);

tree.add(SHA256.generateHash(tleft + tright));

}

// Move to the next level.

levelOffset += levelSize;

}

return 
tree;

}

ITPub博客

一整套基于Java开发的的区块链系统

最新文章