Java什么是区块链

今天我们来聊聊区块链这个热门话题。首先，我们来了解一下什么是区块链。区块链是一种分布式数据库，它由一系列的数据块组成，每个数据块都包含一个时间戳，一个数据哈希值和前一个数据块的哈希值。它是一种去中心化的数据存储系统，可以用于存储和管理数据，以及在网络上传播信息。

接下来，我们来关注一下共识算法，它是区块链系统的核心。共识算法是一种协议，用于确定网络中的一致性，确保网络中的每个节点都能够达成一致。它通过让参与者就某一事件的发生达成一致，从而解决网络中的冲突。常见的共识算法有工作量证明（Proof of Work）、权益证明（Proof of Stake）和拜占庭容错（Byzantine Fault Tolerance）。

最后，我们来聊聊智能合约，它是区块链系统中最重要的一部分。智能合约是使用特定编程语言编写的电子合约，它可以自动执行合约条款，无需人为干预。它可以用于实现货币交易、投票、拍卖等复杂的交易，从而提高效率和安全性。智能合约的安全性取决于程序的设计，因此，开发者需要对其进行严格的测试，以确保它能够正确执行。

总的来说，区块链是一种新兴的技术，它可以改变我们的生活。它可以帮助我们实现去中心化的数据存储和管理，还可以用于实现复杂的交易。它的核心是共识算法和智能合约，它们可以确保网络的安全性和可靠性。

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① Yunnan Beida Jade Bird Java Training tells you the development trend of blockchain technology implementation

With the continuous development of blockchain technology, more and more people are starting to Pay attention to how blockchain technology is implemented to achieve project conversion and development. Today, let’s take a look at the development trends of blockchain technology implementation.

Blockchain is finding ways to form new industries and enterprise applications every day, and it won’t be long before this technology will be everywhere. In the future, start-ups, academic institutions, open source institutions, alliances and financial institutions will all participate in this technology.

The current controversy over the prospects of blockchain focuses on the unclear direction and value of its implementation. In the fog, there are different opinions. Some people say that "blockchain does not make money without ICO", while others are trying to find the true value of blockchain technology in real-life scenarios outside the currency circle.

Here is some content worthy of your attention.

Blockchain Core Technology

When it comes to blockchain core technology, it generally includes the application layer, contract layer, and incentives. Key technologies in layer, consensus layer, network layer, and data layer. The research hotspots here include consensus, distributed ledger, cross-chain technology, P2P network and some application practices. You may ask:

There are currently many blockchain platforms on the market. How to correctly understand and evaluate the underlying technology suitable for enterprise selection?

What are the key pain points and technical challenges faced by blockchain in enterprise-level applications, and how to solve them?

Blocks related to life and medical data What are the experiences and lessons learned during the development and operation of cross-chain projects?

What is the essence of cross-chain? What problems need to be solved? What are the technical difficulties and implementation models?

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What are the characteristics and implementation principles of the file system?

How to implement the DPoS algorithm in Ethereum and its significance?

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Blockchain Finance

When blockchain technology was first proposed, finance was considered to be one of the main application scenarios. 1. Specifically, it includes establishing an inter-bank point-to-point payment settlement system and a cross-border payment system based on blockchain technology, and using blockchain technology to realize the registration and transfer of equity in exchanges.

Blockchain has inherent absolute advantages when applied to the financial field. Subjectively, financial institutions have a strong willingness to explore blockchain applications and need new technologies to improve operational efficiency and cost reduction to respond to the current status of the entire global economy. Objectively speaking, the market space in the financial industry is huge, and a little progress can bring huge benefits. Lijiang Computer Training http://www.kmbdqn.cn/ found that the financial industry is an industry with extremely high requirements for security and stability.If the application of blockchain in the financial field is verified, it will have a huge demonstration effect and be quickly promoted in other industries.

② Honghe Java Training School tells you the consensus algorithm in blockchain technology

We have already explained some explanations and knowledge points about blockchain technology I have shared it with you many times. Today, Honghe Java Course http://www.kmbdqn.cn/ will take a look at some basic definitions and characteristics of consensus algorithms in blockchain technology.

A brief look at the blockchain

The chain in our general ideology is an iron chain, made of iron. One link after another. Figuratively, the blockchain can also be understood in this way, except that it is not made of iron, but connected by blocks with a certain data structure. This is a simple prototype

Popular explanation of consensus

The so-called consensus, in layman’s terms, means that we all agree on the understanding of something. For example, we have daily meetings to discuss issues, or we can judge whether an animal is a cat. After looking at it with the naked eye, we feel it looks like a cat. If it meets the characteristics of a cat, then we think it is a cat. Consensus is a rule.

Continuing with our meeting example. Participants in the meeting discuss and solve problems through meetings.

Compared with the blockchain, miners participating in mining use a certain consensus method (algorithm) to make their own ledger consistent with the ledgers of other nodes. The deeper meaning of keeping the ledger consistent is to keep the block information in the chain consistent.

Why is consensus needed? Is it possible to not need it? Of course not. Without the rules of consensus in life, everything will be chaotic. The blockchain loses consensus rules, and each node does its own thing, losing its consistent meaning.

The corresponding relationship between these two examples is as follows:

Meeting people = mining miners

Meeting = consensus method (algorithm)

Talk about solving problems = make your own ledger consistent with the ledger of other nodes< /p>

If you don’t understand the concept of a node, please first understand it as a miner. A node contains many roles, and miners are one of them.

Consensus algorithm

Currently in the blockchain, nodes allow their own ledgers to match those of other nodes. There are several consensus methods (algorithms) that maintain consistency:

PoW, represented by Bitcoin (BTC)

Disadvantages:

The emergence of mining pools violates the original intention of decentralization to a certain extent, and also makes 51% attacks possible.becomes possible, affecting its security.

There is a huge waste of computing power. Look at the mining pool that consumes a lot of electricity resources. As the difficulty increases, what is mined is not enough to pay the electricity bill

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PoS, represented by Ethereum (ETH), transitioning from PoW to PoS

Disadvantages:

< p>The cost of attackers attacking the network is very low, and they can compete if they own tokens

In addition, nodes with a large number of tokens will have a greater probability of obtaining accounting rights. This will make the network consensus dominated by a few wealthy accounts, thereby losing fairness.

③ Java courses share the component architecture of blockchain technology

With the continuous development of the Internet, more and more people have learned about Some characteristics and usage of blockchain technology. Today we will introduce some elements of blockchain.

The composition of blockchain

Blockchain consists of blocks and chains. Each block contains three elements: data, hash value, and the hash value of the previous block.

The first element of the block is data. The data stored in the block is related to the type of blockchain. For example, blocks in the Bitcoin blockchain store relevant transaction information, including the seller, buyer, and the amount of Bitcoin traded.

The second positive element of the block is the hash value. Each block contains a hash value, which is used to identify a block and all the content it contains. Once a block is created, its hash value is calculated accordingly. Changing something in the block will cause the hash value to change. So in other words: hashes are helpful when you want to detect changes to the contents of a block. If a block's fingerprint changes, it is no longer the same block as before.

The third element of the block is the hash value of the previous block. This element allows links to be formed between blocks and makes the blockchain very secure.

As an example, suppose we have a blockchain containing 3 blocks. Each block contains its own hash and the hash of the previous block. Block No. 3 points to block No. 2, and block No. 2 points to block No. 1. But block No. 1 is a bit special. It cannot point to the previous block because it is the first block. We call block 1 the genesis block.

So, now let's say you tampered with the second block. This will cause the hash value of the second block to change, so the data stored in block 3 will be wrong and illegal. Once the data stored in block No. 3 is illegal, the subsequent blocks must also be illegal.

So if a person wants to tamper with the blockchainFor any block in the block, it must modify this block and all blocks after this block. This will be an onerous task.

Blockchain proof-of-work

However, the method of using hash values ​​alone is not enough to prevent users from tampering with the zone. piece. Because today's computers are powerful enough to calculate thousands of hash values ​​per second. The Java course suggests that you can completely tamper with a block and recalculate the hash values ​​of other blocks, thus making your block legal again.

④ What is blockchain

Blockchain is a new application of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithm. model. Blockchain is an important concept of Bitcoin.

It is essentially a decentralized database. As the underlying technology of Bitcoin, it is a series of data blocks generated using cryptographic methods. Each data block contains a batch of The information of Bitcoin network transactions is used to verify the validity of its information (anti-counterfeiting) and generate the next block.

(4)Extended reading on what is blockchain in Java

Characteristics of blockchain:

1. Deposit certificate< /p>

The "non-tamperable" feature of blockchain provides a solution to the problem of "certificate storage" in economic and social development. As long as the authenticity of the on-chain information and data can be ensured, the blockchain can solve the problem of "storage" and "certification" of information.

For example, in the field of copyright, blockchain can be used to store electronic evidence, which can ensure that it is not tampered with, and can link original platforms, copyright bureaus, judicial agencies and other parties through distributed ledgers, which can greatly Improve the efficiency of handling infringements.

2. Sharing

The "distributed" characteristics of the blockchain can break through the "data barriers" between departments and achieve information and data sharing. Different from centralized data storage, the information on the blockchain will be distributed to each node through point-to-point broadcasting, and all information can be "truthfully recorded" through "whole network witness".

⑤ Peking University Jade Bird Java Training: What are the basic concepts of blockchain programming and development technology

With the continuous development of the Internet, the development and application of blockchain technology have also been brought up. The schedule is up, today’s Java course http://www.kmbdqn.cn/ will let’s learn about the basic concepts that need to be mastered in blockchain programming and development technology.
1. Blockchain technology chain data structure, the head of each block stores the hash value pointing to the previous node, which is connected in sequence.
Based on the P2P network, the distributed node consensus algorithm maintains and updates data to ensure that the data is "non-tamperable".
Use cryptography principles to ensure the security of data transmission and access.
Automated scripts (smart contracts) can be used to program return passes and manipulate data.
Essentially, it is a decentralized database that ultimately solves the problem of trust in Internet transmission.
2. Decentralization The entire network is jointly participated and maintained by each node. It does not rely on a central processing node. Each node is the center.
The storage and update of data are distributed and do not require intermediary or trust structure endorsement.
3. Private chain, public chain and alliance chain Private chain: The qualifications of participating nodes are limited and controllable, and reading and writing are restricted.
Weak centralization solves the problem of trust among "teammates" (within the organization).
Public chain: Open, anyone can read the data on the chain and participate in transactions.
Completely decentralized, the data on the chain cannot be tampered with by any person or institution.
Encourage participants to compete for accounting rights through a reward token mechanism.
Solving the problem of "human beings" (all people) being untrustworthy.
Consortium chain: It is jointly participated, maintained and managed by multiple institutions. The data on the chain is only allowed to be read, written and traded by institutions within the system.
Partially decentralized, each institution runs one or more nodes.
Solve the problem of "organizational" (inter-agency) untrustworthiness.