【实现检查库存、生成订单并存入MySQL数据库】-天翼云

【实现检查库存、生成订单并存入MySQL数据库】

2024-05-31 08:13:27 阅读次数：21

根据雪花算法生成交易订单的id

下面是一个用Java实现的生成雪花算法id的示例代码：

import java.util.concurrent.atomic.AtomicLong;

public class SnowflakeIdGenerator {
    private static final long START_TIMESTAMP = 1600000000000L;
    private static final long WORKER_ID_BITS = 5L;
    private static final long DATACENTER_ID_BITS = 5L;
    private static final long SEQUENCE_BITS = 12L;
    
    private static final long MAX_WORKER_ID = ~(-1L << WORKER_ID_BITS);
    private static final long MAX_DATACENTER_ID = ~(-1L << DATACENTER_ID_BITS);
    
    private static final long WORKER_ID_SHIFT = SEQUENCE_BITS;
    private static final long DATACENTER_ID_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS;
    private static final long TIMESTAMP_LEFT_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS + DATACENTER_ID_BITS;
    
    private static final long SEQUENCE_MASK = ~(-1L << SEQUENCE_BITS);
    
    private final long workerId;
    private final long datacenterId;
    private final AtomicLong sequence;
    private long lastTimestamp;
    
    public SnowflakeIdGenerator(long workerId, long datacenterId) {
        if (workerId > MAX_WORKER_ID || workerId < 0) {
            throw new IllegalArgumentException("Worker ID can't be greater than " + MAX_WORKER_ID + " or less than 0");
        }
        if (datacenterId > MAX_DATACENTER_ID || datacenterId < 0) {
            throw new IllegalArgumentException("Datacenter ID can't be greater than " + MAX_DATACENTER_ID + " or less than 0");
        }
        
        this.workerId = workerId;
        this.datacenterId = datacenterId;
        this.sequence = new AtomicLong(0);
        this.lastTimestamp = -1;
    }
    
    public synchronized long getNextId() {
        long timestamp = System.currentTimeMillis();
        
        if (timestamp < lastTimestamp) {
            throw new RuntimeException("Clock moved backwards. Refusing to generate id");
        }
        
        if (timestamp == lastTimestamp) {
            long sequence = this.sequence.incrementAndGet() & SEQUENCE_MASK;
            if (sequence == 0) {
                timestamp = waitNextMillis(lastTimestamp);
            }
        } else {
            this.sequence.set(0);
        }
        
        lastTimestamp = timestamp;
        
        return ((timestamp - START_TIMESTAMP) << TIMESTAMP_LEFT_SHIFT) |
            (datacenterId << DATACENTER_ID_SHIFT) |
            (workerId << WORKER_ID_SHIFT) |
            sequence;
    }
    
    private long waitNextMillis(long lastTimestamp) {
        long currentTimestamp = System.currentTimeMillis();
        while (currentTimestamp <= lastTimestamp) {
            currentTimestamp = System.currentTimeMillis();
        }
        return currentTimestamp;
    }
}

使用示例：

public class Main {
    public static void main(String[] args) {
        SnowflakeIdGenerator idGenerator = new SnowflakeIdGenerator(1, 1);
        long orderId = idGenerator.getNextId();
        System.out.println("Generated Order ID: " + orderId);
    }
}

这段代码创建了一个SnowflakeIdGenerator实例，并使用workerId和datacenterId作为参数进行初始化。然后调用getNextId()方法生成下一个id。每个id由timestamp、datacenterId、workerId和sequence组成，可以根据需要进行灵活调整。下面是一个用Java实现的生成雪花算法id的示例代码：

import java.util.concurrent.atomic.AtomicLong;

public class SnowflakeIdGenerator {
    private static final long START_TIMESTAMP = 1600000000000L;
    private static final long WORKER_ID_BITS = 5L;
    private static final long DATACENTER_ID_BITS = 5L;
    private static final long SEQUENCE_BITS = 12L;
    
    private static final long MAX_WORKER_ID = ~(-1L << WORKER_ID_BITS);
    private static final long MAX_DATACENTER_ID = ~(-1L << DATACENTER_ID_BITS);
    
    private static final long WORKER_ID_SHIFT = SEQUENCE_BITS;
    private static final long DATACENTER_ID_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS;
    private static final long TIMESTAMP_LEFT_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS + DATACENTER_ID_BITS;
    
    private static final long SEQUENCE_MASK = ~(-1L << SEQUENCE_BITS);
    
    private final long workerId;
    private final long datacenterId;
    private final AtomicLong sequence;
    private long lastTimestamp;
    
    public SnowflakeIdGenerator(long workerId, long datacenterId) {
        if (workerId > MAX_WORKER_ID || workerId < 0) {
            throw new IllegalArgumentException("Worker ID can't be greater than " + MAX_WORKER_ID + " or less than 0");
        }
        if (datacenterId > MAX_DATACENTER_ID || datacenterId < 0) {
            throw new IllegalArgumentException("Datacenter ID can't be greater than " + MAX_DATACENTER_ID + " or less than 0");
        }
        
        this.workerId = workerId;
        this.datacenterId = datacenterId;
        this.sequence = new AtomicLong(0);
        this.lastTimestamp = -1;
    }
    
    public synchronized long getNextId() {
        long timestamp = System.currentTimeMillis();
        
        if (timestamp < lastTimestamp) {
            throw new RuntimeException("Clock moved backwards. Refusing to generate id");
        }
        
        if (timestamp == lastTimestamp) {
            long sequence = this.sequence.incrementAndGet() & SEQUENCE_MASK;
            if (sequence == 0) {
                timestamp = waitNextMillis(lastTimestamp);
            }
        } else {
            this.sequence.set(0);
        }
        
        lastTimestamp = timestamp;
        
        return ((timestamp - START_TIMESTAMP) << TIMESTAMP_LEFT_SHIFT) |
            (datacenterId << DATACENTER_ID_SHIFT) |
            (workerId << WORKER_ID_SHIFT) |
            sequence;
    }
    
    private long waitNextMillis(long lastTimestamp) {
        long currentTimestamp = System.currentTimeMillis();
        while (currentTimestamp <= lastTimestamp) {
            currentTimestamp = System.currentTimeMillis();
        }
        return currentTimestamp;
    }
}

使用示例：

public class Main {
    public static void main(String[] args) {
        SnowflakeIdGenerator idGenerator = new SnowflakeIdGenerator(1, 1);
        long orderId = idGenerator.getNextId();
        System.out.println("Generated Order ID: " + orderId);
    }
}

以下Java代码实现检查库存、生成订单并存入MySQL数据库的示例：

import redis.clients.jedis.Jedis;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.UUID;

public class InventoryManager {
    private static final String REDIS_HOST = "localhost";
    private static final int REDIS_PORT = 6379;
    private static final String REDIS_PASSWORD = "your_redis_password";
    
    private static final String MYSQL_HOST = "localhost";
    private static final int MYSQL_PORT = 3306;
    private static final String MYSQL_DATABASE = "your_mysql_database";
    private static final String MYSQL_USER = "your_mysql_username";
    private static final String MYSQL_PASSWORD = "your_mysql_password";

    public static void main(String[] args) {
        // 模拟商品ID和数量
        String productId = "product1";
        int quantity = 1;

        // 连接Redis
        Jedis jedis = new Jedis(REDIS_HOST, REDIS_PORT);
        jedis.auth(REDIS_PASSWORD);

        // 检查库存
        int stock = Integer.parseInt(jedis.get(productId));
        if (stock >= quantity) {
            // 生成订单ID
            String orderId = UUID.randomUUID().toString();

            // 存储订单到MySQL数据库
            saveOrderToMySQL(orderId, productId, quantity);

            // 更新库存
            jedis.decrBy(productId, quantity);

            System.out.println("订单生成成功，订单ID：" + orderId);
        } else {
            System.out.println("库存不足，无法生成订单");
        }
    }

    private static void saveOrderToMySQL(String orderId, String productId, int quantity) {
        try {
            // 连接MySQL数据库
            Connection conn = DriverManager.getConnection("jdbc:mysql://" + MYSQL_HOST + ":" + MYSQL_PORT + "/" + MYSQL_DATABASE, MYSQL_USER, MYSQL_PASSWORD);

            // 插入订单数据
            String sql = "INSERT INTO orders (order_id, product_id, quantity) VALUES (?, ?, ?)";
            PreparedStatement stmt = conn.prepareStatement(sql);
            stmt.setString(1, orderId);
            stmt.setString(2, productId);
            stmt.setInt(3, quantity);
            stmt.executeUpdate();

            // 关闭数据库连接
            stmt.close();
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

请根据实际情况修改REDIS_HOST、REDIS_PORT、REDIS_PASSWORD、MYSQL_HOST、MYSQL_PORT、MYSQL_DATABASE、MYSQL_USER和MYSQL_PASSWORD的值，以确保与您的实际环境匹配。

这段代码假设您已经在Redis中存储了商品的库存信息，以及在MySQL中创建了名为orders的表，包含order_id、product_id和quantity字段。

在代码执行过程中，它会先连接到Redis，检查商品的库存。如果库存足够，则生成一个随机的订单ID，并将订单存储到MySQL数据库中，同时更新Redis中的库存信息。

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【实现检查库存、生成订单并存入MySQL数据库】

【实现检查库存、生成订单并存入MySQL数据库】

根据雪花算法生成交易订单的id

以下Java代码实现检查库存、生成订单并存入MySQL数据库的示例：

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