Cara untuk meningkatkan prestasi rangka kerja Java

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

public class CustomerCache {

    private static final LoadingCache<Integer, Customer> cache = CacheBuilder.newBuilder()
            .maximumSize(1000)
            .expireAfterAccess(30, TimeUnit.MINUTES)
            .build(new CacheLoader<Integer, Customer>() {
                @Override
                public Customer load(Integer id) throws Exception {
                    return database.get(id); // 从数据库中获取客户信息
                }
            });

    public Customer get(int id) {
        return cache.get(id); // 从缓存中获取客户信息或从数据库中加载
    }
}

import org.apache.commons.pool2.ObjectPool;
import org.apache.commons.pool2.PooledObject;
import org.apache.commons.pool2.PooledObjectFactory;
import org.apache.commons.pool2.impl.DefaultPooledObject;
import org.apache.commons.pool2.impl.GenericObjectPool;

class DataSourcePool {

    private static final ObjectPool<Connection> pool = new GenericObjectPool<>(new PooledObjectFactory<Connection>() {
        @Override
        public PooledObject<Connection> makeObject() throws Exception {
            return new DefaultPooledObject<>(DataSource.getConnection()); // 从数据源获取连接
        }

        @Override
        public void destroyObject(PooledObject<Connection> p) throws Exception {
            p.getObject().close(); // 关闭连接
        }
    });

    public Connection getConnection() {
        try {
            return pool.borrowObject(); // 从池中获取连接
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public void releaseConnection(Connection connection) {
        pool.returnObject(connection); // 将连接归还给池
    }
}

import java.util.concurrent.*;
import java.util.concurrent.locks.ReentrantLock;

class OrderProcessor {

    private final ReentrantLock lock = new ReentrantLock();
    private final ExecutorService executorService = Executors.newFixedThreadPool(4);

    public void process(Order order) {
        executorService.submit(() -> {
            lock.lock();
            try {
                // 执行订单处理逻辑
            } finally {
                lock.unlock();
            }
        });
    }
}

CREATE INDEX idx_order_customer_id ON Orders (customer_id);

SELECT * FROM Orders
WHERE customer_id = ? AND order_status = 'NEW'
ORDER BY order_date DESC
LIMIT 10;

// 使用流式处理代替for循环来计算总金额
List<Order> orders = orderRepo.findAll();
Double totalAmount = orders.stream()
        .map(Order::getAmount)
        .reduce(0.0, Double::sum);