ThreadLocal.withInitial

ThreadLocal的Lambda构造方式

Java8中ThreadLocal对象提供了一个Lambda构造方式，实现了非常简洁的构造方法：withInitial。

这个方法采用Lambda方式传入实现了 Supplier 函数接口的参数。

银行存款实例

@SuppressWarnings("all")
public class Test {
    
    public static void main(String[] args) {
        safeDeposit();
        notSafeDeposit();
    }

    /**
     * 线程安全的存款
     */
    private static void safeDeposit() {
        SafeBank bank = new SafeBank();
        Thread thread1 = new Thread(() -> bank.deposit(200), "jak");
        Thread thread2 = new Thread(() -> bank.deposit(200), "马云");
        Thread thread3 = new Thread(() -> bank.deposit(500), "马化腾");
        thread1.start();
        thread2.start();
        thread3.start();
    }

    /**
     * 非线程安全的存款
     */
    private static void notSafeDeposit() {
        NotSafeBank bank = new NotSafeBank();
        Thread thread1 = new Thread(() -> bank.deposit(200), "jak");
        Thread thread2 = new Thread(() -> bank.deposit(200), "马云");
        Thread thread3 = new Thread(() -> bank.deposit(500), "马化腾");
        thread1.start();
        thread2.start();
        thread3.start();
    }
}
/**
 * 线程安全的银行
 */
class SafeBank {

    /**
     * 当前余额
     */
    private ThreadLocal balance = ThreadLocal.withInitial(() -> 1000);

    /**
     * 存款
     *
     * @param money 存款金额
     */
    public void deposit(int money) {
        String threadName = Thread.currentThread().getName();
        System.out.println(threadName + " -> 当前账户余额为：" + this.balance.get());
        this.balance.set(this.balance.get() + money);
        System.out.println(threadName + " -> 存入 " + money + " 后，当前账户余额为：" + this.balance.get());
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
/**
 * 非线程安全的银行
 */
class NotSafeBank {

    /**
     * 当前余额
     */
    private int balance = 1000;

    /**
     * 存款
     *
     * @param money 存款金额
     */
    public void deposit(int money) {
        String threadName = Thread.currentThread().getName();
        System.out.println(threadName + " -> 当前账户余额为：" + this.balance);
        this.balance += money;
        System.out.println(threadName + " -> 存入 " + money + " 后，当前账户余额为：" + this.balance);
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

参考博客