阅读大约俩分钟
原来ThreadLocal的Lambda构造方式这么简单
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。写法如下：
代码实例
/**
* 当前余额
*/
private ThreadLocal<Integer> balance = ThreadLocal.withInitial(() -> 1000);
用ThreadLocal作为容器，当每个线程访问这个 balance 变量时，ThreadLocal会为每个线程提供一份变量，各个线程互不影响。
银行存款实例
附带一个银行存款的例子。
package com.javapub.source.code.threadlocal;
/**
* ThreadLocal的Lambda构造方式：withInitial
*
* @author
*/
public class ThreadLocalLambdaDemoByJavaPub {
/**
* 运行入口
*
* @param args 运行参数
*/
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), "马云");
Thread thread2 = new Thread(() -> bank.deposit(200), "马化腾");
Thread thread3 = new Thread(() -> bank.deposit(500), "p哥");
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), "张成瑶");
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();
}
}
}
/**
* 线程安全的银行
*/
class SafeBank {
/**
* 当前余额
*/
private ThreadLocal<Integer> 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();
}
}
}
