ThreadLocal接口很简单,有4个方法:
pulblic void set(T vlaue);
pulblic T get();
pulblic void remove();
protected T initialValue();
ThreadLocal类中有一个map,用于存储每一个线程的变量副本,Map中元素的键为线程对象,而值对应线程的变量副本。
package com.billkang.springstudy;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* @author binkang
* @date May 1, 2017
*/
public class SimpleThreadLocal<T> {
private Map<Thread, T> map = Collections.synchronizedMap(new HashMap<Thread, T>());
public void set(T value) {
map.put(Thread.currentThread(), value);
}
public T get() {
Thread currentThread = Thread.currentThread();
T o = map.get(currentThread);
if(o==null && !map.containsKey(currentThread)) {
o = initialVlaue();
map.put(currentThread, o);
}
return o;
}
public T initialVlaue(){
return null;
}
public void remove(){
map.remove(Thread.currentThread());
}
}