java中ThreadLocal核心方法怎么使用

public T get() {
    // 获取当前线程
    Thread t = Thread.currentThread();
    ThreadLocalMap map = getMap(t);
    //若当前线程关联的ThreadLocal不为空则查询
    if (map != null) {
        //根据threadLocal查询对应的Entry
        ThreadLocalMap.Entry e = map.getEntry(this);
        if (e != null) {
            @SuppressWarnings("unchecked")
            T result = (T)e.value;
            return result;
        }
    }
    return setInitialValue();
}
 
 private T setInitialValue() {
     //默认返回null值
     T value = initialValue();
     Thread t = Thread.currentThread();
     ThreadLocalMap map = getMap(t);
     //如果当前调用线程关联的ThreadLocalMap为空则创建，否则设置值进去
     if (map != null)
         map.set(this, value);
     else
         //new ThreadLocalMap(this,value)
         createMap(t, value);
     return value;
 }
 
private Entry getEntry(ThreadLocal<?> key) {
    //根据key获取其在数组的下标位置
    int i = key.threadLocalHashCode & (table.length - 1);
    Entry e = table[i];
    if (e != null && e.get() == key)
        return e;
    else
        return getEntryAfterMiss(key, i, e);
}
 
private Entry getEntryAfterMiss(ThreadLocal<?> key, int i, Entry e) {
    Entry[] tab = table;
    int len = tab.length;
    //数组下标的Entry不为空且关联的threadlocal与查找的threadlocal不一致
    while (e != null) {
        ThreadLocal<?> k = e.get();
        //entry关联的threadlocal与查找的相等则直接返回
        if (k == key)
            return e;
        if (k == null)
            //关联的threadlocal为空，则触发清理key为null的Entry并重新进行rehash旧Entry数组的元素
            //threadLocalMap的hash冲突与hashMap的冲突处理方式不一致，hashMap使用的是链表地址法，
            //而threadLocalMap使用的开放地址法——线性探测，即顺序查找下一位置或者遍历全表，效率较低
            expungeStaleEntry(i);
        else
            //递增下标i的值进行下一轮的查找
            i = nextIndex(i, len);
        e = tab[i];
    }
    return null;
}

//ThreadLocal
public void remove() {
    ThreadLocalMap m = getMap(Thread.currentThread());
    if (m != null)
        //删除当前threadLocal对象关联的Entry
        m.remove(this);
}
 
//ThreadLocalMap
private void remove(ThreadLocal<?> key) {
    Entry[] tab = table;
    int len = tab.length;
    int i = key.threadLocalHashCode & (len-1);
    for (Entry e = tab[i];
         e != null;
         e = tab[i = nextIndex(i, len)]) {
        if (e.get() == key) {
            e.clear();
            expungeStaleEntry(i);
            return;
        }
    }
}