
1、get()方法
(1)获取当前用的线程,并找到线程关联的threadLocalMap
(2)threadLocalMap为空则进行初始化一个新的并返回
(3)threadLocalMap不为空则根据threadlocal作为key查找Entry
(4)若Entry不为空则返回entry对应的值,否则执行第二条
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 | public T get() {
Thread t = Thread.currentThread();
ThreadLocalMap map = getMap(t);
if (map != null ) {
ThreadLocalMap.Entry e = map.getEntry( this );
if (e != null ) {
@SuppressWarnings( "unchecked" )
T result = (T)e.value;
return result;
}
}
return setInitialValue();
}
private T setInitialValue() {
T value = initialValue();
Thread t = Thread.currentThread();
ThreadLocalMap map = getMap(t);
if (map != null )
map.set( this , value);
else
createMap(t, value);
return value;
}
private Entry getEntry(ThreadLocal<?> key) {
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;
while (e != null ) {
ThreadLocal<?> k = e.get();
if (k == key)
return e;
if (k == null )
expungeStaleEntry(i);
else
i = nextIndex(i, len);
e = tab[i];
}
return null ;
}
|
2、remove()方法
(1)获取当前用的线程,并找到线程关联的threadLocalMap
(2)若不为空则删除threadLocalMap中关联的值,否则啥也不做
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | public void remove() {
ThreadLocalMap m = getMap(Thread.currentThread());
if (m != null )
m.remove( this );
}
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 ;
}
}
}
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以上就是java中ThreadLocal核心方法介绍,大家会发现这些方法我们在其他的模块也有使用到。想要对其他核心方法有所了解,也可以在课后自行查阅资料。
(本教程推荐操作环境:windows7系统、java10版,DELL G3电脑。)