threadlocal实例仅作为线程局部变量的==操作类==，以及==线程存储局部变量时的key==。真正的线程局部变量是存储在各自线程的本地，通过thread类中的threadlocal.threadlocalmap threadlocals进行存储。
若希望在线程本地存储多个局部变量需要使用多个threadlocal实例进行操作。
set(t v)方法
通过thread.currentthread()获取当前的线程实例，然后获取当前线程实例里的threadlocal.threadlocalmap threadlocals，若不存在该集合对象则创建。最后，将当前threadlocal实例作为key，将参数值v存储当前线程的threadlocals集合中。即var3.set(this, var1);
get()方法
通过thread.currentthread()获取当前的线程实例，然后获取当前线程实例里的threadlocal.threadlocalmap threadlocals，若该集合对象不为空，则用当前threadlocal实例作为key，从集合对象中获取之前存储的值。即var3 = var2.getentry(this);
我要评论 public t get() {
thread var1 = thread.currentthread();
threadlocal.threadlocalmap var2 = this.getmap(var1);
if (var2 != null) {
threadlocal.threadlocalmap.entry var3 = var2.getentry(this);
if (var3 != null) {
object var4 = var3.value;
return var4;
}
}
return this.setinitialvalue();
}
private t setinitialvalue() {
object var1 = this.initialvalue();
thread var2 = thread.currentthread();
threadlocal.threadlocalmap var3 = this.getmap(var2);
if (var3 != null) {
var3.set(this, var1);
} else {
this.createmap(var2, var1);
}
return var1;
}
public void set(t var1) {
thread var2 = thread.currentthread();
threadlocal.threadlocalmap var3 = this.getmap(var2);
if (var3 != null) {
var3.set(this, var1);
} else {
this.createmap(var2, var1);
}
}
public void remove() {
threadlocal.threadlocalmap var1 = this.getmap(thread.currentthread());
if (var1 != null) {
var1.remove(this);
}
}
threadlocal.threadlocalmap getmap(thread var1) {
return var1.threadlocals;
}
void createmap(thread var1, t var2) {
var1.threadlocals = new threadlocal.threadlocalmap(this, var2);
}
thread类使用threadlocal.threadlocalmap threadlocals集合对象盛装线程局部变量。
public class thread implements runnable {
/* make sure registernatives is the first thing <clinit> does. */
private static native void registernatives();
static {
registernatives();
}
private volatile string name;
private int priority;
private thread threadq;
private long eetop;
/* whether or not to single_step this thread. */
private boolean single_step;
/* whether or not the thread is a daemon thread. */
private boolean daemon = false;
/* jvm state */
private boolean stillborn = false;
/* what will be run. */
private runnable target;
/* the group of this thread */
private threadgroup group;
/* the context classloader for this thread */
private classloader contextclassloader;
/* the inherited accesscontrolcontext of this thread */
private accesscontrolcontext inheritedaccesscontrolcontext;
/* for autonumbering anonymous threads. */
private static int threadinitnumber;
private static synchronized int nextthreadnum() {
return threadinitnumber++;
}
/* threadlocal values pertaining to this thread. this map is maintained
* by the threadlocal class. */
threadlocal.threadlocalmap threadlocals = null;
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尚硅谷JVM从入门到精通宋红康版|第十六章、垃圾回收相关概念
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