线程详解
1.我们都知道一个线程的启动，只有两种方式第一种是继承Thread方法，重写run方法，第二种是实现Runnable，叫个Thread执行
2. 通过代码我们可以看到线程启动方法中，有start0(), 真正去启动一个线程，发现这个方法只是native修饰的方法，这边拓展一下什么是native修饰的方法
public synchronized void start() {
/**
* This method is not invoked for the main method thread or "system"
* group threads created/set up by the VM. Any new functionality added
* to this method in the future may have to also be added to the VM.
*
* A zero status value corresponds to state "NEW".
*/
if (threadStatus != 0)
throw new IllegalThreadStateException();
/* Notify the group that this thread is about to be started
* so that it can be added to the group‘s list of threads
* and the group‘s unstarted count can be decremented. */
group.add(this);
boolean started = false;
try {
start0();
started = true;
} finally {
try {
if (!started) {
group.threadStartFailed(this);
}
} catch (Throwable ignore) {
/* do nothing. If start0 threw a Throwable then
it will be passed up the call stack */
}
}
}
拓展：Native Method，查阅英文文献的解释，"A native method is a Java method whose implementation is provided by non-java code."，准确的说非java实现的方法，主要为了加载文件和动态链接库，可以直接操作系统属性
3. 通过jni实现start0，内部初始化线程，最终会执行，vmSymbols::run_method_name()：即"run"；，也是java线程中run方法
线程的生命周期：初始化(new) --> 可运行状态(start) --> 运行状态（run）& 子状态暂停和阻塞 --> 销亡
具体业务：异步操作，FutureTask，里面有实现Runnable方法
原文：https://www.cnblogs.com/2014-1130/p/14278123.html