线程的初始化、中断以及源码解析

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创建线程

继承THread类

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public class Demo1 extends Thread {
	
	public Demo1(String name) {
		super(name);
	}
	
	@Override
	public void run() {
		while(!interrupted()) {
			System.out.println(getName() + "线程执行了 .. ");
			try {
				Thread.sleep(200);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
	
	public static void main(String[] args) {
		
		Demo1 d1 = new Demo1("first-thread");
		Demo1 d2 = new Demo1("second-thread");
		
		
		d1.start();
		d2.start();
		
//		d1.stop();
		d1.interrupt();
	}
	
}

实现Runable接口

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public class Demo2 implements Runnable {

	@Override
	public void run() {
		while(true) {
			System.out.println("thread running ...");
		}
	}

	public static void main(String[] args) {
		Thread thread = new Thread(new Demo2());
		thread.start();
	}
	
}

线程初始化

Thread构造器

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/**
     * Allocates a new {@code Thread} object. This constructor has the same
     * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
     * {@code (null, null, gname)}, where {@code gname} is a newly generated
     * name. Automatically generated names are of the form
     * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
     */
    public Thread() {
        init(null, null, "Thread-" + nextThreadNum(), 0);
    }

    /**
     * Allocates a new {@code Thread} object. This constructor has the same
     * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
     * {@code (null, target, gname)}, where {@code gname} is a newly generated
     * name. Automatically generated names are of the form
     * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
     *
     * @param  target
     *         the object whose {@code run} method is invoked when this thread
     *         is started. If {@code null}, this classes {@code run} method does
     *         nothing.
     */
    public Thread(Runnable target) {
        init(null, target, "Thread-" + nextThreadNum(), 0);
    }

    /**
     * Creates a new Thread that inherits the given AccessControlContext.
     * This is not a public constructor.
     */
    Thread(Runnable target, AccessControlContext acc) {
        init(null, target, "Thread-" + nextThreadNum(), 0, acc, false);
    }

    /**
     * Allocates a new {@code Thread} object. This constructor has the same
     * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
     * {@code (group, target, gname)} ,where {@code gname} is a newly generated
     * name. Automatically generated names are of the form
     * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
     *
     * @param  group
     *         the thread group. If {@code null} and there is a security
     *         manager, the group is determined by {@linkplain
     *         SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
     *         If there is not a security manager or {@code
     *         SecurityManager.getThreadGroup()} returns {@code null}, the group
     *         is set to the current thread's thread group.
     *
     * @param  target
     *         the object whose {@code run} method is invoked when this thread
     *         is started. If {@code null}, this thread's run method is invoked.
     *
     * @throws  SecurityException
     *          if the current thread cannot create a thread in the specified
     *          thread group
     */
    public Thread(ThreadGroup group, Runnable target) {
        init(group, target, "Thread-" + nextThreadNum(), 0);
    }

    /**
     * Allocates a new {@code Thread} object. This constructor has the same
     * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
     * {@code (null, null, name)}.
     *
     * @param   name
     *          the name of the new thread
     */
    public Thread(String name) {
        init(null, null, name, 0);
    }

    /**
     * Allocates a new {@code Thread} object. This constructor has the same
     * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
     * {@code (group, null, name)}.
     *
     * @param  group
     *         the thread group. If {@code null} and there is a security
     *         manager, the group is determined by {@linkplain
     *         SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
     *         If there is not a security manager or {@code
     *         SecurityManager.getThreadGroup()} returns {@code null}, the group
     *         is set to the current thread's thread group.
     *
     * @param  name
     *         the name of the new thread
     *
     * @throws  SecurityException
     *          if the current thread cannot create a thread in the specified
     *          thread group
     */
    public Thread(ThreadGroup group, String name) {
        init(group, null, name, 0);
    }

    /**
     * Allocates a new {@code Thread} object. This constructor has the same
     * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
     * {@code (null, target, name)}.
     *
     * @param  target
     *         the object whose {@code run} method is invoked when this thread
     *         is started. If {@code null}, this thread's run method is invoked.
     *
     * @param  name
     *         the name of the new thread
     */
    public Thread(Runnable target, String name) {
        init(null, target, name, 0);
    }

    /**
     * Allocates a new {@code Thread} object so that it has {@code target}
     * as its run object, has the specified {@code name} as its name,
     * and belongs to the thread group referred to by {@code group}.
     *
     * <p>If there is a security manager, its
     * {@link SecurityManager#checkAccess(ThreadGroup) checkAccess}
     * method is invoked with the ThreadGroup as its argument.
     *
     * <p>In addition, its {@code checkPermission} method is invoked with
     * the {@code RuntimePermission("enableContextClassLoaderOverride")}
     * permission when invoked directly or indirectly by the constructor
     * of a subclass which overrides the {@code getContextClassLoader}
     * or {@code setContextClassLoader} methods.
     *
     * <p>The priority of the newly created thread is set equal to the
     * priority of the thread creating it, that is, the currently running
     * thread. The method {@linkplain #setPriority setPriority} may be
     * used to change the priority to a new value.
     *
     * <p>The newly created thread is initially marked as being a daemon
     * thread if and only if the thread creating it is currently marked
     * as a daemon thread. The method {@linkplain #setDaemon setDaemon}
     * may be used to change whether or not a thread is a daemon.
     *
     * @param  group
     *         the thread group. If {@code null} and there is a security
     *         manager, the group is determined by {@linkplain
     *         SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
     *         If there is not a security manager or {@code
     *         SecurityManager.getThreadGroup()} returns {@code null}, the group
     *         is set to the current thread's thread group.
     *
     * @param  target
     *         the object whose {@code run} method is invoked when this thread
     *         is started. If {@code null}, this thread's run method is invoked.
     *
     * @param  name
     *         the name of the new thread
     *
     * @throws  SecurityException
     *          if the current thread cannot create a thread in the specified
     *          thread group or cannot override the context class loader methods.
     */
    public Thread(ThreadGroup group, Runnable target, String name) {
        init(group, target, name, 0);
    }

    /**
     * Allocates a new {@code Thread} object so that it has {@code target}
     * as its run object, has the specified {@code name} as its name,
     * and belongs to the thread group referred to by {@code group}, and has
     * the specified <i>stack size</i>.
     *
     * <p>This constructor is identical to {@link
     * #Thread(ThreadGroup,Runnable,String)} with the exception of the fact
     * that it allows the thread stack size to be specified.  The stack size
     * is the approximate number of bytes of address space that the virtual
     * machine is to allocate for this thread's stack.  <b>The effect of the
     * {@code stackSize} parameter, if any, is highly platform dependent.</b>
     *
     * <p>On some platforms, specifying a higher value for the
     * {@code stackSize} parameter may allow a thread to achieve greater
     * recursion depth before throwing a {@link StackOverflowError}.
     * Similarly, specifying a lower value may allow a greater number of
     * threads to exist concurrently without throwing an {@link
     * OutOfMemoryError} (or other internal error).  The details of
     * the relationship between the value of the <tt>stackSize</tt> parameter
     * and the maximum recursion depth and concurrency level are
     * platform-dependent.  <b>On some platforms, the value of the
     * {@code stackSize} parameter may have no effect whatsoever.</b>
     *
     * <p>The virtual machine is free to treat the {@code stackSize}
     * parameter as a suggestion.  If the specified value is unreasonably low
     * for the platform, the virtual machine may instead use some
     * platform-specific minimum value; if the specified value is unreasonably
     * high, the virtual machine may instead use some platform-specific
     * maximum.  Likewise, the virtual machine is free to round the specified
     * value up or down as it sees fit (or to ignore it completely).
     *
     * <p>Specifying a value of zero for the {@code stackSize} parameter will
     * cause this constructor to behave exactly like the
     * {@code Thread(ThreadGroup, Runnable, String)} constructor.
     *
     * <p><i>Due to the platform-dependent nature of the behavior of this
     * constructor, extreme care should be exercised in its use.
     * The thread stack size necessary to perform a given computation will
     * likely vary from one JRE implementation to another.  In light of this
     * variation, careful tuning of the stack size parameter may be required,
     * and the tuning may need to be repeated for each JRE implementation on
     * which an application is to run.</i>
     *
     * <p>Implementation note: Java platform implementers are encouraged to
     * document their implementation's behavior with respect to the
     * {@code stackSize} parameter.
     *
     *
     * @param  group
     *         the thread group. If {@code null} and there is a security
     *         manager, the group is determined by {@linkplain
     *         SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
     *         If there is not a security manager or {@code
     *         SecurityManager.getThreadGroup()} returns {@code null}, the group
     *         is set to the current thread's thread group.
     *
     * @param  target
     *         the object whose {@code run} method is invoked when this thread
     *         is started. If {@code null}, this thread's run method is invoked.
     *
     * @param  name
     *         the name of the new thread
     *
     * @param  stackSize
     *         the desired stack size for the new thread, or zero to indicate
     *         that this parameter is to be ignored.
     *
     * @throws  SecurityException
     *          if the current thread cannot create a thread in the specified
     *          thread group
     *
     * @since 1.4
     */
    public Thread(ThreadGroup group, Runnable target, String name,
                  long stackSize) {
        init(group, target, name, stackSize);
    }

Thread类的init方法初始化线程

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/**
 * Initializes a Thread.
 *
 * @param g the Thread group
 * @param target the object whose run() method gets called
 * @param name the name of the new Thread
 * @param stackSize the desired stack size for the new thread, or
 *        zero to indicate that this parameter is to be ignored.
 * @param acc the AccessControlContext to inherit, or
 *            AccessController.getContext() if null
 * @param inheritThreadLocals if {@code true}, inherit initial values for
 *            inheritable thread-locals from the constructing thread
 */
private void init(ThreadGroup g, Runnable target, String name,
                  long stackSize, AccessControlContext acc,
                  boolean inheritThreadLocals) {
    if (name == null) {
        throw new NullPointerException("name cannot be null");
    }

    this.name = name;

    Thread parent = currentThread();
    SecurityManager security = System.getSecurityManager();
    if (g == null) {
        /* Determine if it's an applet or not */

        /* If there is a security manager, ask the security manager
           what to do. */
        if (security != null) {
            g = security.getThreadGroup();
        }

        /* If the security doesn't have a strong opinion of the matter
           use the parent thread group. */
        if (g == null) {
            g = parent.getThreadGroup();
        }
    }

    /* checkAccess regardless of whether or not threadgroup is
       explicitly passed in. */
    g.checkAccess();

    /*
     * Do we have the required permissions?
     */
    if (security != null) {
        if (isCCLOverridden(getClass())) {
            security.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
        }
    }

    g.addUnstarted();

    this.group = g;
    this.daemon = parent.isDaemon();
    this.priority = parent.getPriority();
    if (security == null || isCCLOverridden(parent.getClass()))
        this.contextClassLoader = parent.getContextClassLoader();
    else
        this.contextClassLoader = parent.contextClassLoader;
    this.inheritedAccessControlContext =
            acc != null ? acc : AccessController.getContext();
    this.target = target;
    setPriority(priority);
    if (inheritThreadLocals && parent.inheritableThreadLocals != null)
        this.inheritableThreadLocals =
            ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);
    /* Stash the specified stack size in case the VM cares */
    this.stackSize = stackSize;

    /* Set thread ID */
    tid = nextThreadID();
}