魅力程序猿

public class SyncMethod implements Runnable{
 
    /** 共享资源(临界资源) */
    public static int i = 0;
 
    /**
     * synchronized 修饰实例方法
     */
    private synchronized void increase(){
        i++;
    }
 
    @Override
    public void run() {
        for(int j = 0; j < 1000000; j++){
            increase();
        }
    }
}
 
public class SyncVerify {
    public static void main(String[] args){
        verifySyncMethod();
    }
 
    /**
     * synchronized修饰实例对象中的实例方法
     */
    private static void verifySyncMethod(){
        try {
            SyncMethod instance = new SyncMethod();
            Thread t1 = new Thread(instance);
            Thread t2 = new Thread(instance);
            t1.start();
            t2.start();
            t1.join();
            t2.join();
            System.out.println(instance.i);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}    
    /**
     * 输出结果:
     * 2000000
     */

public class SyncMethod implements Runnable{
 
    /** 共享资源(临界资源) */
    public static int i = 0;
 
    /**
     * synchronized 修饰实例方法
     */
    private synchronized void increase(){
        i++;
    }
 
    @Override
    public void run() {
        for(int j = 0; j < 1000000; j++){
            increase();
        }
    }
}
 
public static void main(String[] args){
        verifySyncMethodBad();
    }
 
    /**
     * 两个实例对象锁
     */
    private static void verifySyncMethodBad(){
        try {
            SyncMethod instance1 = new SyncMethod();
            SyncMethod instance2 = new SyncMethod();
            Thread t1 = new Thread(instance1);
            Thread t2 = new Thread(instance2);
            t1.start();
            t2.start();
            t1.join();
            t2.join();
            System.out.println(instance1.i);
            System.out.println(instance2.i);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
    /**
     * 输出结果:
     * < 2000000的一个数
     */

public class SyncClass implements Runnable {
 
    public static int i = 0;
 
    /**
     * 作用于静态方法,锁是当前class对象,也就是
     * SyncClass类对应的class对象
     */
    public static synchronized void increase(){
        i++;
    }
 
    @Override
    public void run() {
        for(int j = 0; j < 1000000; j++){
            increase();
        }
    }
 
}
 
public class SyncVerify {
    public static void main(String[] args){
        verifySyncClass();
    }
 
    /**
     * 当synchronized作用于静态方法时，其锁就是当前类的class对象锁
     */
    private static void verifySyncClass(){
        try {
            SyncClass instance1 = new SyncClass();
            SyncClass instance2 = new SyncClass();
            Thread t1 = new Thread(instance1);
            Thread t2 = new Thread(instance2);
            t1.start();
            t2.start();
            t1.join();
            t2.join();
            System.out.println(instance1.i);
            System.out.println(instance2.i);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
    /**
     * 输出结果:
     * 2000000
     */

public class SyncCodeBlock implements Runnable{
    public static int i = 0;
    private static final byte[] sLock = new byte[0];
    @Override
    public void run() {
        //其他逻辑
        //……
        //synchronized(SyncCodeBlock.class){
        //synchronized(this){
        //使用同步代码块对变量i进行同步操作,锁对象为当前对象
        synchronized(sLock){
            for(int j=0;j<1000000;j++){
                i++;
            }
        }
    }
}
 
public class SyncVerify {
    public static void main(String[] args){
        verifySyncCodeBlock();
    }
private static void verifySyncCodeBlock(){
        try {
            SyncCodeBlock instance1 = new SyncCodeBlock();
            SyncCodeBlock instance2 = new SyncCodeBlock();
            Thread t1 = new Thread(instance1);
            Thread t2 = new Thread(instance2);
            t1.start();
            t2.start();
            t1.join();
            t2.join();
            System.out.println(instance1.i);
            System.out.println(instance2.i);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

Last modified 2018-7-1; size 668 bytes
  MD5 checksum f06a26be311de8504de86adc68e9da65
  Compiled from "SyncCodeBlock.java"
public class com.aoaoyi.sync.SyncCodeBlock implements java.lang.Runnable
  minor version: 0
  major version: 52
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
   #1 = Methodref          #6.#27         // java/lang/Object."":()V
   #2 = Fieldref           #5.#28         // com/aoaoyi/sync/SyncCodeBlock.sLock:[B
   #3 = Integer            1000000
   #4 = Fieldref           #5.#29         // com/aoaoyi/sync/SyncCodeBlock.i:I
   #5 = Class              #30            // com/aoaoyi/sync/SyncCodeBlock
   #6 = Class              #31            // java/lang/Object
   #7 = Class              #32            // java/lang/Runnable
   #8 = Utf8               i
   #9 = Utf8               I
  #10 = Utf8               sLock
  #11 = Utf8               [B
  #12 = Utf8               
  #13 = Utf8               ()V
  #14 = Utf8               Code
  #15 = Utf8               LineNumberTable
  #16 = Utf8               LocalVariableTable
  #17 = Utf8               this
  #18 = Utf8               Lcom/aoaoyi/sync/SyncCodeBlock;
  #19 = Utf8               run
  #20 = Utf8               j
  #21 = Utf8               StackMapTable
  #22 = Class              #31            // java/lang/Object
  #23 = Class              #33            // java/lang/Throwable
  #24 = Utf8               
  #25 = Utf8               SourceFile
  #26 = Utf8               SyncCodeBlock.java
  #27 = NameAndType        #12:#13        // "":()V
  #28 = NameAndType        #10:#11        // sLock:[B
  #29 = NameAndType        #8:#9          // i:I
  #30 = Utf8               com/aoaoyi/sync/SyncCodeBlock
  #31 = Utf8               java/lang/Object
  #32 = Utf8               java/lang/Runnable
  #33 = Utf8               java/lang/Throwable
{
  public static int i;
    descriptor: I
    flags: ACC_PUBLIC, ACC_STATIC
 
  public com.aoaoyi.sync.SyncCodeBlock();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."":()V
         4: return
      LineNumberTable:
        line 3: 0
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0       5     0  this   Lcom/aoaoyi/sync/SyncCodeBlock;
 
  public void run();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=2, locals=4, args_size=1
         0: getstatic     #2                  // Field sLock:[B
         3: dup
         4: astore_1
         5: monitorenter                     //注意此处，进入同步方法
         6: iconst_0
         7: istore_2
         8: iload_2
         9: ldc           #3                  // int 1000000
        11: if_icmpge     28
        14: getstatic     #4                  // Field i:I
        17: iconst_1
        18: iadd
        19: putstatic     #4                  // Field i:I
        22: iinc          2, 1
        25: goto          8
        28: aload_1
        29: monitorexit                       //注意此处，退出同步方法
        30: goto          38
        33: astore_3
        34: aload_1
        35: monitorexit                      //注意此处，退出同步方法
        36: aload_3
        37: athrow
        38: return
      Exception table:
         from    to  target type
             6    30    33   any
            33    36    33   any
      LineNumberTable:
        line 9: 0
        line 10: 6
        line 11: 14
        line 10: 22
        line 13: 28
        line 14: 38
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            8      20     2     j   I
            0      39     0  this   Lcom/aoaoyi/sync/SyncCodeBlock;
      StackMapTable: number_of_entries = 4
        frame_type = 253 /* append */
          offset_delta = 8
          locals = [ class java/lang/Object, int ]
        frame_type = 250 /* chop */
          offset_delta = 19
        frame_type = 68 /* same_locals_1_stack_item */
          stack = [ class java/lang/Throwable ]
        frame_type = 250 /* chop */
          offset_delta = 4
 
  static {};
    descriptor: ()V
    flags: ACC_STATIC
    Code:
      stack=1, locals=0, args_size=0
         0: iconst_0
         1: putstatic     #4                  // Field i:I
         4: iconst_0
         5: newarray       byte
         7: putstatic     #2                  // Field sLock:[B
        10: return
      LineNumberTable:
        line 4: 0
        line 5: 4
}
SourceFile: "SyncCodeBlock.java"

public class SyncMethod1 {
    public int i;
 
    public synchronized void syncTask(){
        i++;
    }
}

 Last modified 2018-7-2; size 398 bytes
  MD5 checksum 057ffdc05a05e5c0c4f00acf73d88fd5
  Compiled from "SyncMethod1.java"
public class com.aoaoyi.sync.SyncMethod1
  minor version: 0
  major version: 52
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
   #1 = Methodref          #4.#17         // java/lang/Object."":()V
   #2 = Fieldref           #3.#18         // com/aoaoyi/sync/SyncMethod1.i:I
   #3 = Class              #19            // com/aoaoyi/sync/SyncMethod1
   #4 = Class              #20            // java/lang/Object
   #5 = Utf8               i
   #6 = Utf8               I
   #7 = Utf8               
   #8 = Utf8               ()V
   #9 = Utf8               Code
  #10 = Utf8               LineNumberTable
  #11 = Utf8               LocalVariableTable
  #12 = Utf8               this
  #13 = Utf8               Lcom/aoaoyi/sync/SyncMethod1;
  #14 = Utf8               syncTask
  #15 = Utf8               SourceFile
  #16 = Utf8               SyncMethod1.java
  #17 = NameAndType        #7:#8          // "":()V
  #18 = NameAndType        #5:#6          // i:I
  #19 = Utf8               com/aoaoyi/sync/SyncMethod1
  #20 = Utf8               java/lang/Object
{
  public int i;
    descriptor: I
    flags: ACC_PUBLIC
 
  public com.aoaoyi.sync.SyncMethod1();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."":()V
         4: return
      LineNumberTable:
        line 3: 0
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0       5     0  this   Lcom/aoaoyi/sync/SyncMethod1;
 
  public synchronized void syncTask();
    descriptor: ()V
    flags: ACC_PUBLIC, ACC_SYNCHRONIZED //方法标识ACC_PUBLIC代表public修饰，ACC_SYNCHRONIZED指明该方法为同步方法
    Code:
      stack=3, locals=1, args_size=1
         0: aload_0
         1: dup
         2: getfield      #2                  // Field i:I
         5: iconst_1
         6: iadd
         7: putfield      #2                  // Field i:I
        10: return
      LineNumberTable:
        line 7: 0
        line 8: 10
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0      11     0  this   Lcom/aoaoyi/sync/SyncMethod1;
}
SourceFile: "SyncMethod1.java"

ObjectMonitor() {
    _header       = NULL;
    _count        = 0; //记录个数
    _waiters      = 0,
    _recursions   = 0;
    _object       = NULL;
    _owner        = NULL;
    _WaitSet      = NULL; //处于wait状态的线程，会被加入到_WaitSet
    _WaitSetLock  = 0 ;
    _Responsible  = NULL ;
    _succ         = NULL ;
    _cxq          = NULL ;
    FreeNext      = NULL ;
    _EntryList    = NULL ; //处于等待锁block状态的线程，会被加入到该列表
    _SpinFreq     = 0 ;
    _SpinClock    = 0 ;
    OwnerIsThread = 0 ;
  }

public class SyncMethod implements Runnable{
    static SyncMethod instance = new SyncMethod();
    static int i=0;
    static int j=0;
    @Override
    public void run() {
        for(int j=0;j<1000000;j++){
 
            //this,当前实例对象锁
            synchronized(this){
                i++;
                increase();//synchronized的可重入性
            }
        }
    }
 
    public synchronized void increase(){
        j++;
    }
 
 
    public static void main(String[] args) throws InterruptedException {
        Thread t1=new Thread(instance);
        Thread t2=new Thread(instance);
        t1.start();
	t2.start();
        t1.join();
	t2.join();
        System.out.println(i);
	System.out.println(j);
    }
}

public class SyncCodeBlock1 implements Runnable{
 
    public synchronized void f() {
        System.out.println("Trying to call f()");
        while(true) // Never releases lock
            Thread.yield();
    }
 
    /**
     * 在构造器中创建新线程并启动获取对象锁
     */
    public SyncCodeBlock1() {
        //该线程已持有当前实例锁
        new Thread(() -> {
            f(); // Lock acquired by this thread
        });
    }
    public void run() {
        //中断判断
        while (true) {
            if (Thread.interrupted()) {
                System.out.println("中断线程!!");
                break;
            } else {
                f();
            }
        }
    }
 
 
    public static void main(String[] args) throws InterruptedException {
        SyncCodeBlock1 sync = new SyncCodeBlock1();
        Thread t = new Thread(sync);
        //启动后调用f()方法,无法获取当前实例锁处于等待状态
        t.start();
        TimeUnit.SECONDS.sleep(1);
        //中断线程,无法生效
        t.interrupt();
    }
}

synchronized (obj) {
       obj.wait();
       obj.notify();
       obj.notifyAll();         
 }