AtomicReferenceFieldUpdater api詳解

今天學習AtomicReferenceFieldUpdater類，該類是JUC原子包中的類，通過單元測試代碼把所有public api方法跑了一遍，大致瞭解了底層實現

package test.java.util.concurrent.atomic;


import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.function.BinaryOperator;
import java.util.function.LongBinaryOperator;
import java.util.function.UnaryOperator;

import org.junit.Test;

/**
 * AtomicReferenceFieldUpdater的測試類
 *
 * @author zqw
 * @date 2020-06-20 22:34:19
 */
public class AtomicReferenceFieldUpdaterTest {
    //abstract
    private volatile Integer age;

    /**
     * 初始化採用靜態方法+內部類，私有化構造函數
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testNewUpdater() {
        AtomicReferenceFieldUpdaterTest test=new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        System.out.println(updater.get(test));
    }

    /**
     * 如果指定對象的目標屬性值爲expect的值，則更新成新值，返回true
     * 否則不更新，返回false
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testCompareAndSet() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        System.out.println(updater.compareAndSet(test, null, 2));
        System.out.println(updater.get(test));
    }

    /**
     * 如果指定對象的目標屬性值爲expect的值，則更新成新值，返回true
     * 否則不更新，返回false
     * weakCompareAndSet和compareAndSet暫時未發現區別
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testWeakCompareAndSet() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        System.out.println(updater.weakCompareAndSet(test, null, 2));
        System.out.println(updater.get(test));

    }

    /**
     * 設置指定對象的目標屬性值爲新的值，unsafe.putIntVolatile設置值
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testSet() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        updater.set(test, 22);
        System.out.println(updater.get(test));
    }

    /**
     * 設置指定對象的目標屬性值爲新的值，unsafe.putOrderedInt
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testLazySet() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        updater.lazySet(test, 22);
        System.out.println(updater.get(test));
    }

    /**
     * 獲取指定對象的目標屬性值，需要檢查是否越界
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testGet() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        System.out.println(updater.get(test));
    }

    /**
     * 返回指定對象的目標屬性值，並設置成新的值
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testGetAndSet() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        System.out.println(updater.getAndSet(test, 32));
        System.out.println(updater.get(test));
    }



    /**
     * 返回指定對象的目標屬性值，並更新成新值
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testGetAndUpdate() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
         UnaryOperator operator = new UnaryOperator() {
             @Override
             public Object apply(Object o) {
                 return new Integer(333);
             }
         };
        System.out.println(updater.getAndUpdate(test, operator));
        System.out.println(updater.get(test));

    }

    /**
     * 更新成新值並返回指定對象的目標屬性值
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testUpdateAndGet() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        UnaryOperator operator = new UnaryOperator() {
            @Override
            public Object apply(Object o) {
                return new Integer(333);
            }
        };
        System.out.println(updater.updateAndGet(test, operator));
        System.out.println(updater.get(test));
    }
    /**
     * 返回指定對象的目標屬性值，並更新成新值
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testGetAndAccumulate() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        BinaryOperator operator = new BinaryOperator() {
            @Override
            public Object apply(Object o, Object o2) {
                return o2;
            }
        };
        System.out.println(updater.getAndAccumulate(test, 2, operator));
        System.out.println(updater.get(test));
    }

    /**
     * 更新成新值並返回指定對象的目標屬性值
     *
     * @throws
     * @date 2020/6/20 23:46
     */
    @Test
    public void testAccumulateAndGet() {
        AtomicReferenceFieldUpdaterTest test = new AtomicReferenceFieldUpdaterTest();
        AtomicReferenceFieldUpdater updater = AtomicReferenceFieldUpdater.newUpdater(AtomicReferenceFieldUpdaterTest.class,
                Integer.class,"age");
        BinaryOperator operator = new BinaryOperator() {
            @Override
            public Object apply(Object o, Object o2) {
                return o2;
            }
        };
        System.out.println(updater.accumulateAndGet(test, 2, operator));
        System.out.println(updater.get(test));
    }
}