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‎JdkLearn/src/main/java/com/learnjava/reference/PhantomRefTest.java‎
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‎JdkLearn/src/main/java/com/learnjava/reference/PhantomRefTest.java‎
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+35Lines changed: 35 additions & 0 deletions
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‎JdkLearn/src/main/java/com/learnjava/reference/SoftReferenceTest.java‎
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‎JdkLearn/src/main/java/com/learnjava/reference/SoftReferenceTest.java‎
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‎JdkLearn/src/main/java/com/learnjava/reference/WeakReferenceTest.java‎
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+35-1Lines changed: 35 additions & 1 deletion b/Collapse file
‎JdkLearn/src/main/java/com/learnjava/reference/WeakReferenceTest.java‎
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+35-1Lines changed: 35 additions & 1 deletion
@@ -0,0 +1,35 @@
+package com.learnjava.reference;
+
+import java.lang.ref.PhantomReference;
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
+
+public class PhantomRefTest {
+
+    public static void main(String[] args) throws InterruptedException {
+        ReferenceQueue referenceQueue = new ReferenceQueue();
+
+        // 10mb
+        byte[] buffer = new byte[1024 * 1024 * 10];
+
+        PhantomReference phantomReference = new PhantomReference(buffer, referenceQueue);
+
+        // 字节数组对象，失去了强引用
+        buffer = null;
+
+        Reference ref0 = referenceQueue.poll();
+
+        System.out.println("gc 执行之前， refQueue中是否有数据？" + (ref0 != null ? "有" : "没有"));
+        System.out.println("gc 执行之前, ref引用的对象：" + phantomReference.get());
+
+        System.gc();
+        // 确保gc程序执行
+        Thread.sleep(1000);
+
+        System.out.println("gc 执行之后， ref引用的对象：" + phantomReference.get());
+
+        Reference ref = referenceQueue.poll();
+        System.out.println("gc 执行之后， refQueue中是否有数据？" + (ref != null ? "有" : "没有"));
+        System.out.println("referenceQueue 中获取的 ref与 weakReference中的是否一致？" + (ref == phantomReference));
+    }
+}
@@ -0,0 +1,35 @@
+package com.learnjava.reference;
+
+import java.lang.ref.Reference;
+import java.lang.ref.SoftReference;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+/**
+ * 软引用
+ */
+public class SoftReferenceTest {
+    public static void main(String[] args) throws InterruptedException {
+        List<Reference> refList = new ArrayList<Reference>();
+
+        for (int i = 0; i < 1000; i++) {
+            // 10mb
+            byte[] buffer = new byte[1024 * 1024 * 10];
+
+            SoftReference softReference = new SoftReference(buffer);
+
+            refList.add(softReference);
+        }
+
+        System.gc();
+        Thread.sleep(1000);
+
+        Iterator<Reference> it = refList.iterator();
+
+        while (it.hasNext()) {
+            Reference ref = it.next();
+            System.out.println("当前ref引用的对象：" + ref.get());
+        }
+    }
+}
@@ -1,14 +1,47 @@
 package com.learnjava.reference;
 
+import com.sun.webkit.graphics.Ref;
+
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
 
+/**
+ * soft软引用 gc堆内存不够时，可能会回收
+ * weak弱引用 gc时，内存一定会回收不可用对象
+ * phantom虚引用
+ */
 public class WeakReferenceTest {
     public static void main(String[] args) throws Exception {
+//        test01();
         test02();
     }
 
+    private static void test01() throws InterruptedException {
+        List<Reference> refList = new ArrayList<Reference>();
+
+        for (int i = 0; i < 1000; i++) {
+            // 10mb
+            byte[] buffer = new byte[1024 * 1024 * 10];
+
+            WeakReference weakReference = new WeakReference(buffer);
+
+            refList.add(weakReference);
+        }
+
+        // 将buffer直接全部回收了
+        System.gc();
+        Thread.sleep(1000);
+        Iterator<Reference> iterator = refList.iterator();
+        while (iterator.hasNext()) {
+            Reference ref = iterator.next();
+            System.out.println("当前ref引用的对象：" + ref.get());
+        }
+    }
+
     private static void test02() throws InterruptedException {
         ReferenceQueue refQueue = new ReferenceQueue();
 
@@ -26,9 +59,10 @@ private static void test02() throws InterruptedException {
         // 确保gc程序执行
         Thread.sleep(1000);
 
-        System.out.println("gc 执行之前， ref引用的对象：" + weakReference.get());
+        System.out.println("gc 执行之后， ref引用的对象：" + weakReference.get());
 
         Reference ref = refQueue.poll();
+        System.out.println("gc 执行之后， refQueue中是否有数据？" + (ref != null ? "有" : "没有"));
         System.out.println("referenceQueue 中获取的 ref与 weakReference中的是否一致？" + (ref == weakReference));
     }
 }