代理模式

 1 public class TestNIO {
 2     /**
 3      * 测试堆内存缓冲区
 4      */
 5     @Test
 6     public void test1HeapByteBuffer(){
 7         int size = 1024 * 1024 * 450 ;
 8         ByteBuffer buf = ByteBuffer.allocate(size);
 9         System.out.println(buf.capacity());
10         buf = null ;
11         System.gc();        //OK
12         System.out.println("kkk");
13     }
14     
15     /**
16      * 测试堆内存缓冲区
17      * @throws Exception 
18      */
19     @Test
20     public void test1DirectByteBuffer() throws Exception{
21         
22         int size = 1024 * 1024 * 1024 * 1 ;
23         ByteBuffer buf = ByteBuffer.allocateDirect(size);
24         
25         //通过反射，回收离堆内存
26         Class clazz = Class.forName("java.nio.DirectByteBuffer");
27         Method m = clazz.getDeclaredMethod("cleaner");
28         m.setAccessible(true);
29         Object cleaner = m.invoke(buf);
30         
31         Class cleanerClazz = cleaner.getClass();
32         Method m2 = cleanerClazz.getDeclaredMethod("clean");
33         m2.setAccessible(true);
34         m2.invoke(cleaner);
35         
36         System.out.println(buf.get(1000));
37         System.gc();
38         System.out.println("dd");
39     }
40     /**
41      * 测试垃圾回收
42      */
43     @Test
44     public void testGC(){
45         int size = Integer.MAX_VALUE;
46         byte[] buf = new byte[size];
47         byte[] buf2 = buf ;
48         List<byte[]> list = new ArrayList<byte[]>();
49         list.add(buf2);
50         buf = null ;
51         System.gc();    //进行垃圾回收
52         buf2 = null ;
53         System.gc();    //进行垃圾回收
54         System.out.println("xxx");
55         list.clear();    //清空集合
56         System.gc();    //进行垃圾回收
57         System.out.println("xxx");
58     }
59     
60     /**
61      * 测试垃圾回收
62      */
63     @Test
64     public void testChannel() throws Exception{
65         FileInputStream fis = new FileInputStream("d:/a.txt");
66         FileChannel srcFC = fis.getChannel();
67         
68         FileOutputStream fos = new FileOutputStream("d:/b.txt");
69         FileChannel destFC = fos.getChannel();
70         
71         //定义缓冲区
72         ByteBuffer buf = ByteBuffer.allocate(11);
73         while(srcFC.read(buf) != -1){
74             buf.flip();
75             destFC.write(buf);
76             buf.clear();
77         }
78         fis.close();
79         fos.close();
80     }
81 }