JAVA并發(fā)編程有界緩存的實(shí)現(xiàn)
1、有界緩存的基類
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
|
package cn.xf.cp.ch14;/** * *功能：有界緩存實(shí)現(xiàn)基類 *時(shí)間：下午2:20:00 *文件：BaseBoundedBuffer.java *@author Administrator * * @param <V> */public class BaseBoundedBuffer<V>{ private final V[] buf; private int tail; private int head; private int count; public BaseBoundedBuffer(int capacity) { //初始化數(shù)組 this.buf = (V[]) new Object[capacity]; } //放入一個(gè)數(shù)據(jù),final方法無法被重寫 protected synchronized final void doPut(V v) { buf[tail] = v; if(++tail == buf.length) { tail = 0; } //插入一個(gè)方法，總量++ ++count; } /** * 取出一個(gè)數(shù)據(jù) * @return */ protected synchronized final V doTake() { V v = buf[head]; buf[head] = null; if(++head == buf.length) { head = 0; } --count; return v; } //通過對(duì)count的判斷，來確定數(shù)組是否是滿的 public synchronized final boolean isFull() { return count == buf.length; } public synchronized final boolean isEmpty() { return count == 0; }} |
2、判定前提條件再執(zhí)行操作
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
|
package cn.xf.cp.ch14;/** * *功能：對(duì)插入和獲取元素操作進(jìn)行先行檢查，然后執(zhí)行操作，校驗(yàn)不通過不予操作 *時(shí)間：下午2:33:41 *文件：GrumpyBoundedBuffer.java *@author Administrator * * @param <V> */public class GrumpyBoundedBuffer<V> extends BaseBoundedBuffer<V>{ public GrumpyBoundedBuffer(int size) { super(size); } public synchronized void put(V v) throws Exception { //如果是滿的隊(duì)列，就無法插入新的元素 if(this.isFull()) { throw new Exception("隊(duì)列超出"); } this.doPut(v); } //同理，隊(duì)列為空的就無法取出新的元素 public synchronized V take() throws Exception { if(this.isEmpty()) { throw new Exception("隊(duì)列中無元素"); } return this.doTake(); }} |
3、通過輪詢與休眠來實(shí)現(xiàn)簡單的阻塞
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
package cn.xf.cp.ch14;/** * *功能：通過輪詢與休眠來實(shí)現(xiàn)簡單的阻塞 *時(shí)間：下午2:55:54 *文件：SleepyBoundedBuffer.java *@author Administrator * * @param <V> */public class SleepyBoundedBuffer<V> extends BaseBoundedBuffer<V>{ //2s private static final long SLEEP_GRANULARITY = 2000; public SleepyBoundedBuffer(int capacity) { super(capacity); } //放入隊(duì)列的時(shí)候 public void put(V v) throws InterruptedException { while(true) { //這里不對(duì)循環(huán)上鎖，不然這個(gè)鎖就無法釋放了，不對(duì)休眠上鎖，休眠上鎖，在休眠的時(shí)候別人也無法操作，永遠(yuǎn)都不可能有元素出去 synchronized (this) { //如果隊(duì)列不是滿的，那么就放入元素 if(!this.isFull()) { this.doPut(v); return; } } //否則休眠，退出cpu占用 Thread.sleep(SLEEP_GRANULARITY); } } public V take() throws InterruptedException { while(true) { //這里不對(duì)循環(huán)上鎖，不然這個(gè)鎖就無法釋放了，不對(duì)休眠上鎖，休眠上鎖，在休眠的時(shí)候別人也無法操作，永遠(yuǎn)都不可能有新的元素進(jìn)來 synchronized(this) { //如果數(shù)組部位空，那么就可以取出數(shù)據(jù) if(!this.isEmpty()) { return this.doTake(); } //如果隊(duì)列為空，休眠幾秒再試 } Thread.sleep(SLEEP_GRANULARITY); } } } |
4、條件隊(duì)列
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
|
package cn.xf.cp.ch14;/** * *功能：使用條件隊(duì)列 *時(shí)間：下午3:32:04 *文件：BoundedBuffer.java *@author Administrator * * @param <V> */public class BoundedBuffer<V> extends BaseBoundedBuffer<V>{ public BoundedBuffer(int capacity) { super(capacity); } /** * 放入數(shù)據(jù)元素 * @param v * @throws InterruptedException */ public synchronized void put(V v) throws InterruptedException { while(this.isFull()) { //這里掛起程序，會(huì)釋放鎖 this.wait(); } //如果隊(duì)列不為滿的，那么程序被喚醒之后從新獲取鎖 this.doPut(v); //執(zhí)行結(jié)束，喚醒其他隊(duì)列 this.notifyAll(); } public synchronized V take() throws InterruptedException { while(this.isEmpty()) { this.wait(); } V v = this.doTake(); this.notifyAll(); return v; } } |
感謝閱讀，希望能幫助到大家，謝謝大家對(duì)本站的支持！
