JDK 5.0 특성-스 레 드 잠 금 잠 금
34925 단어 Lock
1 import java.util.concurrent.ExecutorService;
2
3 import java.util.concurrent.Executors;
4
5 import java.util.concurrent.Future;
6
7 import java.util.concurrent.locks.Lock;
8
9 import java.util.concurrent.locks.ReadWriteLock;
10
11 import java.util.concurrent.locks.ReentrantLock;
12
13 import java.util.concurrent.locks.ReentrantReadWriteLock;
14
15
16
17
18
19 /**
20
21 , , , ,
22
23 , , . J2SE5.0
24
25 synchronized . J2SE 5.0 , 、 .
26
27 :
28
29 J2SE5.0 java.util.concurrent.locks.lock , :
30
31 1.ReentrantLock Lock , synchronized .
32
33 2.ReentrantLock lock , , , 1; , , 1; , ,
34
35 , 1.
36
37 3.ReentrantLock unlock , , 1, 0, . , .
38
39 4.ReadWriteLock Lock , . ReentrantReadWriteLock
40
41 5.ReentrantReadWriteLock writeLock , , .
42
43 6.ReentrantReadWriteLock readLock , , , .
44
45 */
46
47 public class Lockers {
48
49 /** Lock . Lock, synchronized */
50
51 public static class LockTest{
52
53 Lock lock = new ReentrantLock();//
54
55 double value = 0d; //
56
57 int addtimes = 0;
58
59 /**
60
61 * value , 2 , ,
62
63 * , synchronized
64
65 */
66
67 public void addValue(double v){
68
69 lock.lock();//
70
71 System.out.println("LockTest to addValue: " + v + " " + System.currentTimeMillis());
72
73 try {
74
75 Thread.sleep(1000);
76
77 }catch(InterruptedException e){
78
79 }
80
81 this.value += v;
82
83 this.addtimes++;
84
85 lock.unlock();
86
87 }
88
89 public double getValue(){
90
91 return this.value;
92
93 }
94
95 }
96
97 public static void testLockTest() throws Exception{
98
99 final LockTest lockTest = new LockTest();
100
101 // 1, lockTest addValue
102
103 Runnable task1 = new Runnable(){
104
105 public void run(){
106
107 lockTest.addValue(55.55);
108
109 }
110
111 };
112
113 // 2, lockTest getValue
114
115 Runnable task2 = new Runnable(){
116
117 public void run(){
118
119 System.out.println("value: " + lockTest.getValue());
120
121 }
122
123 };
124
125 //
126
127 ExecutorService cachedService = Executors.newCachedThreadPool();
128
129 Future future = null;
130
131 // 1 , addValue , ,
132
133 for(int i=0;i<3;i++){
134
135 future = cachedService.submit(task1);
136
137 }
138
139 future.get();// 1
140
141 future = cachedService.submit(task2);// 2,
142
143 future.get();// 2 ,
144
145 cachedService.shutdownNow();
146
147 }
148
149 /**
150
151 * ReadWriteLock Lock, Lock, Lock
152
153 * Lock, Lock
154
155 * Lock , Lock.ReadWriteLock :
156
157 * readLock(): Lock
158
159 * writeLock(): lock, lock
160
161 * ReadWriteLockTest
162
163 * , , ,
164
165 */
166
167 public static class ReadWriteLockTest{
168
169 ReadWriteLock lock = new ReentrantReadWriteLock();//
170
171 double value = 0d; //
172
173 int addtimes = 0;
174
175 /** value , */
176
177 public void addValue(double v){
178
179 // writeLock
180
181 Lock writeLock = lock.writeLock();
182
183 writeLock.lock();
184
185 System.out.println("ReadWriteLockTest to addValue: " + v + " " + System.currentTimeMillis());
186
187 try{
188
189 Thread.sleep(1000);
190
191 }catch(InterruptedException e){
192
193 }
194
195 try{
196
197 //
198
199 this.value += v;
200
201 this.addtimes++;
202
203 }finally{
204
205 writeLock.unlock();
206
207 }
208
209 }
210
211 /**
212
213 * . addValue ,getInfo .
214
215 * , , addValue .
216
217 */
218
219 public String getInfo(){
220
221 // readLock
222
223 Lock readLock = lock.readLock();
224
225 readLock.lock();
226
227 System.out.println("ReadWriteLockTest to getInfo "+System.currentTimeMillis());
228
229 try{
230
231 Thread.sleep(1000);
232
233 }catch(InterruptedException e){
234
235 }
236
237 try{
238
239 return this.value + " : " + this.addtimes;//
240
241 }finally{
242
243 readLock.unlock();// readLock
244
245 }
246
247 }
248
249 }
250
251 public static void testReadWriteLockTest() throws Exception{
252
253 final ReadWriteLockTest readWriteLockTest = new ReadWriteLockTest();
254
255 // 1, lockTest addValue
256
257 Runnable task_1 = new Runnable(){
258
259 public void run(){
260
261 readWriteLockTest.addValue(55.55);
262
263 }
264
265 };
266
267 // 2, lockTest getValue
268
269 Runnable task_2 = new Runnable(){
270
271 public void run(){
272
273 System.out.println("info " + readWriteLockTest.getInfo());
274
275 }
276
277 };
278
279 //
280
281 ExecutorService cachedService_1 = Executors.newCachedThreadPool();
282
283 Future future_1 = null;
284
285 // 5 , 2 1, 2
286
287 for(int i=0;i<2;i++){
288
289 future_1 = cachedService_1.submit(task_1);
290
291 }
292
293 for(int i=0;i<2;i++){
294
295 future_1 = cachedService_1.submit(task_2);
296
297 }
298
299 // 1
300
301 future_1 = cachedService_1.submit(task_1);
302
303 // 5
304
305 // 1 , 1 ; ,
306
307 // 2 ; , ,
308
309 // ,
310
311 // 1 . , , ,
312
313 // . 2
314
315 future_1.get();
316
317 cachedService_1.shutdownNow();
318
319 }
320
321 public static void main(String... args)throws Exception{
322
323 Lockers.testLockTest();
324
325 System.out.println("--------------------------");
326
327 Lockers.testReadWriteLockTest();
328
329 }
330
331 }
332
333 /**
334
335 * ReentrantReadWriteLock :
336
337 * This class does not impose a reader or writer preference ordering for lock access.
338
339 * However, it does support an optional fairness policy.
340
341 * When constructed as fair, threads contend for entry using an approximatelyarrival-order policy.
342
343 * When the write lock is released either the longest-waiting single writer will beassigned the write lock, or if there is a reader waiting longer than any writer, theset of readers will be assigned the read lock.
344
345 * When constructed as non-fair, the order of entry to the lock need not be in arrivalorder.
346
347 * In either case, if readers are active and a writer enters the lock then nosubsequent readers will be granted the read lock until after that writer has acquiredand released the write lock.
348
349 */이 내용에 흥미가 있습니까?
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