博弈Java讲义 - Java线程之ThreadGroup_JAVA_编程开发_程序员俱乐部

Java并发包里面提供了ThreadGroup类可以帮助我们有效地管理线程组。让我们来看一个生动的例子. Java线程组可以有线程对象或者子线程组组成。也就是说ThreadGroup可以是产生线程树。class="Apple-converted-space">?
? 让我们看一个简单的例子，这个例子模仿一个搜索任务，将启动10个线程遍历获取指定目录下面的excel文件列表，一旦有一个线程完成遍历，将中断其余的9个任务。?

1. import?java.io.File;??
2. import?java.util.concurrent.TimeUnit;??
3. ??
4. public?class?SearchTask?implements?Runnable?{??
5. ??
6. ????private?String?rootDir;??
7. ????private?SearchResult?result;??
8. ??
9. ????public?SearchTask(String?rootDir,?SearchResult?result)?{??
10. ????????super();??
11. ????????this.rootDir?=?rootDir;??
12. ????????this.result?=?result;??
13. ????}??
14. ??
15. ????public?String?getRootDir()?{??
16. ????????return?rootDir;??
17. ????}??
18. ??
19. ????public?void?setRootDir(String?rootDir)?{??
20. ????????this.rootDir?=?rootDir;??
21. ????}??
22. ??????
23. ????public?SearchResult?getResult()?{??
24. ????????return?result;??
25. ????}??
26. ??????
27. ????public?void?setResult(SearchResult?result)?{??
28. ????????this.result?=?result;??
29. ????}??
30. ??
31. ????@Override??
32. ????public?void?run()?{??
33. ????????String?name?=?Thread.currentThread().getName();??
34. ????????System.out.printf("Thread?%s:?Start\n",name);??
35. ????????try{??
36. ????????????doSearch(new?File(this.rootDir));??
37. ????????????result.setTaskName(name);??
38. ????????}catch(InterruptedException?e){??
39. ????????????System.out.printf("Thread?%s:?Interrupted\n",name);??
40. ????????????return;??
41. ????????}??
42. ????????System.out.printf("Thread?%s:?End\n",name);??
43. ????}??
44. ??????
45. ????private?void?doSearch(File?root)?throws?InterruptedException{?????
46. ????????if(root?!=?null?&&?root.isDirectory()){??
47. ????????????TimeUnit.SECONDS.sleep(1);??
48. ????????????File[]?files?=?root.listFiles();??
49. ????????????if(?files?!=?null?){??
50. ????????????????for(File?file?:?files){??
51. ????????????????????if(file.isFile()?&&?file.getName().endsWith(".xls")){??
52. ????????????????????????result.getFiles().add(file.getAbsolutePath());??
53. ????????????????????????result.increaseCount();??
54. ????????????????????}else?if(file.isDirectory()){??
55. ????????????????????????doSearch(file);??
56. ????????????????????}??
57. ????????????????}??
58. ????????????}??
59. ????????}??
60. ????}??
61. }??
62. package?com.concurrent.exercise.threadgroup;??
63. ??
64. import?java.util.ArrayList;??
65. import?java.util.List;??
66. ??
67. public?class?SearchResult?{??
68. ??????
69. ????private?int?count?=?0;??
70. ????private?String?taskName;??
71. ????private?List<String>?files?=?new?ArrayList<String>();??
72. ??????
73. ????public?String?getTaskName()?{??
74. ????????return?taskName;??
75. ????}??
76. ??
77. ????public?void?setTaskName(String?taskName)?{??
78. ????????this.taskName?=?taskName;??
79. ????}??
80. ??
81. ????public?void?setCount(int?count)?{??
82. ????????this.count?=?count;??
83. ????}??
84. ??
85. ????public?void?setFiles(List<String>?files)?{??
86. ????????this.files?=?files;??
87. ????}??
88. ??
89. ????public?int?getCount()?{??
90. ????????return?count;??
91. ????}??
92. ??
93. ????public?void?increaseCount()?{??
94. ????????count++;??
95. ????}??
96. ??
97. ????public?List<String>?getFiles(){??
98. ????????return?files;??
99. ????}??
100. ??????
101. }??
102. ??
103. import?java.util.concurrent.TimeUnit;??
104. ??
105. public?class?TestThreadGroup?{??
106. ??
107. ????public?static?void?main(String[]?args){??
108. ????????String?searchDir?=?"D:\\";??
109. ????????ThreadGroup?threadGroup?=?new?ThreadGroup("Searcher");??
110. ????????for(int?i?=?0;?i?<?3;?i++){??
111. ????????????SearchTask?task?=?new?SearchTask(searchDir,new?SearchResult());??
112. ????????????Thread?thread?=?new?Thread(threadGroup,?task);??
113. ????????????thread.start();??
114. ????????????try{??
115. ????????????????TimeUnit.SECONDS.sleep(2);??
116. ????????????}catch(InterruptedException?e)?{??
117. ????????????????e.printStackTrace();??
118. ????????????}??
119. ????????}??
120. ????????waitFinish(threadGroup);??
121. ????????threadGroup.interrupt();??
122. ????}??
123. ??????
124. ????private?static?void?waitFinish(ThreadGroup?threadGroup)?{??
125. ????????while?(threadGroup.activeCount()?>?2)?{??
126. ????????????try?{??
127. ????????????????list(threadGroup);??
128. ????????????????TimeUnit.SECONDS.sleep(1);??
129. ????????????}?catch?(InterruptedException?e)?{??
130. ????????????????e.printStackTrace();??
131. ????????????}??
132. ????????}??
133. ????}??
134. ??
135. ????private?static?void?list(ThreadGroup?threadGroup)?{??
136. ????????assert(threadGroup?!=?null);??
137. ????????threadGroup.list();??
138. ????}??
139. ??????
140. }??

? 在启动三个线程后，进入waitFinish方法，当其中一个线程结束后，waitFinish立即对出并调用ThreadGroup终止剩下的线程。?
? 由于ThreadGroup存储了线程和子线程组对象，可以使用ThreadGroup对一组线程执行统一的操作，比如interrupt.?
? 可以参考Java API Doc知道更多关于ThreadGroup的方法。?