ListUtils.Java---功能類

http://blog.csdn.net/jiangyu1013/article/details/53894218

1. package com.enable.common.utils;
3. import java.lang.reflect.Field;
4. import java.text.NumberFormat;
5. import java.util.Collections;
6. import java.util.Comparator;
7. import java.util.Date;
8. import java.util.List;
10. /**
11. * @author yinaibang
12. * 在數據庫中查出來的列表中，往往需要對不同的字段重新排序。 一般的做法都是使用排序的字段，重新到數據庫中查詢。
13. * 如果不到數據庫查詢，直接在第一次查出來的list中排序，無疑會提高系統的性能。 下面就寫一個通用的方法，對list排序，
14. *
15. * 至少需要滿足以下5點：
16. *
17. * ①.list元素對象類型任意
18. * ---->使用泛型解決
19. *
20. * ②.可以按照list元素對象的任意多個屬性進行排序,即可以同時指定多個屬性進行排序
21. * --->使用java的可變參數解決
22. *
23. * ③.list元素對象屬性的類型可以是數字(byte、short、int、long、float、double等，包括正數、負數、0)、字符串(char、String)、日期(java.util.Date)
24. * --->對於數字：統一轉換為固定長度的字符串解決,比如數字3和123，轉換為"003"和"123" ;再比如"-15"和"7"轉換為"-015"和"007"
25. * --->對於日期：可以先把日期轉化為long類型的數字，數字的解決方法如上
26. *
27. * ④.list元素對象的屬性可以沒有相應的getter和setter方法
28. * --->可以使用java反射進行獲取private和protected修飾的屬性值
29. *
30. * ⑤.list元素對象的對象的每個屬性都可以指定是升序還是降序
31. * -->使用2個重寫的方法(一個方法滿足所有屬性都按照升序(降序)，另外一個方法滿足每個屬性都能指定是升序(降序))
32. *
33. *
34. */
35. public class ListUtils {
36. /**
37. * 對list的元素按照多個屬性名稱排序,
38. * list元素的屬性可以是數字（byte、short、int、long、float、double等，支持正數、負數、0）、char、String、java.util.Date
39. *
40. *
41. * @param lsit
42. * @param sortname
43. * list元素的屬性名稱
44. * @param isAsc
45. * true升序，false降序
46. */
47. public static <E> void sort(List<E> list, final boolean isAsc, final String... sortnameArr) {
48. Collections.sort(list, new Comparator<E>() {
50. public int compare(E a, E b) {
51. int ret = 0;
52. try {
53. for (int i = 0; i < sortnameArr.length; i++) {
54. ret = ListUtils.compareObject(sortnameArr[i], isAsc, a, b);
55. if (0 != ret) {
56. break;
57. }
58. }
59. } catch (Exception e) {
60. e.printStackTrace();
61. }
62. return ret;
63. }
64. });
65. }
67. /**
68. * 給list的每個屬性都指定是升序還是降序
69. *
70. * @param list
71. * @param sortnameArr 參數數組
72. * @param typeArr 每個屬性對應的升降序數組， true升序，false降序
73. */
75. public static <E> void sort(List<E> list, final String[] sortnameArr, final boolean[] typeArr) {
76. if (sortnameArr.length != typeArr.length) {
77. throw new RuntimeException("屬性數組元素個數和升降序數組元素個數不相等");
78. }
79. Collections.sort(list, new Comparator<E>() {
80. public int compare(E a, E b) {
81. int ret = 0;
82. try {
83. for (int i = 0; i < sortnameArr.length; i++) {
84. ret = ListUtils.compareObject(sortnameArr[i], typeArr[i], a, b);
85. if (0 != ret) {
86. break;
87. }
88. }
89. } catch (Exception e) {
90. e.printStackTrace();
91. }
92. return ret;
93. }
94. });
95. }
97. /**
98. * 對2個對象按照指定屬性名稱進行排序
99. *
100. * @param sortname
101. * 屬性名稱
102. * @param isAsc
103. * true升序，false降序
104. * @param a
105. * @param b
106. * @return
107. * @throws Exception
108. */
109. private static <E> int compareObject(final String sortname, final boolean isAsc, E a, E b) throws Exception {
110. int ret;
111. Object value1 = ListUtils.forceGetFieldValue(a, sortname);
112. Object value2 = ListUtils.forceGetFieldValue(b, sortname);
113. String str1 = value1.toString();
114. String str2 = value2.toString();
115. if (value1 instanceof Number && value2 instanceof Number) {
116. int maxlen = Math.max(str1.length(), str2.length());
117. str1 = ListUtils.addZero2Str((Number) value1, maxlen);
118. str2 = ListUtils.addZero2Str((Number) value2, maxlen);
119. } else if (value1 instanceof Date && value2 instanceof Date) {
120. long time1 = ((Date) value1).getTime();
121. long time2 = ((Date) value2).getTime();
122. int maxlen = Long.toString(Math.max(time1, time2)).length();
123. str1 = ListUtils.addZero2Str(time1, maxlen);
124. str2 = ListUtils.addZero2Str(time2, maxlen);
125. }
126. if (isAsc) {
127. ret = str1.compareTo(str2);
128. } else {
129. ret = str2.compareTo(str1);
130. }
131. return ret;
132. }
134. /**
135. * 給數字對象按照指定長度在左側補0.
136. *
137. * 使用案例: addZero2Str(11,4) 返回 "0011", addZero2Str(-18,6)返回 "-000018"
138. *
139. * @param numObj
140. * 數字對象
141. * @param length
142. * 指定的長度
143. * @return
144. */
145. public static String addZero2Str(Number numObj, int length) {
146. NumberFormat nf = NumberFormat.getInstance();
147. // 設置是否使用分組
148. nf.setGroupingUsed(false);
149. // 設置最大整數位數
150. nf.setMaximumIntegerDigits(length);
151. // 設置最小整數位數
152. nf.setMinimumIntegerDigits(length);
153. return nf.format(numObj);
154. }
156. /**
157. * 獲取指定對象的指定屬性值（去除private,protected的限制）
158. *
159. * @param obj
160. * 屬性名稱所在的對象
161. * @param fieldName
162. * 屬性名稱
163. * @return
164. * @throws Exception
165. */
166. public static Object forceGetFieldValue(Object obj, String fieldName) throws Exception {
167. Field field = obj.getClass().getDeclaredField(fieldName);
168. Object object = null;
169. boolean accessible = field.isAccessible();
170. if (!accessible) {
171. // 如果是private,protected修飾的屬性，需要修改為可以訪問的
172. field.setAccessible(true);
173. object = field.get(obj);
174. // 還原private,protected屬性的訪問性質
175. field.setAccessible(accessible);
176. return object;
177. }
178. object = field.get(obj);
179. return object;
180. }
181. }

UserInfo.java

1. package com;
3. import java.text.SimpleDateFormat;
4. import java.util.Date;
5. /**
6. *
7. * @author yinaibang
8. *
9. */
10. public class UserInfo implements java.io.Serializable {
12. private static final long serialVersionUID = -3522051445403971732L;
14. private Integer userId;
15. private String username;
16. private Date birthDate;
17. private Integer age;
18. private float fRate;
19. private char ch;
21. public Date getBirthDate() {
22. return birthDate;
23. }
25. public String getBirthDatestr() {
26. SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");
27. return formater.format(getBirthDate());
28. }
30. public UserInfo(Integer userId, String username, Date birthDate, Integer age, float fRate, char ch) {
31. super();
32. this.userId = userId;
33. this.username = username;
34. this.birthDate = birthDate;
35. this.age = age;
36. this.fRate = fRate;
37. this.ch = ch;
38. }
40. @Override
41. public String toString() {
42. return "UserInfo [userId=" + userId + ", \tusername=" + username + ", \tbirthDate=" + getBirthDatestr()
43. + ", \tage=" + age + ", fRate=" + fRate + ", ch=" + ch + "]";
44. }
46. }

Test.java---測試類

1. package com;
3. import java.text.SimpleDateFormat;
4. import java.util.ArrayList;
5. import java.util.List;
7. import com.enable.common.utils.ListUtils;
9. /**
10. *
11. * @author yinaibang
12. *
13. */
14. public class Test {
16. public static void main(String[] args) throws Exception {
18. Test testObj = new Test();
20. List<UserInfo> list = new ArrayList<UserInfo>();
21. // public UserInfo(Integer userId, String username, Date birthDate,Integer age, float fRate, char ch)
22. SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");
23. UserInfo user1 = new UserInfo(3, "bbb", formater.parse("1980-12-01"), 1, 1.2f, ‘a‘);
24. UserInfo user2 = new UserInfo(0, "126", formater.parse("1900-10-11"), 03, -3.6f, ‘c‘);
25. UserInfo user3 = new UserInfo(12, "5", formater.parse("1973-08-21"), 15, 9.32f, ‘f‘);
26. UserInfo user4 = new UserInfo(465, "1567", formater.parse("2012-01-26"), 20, 12.56f, ‘0‘);
27. UserInfo user5 = new UserInfo(2006, "&4m", formater.parse("2010-05-08"), 100, 165.32f, ‘5‘);
28. UserInfo user6 = new UserInfo(5487, "hf67", formater.parse("2016-12-30"), 103, 56.32f, ‘m‘);
29. UserInfo user7 = new UserInfo(5487,"jigg", formater.parse("2000-10-16"), 103, 56.32f, ‘m‘);
30. UserInfo user8 = new UserInfo(5487, "jigg", formater.parse("1987-07-25"), 103, 56.32f, ‘m‘);
32. list.add(user1);
33. list.add(user2);
34. list.add(user3);
35. list.add(user4);
36. list.add(user5);
37. list.add(user6);
38. list.add(user7);
39. list.add(user8);
41. System.out.println("\n-------原來序列-------------------");
42. testObj.printfUserInfoList(list);
44. // 按userId升序、username降序、birthDate升序排序
45. String [] sortNameArr = {"userId","username","birthDate"};
46. boolean [] isAscArr = {true,false,true};
47. ListUtils.sort(list,sortNameArr,isAscArr);
48. System.out.println("\n--------按按userId升序、username降序、birthDate升序排序（如果userId相同，則按照username降序,如果username相同，則按照birthDate升序）------------------");
49. testObj.printfUserInfoList(list);
51. // 按userId、username、birthDate都升序排序
52. ListUtils.sort(list, true, "userId", "username","birthDate");
53. System.out.println("\n--------按userId、username、birthDate排序（如果userId相同，則按照username升序,如果username相同，則按照birthDate升序）------------------");
54. testObj.printfUserInfoList(list);
56. // 按userId、username都倒序排序
57. ListUtils.sort(list, false, "userId", "username");
58. System.out.println("\n--------按userId和username倒序（如果userId相同，則按照username倒序）------------------");
59. testObj.printfUserInfoList(list);
61. // 按username、birthDate都升序排序
62. ListUtils.sort(list, true, "username", "birthDate");
63. System.out.println("\n---------按username、birthDate升序（如果username相同，則按照birthDate升序）-----------------");
64. testObj.printfUserInfoList(list);
66. // 按birthDate倒序排序
67. ListUtils.sort(list, false, "birthDate");
68. System.out.println("\n---------按birthDate倒序-----------------");
69. testObj.printfUserInfoList(list);
71. // 按fRate升序排序
72. ListUtils.sort(list, true, "fRate");
73. System.out.println("\n---------按fRate升序-----------------");
74. testObj.printfUserInfoList(list);
76. // 按ch倒序排序
77. ListUtils.sort(list, false, "ch");
78. System.out.println("\n---------按ch倒序-----------------");
79. testObj.printfUserInfoList(list);
81. }
83. private void printfUserInfoList(List<UserInfo> list) {
84. for (UserInfo user : list) {
85. System.out.println(user.toString());
86. }
87. }
88. }

運行結果

1. -------原來序列-------------------
2. UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]
3. UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]
4. UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]
5. UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]
6. UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]
7. UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]
8. UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]
9. UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]
11. --------按按userId升序、username降序、birthDate升序排序（如果userId相同，則按照username降序,如果username相同，則按照birthDate升序）------------------
12. UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]
13. UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]
14. UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]
15. UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]
16. UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]
17. UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]
18. UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]
19. UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]
21. --------按userId、username、birthDate排序（如果userId相同，則按照username升序,如果username相同，則按照birthDate升序）------------------
22. UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]
23. UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]
24. UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]
25. UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]
26. UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]
27. UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]
28. UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]
29. UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]
31. --------按userId和username倒序（如果userId相同，則按照username倒序）------------------
32. UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]
33. UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]
34. UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]
35. UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]
36. UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]
37. UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]
38. UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]
39. UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]
41. ---------按username、birthDate升序（如果username相同，則按照birthDate升序）-----------------
42. UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]
43. UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]
44. UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]
45. UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]
46. UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]
47. UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]
48. UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]
49. UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]
51. ---------按birthDate倒序-----------------
52. UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]
53. UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]
54. UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]
55. UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]
56. UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]
57. UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]
58. UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]
59. UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]
61. ---------按fRate升序-----------------
62. UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]
63. UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]
64. UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]
65. UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]
66. UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]
67. UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]
68. UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]
69. UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]
71. ---------按ch倒序-----------------
72. UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]
73. UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]
74. UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]
75. UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]
76. UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]
77. UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]
78. UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]
79. UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]

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java list按照元素對象的指定多個字段屬性進行排序