List自定义对象的排序，根据对象的某一列进行排序

在工作中，经常需要对List对象集合进行排序操作，下面总结下搞个通用排序对象，原理是使用JAVA的

Comparator 接口实现排序不多说直接上“干货”

1、存在实体类：

 1     @Data
 2     @AllArgsConstructor
 3     @NoArgsConstructor
 4     class Book {
 5         private Long id;//编号
 6         private String userName;//书本名称
 7         private double productPrice;//书本价格
 8         private String author;//作者
 9         private Integer weight;//权重
10     }

2、SortList 排序实现通用类：

 1 @Data
 2 @AllArgsConstructor
 3 @NoArgsConstructor
 4 public class SortList<T> implements Comparator<T> {
 5 
 6     //需要比较的对象属性字段名称
 7     private String  propertyName;
 8     //是否是升序排序
 9     private boolean isAsc;
10 
11     /**
12      * 需要的是：根据类中的字段对对象进行排序
13      *
14      * @return
15      */
16 
17     @Override
18     public int compare(T b1, T b2) {
19 
20         Class<?> clz = b1.getClass();
21         Method method = getPropertyMethod(clz, propertyName);
22         try {
23 
24             Object objectOne = method.invoke(b1);
25 
26             Object objectTwo = method.invoke(b2);
27 
28             if (objectOne == null || objectTwo == null) {
29                 return 0;
30             }
31 
32             Comparable value1 = (Comparable) objectOne;
33 
34             Comparable value2 = (Comparable) objectTwo;
35 
36             if (isAsc) {
37                 return value1.compareTo(value2);
38             } else {
39                 return value2.compareTo(value1);
40             }
41         } catch (Exception e) {
42             e.printStackTrace();
43         }
44         return 0;
45     }
46 
47     // 获取类名
48     public static Method getPropertyMethod(Class clz, String propertyName) {
49         Method method = null;
50         try {
51             method = clz.getMethod("get" + firstUpperCase(propertyName));
52         } catch (Exception e) {
53             System.out.println("获取类名发生错误！");
54         }
55         return method;
56     }
57 
58     /**
59      * 首字母大写方法
60      * @param str
61      * @return
62      */
63     public static String firstUpperCase(String str) {
64         char[] ch = str.toCharArray();
65         if (ch[0] >= 'a' && ch[0] <= 'z') {
66             ch[0] = (char) (ch[0] - 32);
67         }
68         return new String(ch);
69     }
70 
71 }

3、实际使用测试如下：主要这么来使用

Collections.sort(bookList, new SortList<Book>("productPrice",true));

测试

 1 @Test
 2     public void sortBook() {
 3         List<Book> bookList = getBookList();
 4         System.out.println("原先的顺序：");
 5         printf(bookList);
 6 
 7         System.out.println("根据价格排序：");
 8         Collections.sort(bookList, new SortList<Book>("productPrice",true));
 9         printf(bookList);
10 
11         System.out.println("根据Id排序：");
12         Collections.sort(bookList, new SortList<Book>("id",false));
13         printf(bookList);
14 
15         System.out.println("根据weight排序：");
16         Collections.sort(bookList, new SortList<Book>("weight",true));
17         printf(bookList);
18 
19         System.out.println("根据userName排序：");
20         Collections.sort(bookList, new SortList<Book>("userName",true));
21         printf(bookList);
22 
23 
24     }
25 
26     public List<Book> getBookList() {
27         List<Book> books = Lists.newArrayList();
28         Book book1 = new Book(1L, "first", 10.00, "zhangsan", 19);
29         Book book2 = new Book(2L, "wirst", 9.00, "zhangsan", 24);
30         Book book3 = new Book(3L, "eirst", 8.00, "zhangsan", 29);
31         Book book4 = new Book(4L, "girst", 7.00, "zhangsan", 13);
32         Book book5 = new Book(5L, "tirst", 6.00, "zhangsan", 14);
33 
34         books.add(book1);
35         books.add(book2);
36         books.add(book3);
37         books.add(book4);
38         books.add(book5);
39 
40         return books;
41     }
42 
43     /**
44      * 打印函数
45      *
46      * @param lisbk
47      */
48     public void printf(List<Book> lisbk) {
49         if (lisbk.isEmpty() || lisbk == null) {
50             System.out.println("没有数据");
51             return;
52         }
53         for (Book book : lisbk) {
54             System.out.println("Id: " + book.getId() + "   userName: " + book.getUserName() + "   price: " + book.getProductPrice() + "  weight:" + book.getWeight());
55         }
56         System.out.println();
57         return;
58     }

执行结果如下：