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：

     @Data
     @AllArgsConstructor
     @NoArgsConstructor
     class Book {
         private Long id;//编号
         private String userName;//书本名称
         private double productPrice;//书本价格
         private String author;//作者
         private Integer weight;//权重
     }

2、SortList  排序实现通用类：

 @Data
 @AllArgsConstructor
 @NoArgsConstructor
 public class SortList<T> implements Comparator<T> {

     //需要比较的对象属性字段名称
     private String  propertyName;
     //是否是升序排序
     private boolean isAsc;

     /**
      * 需要的是：根据类中的字段对对象进行排序
      *
      * @return
      */

     @Override
     public int compare(T b1, T b2) {

         Class<?> clz = b1.getClass();
         Method method = getPropertyMethod(clz, propertyName);
         try {

             Object objectOne = method.invoke(b1);

             Object objectTwo = method.invoke(b2);

             if (objectOne == null || objectTwo == null) {
                 return 0;
             }

             Comparable value1 = (Comparable) objectOne;

             Comparable value2 = (Comparable) objectTwo;

             if (isAsc) {
                 return value1.compareTo(value2);
             } else {
                 return value2.compareTo(value1);
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
         return 0;
     }

     // 获取类名
     public static Method getPropertyMethod(Class clz, String propertyName) {
         Method method = null;
         try {
             method = clz.getMethod("get" + firstUpperCase(propertyName));
         } catch (Exception e) {
             System.out.println("获取类名发生错误！");
         }
         return method;
     }

     /**
      * 首字母大写方法
      * @param str
      * @return
      */
     public static String firstUpperCase(String str) {
         char[] ch = str.toCharArray();
         if (ch[0] >= 'a' && ch[0] <= 'z') {
             ch[0] = (char) (ch[0] - 32);
         }
         return new String(ch);
     }

 }

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

 @Test
     public void sortBook() {
         List<Book> bookList = getBookList();
         System.out.println("原先的顺序：");
         printf(bookList);

         System.out.println("根据价格排序：");
         Collections.sort(bookList, new SortList<Book>("productPrice",true));
         printf(bookList);

         System.out.println("根据Id排序：");
         Collections.sort(bookList, new SortList<Book>("id",false));
         printf(bookList);

         System.out.println("根据weight排序：");
         Collections.sort(bookList, new SortList<Book>("weight",true));
         printf(bookList);

         System.out.println("根据userName排序：");
         Collections.sort(bookList, new SortList<Book>("userName",true));
         printf(bookList);

     }

     public List<Book> getBookList() {
         List<Book> books = Lists.newArrayList();
         Book book1 = new Book(1L, "first", 10.00, "zhangsan", 19);
         Book book2 = new Book(2L, "wirst", 9.00, "zhangsan", 24);
         Book book3 = new Book(3L, "eirst", 8.00, "zhangsan", 29);
         Book book4 = new Book(4L, "girst", 7.00, "zhangsan", 13);
         Book book5 = new Book(5L, "tirst", 6.00, "zhangsan", 14);

         books.add(book1);
         books.add(book2);
         books.add(book3);
         books.add(book4);
         books.add(book5);

         return books;
     }

     /**
      * 打印函数
      *
      * @param lisbk
      */
     public void printf(List<Book> lisbk) {
         if (lisbk.isEmpty() || lisbk == null) {
             System.out.println("没有数据");
             return;
         }
         for (Book book : lisbk) {
             System.out.println("Id: " + book.getId() + "   userName: " + book.getUserName() + "   price: " + book.getProductPrice() + "  weight:" + book.getWeight());
         }
         System.out.println();
         return;
     }

执行结果如下：