封装的排序

Posted 2022-11-28 IT的鱼

package com.mti.scst.util;

import lombok.Data;
import org.apache.commons.beanutils.BeanComparator;
import org.apache.commons.collections.ComparatorUtils;
import org.apache.commons.collections.comparators.ComparableComparator;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

/**
 * 动态实体和动态字段 List排序工具
 *
 * @author huqiao
 * @since 2021-08-23
 */
public class ListBeanSortUtil<T> 

    /**
     * api版本
     *
     * @param list  需要排序的实体集
     * @param filed 排序字段
     * @param order true 升序 false 降序
     */
    public List<T> sort(List<T> list, String filed, boolean order) 
        if (isEmpty(list, filed)) 
            return new ArrayList<>();
        
        Comparator<?> cmp = ComparableComparator.getInstance();
        cmp = order ? ComparatorUtils.nullLowComparator(cmp) : ComparatorUtils.reversedComparator(cmp);
        list.sort(new BeanComparator<>(filed, cmp));
        return list;
    

    /**
     * 算法版
     *
     * @param list  需要排序的实体集
     * @param order true 升序 false 降序
     * @param filed 排序字段
     */
    public List<T> sort(List<T> list, boolean order, String filed) 
        if (isEmpty(list, filed)) 
            return new ArrayList<>();
        
        List<T> newList = new ArrayList<>();
        for (T t : list) 
            if (newList.isEmpty()) 
                newList.add(t);
             else 
                for (int i = newList.size() - 1; i >= 0; i--) 
                    if (order ?
                        (String.valueOf(get(t, filed)).compareTo(String.valueOf(get(newList.get(i), filed))) > 0)
                        :
                        (String.valueOf(get(newList.get(i), filed)).compareTo(String.valueOf(get(t, filed))) > 0)) 
                        newList.add(i + 1, t);
                        break;
                     else if (i == 0) 
                        newList.add(i, t);
                    
                
            
        
        return newList;
    

    private boolean isEmpty(List<T> list, String filed) 
        return list == null || list.isEmpty() || filed == null || filed.isEmpty();
    

    private Object get(T item, String fieldName) 
        try 
            return item.getClass().getMethod(String.format("%s%s%s", "get", fieldName.substring(0, 1).toUpperCase(), fieldName.substring(1))).invoke(item);
         catch (Exception e) 
            return null;
        
    

    public static void main(String[] args) 
        User u1 = new User();
        u1.setA("1");
        u1.setC("2021-11-07 15:30:10");
        User u2 = new User();
        u2.setA("3");
        u2.setC("2021-11-07 15:30:20");
        User u3 = new User();
        u3.setA("2");
        u3.setC("2021-11-07 15:40:30");
        User u4 = new User();
        u4.setA("2");
        u4.setC("2021-11-08 15:40:30");
        User u5 = new User();
        u5.setA("1");
        u5.setC("2021-11-06 15:40:30");
        List<User> list = new ArrayList<>();
        list.add(u1);
        list.add(u2);
        list.add(u3);
        list.add(u4);
        list.add(u5);
        ListBeanSortUtil<User> l = new ListBeanSortUtil<>();
//        List<User> result = l.sort(list, false, "c");
//        System.out.println(result);
        List<User> result2 = l.sort(list, "c", false);
        System.out.println(result2);
    

    @Data
    static class User 
        private String a;
        private int b;
        private String c;

        public String getA() 
            return a;
        

        public void setA(String a) 
            this.a = a;
        

        public int getB() 
            return b;
        

        public void setB(int b) 
            this.b = b;
        

        public String getC() 
            return c;
        

        public void setC(String c) 
            this.c = c;