java: 列表根据其中字段封装排序

1. 泛型实现列表封装排序

package com.ycyj.gongshi.api.tools;

import com.ycyj.gongshi.api.check.Students;
import lombok.extern.slf4j.Slf4j;

import java.lang.reflect.Field;
import java.util.*;


@Slf4j
public class ListOrderUtil<T> {
    private List<T> mArrayList;//数据集合
    private LinkedHashMap<String, Integer> mOrderList = new LinkedHashMap<>();//所有的排序字段
    private Class mClass;//当天T的Class
    public static int ORDER_ASC = 1;//正序排列
    public static int ORDER_DESC = -1;//倒序排列

    public ListOrderUtil(List<T> arrayList, Class<T> tClass) {
        this.mArrayList = arrayList;
        this.mClass = tClass;
    }

    /**
     * 设置排序字段（按照设置的先后顺序对其进行排序）
     *
     * @param fieldName    字段名称
     * @param orderPattern 排序模式
     * @return
     */
    public ListOrderUtil setOrderField(String fieldName, int orderPattern) {
        this.mOrderList.put(fieldName, orderPattern);
        return this;
    }

    /**
     * 对数据集合进行排序
     *
     * @return
     */
    public List<T> order() {
        this.mArrayList.sort(new Comparator<T>() {
            @Override
            public int compare(T o1, T o2) {
                Field field = null;
                int order = 0;
                for (Map.Entry<String, Integer> item : mOrderList.entrySet()) {
                    try {
                        field = mClass.getDeclaredField(item.getKey());
                        field.setAccessible(true);
                        if (field == null) {
                            throw new NoSuchFieldException(item.getKey());
                        }
                        if (item.getValue() == ORDER_ASC) {
                            order = field.get(o1).toString().compareTo(field.get(o2).toString());
                        } else {
                            order = field.get(o2).toString().compareTo(field.get(o1).toString());
                        }
                        if (order != 0) {
                            return order;
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                return 0;
            }
        });
        return this.mArrayList;
    }

    public static void main(String[] args){

        //添加测试数据
        ArrayList<Students> students = new ArrayList();

        Students students1 = new Students(1001, 22, "djk");
        Students students2 = new Students(1002, 18, "xxh");
        Students students3 = new Students(1003, 31, "wyd");
        Students students4 = new Students(1002, 18, "wxz");
        Students students5 = new Students(1005, 19, "sxn");
        Students students6 = new Students(1004, 32, "ljc");

        students.add(students1);
        students.add(students2);
        students.add(students3);
        students.add(students4);
        students.add(students5);
        students.add(students6);

        //排序使用
        ListOrderUtil<Students> listOrderUtil = new ListOrderUtil<>(students, Students.class);
        //1、使用studentId正序排列
        listOrderUtil.setOrderField("studentId", ListOrderUtil.ORDER_ASC).order();

        //2、使用studentId和age进行多字段排序,studentId正序为首，若想等便以age进行倒序排列。
        listOrderUtil.setOrderField("studentId", ListOrderUtil.ORDER_ASC)
                .setOrderField("age", ListOrderUtil.ORDER_DESC);

        //3、多字段排序
        listOrderUtil.setOrderField("studentId", ListOrderUtil.ORDER_ASC)
                .setOrderField("age", ListOrderUtil.ORDER_DESC)
                .setOrderField("studentName", ListOrderUtil.ORDER_DESC)
                .order();


        for (int i = 0; i < students.size(); i++) {
            var item = (students.get(i));
            //log.debug(String.valueOf(item));
            System.out.println(item.toString());
        }

    }


}

　　

2. 依赖Student类

package com.ycyj.gongshi.api.check;

import lombok.ToString;

import java.util.Comparator;

@ToString
public class Students {
    private int studentId;
    private int age;
    private String studentName;

    public Students() {
    }

    public Students(int studentId, int age, String studentName) {
        this.studentId = studentId;
        this.age = age;
        this.studentName = studentName;
    }

    public int getStudentId() {
        return studentId;
    }

    public void setStudentId(int studentId) {
        this.studentId = studentId;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

}