java list按照元素对象的指定多个字段属性进行排序

ListUtils.Java---功能类

[java] view
plain copy

package com.enable.common.utils;

import java.lang.reflect.Field;

import java.text.NumberFormat;

import java.util.Collections;

import java.util.Comparator;

import java.util.Date;

import java.util.List;

/**

* @author yinaibang

* 在数据库中查出来的列表中，往往需要对不同的字段重新排序。 一般的做法都是使用排序的字段，重新到数据库中查询。

* 如果不到数据库查询，直接在第一次查出来的list中排序，无疑会提高系统的性能。 下面就写一个通用的方法，对list排序，

*

* 至少需要满足以下5点：

*

* ①.list元素对象类型任意

* ---->使用泛型解决

*

* ②.可以按照list元素对象的任意多个属性进行排序,即可以同时指定多个属性进行排序

* --->使用java的可变参数解决

*

* ③.list元素对象属性的类型可以是数字(byte、short、int、long、float、double等，包括正数、负数、0)、字符串(char、String)、日期(java.util.Date)

* --->对于数字：统一转换为固定长度的字符串解决,比如数字3和123，转换为"003"和"123" ;再比如"-15"和"7"转换为"-015"和"007"

* --->对于日期：可以先把日期转化为long类型的数字，数字的解决方法如上

*

* ④.list元素对象的属性可以没有相应的getter和setter方法

* --->可以使用java反射进行获取private和protected修饰的属性值

*

* ⑤.list元素对象的对象的每个属性都可以指定是升序还是降序

* -->使用2个重写的方法(一个方法满足所有属性都按照升序(降序)，另外一个方法满足每个属性都能指定是升序(降序))

*

*

*/

public class ListUtils {

/**

* 对list的元素按照多个属性名称排序,

* list元素的属性可以是数字（byte、short、int、long、float、double等，支持正数、负数、0）、char、String、java.util.Date

*

*

* @param lsit

* @param sortname

* list元素的属性名称

* @param isAsc

* true升序，false降序

*/

public static <E> void sort(List<E> list, final boolean isAsc, final String... sortnameArr) {

Collections.sort(list, new Comparator<E>() {

public int compare(E a, E b) {

int ret = 0;

try {

for (int i = 0; i < sortnameArr.length; i++) {

ret = ListUtils.compareObject(sortnameArr[i], isAsc, a, b);

if (0 != ret) {

break;

}

}

} catch (Exception e) {

e.printStackTrace();

}

return ret;

}

});

}

/**

* 给list的每个属性都指定是升序还是降序

*

* @param list

* @param sortnameArr 参数数组

* @param typeArr 每个属性对应的升降序数组， true升序，false降序

*/

public static <E> void sort(List<E> list, final String[] sortnameArr, final boolean[] typeArr) {

if (sortnameArr.length != typeArr.length) {

throw new RuntimeException("属性数组元素个数和升降序数组元素个数不相等");

}

Collections.sort(list, new Comparator<E>() {

public int compare(E a, E b) {

int ret = 0;

try {

for (int i = 0; i < sortnameArr.length; i++) {

ret = ListUtils.compareObject(sortnameArr[i], typeArr[i], a, b);

if (0 != ret) {

break;

}

}

} catch (Exception e) {

e.printStackTrace();

}

return ret;

}

});

}

/**

* 对2个对象按照指定属性名称进行排序

*

* @param sortname

* 属性名称

* @param isAsc

* true升序，false降序

* @param a

* @param b

* @return

* @throws Exception

*/

private static <E> int compareObject(final String sortname, final boolean isAsc, E a, E b) throws Exception {

int ret;

Object value1 = ListUtils.forceGetFieldValue(a, sortname);

Object value2 = ListUtils.forceGetFieldValue(b, sortname);

String str1 = value1.toString();

String str2 = value2.toString();

if (value1 instanceof Number && value2 instanceof Number) {

int maxlen = Math.max(str1.length(), str2.length());

str1 = ListUtils.addZero2Str((Number) value1, maxlen);

str2 = ListUtils.addZero2Str((Number) value2, maxlen);

} else if (value1 instanceof Date && value2 instanceof Date) {

long time1 = ((Date) value1).getTime();

long time2 = ((Date) value2).getTime();

int maxlen = Long.toString(Math.max(time1, time2)).length();

str1 = ListUtils.addZero2Str(time1, maxlen);

str2 = ListUtils.addZero2Str(time2, maxlen);

}

if (isAsc) {

ret = str1.compareTo(str2);

} else {

ret = str2.compareTo(str1);

}

return ret;

}

/**

* 给数字对象按照指定长度在左侧补0.

*

* 使用案例: addZero2Str(11,4) 返回 "0011", addZero2Str(-18,6)返回 "-000018"

*

* @param numObj

* 数字对象

* @param length

* 指定的长度

* @return

*/

public static String addZero2Str(Number numObj, int length) {

NumberFormat nf = NumberFormat.getInstance();

// 设置是否使用分组

nf.setGroupingUsed(false);

// 设置最大整数位数

nf.setMaximumIntegerDigits(length);

// 设置最小整数位数

nf.setMinimumIntegerDigits(length);

return nf.format(numObj);

}

/**

* 获取指定对象的指定属性值（去除private,protected的限制）

*

* @param obj

* 属性名称所在的对象

* @param fieldName

* 属性名称

* @return

* @throws Exception

*/

public static Object forceGetFieldValue(Object obj, String fieldName) throws Exception {

Field field = obj.getClass().getDeclaredField(fieldName);

Object object = null;

boolean accessible = field.isAccessible();

if (!accessible) {

// 如果是private,protected修饰的属性，需要修改为可以访问的

field.setAccessible(true);

object = field.get(obj);

// 还原private,protected属性的访问性质

field.setAccessible(accessible);

return object;

}

object = field.get(obj);

return object;

}

}

UserInfo.java

[java] view
plain copy

package com;

import java.text.SimpleDateFormat;

import java.util.Date;

/**

*

* @author yinaibang

*

*/

public class UserInfo implements java.io.Serializable {

private static final long serialVersionUID = -3522051445403971732L;

private Integer userId;

private String username;

private Date birthDate;

private Integer age;

private float fRate;

private char ch;

public Date getBirthDate() {

return birthDate;

}

public String getBirthDatestr() {

SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");

return formater.format(getBirthDate());

}

public UserInfo(Integer userId, String username, Date birthDate, Integer age, float fRate, char ch) {

super();

this.userId = userId;

this.username = username;

this.birthDate = birthDate;

this.age = age;

this.fRate = fRate;

this.ch = ch;

}

@Override

public String toString() {

return "UserInfo [userId=" + userId + ", \tusername=" + username + ", \tbirthDate=" + getBirthDatestr()

+ ", \tage=" + age + ", fRate=" + fRate + ", ch=" + ch + "]";

}

}

Test.java---测试类

[java] view
plain copy

package com;

import java.text.SimpleDateFormat;

import java.util.ArrayList;

import java.util.List;

import com.enable.common.utils.ListUtils;

/**

*

* @author yinaibang

*

*/

public class Test {

public static void main(String[] args) throws Exception {

Test testObj = new Test();

List<UserInfo> list = new ArrayList<UserInfo>();

// public UserInfo(Integer userId, String username, Date birthDate,Integer age, float fRate, char ch)

SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");

UserInfo user1 = new UserInfo(3, "bbb", formater.parse("1980-12-01"), 1, 1.2f, 'a');

UserInfo user2 = new UserInfo(0, "126", formater.parse("1900-10-11"), 03, -3.6f, 'c');

UserInfo user3 = new UserInfo(12, "5", formater.parse("1973-08-21"), 15, 9.32f, 'f');

UserInfo user4 = new UserInfo(465, "1567", formater.parse("2012-01-26"), 20, 12.56f, '0');

UserInfo user5 = new UserInfo(2006, "&4m", formater.parse("2010-05-08"), 100, 165.32f, '5');

UserInfo user6 = new UserInfo(5487, "hf67", formater.parse("2016-12-30"), 103, 56.32f, 'm');

UserInfo user7 = new UserInfo(5487,"jigg", formater.parse("2000-10-16"), 103, 56.32f, 'm');

UserInfo user8 = new UserInfo(5487, "jigg", formater.parse("1987-07-25"), 103, 56.32f, 'm');

list.add(user1);

list.add(user2);

list.add(user3);

list.add(user4);

list.add(user5);

list.add(user6);

list.add(user7);

list.add(user8);

System.out.println("\n-------原来序列-------------------");

testObj.printfUserInfoList(list);

// 按userId升序、username降序、birthDate升序排序

String [] sortNameArr = {"userId","username","birthDate"};

boolean [] isAscArr = {true,false,true};

ListUtils.sort(list,sortNameArr,isAscArr);

System.out.println("\n--------按按userId升序、username降序、birthDate升序排序（如果userId相同，则按照username降序,如果username相同，则按照birthDate升序）------------------");

testObj.printfUserInfoList(list);

// 按userId、username、birthDate都升序排序

ListUtils.sort(list, true, "userId", "username","birthDate");

System.out.println("\n--------按userId、username、birthDate排序（如果userId相同，则按照username升序,如果username相同，则按照birthDate升序）------------------");

testObj.printfUserInfoList(list);

// 按userId、username都倒序排序

ListUtils.sort(list, false, "userId", "username");

System.out.println("\n--------按userId和username倒序（如果userId相同，则按照username倒序）------------------");

testObj.printfUserInfoList(list);

// 按username、birthDate都升序排序

ListUtils.sort(list, true, "username", "birthDate");

System.out.println("\n---------按username、birthDate升序（如果username相同，则按照birthDate升序）-----------------");

testObj.printfUserInfoList(list);

// 按birthDate倒序排序

ListUtils.sort(list, false, "birthDate");

System.out.println("\n---------按birthDate倒序-----------------");

testObj.printfUserInfoList(list);

// 按fRate升序排序

ListUtils.sort(list, true, "fRate");

System.out.println("\n---------按fRate升序-----------------");

testObj.printfUserInfoList(list);

// 按ch倒序排序

ListUtils.sort(list, false, "ch");

System.out.println("\n---------按ch倒序-----------------");

testObj.printfUserInfoList(list);

}

private void printfUserInfoList(List<UserInfo> list) {

for (UserInfo user : list) {

System.out.println(user.toString());

}

}

}

运行结果

[java] view
plain copy

-------原来序列-------------------

UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]

UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]

UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]

UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]

UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]

UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]

--------按按userId升序、username降序、birthDate升序排序（如果userId相同，则按照username降序,如果username相同，则按照birthDate升序）------------------

UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]

UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]

UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]

UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]

UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]

UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]

--------按userId、username、birthDate排序（如果userId相同，则按照username升序,如果username相同，则按照birthDate升序）------------------

UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]

UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]

UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]

UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]

UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]

UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]

--------按userId和username倒序（如果userId相同，则按照username倒序）------------------

UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]

UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]

UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]

UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]

UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]

UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]

---------按username、birthDate升序（如果username相同，则按照birthDate升序）-----------------

UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]

UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]

UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]

UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]

UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]

UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]

---------按birthDate倒序-----------------

UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]

UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]

UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]

UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]

UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]

UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]

UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]

---------按fRate升序-----------------

UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]

UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]

UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]

UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]

UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]

UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]

---------按ch倒序-----------------

UserInfo [userId=5487, username=hf67, birthDate=2016-12-30, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=2000-10-16, age=103, fRate=56.32, ch=m]

UserInfo [userId=5487, username=jigg, birthDate=1987-07-25, age=103, fRate=56.32, ch=m]

UserInfo [userId=12, username=5, birthDate=1973-08-21, age=15, fRate=9.32, ch=f]

UserInfo [userId=0, username=126, birthDate=1900-10-11, age=3, fRate=-3.6, ch=c]

UserInfo [userId=3, username=bbb, birthDate=1980-12-01, age=1, fRate=1.2, ch=a]

UserInfo [userId=2006, username=&4m, birthDate=2010-05-08, age=100, fRate=165.32, ch=5]

UserInfo [userId=465, username=1567, birthDate=2012-01-26, age=20, fRate=12.56, ch=0]