工作中遇到按照类的某个属性排列，这个属性是个枚举类型，按照要求的优先级排列。
可以使用ComparatorChain、BeanComparator、FixedOrderComparator实现。
举一个例子：
学生类：包含姓名、年龄、性别、性格。性格是个枚举类型。
性格类：枚举类型，分为四类：内向，外向，太监，不知道四种类型。
SortUtil类：排序类。
Student.java
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import java.util.ArrayList;
import java.util.List;
public class Student {
private String name;
private int age;
private boolean sex;
private Character character;
public Student(String name, int age, boolean sex, Character character){
this.name = name;
this.age = age;
this.sex = sex;
this.character = character;
}
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setAge(int age) {
this.age = age;
}
public int getAge() {
return age;
}
public void setSex(boolean sex) {
this.sex = sex;
}
public boolean getSex() {
return sex;
}
public void setCharacter(Character character) {
this.character = character;
}
public Character getCharacter() {
return character;
}
@Override
public String toString() {
String sexString = sex == false ? "male" : "female";
return "名字：" + name + " 年龄: " + age + " 性别: " + sexString + " 性格: " + character;
}
public static void main(String args[]) {
Student student1 = new Student("spring", 20, false, Character.IN);
Student student2 = new Student("summer", 18, false, Character.OUT );
Student student3 = new Student("automn", 25, false, Character.UNKNOWN );
Student student4 = new Student("winter", 25, true, Character.UNKNOWN);
List<Student> list1 = new ArrayList<Student>();
list1.add(student1);
list1.add(student3);
list1.add(student2);
list1.add(student4);
System.out.println("没有排序之前：");
for(Student student : list1) {
System.out.println(student);
}
SortUtil.sortByWhat(list1);
System.out.println("排序之后：");
for(Student student : list1) {
System.out.println(student);
}
}
}
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Character类：
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public enum Character {
IN("内向"),
OUT("外向"),
BOTH("太监"),
UNKNOWN("不知道");
private String name;
private Character(String name) {
this.name = name;
}
public String getName() {
return name;
}
public String toString() {
return name;
}
}
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SortUtil类：
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import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import org.apache.commons.beanutils.BeanComparator;
import org.apache.commons.collections.comparators.ComparatorChain;
import org.apache.commons.collections.comparators.FixedOrderComparator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class SortUtil {
private static final Log Logger = LogFactory.getLog(SortUtil.class);
@SuppressWarnings("unchecked")
public static void sortByWhat(List<Student> list){
try{
Character[] CharacterType = {Character.UNKNOWN,Character.IN ,Character.OUT,Character.BOTH};
Comparator TypeComparator = new FixedOrderComparator(CharacterType);
ComparatorChain moInfoComparator = new ComparatorChain();
moInfoComparator.addComparator(new BeanComparator("character",TypeComparator));
moInfoComparator.addComparator(new BeanComparator("age"),true);
moInfoComparator.addComparator(new BeanComparator("name"));
moInfoComparator.addComparator(new BeanComparator("sex"));
Collections.sort(list, moInfoComparator);
} catch (Exception e) {
Logger.error(e.getMessage());
}
}
}
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moInfoComparator.addComparator(new BeanComparator(“character”,TypeComparator));
这个类中首先按照性格属性来排序，利用FixedOrderComparator设置优先级，性格属性Character.UNKOWN排第一，
然后IN，其次OUT，最后BOTH。如果性格属性相同，按照age排序，true表示逆序（默认排序是从小到大），然后按
照name，最后按照sex属性排序。
需要导入commons-beanutils,commons-logging,commons-collections包。
结果：
可以看到排序之后首先按照性格排序，性格是枚举类型，排序规则用FixedOrderComparator定义，性格相同按照年龄，所以：
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moInfoComparator.addComparator(new BeanComparator("age"),true);
moInfoComparator.addComparator(new BeanComparator("name"));
moInfoComparator.addComparator(new BeanComparator("sex"));
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这四句话的顺序决定了先已哪个属性排序。