java反射之对象通用排序

http://blog.csdn.net/youjianbo_han_87/article/details/2591584

 

 

 

java反射之对象通用排序

 

 

/**   
* @Title: ObjectSort.java
* @Package sort
* @Description: TODO(用一句话描述该文件做什么)
* @author youjianbo   
* @date 2011-3-9 上午10:28:53
* @version V1.0   
*/  
package sort;

import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.text.CollationKey;
import java.text.Collator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class ObjectSort {

    /**
     * @param args
     */
    public static void main(String[] args) {
        /**
         *
         * author： youjianbo
         * date：2008-6-27
         * purpose： 根据对象的某个或者某些属性排序
         * Java里面包含8个基本数据类型，分别是：boolean、byte、char、short、int、float、douboe、long
         * 只比较非boolean和byte类型的属性，和大多数运用环境适应，如果有特殊要求，请自己修改。
         * 使用时只要将对象属性列表和需要排序的List传入即可
         * **/
        List arrayDemo = new ArrayList();
       
        Person p1 = new Person();
        p1.setName("张三");
        p1.setAge(200);
        p1.setSalary(100);
       
        Person p2 = new Person();
        p2.setName("李四");
        p2.setAge(22);
        p2.setSalary(100);
       
        Person p3 = new Person();
        p3.setName("王五");
        p3.setAge(25);
        p3.setSalary(1900);
       
        Person p4 = new Person();
        p4.setName("赵六");
        p4.setAge(25);
        p4.setSalary(3000);
       
        Person p5 = new Person();
        p5.setName("刘七");
        p5.setAge(30);
        p5.setSalary(2000);
       
        Person p6 = new Person();
        p6.setName("吕八");
        p6.setAge(25);
        p6.setSalary(2000);
       
        Person p7= new Person();
        p7.setName("扣九");
        p7.setAge(26);
        p7.setSalary(2000);
       
        Person p8= new Person();
        p8.setName("扣九哥哥");
        p8.setAge(22);
        p8.setSalary(2000);
       
        arrayDemo.add(p1);
        arrayDemo.add(p2);
        arrayDemo.add(p3);
        arrayDemo.add(p4);
        arrayDemo.add(p5);
        arrayDemo.add(p6);
        arrayDemo.add(p7);
        arrayDemo.add(p8);
       
        //*********开始比较********//
        CommonComparator comparator = new CommonComparator();
       
//        System.out.println("------0.按照名称从小到大比较---------");
//        comparator.setFields_user(new String[]{"name"});
//        Collections.sort(arrayDemo, comparator);
//        for(int i=0;i<arrayDemo.size();i++)
//        {
//            Person person = (Person)arrayDemo.get(i);
//            System.out.println("用户名："+person.getName()+" 年龄："+person.getAge()+" 月薪："+person.getSalary());
//        }
//        System.out.println("------1.按照年龄从小到大比较---------");
//        comparator.setFields_user(new String[]{"age"});
//        Collections.sort(arrayDemo, comparator);
//        for(int i=0;i<arrayDemo.size();i++)
//        {
//            Person person = (Person)arrayDemo.get(i);
//            System.out.println("用户名："+person.getName()+" 年龄："+person.getAge()+" 月薪："+person.getSalary());
//        }
//         
//        System.out.println("------1.按照月薪从低到高比较---------");
//        comparator.setFields_user(new String[]{"salary"});
//        Collections.sort(arrayDemo, comparator);
//        for(int i=0;i<arrayDemo.size();i++)
//        {
//            Person person = (Person)arrayDemo.get(i);
//            System.out.println("用户名："+person.getName()+" 年龄："+person.getAge()+" 月薪："+person.getSalary());
//        }
       
//        System.out.println("------1.按照年龄和月薪从低到高比较---------");
//        comparator.setFields_user(new String[]{"age","salary"});
//        Collections.sort(arrayDemo, comparator);
//        for(int i=0;i<arrayDemo.size();i++)
//        {
//            Person person = (Person)arrayDemo.get(i);
//            System.out.println("用户名："+person.getName()+" 年龄："+person.getAge()+" 月薪："+person.getSalary());
//        }
//       
//        System.out.println("------1.按照月薪和年龄从低到高比较---------");
//        comparator.setFields_user(new String[]{"salary","age"});
//        Collections.sort(arrayDemo, comparator);
//        for(int i=0;i<arrayDemo.size();i++)
//        {
//            Person person = (Person)arrayDemo.get(i);
//            System.out.println("用户名："+person.getName()+" 年龄："+person.getAge()+" 月薪："+person.getSalary());
//        }
        System.out.println("------1.按照姓名,年龄和月薪从低到高比较---------");
        comparator.setFields_user(new String[]{"name","age","salary"});
        Collections.sort(arrayDemo, comparator);
        for(int i=0;i<arrayDemo.size();i++)
        {
            Person person = (Person)arrayDemo.get(i);
            System.out.println("用户名："+person.getName()+"--- 年龄："+person.getAge()+"---- 月薪："+person.getSalary());
        }
     
        System.out.println("------1.按照月薪和年龄从低到高比较---------");
        comparator.setFields_user(new String[]{"salary","age"});
        Collections.sort(arrayDemo, comparator);
        for(int i=0;i<arrayDemo.size();i++)
        {
            Person person = (Person)arrayDemo.get(i);
            System.out.println("用户名："+person.getName()+" 年龄："+person.getAge()+" 月薪："+person.getSalary());
        }
    }

}

class CommonComparator implements Comparator
{
    /***
     * @param
     * 比较对象的属性用String[]的形式传过来
     * 比较的对象一定要符合javaBean，即要有Set,Get方法
     * */
    String[] fields_user = null;
   
   
    public String[] getFields_user() {
        return fields_user;
    }
    public void setFields_user(String[] fields_user) {
        this.fields_user = fields_user;
    }
    /**
     * 定义排序规则
     * 如果按照不止一个属性进行排序
     * 这按照属性的顺序进行排序,类是sql order by
     * 即只要比较出同位置的属性就停止
     * */
    public int compare(Object obj1, Object obj2)
    {
        //没有属性，则不排序
        if(fields_user == null || fields_user.length<=0)
        {
            return 2;//不比较
        }
        for(int i=0;i<fields_user.length;i++)
        {
            return compareField(obj1,obj2,fields_user[i]);
        }
        return 0;
    }
    /**
     * @param fieldName
     * 根据属性名排序
     * */
    private static int compareField(Object o1,Object o2,String fieldName)
    {
            try
            {
                Object value1 = getFieldValueByName(fieldName,o1);
                Object value2 = getFieldValueByName(fieldName,o2);
              
                //--字符串比较
                if(value1 instanceof String)
                {
                  String v1 = getFieldValueByName(fieldName,o1).toString();
                  String v2 = getFieldValueByName(fieldName,o2).toString();
                    Collator myCollator = Collator.getInstance();
                    CollationKey[] keys = new CollationKey[5];
                    keys[0] = myCollator.getCollationKey(v1);
                    keys[1] = myCollator.getCollationKey(v2);
                    return (keys[0].compareTo(keys[1]));
                    //-------中文会有问题--------
//                  String v1 = getFieldValueByName(fieldName,o1).toString();
//                  String v2 = getFieldValueByName(fieldName,o2).toString();
//                 
//                  if(v1.compareTo(v2)>0){
//                      return 1;
//                  }else if(v1.compareTo(v2)==0)                  {
//                      return 0;
//                  }else{
//                      return -1;
//                  }
                }
                //--非比较属性不比较
                else if("java.lang.Boolean".equals(value1.getClass().getName()) || "java.lang.Byte".equals(value1.getClass().getName()))
                {
                    return 0;
                }else
                {
                    BigDecimal b1 = new BigDecimal(value1.toString());
                    BigDecimal b2 = new BigDecimal(value2.toString());
                    return b1.compareTo(b2);
                }

            } catch (Exception e)
            {
                System.out.println("-----------------------------------------------------------------------------");
                System.out.println("---------对象的该属性不存在或者不允许在此安全级别上反射该属性，详情请查阅JAVA DOC--------");
                System.out.println("-----------------------------------------------------------------------------");
                e.printStackTrace();
            }
            //小于
            return -1;
    }
    /**
     * @param
     * fieldName 属性名
     * obj 对象
     * 反射获得该属性的值
     * */
    private static Object getFieldValueByName(String fieldName,Object obj)
    {
        try
        {
            String Letter = fieldName.substring(0,1).toUpperCase();
            String methodStr = "get"+Letter+fieldName.substring(1);
            Method method = obj.getClass().getMethod(methodStr, new Class[]{});
   
            Object value = method.invoke(obj, new Object[]{});
            
            return value;
        }catch(Exception e)
        {
            System.out.println("------------------------------------------------------");
            System.out.println("---------该"+fieldName+"属性不存在----------------------");
            System.out.println("------------------------------------------------------");
            return null;
        }
    }
}

class Person
{
    public Person(){}
   
    private String name;
    private int age;
    private long salary;
   
    public long getSalary() {
        return salary;
    }
    public void setSalary(long salary) {
        this.salary = salary;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}