org.apache.commons.beanutils.BeanUtils
1.BeanUtils基本用法：java 代码
[*]package com.beanutil;
[*]
[*]import java.util.Map;
[*]
[*]public class User {
[*]
[*] private Integer id;
[*] private Map map;
[*] private String username;
[*] public Integer getId() {
[*] return id;
[*] }
[*] public void setId(Integer id) {
[*] this.id = id;
[*] }
[*] public Map getMap() {
[*] return map;
[*] }
[*] public void setMap(Map map) {
[*] this.map = map;
[*] }
[*] public String getUsername() {
[*] return username;
[*] }
[*] public void setUsername(String username) {
[*] this.username = username;
[*] }
[*]
[*]
[*]}
java 代码
[*]public class Order {
[*] private User user;
[*] private Integer id;
[*] private String desc;
[*] public String getDesc() {
[*] return desc;
[*] }
[*] public void setDesc(String desc) {
[*] this.desc = desc;
[*] }
[*] public Integer getId() {
[*] return id;
[*] }
[*] public void setId(Integer id) {
[*] this.id = id;
[*] }
[*] public User getUser() {
[*] return user;
[*] }
[*] public void setUser(User user) {
[*] this.user = user;
[*] }
[*]
[*]
[*]}
java 代码
[*]
[*]import java.util.HashMap;
[*]import java.util.Map;
[*]
[*]import org.apache.commons.beanutils.BeanUtils;
[*]
[*]public class Test {
[*]
[*] private User user = new User();
[*] private Order order1 = new Order();
[*] private Order order2 = new Order();
[*] private Order order3 = new Order();
[*] private Map map = new HashMap();
[*] private User user1 = new User();
[*]
[*] public Test(){
[*] init();
[*] }
[*] public static void main(String[] args) throws Exception{
[*] Test test = new Test();
[*] //输出某个对象的某个属性
[*] System.out.println(BeanUtils.getProperty(test.user, "username"));
[*]
[*] //输出某个对象的内嵌属性,只要使用点号分隔
[*] System.out.println(BeanUtils.getProperty(test.order1, "user.username"));
[*]
[*] //BeanUtils还支持List和Map类型的属性,对于Map类型，则需要以"属性名（key值）"的
[*] //对于Indexed，则为"属性名[索引值]"，注意对于ArrayList和数组都可以用一样的方式进行操作
[*] System.out.println(BeanUtils.getProperty(test.user1, "map(order2).desc"));
[*]
[*] //拷贝对象的属性值
[*] User tempUser = new User();
[*] BeanUtils.copyProperties(tempUser, test.user1);
[*]
[*] System.out.println(tempUser.getUsername());
[*] System.out.println(tempUser.getId());
[*]
[*]
[*]
[*]
[*] }
[*]
[*] //初始化
[*] public void init(){
[*]
[*]
[*] user.setId(0);
[*] user.setUsername("zhangshan");
[*]
[*]
[*] order1.setId(1);
[*] order1.setDesc("order1");
[*] order1.setUser(user);
[*]
[*]
[*]
[*] order2.setId(2);
[*] order2.setDesc("order2");
[*] order2.setUser(user);
[*]
[*]
[*] order3.setId(3);
[*] order3.setDesc("order3");
[*] order3.setUser(user);
[*]
[*]
[*] map.put("order1", order1);
[*] map.put("order2", order2);
[*] map.put("order3", order3);
[*]
[*]
[*] user1.setId(1);
[*] user1.setUsername("lisi");
[*] user1.setMap(map);
[*]
[*]
[*] }
[*]}
输出结果为：
zhangshan
zhangshan
order2
lisi
1
2. BeanCompartor 动态排序
A:动态设定Bean按照哪个属性来排序，而不再需要再实现bean的Compare接口进行复杂的条件判断
java 代码
[*]//动态设定Bean按照哪个属性来排序，而不再需要再实现bean的Compare接口进行复杂的条件判断
[*] List<order></order> list = new ArrayList<order></order>();
[*]
[*] list.add(test.order2);
[*] list.add(test.order1);
[*] list.add(test.order3);
[*]
[*] //未排序前
[*] for(Order order : list){
[*] System.out.println(order.getId());
[*] }
[*] //排序后
[*] Collections.sort(list, new BeanComparator("id"));
[*] for(Order order : list){
[*] System.out.println(order.getId());
[*] }
B:支持多个属性的复合排序
java 代码
[*]//支持多个属性的复合排序
[*] List <beancomparator></beancomparator> sortFields = new ArrayList<beancomparator></beancomparator>();
[*] sortFields.add(new BeanComparator("id"));
[*] sortFields.add(new BeanComparator("desc"));
[*] ComparatorChain multiSort = new ComparatorChain(sortFields);
[*] Collections.sort(list, multiSort);
[*]
[*] for(Order order : list){
[*] System.out.println(order.getId());
[*] }
C:使用ComparatorUtils进一步指定排序条件
上面的排序遇到属性为null就会抛出异常, 也不能设定升序还是降序。
不过，可以借助commons-collections包的ComparatorUtils
BeanComparator，ComparableComparator和ComparatorChain都是实现了Comparator这个接口
java 代码
[*]//上面的排序遇到属性为null就会抛出异常, 也不能设定升序还是降序。
[*] //不过，可以借助commons-collections包的ComparatorUtils
[*] //BeanComparator，ComparableComparator和ComparatorChain都是实现了Comparator这个接口
[*] Comparator mycmp = ComparableComparator.getInstance();
[*] mycmp = ComparatorUtils.nullLowComparator(mycmp); //允许null
[*] mycmp = ComparatorUtils.reversedComparator(mycmp); //逆序
[*] Comparator cmp = new BeanComparator("id", mycmp);
[*] Collections.sort(list, cmp);
[*] for(Order order : list){
[*] System.out.println(order.getId());
[*] }
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