用于示範的javabean
import java.util.Date;
public class People
private String name;
private int age;
private Date birth;
public People(String name, int age, Date birth) {
super();
this.name = name;
this.age = age;
this.birth = birth;
}
public People() {
super();
// TODO Auto-generated constructor stub
}
@Override
public String toString() {
return "People [name=" + name + ", age=" + age + ", birth=" + birth + "]";
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Date getBirth() {
return birth;
}
public void setBirth(Date birth) {
this.birth = birth;
}
}
測試(所有測試隻與源javabean屬性值有關,與目标javabean屬性值無關)
當源javabean屬性均有值時的目标javabean屬性複制情況
@Test
public void springBeanUtilsTest(){
People oldPeople = new People("oldName",100,new Date());
People newPeople = new People();
//BeanUtils.copyProperties(Object source,Object target);
BeanUtils.copyProperties(oldPeople, newPeople);
System.out.println(oldPeople);
System.out.println(newPeople);
}
輸出結果如下
People [name=oldName, age=100, birth=Wed Jul 19 18:46:13 CST 2017]
People [name=oldName, age=100, birth=Wed Jul 19 18:46:13 CST 2017]
當源javabean非Date類型的屬性值為null時目标javabean屬性的複制情況
@Test
public void springBeanUtilsTest(){
People oldPeople = new People(null,100,new Date());
People newPeople = new People("newName",20,null);
//BeanUtils.copyProperties(Object source,Object target);
BeanUtils.copyProperties(oldPeople, newPeople);
System.out.println(oldPeople);
System.out.println(newPeople);
}
輸出結果如下
注意:目标javabean中的非null屬性值被覆寫為null了
People [name=null, age=100, birth=Wed Jul 19 19:04:48 CST 2017]
People [name=null, age=100, birth=Wed Jul 19 19:04:48 CST 2017]
當源javabean中Date類型的屬性值為null時目标javabean中屬性值的複制情況
@Test
public void springBeanUtilsTest(){
People oldPeople = new People("oldName",100,null);
People newPeople = new People("newName",20,new Date());
//BeanUtils.copyProperties(Object source,Object target);
BeanUtils.copyProperties(oldPeople, newPeople);
System.out.println(oldPeople);
System.out.println(newPeople);
}
輸出結果如下
People [name=oldName, age=100, birth=null]
People [name=oldName, age=100, birth=null]
BeanUtils.copyProperties(Object source,Object target);方法有一個不足的地方,就是當source裡的屬性對應的屬性值為null時,也會覆寫掉target裡相同屬性名的屬性,即使target中該屬性值已存在且不為null的屬性值,這顯然有些不合理,這是我們可以使用它的一個重載方法:
BeanUtils.copyProperties(Object source,Object target, String... ignoreProperties);
最後一個參數的含義是,複制屬性值時忽略的屬性名稱,所有我們隻要找出source中屬性值為null的屬性名稱數組即可,方法如下:
/**
*
* @Title: getNullPropertyNames
* @Description: 擷取一個對象中屬性值為null的屬性名字元串數組
* @param source
* @return
public static String[] getNullPropertyNames (Object source) {
final BeanWrapper src = new BeanWrapperImpl(source);
java.beans.PropertyDescriptor[] pds = src.getPropertyDescriptors();
Set<String> emptyNames = new HashSet<String>();
for(java.beans.PropertyDescriptor pd : pds) {
Object srcValue = src.getPropertyValue(pd.getName());
if (srcValue == null) emptyNames.add(pd.getName());
}
String[] result = new String[emptyNames.size()];
return
@Test
public void copyBeanNotNull(){
People oldPeople = new People(null, 100, null);
People newPeople = new People("newName", 20, new Date());
//BeanUtils.copyProperties(Object source,Object target, String... ignoreProperties);
BeanUtils.copyProperties(oldPeople, newPeople, getNullPropertyNames(oldPeople));
System.out.println(oldPeople);
System.out.println(newPeople);
for(String key : getNullPropertyNames(oldPeople)){
System.out.println(key);
}
}
People [name=null, age=100, birth=null]
People [name=newName, age=100, birth=Wed Jul 19 23:31:05 CST 2017]
name