JSP 开发之Spring BeanUtils组件使用
JSP开发之SpringBeanUtils组件使用
用于演示的javabean
importjava.util.Date;
publicclassPeople{
privateStringname;
privateintage;
privateDatebirth;
publicPeople(Stringname,intage,Datebirth){
super();
this.name=name;
this.age=age;
this.birth=birth;
}
publicPeople(){
super();
//TODOAuto-generatedconstructorstub
}
@Override
publicStringtoString(){
return"People[name="+name+",age="+age+",birth="+birth+"]";
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
publicintgetAge(){
returnage;
}
publicvoidsetAge(intage){
this.age=age;
}
publicDategetBirth(){
returnbirth;
}
publicvoidsetBirth(Datebirth){
this.birth=birth;
}
}
测试（所有测试只与源javabean属性值有关，与目标javabean属性值无关）
当源javabean属性均有值时的目标javabean属性复制情况
@Test
publicvoidspringBeanUtilsTest(){
PeopleoldPeople=newPeople("oldName",100,newDate());
PeoplenewPeople=newPeople();
//BeanUtils.copyProperties(Objectsource,Objecttarget);
BeanUtils.copyProperties(oldPeople,newPeople);
System.out.println(oldPeople);
System.out.println(newPeople);
}
输出结果如下
People[name=oldName,age=100,birth=WedJul1918:46:13CST2017] People[name=oldName,age=100,birth=WedJul1918:46:13CST2017]
当源javabean非Date类型的属性值为null时目标javabean属性的复制情况
@Test
publicvoidspringBeanUtilsTest(){
PeopleoldPeople=newPeople(null,100,newDate());
PeoplenewPeople=newPeople("newName",20,null);
//BeanUtils.copyProperties(Objectsource,Objecttarget);
BeanUtils.copyProperties(oldPeople,newPeople);
System.out.println(oldPeople);
System.out.println(newPeople);
}
输出结果如下
注意:目标javabean中的非null属性值被覆盖为null了
People[name=null,age=100,birth=WedJul1919:04:48CST2017] People[name=null,age=100,birth=WedJul1919:04:48CST2017]
当源javabean中Date类型的属性值为null时目标javabean中属性值的复制情况
@Test
publicvoidspringBeanUtilsTest(){
PeopleoldPeople=newPeople("oldName",100,null);
PeoplenewPeople=newPeople("newName",20,newDate());
//BeanUtils.copyProperties(Objectsource,Objecttarget);
BeanUtils.copyProperties(oldPeople,newPeople);
System.out.println(oldPeople);
System.out.println(newPeople);
}
输出结果如下
People[name=oldName,age=100,birth=null] People[name=oldName,age=100,birth=null]
BeanUtils.copyProperties(Objectsource,Objecttarget);方法有一个不足的地方，就是当source里的属性对应的属性值为null时，也会覆盖掉target里相同属性名的属性，即使target中该属性值已存在且不为null的属性值，这显然有些不合理，这是我们可以使用它的一个重载方法：
BeanUtils.copyProperties(Objectsource,Objecttarget,String...ignoreProperties);
最后一个参数的含义是，复制属性值时忽略的属性名称，所有我们只要找出source中属性值为null的属性名称数组即可，方法如下：
/**
*
*@Title:getNullPropertyNames
*@Description:获取一个对象中属性值为null的属性名字符串数组
*@paramsource
*@return
*/
publicstaticString[]getNullPropertyNames(Objectsource){
finalBeanWrappersrc=newBeanWrapperImpl(source);
java.beans.PropertyDescriptor[]pds=src.getPropertyDescriptors();
SetemptyNames=newHashSet();
for(java.beans.PropertyDescriptorpd:pds){
ObjectsrcValue=src.getPropertyValue(pd.getName());
if(srcValue==null)emptyNames.add(pd.getName());
}
String[]result=newString[emptyNames.size()];
returnemptyNames.toArray(result);
}
测试
@Test
publicvoidcopyBeanNotNull(){
PeopleoldPeople=newPeople(null,100,null);
PeoplenewPeople=newPeople("newName",20,newDate());
//BeanUtils.copyProperties(Objectsource,Objecttarget,String...ignoreProperties);
BeanUtils.copyProperties(oldPeople,newPeople,getNullPropertyNames(oldPeople));
System.out.println(oldPeople);
System.out.println(newPeople);
for(Stringkey:getNullPropertyNames(oldPeople)){
System.out.println(key);
}
}
输出结果如下
People[name=null,age=100,birth=null] People[name=newName,age=100,birth=WedJul1923:31:05CST2017] name birth
以上就是JSP中SpringBeanUtils组件的使用，如有疑问请留言或者到本站社区交流讨论，感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！