JSP 研发之Spring BeanUtils组件使用
发布时间：2023-06-08 13:41:49 所属栏目：教程 来源：
导读：avaBean在程序中的操作非常频繁，但总有一些开源组件易于使用和扩展，为众多开发人员提供了便利，下面一起来了解JSP 开发之Spring BeanUtils组件使用的知识。
JSP 开发之Spring BeanUtils组件使用
用于演示的
JSP 开发之Spring BeanUtils组件使用
用于演示的
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avaBean在程序中的操作非常频繁，但总有一些开源组件易于使用和扩展，为众多开发人员提供了便利，下面一起来了解JSP 开发之Spring BeanUtils组件使用的知识。 JSP 开发之Spring BeanUtils组件使用 用于演示的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; }} 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 @Testpublic 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);} 输出结果如下 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] 当源javabean非Date类型的属性值为null时目标javabean属性的复制情况 @Testpublic 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);} 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=Wed Jul 19 19:04:48 CST 2017]People [name=null, age=100, birth=Wed Jul 19 19:04:48 CST 2017] 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 @Testpublic 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);} 输出结果如下 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(Object source,Object target, 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 * @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 emptyNames.toArray(result);} 测试 @Testpublic 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); }} 输出结果如下 People [name=null, age=100, birth=null]People [name=newName, age=100, birth=Wed Jul 19 23:31: （编辑：聊城站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
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