Jakarta Commons Cookbook读书笔记--Commons BeanUtils

Jakarta Commons Cookbook读书笔记--Commons BeanUtils

Jakarta Commons Cookbook读书笔记系列

2 Apache Commons BeanUtils 1.7
功能说明：顾名思义，Bean Utility就是Bean小工具，主要是封装了反射（reflection）和自省（introspection）的API（可以查看java.lang.reflect和java.beans文档），对bean进行操作。
主要功能：操作Bean的属性，针对Bean属性排序，Bean和Map的转换，创建动态的Bean等
 
2.1 org.apache.commons.beanutils.PropertyUtils 利用反射操作bean的属性
getSimpleProperty()通过反射读取属性

Person person = new  Person();
person.setName = ( " heis " );
String name = (String)PropertyUtils.getSimpleProperty(person, " name " ); -> heis

getNestedProperty()检索嵌套的bean属性

Book book = new  Book();
book.setAuthor(person);
String authorName = (String)PropertyUtils.getNestedProperty(book, " author.name " ); // 得到person的name

getIndexedProperty()访问数组或List型内Object的属性

Chapter chapter1 = new  Chapter();
Chapter chapter2 = new  Chapter();
book.getChapters().add(chapter1);
book.getChapters().add(chapter2);
Chapter chapter = (Chapter)PropertyUtils.getIndexedProperty(book, " chapter[0] " );

getMappedProperty()访问Map型bean属性的值

Person person = new  Person();
person.setName = ( " heis " );
Map favorites = new  HashMap();
favorites.put( " food " , " rice " );
person.setFavorite(favorites);
String favorFood = (String)PropertyUtils.getMappedProperty(person, " favorites(food) " ); -> rice

getProperty()和setProperty()可以访问任何bean属性，通过表达式可以完成上面方法的功能

这是一个树型的Bean属性视图
Book book
|-- List authors
       |-- [ 0 ] -> Person person
                     |-- Map favorites
                              |-- Entry(key -> " food " ,value -> "" )
PropertyUtils.setProperty(book, " authors[0].favorites(food) " , " rice " );
String favorFood = (String)PropertyUtils.getProperty(book, " authors[0].favorites(food) " ); -> rice

isReadable()和isWritable()检查bean是否可读（有getter）或可写（有setter）

PropertyUtils.isReadable(book, " name " );
PropertyUtils.isWritable(book, " name " );

getPropertyType()获取属性类型

System.out.println(PropertyUtils.getPropertyType(person, " favorites " )); -> java.util.Map

copyProperty()复制Bean属性,只复制引用，final类型和原始类型（primitive type）

Book book1 = new  Book();
book1.setName( " Commons Cookbook Notes " );
Book book2 = new  Book();
PropertyUtils.copyProperty(book2,book1); // 将book1的name属性copy到book2

describe()创建包含Bean属性的Map

Person person = new  Person();
person.setName( " heis " );
Book book = new  Book();
book.setName( " Commons Cookbook Notes " );
book.setAuthor(person);
Map propMap = PropertyUtils.describe(book);
propMap.get( " name " ); -> Commons Cookbook Notes
propMap.get( " author " ); -> person

Jakarta Commons Cookbook读书笔记系列



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