BeanUtils简要描述
beanutils,顾名思义,是java bean的一个工具类,可以帮助我们方便的读取(get)和设置(set)bean属性值、动态定义和访问bean属性;
细心的话,会发现其实JDK已经提供了一个java.beans包,同样可以实现以上功能,只不过使用起来比较麻烦,所以诞生了apache commons beanutils;
看源码就知道,其实apache commons beanutils就是基于jdk的java.beans包实现的。
Java Bean
在介绍apache commons beanutils之前,很有必要先了解下javabean。
apache commons beanutils就是基于JavaBeans的设计命名规范来实现的,如下是一个简单的javabean示例:
/* * File Name: Employee.java * Description: * Author: PiChen * Create Date: 2017年5月29日 */ package apache.commons.beanutils.example.pojo; import java.util.Date; /** * * @author PiChen * @version 2017年5月29日 */ public class Employee { private String firstName; private String lastName; private Date hireDate; private boolean isManager;/** * @return the firstName */ public String getFirstName() { return firstName; } /** * @param firstName the firstName to set */ public void setFirstName(String firstName) { this.firstName = firstName; } /** * @return the lastName */ public String getLastName() { return lastName; } /** * @param lastName the lastName to set */ public void setLastName(String lastName) { this.lastName = lastName; } /** * @return the hireDate */ public Date getHireDate() { return hireDate; } /** * @param hireDate the hireDate to set */ public void setHireDate(Date hireDate) { this.hireDate = hireDate; } /** * @return the isManager */ public boolean isManager() { return isManager; } /** * @param isManager the isManager to set */ public void setManager(boolean isManager) { this.isManager = isManager; } /** * @return the fullName */ public String getFullName() { return firstName + " " + lastName; } }
javabean一般有以下几个特性:
1、类必须是public访问权限,且需要有一个public的无参构造方法,之所以这样主要是方便利用Java的反射动态创建对象实例:
Class beanClass = Class.forName(className); Object beanInstance = beanClass.newInstance();
2、由于javabean的构造方法是无参的,所以我们的bean的行为配置(即设置bean的属性值,方法对应行为,属性对应数据)不能在构造方法完成,取而代之的是通过一系列的set方法来设置属性值,通过setter方法,我们可以改变javabean呈现出来的行为和内部数据,这里的setter方法会按一定的约定来命名,如setHireDate、setName。。。
3、读取和设置bean属性值的命名约定,即getter方法和setter方法,不过这里需要特别注意boolean类型的约定,如下示例:
private String firstName; private String lastName; private Date hireDate; private boolean isManager; public String getFirstName(); public void setFirstName(String firstName); public String getLastName(); public void setLastName(String lastName); public Date getHireDate(); public void setHireDate(Date hireDate); public boolean isManager(); public void setManager(boolean manager);
4、并不是必须为每个属性提供setter和getter方法,我们可以只定义一个属性的getter方法而不定义setter方法,这样的属性一般是只读属性;
访问基本数据类型的Bean属性
简述:
这类属性指的是Integer, Double, Float, boolean等,,,, 注意这里还包括String,其实像HashMap,ArrayList, 等属性都可以设置,只不过Map里面的键值对、List索引处的值无法通过这两个API访问,需要使用专门的API来处理,接下来将会介绍;
访问API:
PropertyUtils.getSimpleProperty(Object, String)
PropertyUtils.setSimpleProperty(Object, String, Object)
调用示例:
/* * File Name: Main.java * Description: * Author: PiChen * Create Date: 2017年5月29日 */ package apache.commons.beanutils.example.propertyaccess; import java.lang.reflect.InvocationTargetException; import org.apache.commons.beanutils.PropertyUtils; import apache.commons.beanutils.example.pojo.Employee; /** * * @author PiChen * @version 2017年5月29日 */ public class BasicPropertyAccess { /** * * * @param args * @throws NoSuchMethodException * @throws InvocationTargetException * @throws IllegalAccessException */ public static void main(String[] args) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { Employee employee = new Employee(); String firstName = (String) PropertyUtils.getSimpleProperty(employee, "firstName"); String lastName = (String) PropertyUtils.getSimpleProperty(employee, "lastName"); firstName = firstName == null ? "Pi" : ""; lastName = lastName == null ? "Chen" : ""; PropertyUtils.setSimpleProperty(employee, "firstName", firstName); PropertyUtils.setSimpleProperty(employee, "lastName", lastName); System.out.println(employee.getFullName()); } }
访问索引类型的Bean属性
简述:
可索引的属性,如ArrayList, 数组等,可以通过下标索引来访问Bean属性的值, 同理可设置value;
访问API
PropertyUtils.getIndexedProperty(Object, String)
PropertyUtils.getIndexedProperty(Object, String, int)
PropertyUtils.setIndexedProperty(Object, String, Object)
PropertyUtils.setIndexedProperty(Object, String, int, Object)
调用示例
Bean:
package apache.commons.beanutils.example.pojo; import java.util.List; public class IndexedBean { private List<Employee> employeeList; private Integer[] intArr; /** * @return the employeeList */ public List<Employee> getEmployeeList() { return employeeList; } /** * @param employeeList the employeeList to set */ public void setEmployeeList(List<Employee> employeeList) { this.employeeList = employeeList; } /** * @return the intArr */ public Integer[] getIntArr() { return intArr; } /** * @param intArr the intArr to set */ public void setIntArr(Integer[] intArr) { this.intArr = intArr; } }
调用example:
/* * File Name: Main.java * Description: * Author: PiChen * Create Date: 2017年5月29日 */ package apache.commons.beanutils.example.propertyaccess; import java.lang.reflect.InvocationTargetException; import java.util.ArrayList; import java.util.List; import org.apache.commons.beanutils.PropertyUtils; import apache.commons.beanutils.example.pojo.Employee; import apache.commons.beanutils.example.pojo.IndexedBean; /** * * @author PiChen * @version 2017年5月29日 */ public class IndexedPropertiesAccess { /** * * * @param args * @throws NoSuchMethodException * @throws InvocationTargetException * @throws IllegalAccessException */ public static void main(String[] args) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { // 初始工作 IndexedBean indexedBean = new IndexedBean(); List<Employee> employeeList = new ArrayList<Employee>(); Employee e1 = new Employee(); e1.setLastName("Chen"); Employee e2 = new Employee(); e2.setLastName("Wang"); employeeList.add(e1); employeeList.add(e2); indexedBean.setEmployeeList(employeeList); indexedBean.setIntArr(new Integer[]{ 0, 1, 2 }); // API测试 int index0 = 0; String name0 = "employeeList[" + index0 + "]"; Employee employee0 = (Employee) PropertyUtils.getIndexedProperty(indexedBean, name0); System.out.println(employee0.getLastName()); int index1 = 1; String name1 = "employeeList[" + index1 + "]"; Employee employee1 = (Employee) PropertyUtils.getIndexedProperty(indexedBean, name1); System.out.println(employee1.getLastName()); Employee employee00 = (Employee) PropertyUtils.getIndexedProperty(indexedBean,"employeeList", 0); Employee employee11 = (Employee) PropertyUtils.getIndexedProperty(indexedBean,"employeeList", 1); System.out.println(employee00.getLastName()); System.out.println(employee11.getLastName()); Integer i = (Integer) PropertyUtils.getIndexedProperty(indexedBean,"intArr", 1); System.out.println(i); } }
访问Map映射类型的Bean属性
简述:
常见的HashMap,TreeMap等,可以通过key来访问Bean属性值,同理可设置value;
访问API:
PropertyUtils.getMappedProperty(Object, String)
PropertyUtils.getMappedProperty(Object, String, String)
PropertyUtils.setMappedProperty(Object, String, Object)
PropertyUtils.setMappedProperty(Object, String, String, Object)
调用示例:
map bean:
/* * File Name: MappedBean.java * Description: * Author: PiChen * Create Date: 2017年5月29日 */ package apache.commons.beanutils.example.pojo; import java.util.Map; /** * * @author PiChen * @version 2017年5月29日 */ public class MappedBean { private Map<String, Object> mapProperty; /** * @return the mapProperty */ public Map<String, Object> getMapProperty() { return mapProperty; } /** * @param mapProperty the mapProperty to set */ public void setMapProperty(Map<String, Object> mapProperty) { this.mapProperty = mapProperty; } }
使用example:
/* * File Name: MapPropertyAccess.java * Description: * Author: PiChen * Create Date: 2017年5月29日 */ package apache.commons.beanutils.example.propertyaccess; import java.lang.reflect.InvocationTargetException; import java.util.HashMap; import java.util.Map; import org.apache.commons.beanutils.PropertyUtils; import apache.commons.beanutils.example.pojo.MappedBean; /** * * @author PiChen * @version 2017年5月29日 */ public class MapPropertyAccess { public static void main(String[] args) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { MappedBean employee = new MappedBean(); Map<String, Object> map = new HashMap<String, Object>(); //employee.setMapProperty(map); PropertyUtils.setSimpleProperty(employee, "mapProperty", map); PropertyUtils.setMappedProperty(employee, "mapProperty", "testKey1", "testValue1"); PropertyUtils.setMappedProperty(employee, "mapProperty(testKey2)", "testValue2"); System.out.println(employee.getMapProperty().get("testKey1")); System.out.println(employee.getMapProperty().get("testKey2")); } }
访问嵌套类型的Bean属性
简述:
指的是对象内嵌套对象
访问API:
PropertyUtils.getNestedProperty(Object, String)
PropertyUtils.setNestedProperty(Object, String, Object)
调用示例:
嵌套bean:
/* * File Name: NestedBean.java * Description: * Author: PiChen * Create Date: 2017年5月29日 */ package apache.commons.beanutils.example.pojo; import java.util.List; import java.util.Map; /** * * @author PiChen * @version 2017年5月29日 */ public class NestedBean { private List<Employee> listProperty; private Map<String, Employee> mapProperty; /** * @return the listProperty */ public List<Employee> getListProperty() { return listProperty; } /** * @param listProperty the listProperty to set */ public void setListProperty(List<Employee> listProperty) { this.listProperty = listProperty; } /** * @return the mapProperty */ public Map<String, Employee> getMapProperty() { return mapProperty; } /** * @param mapProperty the mapProperty to set */ public void setMapProperty(Map<String, Employee> mapProperty) { this.mapProperty = mapProperty; } }
使用example:
/* * File Name: NestedPropertyAccess.java * Description: * Author: PiChen * Create Date: 2017年5月29日 */ package apache.commons.beanutils.example.propertyaccess; import java.lang.reflect.InvocationTargetException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.commons.beanutils.PropertyUtils; import apache.commons.beanutils.example.pojo.Employee; import apache.commons.beanutils.example.pojo.NestedBean; /** * * @author PiChen * @version 2017年5月29日 */ public class NestedPropertyAccess { public static void main(String[] args) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { Employee e = new Employee(); e.setLastName("Chen"); NestedBean nestedBean = new NestedBean(); List<Employee> list = new ArrayList<Employee>(); list.add(e); Map<String, Employee> map = new HashMap<String, Employee>(); map.put("testKey", e); nestedBean.setListProperty(list); nestedBean.setMapProperty(map); String lastName = (String) PropertyUtils.getNestedProperty(nestedBean, "mapProperty(testKey).lastName"); System.out.println(lastName); String lastName2 = (String) PropertyUtils.getNestedProperty(nestedBean, "listProperty[0].lastName"); System.out.println(lastName2); } }
访问所有类型的Bean属性
简述
通过以上API的使用,我们了解了各类bean属性的访问方法,其实还有一种通用的方法,适用于各类bean属性类型;
访问API
使用示例,这里直接以嵌套类型属性为例
/* * File Name: NestedPropertyAccess.java * Description: * Author: PiChen * Create Date: 2017年5月29日 */ package apache.commons.beanutils.example.propertyaccess; import java.lang.reflect.InvocationTargetException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.commons.beanutils.PropertyUtils; import apache.commons.beanutils.example.pojo.Employee; import apache.commons.beanutils.example.pojo.NestedBean; /** * * @author PiChen * @version 2017年5月29日 */ public class NestedPropertyAccess { public static void main(String[] args) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { Employee e = new Employee(); e.setLastName("Chen"); NestedBean nestedBean = new NestedBean(); List<Employee> list = new ArrayList<Employee>(); list.add(e); Map<String, Employee> map = new HashMap<String, Employee>(); map.put("testKey", e); nestedBean.setListProperty(list); nestedBean.setMapProperty(map); String lastName2 = (String) PropertyUtils.getProperty(nestedBean, "listProperty[0].lastName"); System.out.println(lastName2); PropertyUtils.setProperty(nestedBean, "listProperty[0].lastName", "Hello World"); System.out.println(nestedBean.getListProperty().get(0).getLastName()); } }
参考资料
commons.apache.org/proper/commons-beanutils/javadocs/v1.9.3/apidocs/org/apache/commons/beanutils/package-summary.html
源码链接:
https://github.com/peterchenhdu/apache-commons-beanutils-example