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
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:
![](https://img.laitimes.com/img/9ZDMuAjOiMmIsIjOiQnIsIiZpdmLrN2bsJEZlR3YhJHdu92Qvw1cy9GdhNWak5WSn5WaulGb0V3TvwVbvNmLzd2bsJmbj5ycldWYtl2Lc9CX6MHc0RHaiojIsJye.gif)
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;
}
}
View Code
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
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)
map bean:
![](https://img.laitimes.com/img/9ZDMuAjOiMmIsIjOiQnIsIiZpdmLrN2bsJEZlR3YhJHdu92Qvw1cy9GdhNWak5WSn5WaulGb0V3TvwVbvNmLzd2bsJmbj5ycldWYtl2Lc9CX6MHc0RHaiojIsJye.gif)
/*
* 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
指的是对象内嵌套对象
-
PropertyUtils.getNestedProperty(Object, String)
-
PropertyUtils.setNestedProperty(Object, String, Object)
嵌套bean:
![](https://img.laitimes.com/img/9ZDMuAjOiMmIsIjOiQnIsIiZpdmLrN2bsJEZlR3YhJHdu92Qvw1cy9GdhNWak5WSn5WaulGb0V3TvwVbvNmLzd2bsJmbj5ycldWYtl2Lc9CX6MHc0RHaiojIsJye.gif)
/*
* 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;
}
}
/*
* 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;
-
PropertyUtils.getProperty(Object, String)
-
PropertyUtils.setProperty(Object, String, Object)
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
@Author 风一样的码农
@HomePageUrl http://www.cnblogs.com/chenpi/
@Copyright 转载请注明出处,谢谢~