Commons BeanUtils

一）此包的下载
    http://commons.apache.org/beanutils/download_beanutils.cgi  此包目前最新的版本是1.8.3

二）此包的功能
    用于处理JavaBeans。它利用Java的反射机制，从动态的生成对bean的getter和setter的调用代码，到模拟创建一个动态的bean，等等。这个包看似简单，却是很多开源项目的基石：如在著名的Struts和Spring Framework中，我们都能找到BeanUtils的影子。

三）此包的API
    http://commons.apache.org/beanutils/v1.8.3/apidocs/index.html

    从 1.7.0 版本开始 BeanUtils被细分成3种架包:
    commons-beanutils.jar - 包含所有BeanUtils内容的架包
    commons-beanutils-core.jar - 除去Collections内容的架包
    commons-beanutils-bean-collections.jar - 仅有Collections内容的架包（此部分内容依赖于Commons Collections ）

四）常用类：
    DynaBean -- 该接口定义的是一个动态的JavaBean，它的属性类型、名称和值都是可以动态改变的。
    DynaClass -- 该接口定义的是针对实现了DynaBean接口的类的java.lang.Class对象，提供如getName()、newInstance()等方法。
    DynaProperty -- 用于描述DynaBean的属性

五）代码样例

 /** Address.java */
package sean.study.commons.beanutils;
 
public class Address {
    private String zipCode;
    private String addr;
    private String city;
    private String country;
 
    public Address() {}
    public Address(String zipCode, String addr, String city, String country) {
        this.zipCode = zipCode;
        this.addr = addr;
        this.city = city;
        this.country = country;
    }
    public String getAddr() {
        return addr;
    }
    public void setAddr(String addr) {
        this.addr = addr;
    }
    public String getCity() {
        return city;
    }
    public void setCity(String city) {
        this.city = city;
    }
    public String getCountry() {
        return country;
    }
    public void setCountry(String country) {
        this.country = country;
    }
    public String getZipCode() {
        return zipCode;
    }
    public void setZipCode(String zipCode) {
        this.zipCode = zipCode;
    }
 
}
 
/** Customer.java */
package sean.study.commons.beanutils;
 
public class Customer {
    private long id;
    private String name;
    private Address[] addresses;
 
    public Customer() {}
    public Customer(long id, String name, Address[] addresses) {
        this.id = id;
        this.name = name;
        this.addresses = addresses;
    }
    public Address[] getAddresses() {
        return addresses;
    }
    public void setAddresses(Address[] addresses) {
        this.addresses = addresses;
    }
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

我们来看看通常我们是怎样利用Commons BeanUtils来完成一些基本的JavaBean和DynaBean操作：

package sean.study.commons.beanutils;
 
import org.apache.commons.beanutils.BasicDynaBean;
import org.apache.commons.beanutils.BasicDynaClass;
import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.beanutils.DynaProperty;
import org.apache.commons.beanutils.PropertyUtils;
import org.apache.commons.lang.StringUtils;
 
public class BeanUtilsUsage {
 
    public static void main(String[] args) throws Exception {
        demoNormalJavaBeans();
        demoDynaBeans();
    }
 
    public static void demoNormalJavaBeans() throws Exception {
 
        System.out.println(StringUtils.center(" demoNormalJavaBeans ", 40, "="));
       
        // data setup
        Address addr1 = new Address("CA1234", "xxx", "Los Angeles", "USA");
        Address addr2 = new Address("100000", "xxx", "Beijing", "China");
        Address[] addrs = new Address[2];
        addrs[0] = addr1;
        addrs[1] = addr2;
        Customer cust = new Customer(123, "John Smith", addrs);
       
        // accessing the city of first address
        String cityPattern = "addresses[0].city";
        String name = (String) PropertyUtils.getSimpleProperty(cust, "name");
        String city = (String) PropertyUtils.getProperty(cust, cityPattern);
        Object[] rawOutput1 = new Object[] { "The city of customer ", name,
                "'s first address is ", city, "." };
        System.out.println(StringUtils.join(rawOutput1));
       
        // setting the zipcode of customer's second address
        String zipPattern = "addresses[1].zipCode";
        if (PropertyUtils.isWriteable(cust, zipPattern)) {//PropertyUtils
            System.out.println("Setting zipcode ...");
            PropertyUtils.setProperty(cust, zipPattern, "200000");//PropertyUtils
        }
        String zip = (String) PropertyUtils.getProperty(cust, zipPattern);//PropertyUtils
        Object[] rawOutput2 = new Object[] { "The zipcode of customer ", name,
                "'s second address is now ", zip, "." };
        System.out.println(StringUtils.join(rawOutput2));
       
        System.out.println();
    }
 
    public static void demoDynaBeans() throws Exception {
 
        System.out.println(StringUtils.center(" demoDynaBeans ", 40, "="));
       
        // creating a DynaBean
        DynaProperty[] dynaBeanProperties = new DynaProperty[] {//DynaProperty
                new DynaProperty("name", String.class),
                new DynaProperty("inPrice", Double.class), 
                new DynaProperty("outPrice", Double.class),
        };
        BasicDynaClass cargoClass = new BasicDynaClass("Cargo", BasicDynaBean.class, dynaBeanProperties); //BasicDynaClass  BasicDynaBean
        DynaBean cargo = cargoClass.newInstance();//DynaBean
       
        // accessing a DynaBean
        cargo.set("name", "Instant Noodles");
        cargo.set("inPrice", new Double(21.3));
        cargo.set("outPrice", new Double(23.8));
        System.out.println("name: " + cargo.get("name"));
        System.out.println("inPrice: " + cargo.get("inPrice"));
        System.out.println("outPrice: " + cargo.get("outPrice"));
 
        System.out.println();
    }
}

上述代码运行结果如下：

========= demoNormalJavaBeans ==========
The city of customer John Smith's first address is Los Angeles.
Setting zipcode ...
The zipcode of customer John Smith's second address is now 200000.

============ demoDynaBeans =============
name: Instant Noodles
inPrice: 21.3
outPrice: 23.8