假定我們有如下兩個標準的JavaBean：
/** 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;
}
}
我們來看看通常我們是怎樣利用Commons BeanUtils來完成一些基本的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)) {
System.out.println("Setting zipcode ...");
PropertyUtils.setProperty(cust, zipPattern, "200000");
}
String zip = (String) PropertyUtils.getProperty(cust, zipPattern);
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[] {
new DynaProperty("name", String.class),
new DynaProperty("inPrice", Double.class),
new DynaProperty("outPrice", Double.class),
};
BasicDynaClass cargoClass = new BasicDynaClass("Cargo", BasicDynaBean.class, dynaBeanProperties);
DynaBean cargo = cargoClass.newInstance();
// 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();
}
}
上述代碼運行結果如下：
========= 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
以上代碼簡單說明了一下BeanUtils常見的基本用法，還有很多高階或者更具體的應用及原理，這里無法一一講到，而且有很多筆者也不熟悉、不了解，對BeanUtils的講解就到此吧。如果你有興趣，或者還不是很清楚為什么像這樣動態的或者說松散的訪問JavaBean是有必要的，可以把Struts的源碼拿下來研究一下，看看FormBean以及DynaActionForm這些是如何被動態創建的，一定會有收獲。