Understanding BeanUtils

In many ways, BeanUtils can be considered a metadata wrapper that makes it as easy to work with a JavaBean as a Map. The properties are the keys, and property values can be set by simply setting the property as a value. For example:

myUser.setName("Bob");

...can instead be written:

BeanUtils.setProperty(myUser, "name", "Bob");

Similarly, an array of the properties available for myUser can be simply retrieved:

DynaProperty[] properties = WrapDynaClass.
createDynaClass(myUser.class).getDynaProperties();

This offers two key advantages: it allows you to decouple components of your application, and it allows you to build frameworks and tools to take advantage of the JavaBeans framework.

As shown in Figure 7-1, the BeanUtils package draws a distinction between a DynaClass, which describes a class, and a DynaBean, which describes a particular object instance. This notion can actually be extended a bit—a DynaClass can be used as a wrapper for a JDBC ResultSet, for example (in which the properties correspond to the returned results), and individual records can be returned as DynaBeans.

Figure 7-1. BeanUtils class diagram.

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One aspect of the BeanUtils package worth calling out is the notion of a Converter. This provides a generic way to retrieve and set values across a suite of properties using String values, regardless of the type of the property. For example, you may want to set a property with a type of int using a String such as "2". The Converter package takes care of these details for you.

The following types are supported by built-in converters:

• BigDecimal

• BigInteger

• Boolean

• Byte

• Character

• Class

• Double

• File

• Float

• Integer

• Long

• Short

• SqlDate

• SqlTime

• SqlTimestamp

• String

• URL

• Abstract array

• Boolean array

• Byte array

• Character array

• Double array

• Float array

• Integer array

• Long array

• Short array

• String array