BeanUtil

BeanUtil is bean manipulation library, that in a nutshell, allows setting and reading bean properties. Several features make BeanUtil distinct:

  • fast (if not the fastest) bean manipulation utility
  • works with both attributes and properties
  • nested properties can be arrays, lists and maps
  • missing inner properties may be created
  • may work silently (no exception is thrown)
  • offers few populate methods
  • has strong-type conversion library

Flavors of BeanUtil

Before we jump into the details, let's quickly learn what types of BeanUtil exists. Implementations differ in the way how they threat private properties, if they throw exceptions and, finally, if they force creation of missing inner properties (more details later). You can build your own implementation easily using BeanUtilBean, but these are already provided:

name access privates throws exception? force missing properties?
BeanUtil.pojo no yes no
BeanUtil.declared yes yes no
BeanUtil.silent no no no
BeanUtil.forced no yes yes
BeanUtil.declaredSilent yes no no
BeanUtil.declaredForced yes no yes
BeanUtil.declaredForcedSilent yes no yes
BeanUtil.forcedSilent no no yes

Let' jump into details!

Working with bean properties

In BeanUtil world, bean property is a class field with its optional setter and getter (aka accessors) methods. When accessing properties, BeanUtil first tries to use accessors methods. If they don't exist, BeanUtil fail-backs to using the field of the same visibility. Therefore, existence of accessors methods is not required and depends on usage, what often may be handy. BeanUtil is used internally inside the Jodd library, so this behavior applies everywhere.

Simple bean:

    public class Foo {
        private String readwrite;   // with getter and setter
        private String readonly;    // with getter
        ...
    }

Usage:

    Foo foo = new Foo();
    BeanUtil.pojo.setProperty(foo, "readwrite", "data");
    BeanUtil.pojo.getProperty(foo, "readwrite");
    BeanUtil.declared.setProperty(foo, "readonly", "data");

Lines #2 and #3 show common and expected BeanUtil usage: setting value of read-write property through it's accessors methods. Setting readonly property in above example is only possible with default implementation, so we use BeanUtil.declared. This variant first tries to use setReadonly() method, but since such method doesn't exist, field value is accessed directly.

Nested properties

BeanUtil supports nested properties. Nested properties can be java beans, a List, a Map or an array element:

    BeanUtil.pojo.getProperty(cbean, "list[0].map[foo].foo");
    BeanUtil.pojo.setProperty(cbean, "arr[4].map[elem.boo].foo", "test");

When accessing nested properties, BeanUtil access one property at time and, by default, expects that all inner properties exist i.e. are not-null. Above example is executed like the following pseudo-code:

    cbean.getList().get(0).get("foo").getFoo();
    cbean.getArr()[4].get("elem.boo").setFoo("test");

Forced setting of nested properties

Setting of nested properties fails if one of the inner elements is null. Using forced feature of BeanUtil, such properties still may be set!

    BeanUtil.forced.setProperty(x, "y.foo", value);
    BeanUtil.forced.setProperty(x, "yy[2].foo", "xxx");

If the object x in above example has uninitialized property y, BeanUtil will first create a new instance of y's type, and set it to property y. Then, foo property of newly created object y will be set. In the second example, yy is an array. If it is uninitialized, BeanUtil will create a new array of length 3. Then, it will create a new instance of yy's type that will be stored as third element of the array. Finally, the foo property is set.

In forced mode, BeanUtil tries to instantiate all uninitialized properties needed for setting the final property. Instantiation depends of the inner property type: if it is a simple bean, no-args constructor will be invoked. If it is a list, new ArrayList will be created. Similar applies for arrays and map types. Additionally, BeanUtil will check the length of existing initialized arrays and lists and if the current size is not enough, list or array will be expanded by adding null elements up to the new size.

Generics support

When creating a new element of an list, BeanUtil will consider existing generics information in order to create element of correct type.

Silent mode (no exceptions)

Property setting may fail for various reasons, causing an unchecked exception BeanUtilException to be thrown. Sometimes this is not desired behavior. For these cases, BeanUtil offers silent implementation that does not throw any exception at all.

Maps and lists instead of beans

You can pass maps and list instead of beans as a root object. Just omit the bean name (since we do not work on a bean anymore):

    Properties properties = new Properties();
    BeanUtil.pojo.setProperty(property, "[ldap.auth.enabled]", "true");

Testing of property existence

BeanUtil also offers convenient way to test if some property exists:

    BeanUtil.pojo.hasProperty(fb, "fooInteger")

Type conversion

When setting properties, BeanUtil converts type of provided value to match the destination. For this purpose it uses Jodds type converter utility.

Getting properties always returns an Object. If you need to cast it to some type, you can use TypeConverterManager#convertType. The following snippet (from Liferay portal) shows the usage:

    public boolean getBoolean(Object bean, String param, boolean defaultValue) {
        Boolean booleanValue = null;
        if (bean != null) {
            Object value = BeanUtil.pojo.getProperty(bean, param);
            beanValue = TypeConverterManager.convertType(value, Boolean.class);
        } catch (Exception ex) {
            // log error
        }
        if (booleanValue == null) {
            return defaultValue;
        } else {
            return booleanValue.booleanValue();
        }
    }

BeanUtilBean

BeanUtil is just an intreface. BeanUtilBean is the class that contains all the logic. You can create your variant of bean utilities and share it in your code. It should be thread-safe.

BeanCopy

There is more: BeanCopy class offers copying functionality. It copies properties from source to destination bean.

BeanTemplateParser

BeanTemplateParser is based on StringTemplateParser. a string template with JSP-alike markers that indicates where provided context values will be injected. Usage is quite simple:

    // prepare template
    String template = "Hello ${user.name}. Today is ${dayName}.";
    ...

    // prepare context
    Foo foo = new Foo();
    foo.getUser().setName("John Doe");
    foo.setDayName("Saturday");
    ...
    // parse
    BeanTemplateParser btp = new BeanTemplateParser();
    String result = btp.parse(template, foo);
    // result == "Hello John Doe. Today is Saturday."

Performance test

BeanUtil seems almost 20% faster compared to Commons BeanUtils v1.8. However, the performance is not the only reason why BeanUtil is a good choice, as seen above.

BeanUtil performance test