Dozer supports copying an object by reference. No conversion/transformation is done for such objects. This approach allows to decrease a number of object allocations, but is applicable only when Java Beans are to be thrown away (Garbage Collected) after transformation. This approach is generally recommended for performance tuning of the mapping process when possible. Make sure that both object types are the same or you will run into casting problems. The default value is 'false'.
<field copy-by-reference="true">
<a>copyByReference</a>
<b>copyByReferencePrime</b>
</field>
This is also supported at the class level. Just define the classes you want to be copied by reference in the configuration block.
<configuration>
...
<copy-by-references>
<copy-by-reference>
org.dozer.vo.NoExtendBaseObjectGlobalCopyByReference
</copy-by-reference>
</copy-by-references>
</configuration>
On the class level wildcard expressions are allowed. Copy by reference is applied via mask, which can inlcude multiple wildcard (*) characters.
<configuration>
...
<copy-by-references>
<copy-by-reference>
org.dozer.vo.*
</copy-by-reference>
<copy-by-reference>
org.dozer.*.vo.*DTO
</copy-by-reference>
</copy-by-references>
</configuration>
Using a field mapping it is possible to map where N == 0 (self, or this). In the following example SimpleAccount is mapped to Address. It is also mapped to Account. Suppose Address was an attribute on Account. How could we map the values on SimpleAccount to that property? The answer is to use the keyword (this) to denote using the class being mapped as the source object.
<mapping>
<classa>org.dozer.vo.self.SimpleAccount</classa>
<classb>org.dozer.vo.self.Account</classb>
<field>
<a>this</a>
<b>address</b>
</field>
</mapping>
<mapping>
<classa>org.dozer.vo.self.SimpleAccount</classa>
<classb>org.dozer.vo.self.Address</classb>
<field>
<a>streetName</a>
<b>street</b>
</field>
</mapping>