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XML Schema complex types define constructs containing more complex information than a simple type. The most simple complex types define an empty element with an attribute. More intricate complex types are made up of a collection of elements.
By default, an XML Schema complex type is mapped to a Java class, with a member variable to represent each element and attribute listed in the XML Schema definition. The class has setters and getters for each member variable.
XML Schema complex types are defined using the complexType element. The
complexType element wraps the rest of elements used to define the structure of the data. It can
appear either as the parent element of a named type definition, or as the child of an element
element anonymously defining the structure of the information stored in the element. When the
complexType element is used to define a named type, it requires the use of the
name attribute. The name attribute specifies a unique identifier
for referencing the type.
Complex type definitions that contain one or more elements have one of the child elements described in Table 13.1. These elements determine how the specified elements appear in an instance of the type.
Table 13.1. Elements for Defining How Elements Appear in a Complex Type
| Element | Description |
|---|---|
all | All of the elements defined as part of the complex type must appear in an instance of the type. However, they can appear in any order. |
choice | Only one of the elements defined as part of the complex type can appear in an instance of the type. |
sequence | All of the elements defined as part of the complex type must appear in an instance of the type, and they must also appear in the order specified in the type definition. |
![[Note]](imagesdb/note.gif) | Note |
|---|---|
If a complex type definition only uses attributes, you do not need one of the elements described in Table 13.1. |
After deciding how the elements will appear, you define the elements by adding one or more
element element children to the definition.
Example 13.1 shows a complex type definition in XML Schema.
Example 13.1. XML Schema Complex Type
<complexType name="sequence">
<sequence>
<element name="name" type="xsd:string" />
<element name="street" type="xsd:short" />
<element name="city" type="xsd:string" />
<element name="state" type="xsd:string" />
<element name="zipCode" type="xsd:string" />
</sequence>
</complexType>XML Schema complex types are mapped to Java classes. Each element in the complex type definition is mapped to a member variable in the Java class. Getter and setter methods are also generated for each element in the complex type.
All generated Java classes are decorated with the @XmlType annotation. If the mapping is for a named complex type, the annotations name is set to the value of the complexType element's name attribute. If the complex type is defined as part of an element definition, the value of the @XmlType annotation's name property is the value of the element element's name attribute.
| Note |
|---|---|
As described in Java mapping of elements with an in-line type, the generated class is decorated with the
|
To provide the runtime with guidelines indicating how the elements of the XML Schema complex type should be handled, the code generators alter the annotations used to decorate the class and its member variables.
All complex types are defined using the all element. They are annotated as
follows:
The @XmlType annotation's propOrder property is empty.
Each element is decorated with the @XmlElement annotation.
The @XmlElement annotation's required property is set to true.
Example 13.2 shows the mapping for an all complex type with two elements.
Example 13.2. Mapping of an All Complex Type
@XmlType(name = "all", propOrder = {
})
public class All {
@XmlElement(required = true)
protected BigDecimal amount;
@XmlElement(required = true)
protected String type;
public BigDecimal getAmount() {
return amount;
}
public void setAmount(BigDecimal value) {
this.amount = value;
}
public String getType() {
return type;
}
public void setType(String value) {
this.type = value;
}
}Choice complex types are defined using the choice element. They are annotated
as follows:
The @XmlType annotation's propOrder property lists the names of the elements in the order they appear in the XML Schema definition.
None of the member variables are annotated.
Example 13.3 shows the mapping for a choice complex type with two elements.
Example 13.3. Mapping of a Choice Complex Type
@XmlType(name = "choice", propOrder = {
"address",
"floater"
})
public class Choice {
protected Sequence address;
protected Float floater;
public Sequence getAddress() {
return address;
}
public void setAddress(Sequence value) {
this.address = value;
}
public Float getFloater() {
return floater;
}
public void setFloater(Float value) {
this.floater = value;
}
}A sequence complex type is defined using the sequence element. It is annotated
as follows:
The @XmlType annotation's propOrder property lists the names of the elements in the order they appear in the XML Schema definition.
Each element is decorated with the @XmlElement annotation.
The @XmlElement annotation's required property is set to true.
Example 13.4 shows the mapping for the complex type defined in Example 13.1.
Example 13.4. Mapping of a Sequence Complex Type
@XmlType(name = "sequence", propOrder = {
"name",
"street",
"city",
"state",
"zipCode"
})
public class Sequence {
@XmlElement(required = true)
protected String name;
protected short street;
@XmlElement(required = true)
protected String city;
@XmlElement(required = true)
protected String state;
@XmlElement(required = true)
protected String zipCode;
public String getName() {
return name;
}
public void setName(String value) {
this.name = value;
}
public short getStreet() {
return street;
}
public void setStreet(short value) {
this.street = value;
}
public String getCity() {
return city;
}
public void setCity(String value) {
this.city = value;
}
public String getState() {
return state;
}
public void setState(String value) {
this.state = value;
}
public String getZipCode() {
return zipCode;
}
public void setZipCode(String value) {
this.zipCode = value;
}
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