XsdParser：一种将XSD文件解析为Java结构的解析器

[](https://search.maven.org/#artifactdetails%7Ccom.github.xmlet%7CxsdParser%7C1.0.7%7Cjar) [](https://sonarcloud.io/dashboard?id=com.github.xmlet%3AxsdParser) [](https://sonarcloud.io/component_measures/domain/Coverage?id=com.github.xmlet%3AxsdParser) [](https://sonarcloud.io/dashboard?id=com.github.xmlet%3AxsdParser) [](https://sonarcloud.io/dashboard?id=com.github.xmlet%3AxsdParser) # XsdParser <div align="justify"> XsdParser is a library that parses a XML Definition file (.xsd) into a list of java objects. Each different XSD tag has a corresponding Java class and the attributes of a given XSD type are represented as fields of that class. All these classes derive from the same abstract class, <i>XsdAbstractElement</i>. All Java representations of the XSD elements follow the schema definition for XSD. For example, the <i>xsd:annotation</i> tag only allows <i>xsd:appinfo</i> and <i>xsd:documentation</i> as children nodes, and also can have an attribute named <i>id</i>, therefore XsdParser has the following class (simplified for example purposes): <br /> <br /> </div> ```java public class XsdAnnotation extends XsdAbstractElement { private String id; private List<XsdAppInfo> appInfoList = new ArrayList<>(); private List<XsdDocumentation> documentations = new ArrayList<>(); // (...) } ``` <div align="justify"> The set of rules followed by this library can be consulted in the following URL: <a href="http://www.datypic.com/sc/xsd/s-xmlschema.xsd.html">XSD Schema</a> </div> ## Installation <div align="justify"> First, in order to include it to your Maven project, simply add this dependency: <br /> <br /> </div> ```xml <dependency> <groupId>com.github.xmlet</groupId> <artifactId>xsdParser</artifactId> <version>1.1.2</version> </dependency> ``` ## Usage example <div align="justify"> A simple example: <br /> <br /> </div> ```java public class ParserApp { public static void main(String [] args) { String filePath = "Your file path here."; XsdParser parserInstance1 = new XsdParser(filePath); //or String jarPath = "Your jar path here."; String jarXsdPath = "XSD file path, relative to the jar root."; XsdParserJar parserInstance2 = new XsdParserJar(jarPath, jarXsdPath); Stream<XsdElement> elementsStream = parserInstance1.getResultXsdElements(filePath); Stream<XsdSchema> schemasStream = parserInstance1.getResultXsdSchemas(filePath); } } ``` <div align="justify"> After parsing the file like shown above it's possible to start to navigate in the resulting parsed elements. In the image below it is presented the class diagram that could be useful before trying to start navigating in the result. There are multiple abstract classes that allow to implement shared features and reduce duplicated code. <br /> <br /> <img src="https://raw.githubusercontent.com/xmlet/XsdParser/master/src/main/java/org/xmlet/xsdparser/xsdelements/xsdelements.png"/> </div> ### Navigation <div align="justify"> Below a simple example is presented. After parsing the XSD snippet the parsed elements can be accessed with the respective java code. <br /> <br /> </div> ```xml <?xml version='1.0' encoding='utf-8' ?> <xsd:schema xmlns='http://schemas.microsoft.com/intellisense/html-5' xmlns:xsd='http://www.w3.org/2001/XMLSchema'> <xsd:group name="flowContent"> <xsd:all> <xsd:element name="elem1"/> </xsd:all> </xsd:group> <xs:element name="html"> <xs:complexType> <xsd:choice> <xsd:group ref="flowContent"/> </xsd:choice> <xs:attribute name="manifest" type="xsd:anyURI" /> </xs:complexType> </xs:element> </xsd:schema> ``` <div align="justify"> The result could be consulted in the following way: <br /> <br /> </div> ```java public class ParserApp { public static void main(String [] args) { //(...) XsdElement htmlElement = elementsStream.findFirst().get(); XsdComplexType htmlComplexType = htmlElement.getXsdComplexType(); XsdAttribute manifestAttribute = htmlComplexType.getXsdAttributes().findFirst().get(); XsdChoice choiceElement = htmlComplexType.getChildAsChoice(); XsdGroup flowContentGroup = choiceElement.getChildrenGroups().findFirst().get(); XsdAll flowContentAll = flowContentGroup.getChildAsAll(); XsdElement elem1 = flowContentAll.getChildrenElements().findFirst().get(); } } ``` ## Parsing Strategy <div align="justify"> In order to minimize the number of passages in the file, which take more time to perform, this library chose to parse all the elements and then resolve the references present. To parse the XSD file we use the DOM library, which converts all the XSD elements into <i>Node</i> objects, from where we extract all the XSD information into our XSD respective classes. <br /> <br /> Our parse process is also based on a tree approach, which means that when we invoke the <i>XsdSchema parse</i> function the whole document will be parsed, because each <i>XsdAbstractElement</i> class extracts its respective information, i.e. a <i>XsdSchema</i> instance extracts information from the received xsd:schema <i>Node</i> object, and also invokes the respective parse function for each children elements present in its current <i>Node</i> object. </div> ### Type Validations <div align="justify"> This library was born with an objective in mind, it should strictly follow the XSD language rules. To guarantee that we used the Visitor pattern. We used this pattern to add a layer of control regarding different XSD types interactions. In the presented code snippet we can observe how this works: <br /> <br /> </div> ```java class XsdComplexContentVisitor extends XsdAnnotatedElementsVisitor { private final XsdComplexContent owner; @Override public void visit(XsdRestriction element) { owner.setRestriction(ReferenceBase.createFromXsd(element)); } @Override public void visit(XsdExtension element) { owner.setExtension(ReferenceBase.createFromXsd(element)); } } ``` <div align="justify"> In this example we can see that <i>XsdComplexContentVisitor</i> class only implements two methods, <i>visit(XsdRestriction element)</i> and <i>visit(XsdExtension element)</i>. This means that the <i>XsdComplexContentVisitor</i> type only allows these two types, i.e. <i>XsdRestriction</i> and <i>XsdExtension</i>, to interact with <i>XsdComplexContent</i>, since these two types are the only types allowed as <i>XsdComplexContent</i> children elements. </div> <div align="justify"> The XSD syntax also especifies some other restrictions, namely regarding attribute possible values or types. For example the <i>finalDefault</i> attribute of the xsd:schema elements have their value restricted to six distinct values: <br /> <br /> <ul> <li> DEFAULT ("") </li> <li> EXTENSION ("extension") </li> <li> RESTRICTION ("restriction") </li> <li> LIST("list") </li> <li> UNION("union") </li> <li>