Commons Betwixt应用

Betwixt是Apache Commons 的一个工具包，提供将 JavaBean 映射至 XML 文档，以及相反映射的服务。 下面是个简单的例子。把Student 转换成 xml。 Student.java 代码如下：

package betwixt;public class Student {private String studentId;private int studentAge;public String getStudentId() {return studentId;}public void setStudentId(String studentId) {this.studentId = studentId;}public int getStudentAge() {return studentAge;}public void setStudentAge(int studentAge) {this.studentAge = studentAge;}}

测试代码：

 

 For example:

package betwixt;import java.beans.IntrospectionException;import java.io.FileReader;import java.io.IOException;import java.io.StringWriter;import org.apache.commons.betwixt.IntrospectionConfiguration;import org.apache.commons.betwixt.XMLIntrospector;import org.apache.commons.betwixt.io.BeanWriter;import org.apache.commons.betwixt.strategy.CapitalizeNameMapper;import org.apache.commons.betwixt.strategy.DecapitalizeNameMapper;import org.apache.commons.betwixt.strategy.HyphenatedNameMapper;import org.xml.sax.InputSource;import org.xml.sax.SAXException;public class TestBetwixt {/** * @param args * @throws IntrospectionException * @throws SAXException * @throws IOException */public static void main(String[] args) throws IOException, SAXException,IntrospectionException {StringWriter outputWriter = new StringWriter();// Betwixt just writes out the bean as a fragment// So if we want well-formed xml, we need to add the prologoutputWriter.write("<?xml version='1.0' ?>");// Create a BeanWriter which writes to our prepared streamBeanWriter br = new BeanWriter(outputWriter);XMLIntrospector introspector = new XMLIntrospector();HyphenatedNameMapper hp = new HyphenatedNameMapper(); //letter is hyphen as mp3File ==> mp3-fileDecapitalizeNameMapper dp = new DecapitalizeNameMapper(); //letter is lowerCapitalizeNameMapper cp = new CapitalizeNameMapper(); //letter is capitalIntrospectionConfiguration config = new IntrospectionConfiguration();config.setAttributesForPrimitives(false);config.setElementNameMapper(cp);config.setAttributeNameMapper(hp);introspector.setConfiguration(config);br.setXMLIntrospector(introspector);// Sets "/t" used for pretty print indentsbr.setIndent("/t");// Set whether generated ID attribute values should be added to the// elements If this property is set to false, thenbr.getBindingConfiguration().setMapIDs(false);// Switch on formatted output.br.enablePrettyPrint();// empty elements will be written as <a><a></a> when true,will be written// as <a></a> when false.br.setEndTagForEmptyElement(true);br.writeXmlDeclaration("");// beanWriter.write("Msg", music);Student student = new Student();student.setStudentId("asdf");student.setStudentAge(234);br.write(student);System.out.println(outputWriter.toString());outputWriter.close();}}
print 如下:

<?xml version='1.0' ?>  <Student>    <StudentAge>234</StudentAge>    <StudentId>asdf</StudentId>  </Student> 

我们也可以指定一个模板。模板的名字同bean名称相同，后缀为.betwixt。 Student.betwixt 如下：

<info primitiveTypes="element"> <element name="student">          <element name="student_number" property="studentId"/>            <element name="student_age" property="studentAge"/>  </element></info> 

test 代码改为:

FileReader fileReader = new FileReader("Student.betwixt"); InputSource is = new InputSource(fileReader); XMLIntrospector introspector = new XMLIntrospector(); // Registers Student class mapping Student-betwixt file. introspector.register(Student.class, is); introspector.getConfiguration().setAttributesForPrimitives(false); br.setXMLIntrospector(introspector);

print message as follows:

 

<?xml version='1.0' ?> <student> <student_number>asdf</student_number> <student_age>234</student_age> </student>

 

上面我们介绍的是单个javaBean的映射。下面介绍下映射多个javaBean的情况。 为了能在单个文件中匹配多个不同的类, 这个xml格式文档扩展了 .betwixt文件. root element 是<betwixt-config>.它包含了一个或多个class elements。每个指定的class为了映射到对应的javaBean。

   <?xml version="1.0"?>  <betwixt-config>  <!--name of the class to map -->   <class name="org.some.package.MyClass">   <!-- standard definitions (same as in standard .betwixt file)    -->     <element name="repository-registration-result">       <element name="repository-id" property="repositoryId"/>       <element name="id-mapping" property="idMapping" class="org.some.package.SomeOtherClass"/>       <element name="status" property="status"/>       <element name="exception" property="exception"/>       <element name="primary-luid" property="primaryLuid"/>       <addDefaults add-properties='false'/>     </element>   </class>  ...   <!--additional class mappings -->   <class>  ...   </class>  ...  </betwixt-config>