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 prolog outputWriter.write("<?xml version='1.0' ?>"); // Create a BeanWriter which writes to our prepared stream BeanWriter br = new BeanWriter(outputWriter); XMLIntrospector introspector = new XMLIntrospector(); HyphenatedNameMapper hp = new HyphenatedNameMapper(); //letter is hyphen as mp3File ==> mp3-file DecapitalizeNameMapper dp = new DecapitalizeNameMapper(); //letter is lower CapitalizeNameMapper cp = new CapitalizeNameMapper(); //letter is capital IntrospectionConfiguration config = new IntrospectionConfiguration(); config.setAttributesForPrimitives(false); config.setElementNameMapper(cp); config.setAttributeNameMapper(hp); introspector.setConfiguration(config); br.setXMLIntrospector(introspector); // Sets "/t" used for pretty print indents br.setIndent("/t"); // Set whether generated ID attribute values should be added to the // elements If this property is set to false, then br.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>