commons-digest笔记

本文为转载且为截取的片段，如有需要请访问 原帖

待解析的xml

<?xml version="1.0"?>
<academy name="JAcademy">
	<student name="JavaBoy" division="A">
		<course>
			<id>C1</id>
			<name>JSP</name>
		</course>
		<course>
			<id>C2</id>
			<name>Servlets</name>
		</course>
	</student>
	<student name="JavaGirl" division="B">
		<course>
			<id>C3</id>
			<name>EJB</name>
		</course>
	</student>
	<teacher name="JavaGuru">
		<certification>SCJP</certification>
		<certification>SCWCD</certification>
	</teacher>
	<teacher name="JavaMaster">
		<certification>OCP</certification>
		<certification>SCJP</certification>
		<certification>SCEA</certification>
	</teacher>
</academy>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE digester-rules PUBLIC
   "-//Jakarta Apache //DTD digester-rules XML V1.0//EN"
   "digester-rules.dtd">
<digester-rules>
	<pattern value="academy">
		<object-create-rule classname="cn.com.legendapl.xmldigest.config.ConfigBean" />
		<set-properties-rule />
		
		<pattern value="student">
			<object-create-rule classname="cn.com.legendapl.xmldigest.config.StudentBean" />
			<set-properties-rule />
			<pattern value="course">
				<object-create-rule classname="cn.com.legendapl.xmldigest.config.CourseBean" />
				<set-properties-rule />
				<bean-property-setter-rule pattern="id" />
				<bean-property-setter-rule pattern="name" />
				<set-next-rule methodname="addCourseBean" />
			</pattern>
			<set-next-rule methodname="addStudentBean" />
		</pattern>
		
		<pattern value="teacher">
			<object-create-rule classname="cn.com.legendapl.xmldigest.config.TeacherBean" />
			<set-properties-rule />
			<call-method-rule pattern="certification" methodname="addCertification" paramcount="1"/>
			<call-param-rule pattern="certification" paramnumber="0"/>
			<set-next-rule methodname="addTeacherBean" />
		</pattern>
	</pattern>
</digester-rules>

四个配置类。为了简单和节约博客的空间，getter/setter已删去。

public class AcademyBean {

	private String name;
	private List<StudentBean> studentList = new ArrayList<StudentBean>();
	private List<TeacherBean> teacherList = new ArrayList<TeacherBean>();
	
	public static URL getRuleFile() {
		return AcademyBean.class.getClassLoader().getResource("cn/com/legendapl/xmldigest/config/rule.xml");
	}

	public void addTeacherBean(TeacherBean bean) {
		this.teacherList.add(bean);
	}

	public void addStudentBean(StudentBean bean) {
		this.studentList.add(bean);
	}
}

public class StudentBean {

	private String name;
	private String division;
	
	private List<CourseBean> courseBeans = new ArrayList<CourseBean>();
	
	public void addCourseBean(CourseBean bean) {
		courseBeans.add(bean);
	}
}

public class CourseBean {
	private String id;
	private String name;
}

public class TeacherBean {

	private String name;
	private Set<String> certifications = new HashSet<String>();

	public void addCertification(String certification) {
		this.certifications.add(certification);
	}
}

读取配置的工具类也可以做一个

public final class ConfigUtils {

	private ConfigUtils() {}
	
	private static AcademyBean config = null;
	
	public static AcademyBean getConfig() {
		if (config == null) {
			Digester digester = DigesterLoader.createDigester(AcademyBean.getRuleFile());
			try {
				config = (AcademyBean)digester.parse(ConfigUtils.class.getClassLoader().getResource("academy.xml"));
			} catch (Exception e) {
				throw new RuntimeException(e.getMessage(), e);
			}
		}
		return config;
	}
	
}

下面还有一个更详细的参考
http://onjava.com/pub/a/onjava/2002/10/23/digester.html

附件里放着rule.xml的dtd文件开放时放在rule.xml同一个目录即可