怎么样？
介绍一个称为选项的通用超类：
import javax.xml.bind.annotation.XmlAttribute;public abstract class Options { private String name; @XmlAttribute public String getName() { return name; } public void setName(String name) { this.name = name; }}然后在带有选项列表的类（在本示例中为Configuration）上，在该属性上指定一个@XmlJavaTypeAdapter：
import java.util.ArrayList;import java.util.List;import javax.xml.bind.annotation.XmlRootElement;import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;@XmlRootElementpublic class Configuration { private List<Options> section = new ArrayList<Options>(); @XmlJavaTypeAdapter(OptionsAdapter.class) public List<Options> getSection() { return section; } public void setSection(List<Options> section) { this.section = section; }}XmlAdapter看起来像这样：
import javax.xml.bind.annotation.adapters.XmlAdapter;public class OptionsAdapter extends XmlAdapter<AdaptedOptions, Options> { @Override public Options unmarshal(AdaptedOptions v) throws Exception { if("default_options".equals(v.name)) { DefaultOptions options = new DefaultOptions(); options.setName(v.getName()); options.setDefaultPort(Integer.valueOf(v.map.get("default_port"))); options.setLogLevel(v.map.get("log_level")); return options; } else { CustomOptions options = new CustomOptions(); options.setName(v.getName()); options.setCompatibility(v.map.get("compatibility")); options.setMemory(v.map.get("memory")); return options; } } @Override public AdaptedOptions marshal(Options v) throws Exception { AdaptedOptions adaptedOptions = new AdaptedOptions(); adaptedOptions.setName(v.getName()); if(DefaultOptions.class == v.getClass()) { DefaultOptions options = (DefaultOptions) v; adaptedOptions.map.put("default_port", String.valueOf(options.getDefaultPort())); adaptedOptions.map.put("log_level", options.getLogLevel()); } else { CustomOptions options = (CustomOptions) v; adaptedOptions.map.put("compatibility", options.getCompatibility()); adaptedOptions.map.put("memory", options.getMemory()); } return adaptedOptions; }}AdaptedOptions看起来像：
import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Map.Entry;import javax.xml.bind.Marshaller;import javax.xml.bind.Unmarshaller;import javax.xml.bind.annotation.XmlAttribute;import javax.xml.bind.annotation.XmlElement;import javax.xml.bind.annotation.XmlValue;public class AdaptedOptions extends Options { @XmlAttribute String name; @XmlElement List<Value> value = new ArrayList<Value>(); Map<String, String> map = new HashMap<String, String>(); public void beforeMarshal(Marshaller marshaller) { for(Entry<String, String> entry : map.entrySet()) { Value aValue = new Value(); aValue.name = entry.getKey(); aValue.value = entry.getValue(); value.add(aValue); } } public void afterUnmarshal(Unmarshaller unmarshaller, Object parent) { for(Value aValue : value) { map.put(aValue.name, aValue.value); } } private static class Value { @XmlAttribute String name; @XmlValue String value; }}
