求大神路过，JAXB怎样处理动态集合啊?

[snzke]

就是当我用JAXB转xml字符串为java对象时，里面包含有集合对象。但是集合对象中的类型又不固定。

我想用java的多态来实现，但是好像JAXB并不能识别。

简单核心代码如下：

	import java.sql.ResultSet;
	import java.sql.SQLException;
	import java.util.ArrayList;
	import java.util.List;
	
	import org.springframework.jdbc.core.JdbcTemplate;
	import org.springframework.jdbc.core.RowMapper;
		
	import com.keer.common.domain.ListBean;
	import com.keer.common.domain.Person;
	
	public class Test{
		
		private JdbcTemplate jdbcTemplate;
		
		//这是Test类型
		public String getAc01All() {
			String sql ="select aac001,aac002,aac003 from ac01";
			List<Person> list = jdbcTemplate.query(sql, new RowMapper<Person>(){
				public Person mapRow(ResultSet rs, int rowNum) throws SQLException {
					Person p = new Person();
					p.setAac001(rs.getString("aac001"));
					p.setAac002(rs.getString("aac002"));
					p.setAac003(rs.getString("aac003"));
					return p;
				}
			});
			ListBean<Person> lb = new ListBean<Person>();
			
			String s =list2XML(lb.getClass(),list);	
			
			System.out.println(s);
			return s;
		}


		public String list2XML(Class<?> cla,List<?> list,Class<?> clas){
			StringWriter writer = new StringWriter();
			ListBean lb =null;
			try {
				
				Object o=cla.newInstance();
				if(o instanceof ListBean){
					lb = (ListBean)o;
					lb.setList(list);
				}
				JAXBContext context = null;
				if(null != clas){
					context = JAXBContext.newInstance(cla,clas);
				}else{
					context = JAXBContext.newInstance(cla);
				}
				
				marshallXmlType(lb, writer);
			} catch (Exception e) {
				e.printStackTrace();
			}
			  return writer.toString();
		}
		
		
		public static <T> void marshallXmlType(T value, Writer os) {  
			try {  
				Class<T> clzz = (Class<T>)value.getClass();  
				JAXBContext context = JAXBContext.newInstance(clzz);
				Marshaller m = context.createMarshaller();
				m.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
				m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
				m.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.FALSE);
				m.setAdapter(ListAdapter.class,new ListAdapter<Person>());
				QName name = new QName(clzz.getSimpleName());
				JAXBElement<T> element = new JAXBElement<T>(name, clzz, value);  
				m.marshal(element, os);  
			} catch (JAXBException e) {  
				e.printStackTrace();  
			}
		}
		
		public static void main(String[] args) {
			System.out.println(new PersonInfo().getAc01All());
		}
	}

	//List模型类
	
	import java.util.List;

	import javax.xml.bind.annotation.XmlAttribute;
	import javax.xml.bind.annotation.XmlRootElement;
	import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

	@XmlRootElement(name = "ListBean")
	public class ListBean<T> {
		
		private String name;
		private List<T> list;
		
		@XmlJavaTypeAdapter(ListAdapter.class)
		public List<T> getList() {
			return  list;
		}
	 
		public void setList(List<T> list) {
			this.list = list;
		}
		
		@XmlAttribute
		public String getName() {
			return name;
		}
	 
		public void setName(String name) {
			this.name = name;
		}
	}

	//模型类

	import javax.xml.bind.annotation.XmlAccessType;
	import javax.xml.bind.annotation.XmlAccessorType;
	import javax.xml.bind.annotation.XmlElement;
	import javax.xml.bind.annotation.XmlRootElement;
	import javax.xml.bind.annotation.XmlType;
	
	@XmlRootElement(name = "Person")
	public class Person extends Domain {

		@XmlElement(required = true)
		protected String aac001;
		@XmlElement(required = true)
		protected String aac002;
		@XmlElement(required = true)
		protected String aac003;
	}
	
	//xml2集合转换类
	import java.util.ArrayList;
	import java.util.List;

	import javax.xml.bind.annotation.adapters.XmlAdapter;
	
	public class ListAdapter<T extends Domain> extends XmlAdapter<Domain [], List<Domain>> {

		public T [] marshal(List<Domain> domains) throws Exception {
			Domain [] dos = new Domain[domains.size()];
			int i = 0;
			for (Domain domain : domains) {
				dos[i++] = domain;
				System.out.println(domain.getClass().getSimpleName());
			}
			return (T[]) dos;
		}

		public List<Domain> unmarshal(Domain [] paramValueType) throws Exception {
			List<Domain> list = new ArrayList<Domain>();
			for (Domain domain : list) {
				list.add(domain);
			}
			return list;
		}
	}
	
	//抽象模型类
	
	import java.io.Serializable;

	import javax.xml.bind.annotation.XmlRootElement;
	
	@XmlRootElement(name = "Domain")
	public class Domain implements Serializable {
		private static final long serialVersionUID = -3851152784887793734L;
	}
	

期望输出的xml格式内容为：

	<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
	<ListBean>
		<Domain>
			<aac001>3001415720</aac001>
			<aac002>542336197608166802</aac002>
			<aac003>巴桑</aac003>
		</Domain>
		<Domain>
			<aac001>3001415721</aac001>
			<aac002>542336196407126826</aac002>
			<aac003>罗布卓玛</aac003>
		</Domain>
		<Domain>
			<aac001>3001415722</aac001>
			<aac002>542336196507030020</aac002>
			<aac003>普珍</aac003>
		</Domain>
	</ListBean>

但是现在代码的输出是这样：

	<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
	<ListBean>
		<list>
			<item/>
			<item/>
			<item/>
		</list>
	</ListBean>

[cseu]

泛型类型是可以识别的
要达到你的效果，可以这样改
in ListBean

    @XmlElement(name = "Domain")
    public List<T> getList() {
        return  list;
    }

获取JAXBContext时，

JAXBContext context = JAXBContext.newInstance(ListBean.class,Person.class);

其他不必要的代码都可以删除

[「已注销」]

大神啊我照你说的那样做了，但是要报错：

[javax.xml.bind.JAXBException: class com.keer.common.domain.Person nor any of its super class is known to this context.]

你能不能写一个小小的demo啊，小demo就行了，谢谢

[cseu]

基于你的代码

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import java.util.List;

@XmlRootElement(name = "ListBean")
public class ListBean<T> {

    private String name;
    private List<T> list;

    @XmlElement(name = "Domain")
    public List<T> getList() {
        return list;
    }

    public void setList(List<T> list) {
        this.list = list;
    }

    @XmlAttribute
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import java.io.ByteArrayOutputStream;
import java.util.ArrayList;
import java.util.List;

public class Test {
    public static void main(String[] args) {
        Person person = new Person();
        person.aac001="aac001";
        person.aac002="aac002";
        person.aac003="aac003";

        List<Person> personList = new ArrayList<Person>();
        personList.add(person);

        ListBean<Person> listBean = new ListBean<Person>();
        listBean.setList(personList);

        try {
            JAXBContext context = JAXBContext.newInstance(ListBean.class, Person.class);
            Marshaller m = context.createMarshaller();
            m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);

            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            m.marshal(listBean,outputStream);
            System.out.println(outputStream);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

其他Domain，Person类一样
我这里跑出来结果是

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ListBean>
    <Domain xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="person">
        <aac001>aac001</aac001>
        <aac002>aac002</aac002>
        <aac003>aac003</aac003>
    </Domain>
</ListBean>

[「已注销」]

谢谢你啦 cseu 。问题解决了，原来是我的Person对象里面有多余的注解，而且转换方式也不一样。现在好了。真心感谢你！