JAXB 如何序列化List<Map<String, String>>

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JAXB 如何序列化List<Map<String, String>>5

bean结构简单如下

public class User {
	private int count;
	private List<Map<String, String>> rows;
        
｝

getter、setter省略
如何才能序列化成下面的格式

<user>
	<count></count>
	<rows>
		<row>
			<id></id>
			<name></name>
		</row>
		<row>
			<id></id>
			<name></name>
		</row>
	</rows>
<user>

其中id、name为Map中的Key。
望各位不吝赐教，谢谢

jaxb

2013年9月29日 15:10

coolbeer
26
0 0 3

1个答案按时间排序按投票排序

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采纳的答案

import java.io.StringReader;
import java.io.StringWriter;
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.JAXBContext;
import javax.xml.bind.JAXBException;
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.adapters.XmlAdapter;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

@XmlRootElement(name = "user")
@XmlAccessorType(XmlAccessType.FIELD)
public class User {

	/**
	 * 
	 *JAXB XML适配器
	 *
	 */
	public static class UserRowsXmlAdapter extends
			XmlAdapter<Object, List<Map<String, String>>> {

		/**
		 * 把 JAVA转化成ELEMENT对象
		 */
		@Override
		public Object marshal(List<Map<String, String>> rows) throws Exception {

			DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
			DocumentBuilder db = dbf.newDocumentBuilder();
			Document document = db.newDocument();
			Element rootElement = document.createElement("myrows");// 这里名字随便,以外面为准,JAXB会自动替换名字的
			document.appendChild(rootElement);

			for (Map<String, String> row : rows) {

				Element rowEle = document.createElement("row");

				Element idEle = document.createElement("id");
				Element nameEle = document.createElement("name");

				Entry<String, String> entry = row.entrySet().iterator().next();// 第一个ENTRY
				String id = entry.getKey();// ID
				String name = entry.getValue();// NAME

				idEle.setTextContent(id);
				nameEle.setTextContent(name);
				rowEle.appendChild(idEle);
				rowEle.appendChild(nameEle);
				rootElement.appendChild(rowEle);
			}
			return rootElement;
		}

		/**
		 * 把XML ELEMENT转化成JAVA对象
		 */
		@Override
		public List<Map<String, String>> unmarshal(Object rowsElement)
				throws Exception {

			if (rowsElement == null) {
				return null;
			}

			Element rowsEle = (Element) rowsElement;

			NodeList rowNodes = rowsEle.getChildNodes();
			int rowCount = (rowNodes == null ? 0 : rowNodes.getLength());
			if (rowCount == 0) {
				return null;
			}
			List<Map<String, String>> result = new ArrayList<Map<String, String>>(
					rowCount);

			for (int i = 0; i < rowCount; i++) {
				Node rowNode = rowNodes.item(i);
				if (!"row".equals(rowNode.getNodeName())) {
					System.out.println("发现非法节点:" + rowNode.getNodeName()
							+ "忽略.");
					continue;
				}
				NodeList idNameNodes = rowNode.getChildNodes();
				int nodeSize = (idNameNodes == null ? 0 : idNameNodes
						.getLength());
				if (nodeSize == 0) {
					continue;
				}
				Map<String, String> row = new HashMap<String, String>();
				String id = null;
				String name = null;
				for (int j = 0; j < nodeSize; j++) {
					Node node = idNameNodes.item(j);
					String nodeName = node.getNodeName();
					String nodeValue = node.getTextContent();
					if ("id".equals(nodeName)) {
						id = nodeValue;
					} else if ("name".equals(nodeName)) {
						name = nodeValue;
					}
					if (id != null && name != null) {
						break;
					}
				}

				if (id != null) {
					row.put(id, name);
				} else {
					System.out.println("未在row节点里发现id节点,忽略.");
				}
				result.add(row);
			}

			return result;
		}

	}
	
	@XmlElement(name="count")
	private int count;
	@XmlElement(name="rows")
	@XmlJavaTypeAdapter(UserRowsXmlAdapter.class)
	private List<Map<String, String>> rows;

	public int getCount() {
		return count;
	}

	public void setCount(int count) {
		this.count = count;
	}

	public List<Map<String, String>> getRows() {
		return rows;
	}

	public void setRows(List<Map<String, String>> rows) {
		this.rows = rows;
	}

	@Override
	public String toString() {
		return "User [count=" + count + ", rows=" + rows + "]";
	}

	public static void main(String[] args) throws JAXBException {
		User u = new User();
		List<Map<String, String>> rows = new ArrayList<Map<String, String>>(2);
		Map<String, String> row = new HashMap<String, String>();
		row.put("1", "土豆");// userid=1,username=土豆
		rows.add(row);
		row = new HashMap<String, String>();
		row.put("2", "洋葱");// userid=2,username=洋葱
		rows.add(row);
		u.setCount(rows.size());
		u.setRows(rows);

		JAXBContext jc = JAXBContext.newInstance(User.class);
		StringWriter writer = new StringWriter();
		jc.createMarshaller().marshal(u, writer);
		System.out.println("Marshalled xml==>");
		System.out.println(writer);
		String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>"
				+ "<user><count>2</count><rows><row><id>1</id><name>土豆</name>"
				+ "</row><row><id>2</id><name>洋葱</name>"
				+ "</row></rows></user>";

		User newu = (User) jc.createUnmarshaller().unmarshal(
				new StringReader(xml));
		System.out.println("UnMarshalled user==>");
		System.out.println(newu);
	}

}

输出结果：


Marshalled xml==>

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><user><count>2</count><rows><row><id>1</id><name>土豆</name></row><row><id>2</id><name>洋葱</name></row></rows></user>

UnMarshalled user==>

User [count=2, rows=[{1=土豆}, {2=洋葱}]]

2013年9月29日 20:40

anson2003
60
0 0 4