JAXB 如何序列化List<Map<String, String>>

Java代码 收藏代码

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：

Java代码 收藏代码

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}]]