目录

1、导入用到的jar包

2、xml格式转换为json格式

3、json格式转换为xml格式


我们经常会碰到Json和Xml相互转换,但是转换过程中经常出现各种奇葩问题,比如多节点了或少节点了,或者转换后的格式不对,多了空数组,还有就是遇到带属性的xml格式转换完之后属性没了等等,今天就手把手教你完美解决这些坑。上代码

1、导入用到的jar包

<dependency>
	<groupId>net.sf.json-lib</groupId>
	<artifactId>json-lib</artifactId>
	<version>2.4</version>
    <!-- 加入jdk15,不然jar包下载不下来 -->
	<classifier>jdk15</classifier>
</dependency>
<dependency>
	<groupId>xom</groupId>
	<artifactId>xom</artifactId>
	<version>1.2.5</version>
	<type>jar</type>
	<scope>compile</scope>
</dependency>

<!-- json 转xml用 -->
<dependency>
	<groupId>org.dom4j</groupId>
	<artifactId>dom4j</artifactId>
	<version>2.0.0</version>
</dependency>

2.1、xml格式转换为json格式

会丢失节点,如以下列子会丢student节点,但是如果xml存在属性节点,该方法不会丢失,会转换为@+属性名称

public static void main(String[] args) {
	String dest="";
	String result="<?xml version="1.0" encoding="UTF-8"?><class><name>实验1班</name><no>2020</no><students><student><name>张三</name><sex>女</sex></student><student><name>李四</name><sex>男</sex></student></students></class>
" ;
	if (result != null) {
		Pattern p = Pattern.compile("\\s{3,}|\t|\r|\n");//去掉多余的空格(跳过开头<?xml version="1.0" encoding="UTF-8"/>中的空格)
		Matcher m = p.matcher(result);
		dest = m.replaceAll("");
		System.out.println(dest);
	}
	//将xml转为json(注:如果是元素的属性,会在json里的key前加一个@标识)
	XMLSerializer xmlSerializer = new XMLSerializer();
	//将输出的[]转换为""
	String json = xmlSerializer.read(dest).toString().replace("[]", "\"\"");
	System.out.println(json);
    //{"name":"实验1班","no":"2020","students":[{"name":"张三","sex":"女"},{"name":"李四","sex":"男"}]}
}

最终的结果为

{
    "name": "实验1班",
    "no": "2020",
    "students": [
        {
            "name": "张三",
            "sex": "女"
        },
        {
            "name": "李四",
            "sex": "男"
        }
    ]
}

2.2 xml 转json格式(不会丢失节点)

该方法是先将xml转换为map,再转为json,但是该方法会丢失xml的属性节点。

import net.sf.json.JSONObject;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;

import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class XmlToJson {
    public static void main(String[] args) {
        String dest="";
        String xmlStr="<?xml version=\"1.0\" encoding=\"UTF-8\"?><class><name>实验1班</name><no>2020</no><students><student><name>张三</name><sex>女</sex></student><student><name>李四</name><sex>男</sex></student></students></class>" ;
        if (!"".equals(xmlStr)) {
            Pattern p = Pattern.compile("\\s{3,}|\t|\r|\n");//去掉多余的空格和换行(跳过开头<?xml version="1.0" encoding="UTF-8"/>中的空格)
            Matcher m = p.matcher(xmlStr);
            dest = m.replaceAll("");
        }
        Map<String, Object> stringObjectMap = Xml2Map(dest);
        JSONObject jsonObject = (JSONObject) JSONObject.fromObject(stringObjectMap);
        System.out.println(jsonObject);
    //{"no":"2020","name":"实验1班","students":{"student":[{"sex":"女","name":"张三"},{"sex":"男","name":"李四"}]}}
    }

    public static Map<String, Object> Xml2Map(String result) {
        Document doc = null;
        try {
            doc = DocumentHelper.parseText(result);
        } catch (DocumentException e) {
            e.printStackTrace();
        }
        Map<String, Object> map = new HashMap<String, Object>();
        if (result == null) {
            return map;
        }
        Element root = doc.getRootElement();
        for (Iterator iterator = root.elementIterator(); iterator.hasNext();) {
            Element e = (Element) iterator.next();
            List list = e.elements();
            if (list.size() > 0) {
                map.put(e.getName(), Element2Map(e));
            } else
                map.put(e.getName(), e.getText());
        }
        return map;
    }

    public static Map Element2Map(Element e) {
        Map map = new HashMap();
        List list = e.elements();
        if (list.size() > 0) {
            for (int i = 0; i < list.size(); i++) {
                Element iter = (Element) list.get(i);
                List mapList = new ArrayList();

                if (iter.elements().size() > 0) {
                    Map m = Element2Map(iter);
                    if (map.get(iter.getName()) != null) {
                        Object obj = map.get(iter.getName());
                        if (!obj.getClass().getName()
                                .equals("java.util.ArrayList")) {
                            mapList = new ArrayList();
                            mapList.add(obj);
                            mapList.add(m);
                        }
                        if (obj.getClass().getName()
                                .equals("java.util.ArrayList")) {
                            mapList = (List) obj;
                            mapList.add(m);
                        }
                        map.put(iter.getName(), mapList);
                    } else
                        map.put(iter.getName(), m);
                } else {
                    if (map.get(iter.getName()) != null) {
                        Object obj = map.get(iter.getName());
                        if (!obj.getClass().getName().equals("java.util.ArrayList")) {
                            mapList = new ArrayList();
                            mapList.add(obj);
                            mapList.add(iter.getText());
                        }
                        if (obj.getClass().getName().equals("java.util.ArrayList")) {
                            mapList = (List) obj;
                            mapList.add(iter.getText());
                        }
                        map.put(iter.getName(), mapList);
                    } else
                        map.put(iter.getName(), iter.getText());
                }
            }
        } else
            map.put(e.getName(), e.getText());
        return map;
    }
}

转换结果符合要求,没有丢失节点

{
    "no": "2020",
    "name": "实验1班",
    "students": {
        "student": [
            {
                "sex": "女",
                "name": "张三"
            },
            {
                "sex": "男",
                "name": "李四"
            }
        ]
    }
}

 

3、json格式转换为xml格式

假设我们要把刚才转出的json转换为xml

public static void main(String[] args) {
    String jsonStr = "{"name":"实验1班","no":"2020","students":[{"name":"张三","sex":"女"},{"name":"李四","sex":"男"}]}";
    String xmlStr = json2XmlString(jsonStr,"class");
    System.out.println(xmlStr);
    //<?xml version="1.0" encoding="utf-8"?><class><name>实验1班</name><no>2020</no><students><name>张三</name><sex>女</sex><name>李四</name><sex>男</sex></students></class>

}

/**
* 
* @param jsonStr json字符串
* @param rootName xml 最外层节点名称,如<class></class>
* @return
*/
public static String json2XmlString(String jsonStr,String rootName){
	StringBuffer sb = new StringBuffer();
	String xmlStr = "";
	JSONObject json = JSONObject.fromObject(jsonStr);
	XMLSerializer xmlSerializer = new XMLSerializer();
	xmlSerializer.setRootName(rootName);
	xmlSerializer.setTypeHintsEnabled(false);
	String xml = xmlSerializer.write(json);
	xml = xml.replace("<o>", "").replace("</o>", "");
	xml = xml.replace("<e>", "").replace("</e>", "");
	xml = xml.replaceAll("\r\n", "").concat("\r\n");
	Document document;

	try {
		document = DocumentHelper.parseText(xml);
		xmlStr = document.getRootElement().asXML();
	} catch (DocumentException e) {
		e.printStackTrace();
	}
	sb.append("<?xml version=\"1.0\" encoding=\"utf-8\"?>")
			.append(xmlStr);
	return sb.toString();
}

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