需要用到的net.sf.json和org.dom4j 本例用的包为： json-lib-2.4-jdk15.jar dom4j-1.6.1.jar
引入包之后，直接复制下面这个工具类使用
package com.java; import net.sf.json.JSONArray; import net.sf.json.JSONObject; import org.dom4j.Document; import org.dom4j.DocumentException; import org.dom4j.DocumentHelper; import org.dom4j.Element; import java.io.*; import java.util.Arrays; import java.util.List; /** * JSON与XML互转，工具类 */ public class JsonXmlUtil { private static final char EOFC = (char) -1; /** * JSON 转 XML * * @param jsonString JSON字符串 */ public static String getXmlFromJson(String jsonString) throws IOException { InputStream in = new ByteArrayInputStream(jsonString.getBytes()); ByteArrayOutputStream out = new ByteArrayOutputStream(); translate(in, out); return out.toString(); } /** * 将xml转换为JSON对象 * * @param xml xml字符串 */ public static JSONObject getJsonFromXml(String xml) throws Exception { return getJsonFromXml(xml, ""); } /** * 将xml转换为JSON对象 * * @param xml xml字符串 * @param parseArrayNames （如果xml中的一个节点不是数组，而你又需要将它转化为json数组），请填写该节点名称，多个值时用逗号分隔 * @return * @throws Exception */ public static JSONObject getJsonFromXml(String xml, String parseArrayNames) throws DocumentException { JSONObject jsonObject = new JSONObject(); Document document = DocumentHelper.parseText(xml); //获取根节点元素对象 Element root = document.getRootElement(); iterateNodes(root, jsonObject, parseArrayNames); return jsonObject; } /** * 将 JSON输入流 转化为 XML输出流 */ private static void translate(InputStream in, OutputStream out) throws IOException, IllegalArgumentException { InputStreamReader re = new InputStreamReader(in); char c; while ((c = (char) re.read()) != EOFC) { switch (c) { case '{': translateObject(re, out); break; case '[': translateArray(re, out, null); break; default: if (Character.isSpaceChar(c)) { break; } else { throw new IllegalArgumentException("invalid character:" + c + " (" + (int) c + ")"); } } } } private static void translateArray(InputStreamReader re, OutputStream out, String tname) throws IOException, IllegalArgumentException { char c; while ((c = (char) re.read()) != EOFC) { switch (c) { case '{': translateObject(re, out); break; case '[': translateArray(re, out, tname); break; case ',': if (tname != null) { out.write("</".getBytes()); out.write(tname.getBytes()); out.write("><".getBytes()); out.write(tname.getBytes()); out.write(">".getBytes()); } break; case ']': return; case '"': String n = readStringToken(re); if (n != null) { out.write(n.getBytes()); } break; default: if (Character.isSpaceChar(c)) { break; } else { out.write(("" + c).getBytes()); } } } } private static String readStringToken(InputStreamReader re) throws IOException { StringBuilder b = new StringBuilder(); char c; boolean esc = false; while ((c = (char) re.read()) != EOFC) { switch (c) { case '\\': esc = true; break; case 'n': if (!esc) { b.append(c); } else { b.append((char) 10); esc = false; } break; case 'r': if (!esc) { b.append(c); } else { b.append((char) 13); esc = false; } break; case 't': if (!esc) { b.append(c); } else { b.append((char) 9); esc = false; } break; case 'u': if (!esc) { b.append(c); } else { StringBuilder sb = new StringBuilder(6); sb.append("0x"); sb.append((char) re.read()); sb.append((char) re.read()); sb.append((char) re.read()); sb.append((char) re.read()); b.append((char) Integer.decode(sb.toString()).intValue()); esc = false; } break; case '"': if (!esc) { return b.toString(); } default: b.append(c); esc = false; } } return b.toString(); } private static boolean translateValue(InputStreamReader re, OutputStream out, String tname) throws IOException, IllegalArgumentException { char c; while ((c = (char) re.read()) != EOFC) { switch (c) { case '[': translateArray(re, out, tname); return false; case '{': translateObject(re, out); return false; case '"': String v = readStringToken(re); outs(out, v); return false; case 'n': re.read(); // u re.read(); // l re.read(); // l return false; case ' ': break; case '}': return true; case ',': return false; default: outc(out, c); break; } } return false; } private static void outs(OutputStream out, String s) throws IOException { if (s != null) { for (int i = 0, l = s.length(); i < l; i++) { outc(out, s.charAt(i)); } } } private static void outc(OutputStream out, char c) throws IOException { switch (c) { case '<': out.write("<".getBytes()); break; case '>': out.write(">".getBytes()); break; case '\"': out.write(""".getBytes()); break; case '&': out.write("&".getBytes()); break; case '\'': out.write("'".getBytes()); break; default: // if (c > 0x7f) { // if (c < 0x400 || c > 0x4FF) { // out.write(("&#" + ((int) c) + ";").getBytes()); // } else { // out.write(("" + c).getBytes()); // } // } else { // out.write(("" + c).getBytes()); // } out.write(("" + c).getBytes()); } } private static void translateObject(InputStreamReader re, OutputStream out) throws IOException, IllegalArgumentException { char c; String field = null; while ((c = (char) re.read()) != EOFC) { switch (c) { case ':': if (field != null) { out.write("<".getBytes()); out.write(field.getBytes()); out.write(">".getBytes()); } boolean eoo = translateValue(re, out, field); if (field != null) { out.write("</".getBytes()); out.write(field.getBytes()); out.write(">".getBytes()); } if (eoo) { return; } break; case '"': field = readStringToken(re); break; case '}': return; default: } } } /** * 遍历元素 * * @param node 元素 * @param json 将元素遍历完成之后放进JSON对象 */ private static void iterateNodes(Element node, JSONObject json, String parseArrayNames) { //获取当前元素的名称 String nodeName = node.getName(); List<String> parseArrayNamesList = Arrays.asList(parseArrayNames.split(",")); //判断已遍历的JSON中是否已经有了该元素的名称 if (json.containsKey(nodeName) || parseArrayNamesList.contains(nodeName)) { //该元素在同级下有多个 Object Object = json.get(nodeName); JSONArray array = new JSONArray(); if (Object instanceof JSONArray) { array = (JSONArray) Object; } else if (Object != null) { array = new JSONArray(); array.add(Object); } //获取该元素下所有子元素 List<Element> listElement = node.elements(); if (listElement.isEmpty()) { //该元素无子元素，获取元素的值 String nodeValue = node.getTextTrim(); array.add(nodeValue); json.put(nodeName, array); return; } //有子元素 JSONObject newJson = new JSONObject(); //遍历所有子元素 for (Element e : listElement) { //递归 iterateNodes(e, newJson, parseArrayNames); } array.add(newJson); json.put(nodeName, array); return; } //该元素同级下第一次遍历 //获取该元素下所有子元素 List<Element> listElement = node.elements(); if (listElement.isEmpty()) { //该元素无子元素，获取元素的值 String nodeValue = node.getTextTrim(); json.put(nodeName, nodeValue); return; } //有子节点，新建一个JSONObject来存储该节点下子节点的值 JSONObject object = new JSONObject(); //遍历所有一级子节点 for (Element e : listElement) { //递归 iterateNodes(e, object, parseArrayNames); } json.put(nodeName, object); return; } }用法示例：
import net.sf.json.JSONObject; import static com.java.JsonXmlUtil.getJsonFromXml; import static com.java.JsonXmlUtil.getXmlFromJson; public class MyTest3 { public static void main(String[] args) throws Exception { //json转xml String jsonString = "{\"result\":{\"userList\":[{\"name\":\"zs\",\"age\":21},{\"name\":\"bb\",\"age\":35}]}}"; String xml = getXmlFromJson(jsonString); System.out.println("输入的json为："); System.out.println(jsonString); System.out.println("输出的xml为："); System.out.println(xml); System.out.println("------------------------" + "分割线" + "------------------------"); //xml转json String input_xml = "<result>" + "<userList><name>zs</name><age>21</age></userList>" + "<userList><name>bb</name><age>35</age></userList>" + "</result>"; //JSONObject json = getJsonFromXml(input_xml);//减少xml中userList的个数到1个，对比一下两者的区别 JSONObject json = getJsonFromXml(input_xml, "userList"); System.out.println("输入的xml为："); System.out.println(input_xml); System.out.println("输出的json为："); System.out.println(json); } }效果展示：
