xml与java代码相互装换的工具类

这是一个java操作xml文件的工具类，最大的亮点在于能够通过工具类直接生成xml同样层次结构的java代码，也就是说，只要你定义好了xml的模板，就能一键生成java代码。省下了自己再使用工具类写代码的时间，极大得提高了效率。

开源oschina的git地址：https://git.oschina.net/lv-success/createXml.git
喜欢就点个赞哈。。。。

首先来看看工具类代码

package com.lfq.createXml;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Validator;

import org.apache.commons.lang3.StringUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

/**
* 操作xml文件以及生成java代码的工具
* @author lfq
* @since 1.0, Jun 12, 2007
*/
public final class XmlUtils {

private static final String XMLNS_XSI = "xmlns:xsi";
private static final String XSI_SCHEMA_LOCATION = "xsi:schemaLocation";
private static final String LOGIC_YES = "yes";
private static final String DEFAULT_ENCODE = "UTF-8";
private static final String REG_INVALID_CHARS = "&#\\d+;";

/**
* Creates a new document instance.
*
* @return a new document instance
* @throws XmlException problem creating a new document
*/
public static Document newDocument() throws XmlException {
Document doc = null;

try {
doc = DocumentBuilderFactory.newInstance().newDocumentBuilder()
.newDocument();
} catch (ParserConfigurationException e) {
throw new XmlException(e);
}

return doc;
}

/**
* Parses the content of the given XML file as an XML document.
*
* @param file the XML file instance
* @return the document instance representing the entire XML document
* @throws XmlException problem parsing the XML file
*/
public static Document getDocument(File file) throws XmlException {
InputStream in = getInputStream(file);
return getDocument(in);
}

/**
* Parses the content of the given stream as an XML document.
*
* @param in the XML file input stream
* @return the document instance representing the entire XML document
* @throws XmlException problem parsing the XML input stream
*/
public static Document getDocument(InputStream in) throws XmlException {
Document doc = null;

try {
DocumentBuilder builder = DocumentBuilderFactory.newInstance()
.newDocumentBuilder();
doc = builder.parse(in);
} catch (ParserConfigurationException e) {
throw new XmlException(e);
} catch (SAXException e) {
throw new XmlException(XmlException.XML_PARSE_ERROR, e);
} catch (IOException e) {
throw new XmlException(XmlException.XML_READ_ERROR, e);
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
// nothing to do
}
}
}

return doc;
}

/**
* Creates a root element as well as a new document with specific tag name.
*
* @param tagName the name of the root element
* @return a new element instance
* @throws XmlException problem generating a new document
*/
public static Element createRootElement(String tagName) throws XmlException {
Document doc = newDocument();
Element root = doc.createElement(tagName);
doc.appendChild(root);
return root;
}

/**
* Gets the root element from input stream.
*
* @param in the XML file input stream
* @return the root element of parsed document
* @throws XmlException problem parsing the XML file input stream
*/
public static Element getRootElementFromStream(InputStream in)
throws XmlException {
return getDocument(in).getDocumentElement();
}

/**
* Gets the root element from given XML file.
*
* @param fileName the name of the XML file
* @return the root element of parsed document
* @throws XmlException problem parsing the XML file
*/
public static Element getRootElementFromFile(File file)
throws XmlException {
return getDocument(file).getDocumentElement();
}

/**
* Gets the root element from the given XML payload.
*
* @param payload the XML payload representing the XML file.
* @return the root element of parsed document
* @throws XmlException problem parsing the XML payload
*/
public static Element getRootElementFromString(String payload)
throws XmlException {
if (payload == null || payload.trim().length() < 1) {
throw new XmlException(XmlException.XML_PAYLOAD_EMPTY);
}

byte[] bytes = null;

try {
bytes = payload.getBytes(DEFAULT_ENCODE);
} catch (UnsupportedEncodingException e) {
throw new XmlException(XmlException.XML_ENCODE_ERROR, e);
}

InputStream in = new ByteArrayInputStream(bytes);
return getDocument(in).getDocumentElement();
}

/**
* Gets the descendant elements list from the parent element.
*
* @param parent the parent element in the element tree
* @param tagName the specified tag name
* @return the NOT NULL descendant elements list
*/
public static List<Element> getElements(Element parent, String tagName) {
NodeList nodes = parent.getElementsByTagName(tagName);
List<Element> elements = new ArrayList<Element>();

for (int i = 0; i < nodes.getLength(); i++) {
Node node = nodes.item(i);
if (node instanceof Element) {
elements.add((Element) node);
}
}

return elements;
}

/**
* Gets the immediately descendant element from the parent element.
*
* @param parent the parent element in the element tree
* @param tagName the specified tag name.
* @return immediately descendant element of parent element, NULL otherwise.
*/
public static Element getElement(Element parent, String tagName) {
List<Element> children = getElements(parent, tagName);

if (children.isEmpty()) {
return null;
} else {
return children.get(0);
}
}

/**
* Gets the immediately child elements list from the parent element.
*
* @param parent the parent element in the element tree
* @param tagName the specified tag name
* @return the NOT NULL immediately child elements list
*/
public static List<Element> getChildElements(Element parent, String tagName) {
NodeList nodes = parent.getElementsByTagName(tagName);
List<Element> elements = new ArrayList<Element>();

for (int i = 0; i < nodes.getLength(); i++) {
Node node = nodes.item(i);
if (node instanceof Element && node.getParentNode() == parent) {
elements.add((Element) node);
}
}

return elements;
}

/**
* Gets the immediately child element from the parent element.
*
* @param parent the parent element in the element tree
* @param tagName the specified tag name
* @return immediately child element of parent element, NULL otherwise
*/
public static Element getChildElement(Element parent, String tagName) {
List<Element> children = getChildElements(parent, tagName);

if (children.isEmpty()) {
return null;
} else {
return children.get(0);
}
}

/**
* Gets the value of the child element by tag name under the given parent
* element. If there is more than one child element, return the value of the
* first one.
*
* @param parent the parent element
* @param tagName the tag name of the child element
* @return value of the first child element, NULL if tag not exists
*/
public static String getElementValue(Element parent, String tagName) {
String value = null;

Element element = getElement(parent, tagName);
if (element != null) {
value = element.getTextContent();
}

return value;
}

/**
* Appends the child element to the parent element.
*
* @param parent the parent element
* @param tagName the child element name
* @return the child element added to the parent element
*/
public static Element appendElement(Element parent, String tagName) {
Element child = parent.getOwnerDocument().createElement(tagName);
parent.appendChild(child);
return child;
}

/**
* Appends the child element as well as value to the parent element.
*
* @param parent the parent element
* @param tagName the child element name
* @param value the child element value
* @return the child element added to the parent element
*/
public static Element appendElement(Element parent, String tagName,
String value) {
Element child = appendElement(parent, tagName);
child.setTextContent(value);
return child;
}

/**
* Appends another element as a child element.
*
* @param parent the parent element
* @param child the child element to append
*/
public static void appendElement(Element parent, Element child) {
Node tmp = parent.getOwnerDocument().importNode(child, true);
parent.appendChild(tmp);
}

/**
* Appends the CDATA element to the parent element.
*
* @param parent the parent element
* @param tagName the CDATA element name
* @param value the CDATA element value
* @return the CDATA element added to the parent element
*/
public static Element appendCDATAElement(Element parent, String tagName,
String value) {
Element child = appendElement(parent, tagName);
if (value == null) { // avoid "null" word in the XML payload
value = "";
}

Node cdata = child.getOwnerDocument().createCDATASection(value);
child.appendChild(cdata);
return child;
}

/**
* Converts the Node/Element instance to XML payload.
*
* @param node the node/element instance to convert
* @return the XML payload representing the node/element
* @throws XmlException problem converting XML to string
*/
public static String childNodeToString(Node node) throws XmlException {
String payload = null;

try {
Transformer tf = TransformerFactory.newInstance().newTransformer();

Properties props = tf.getOutputProperties();
props.setProperty(OutputKeys.OMIT_XML_DECLARATION, LOGIC_YES);
tf.setOutputProperties(props);

StringWriter writer = new StringWriter();
tf.transform(new DOMSource(node), new StreamResult(writer));
payload = writer.toString();
payload = payload.replaceAll(REG_INVALID_CHARS, " ");
} catch (TransformerException e) {
throw new XmlException(XmlException.XML_TRANSFORM_ERROR, e);
}

return payload;
}

/**
* Converts the Node/Document/Element instance to XML payload.
*
* @param node the node/document/element instance to convert
* @return the XML payload representing the node/document/element
* @throws XmlException problem converting XML to string
*/
public static String nodeToString(Node node) throws XmlException {
String payload = null;

try {
Transformer tf = TransformerFactory.newInstance().newTransformer();

Properties props = tf.getOutputProperties();
props.setProperty(OutputKeys.INDENT, LOGIC_YES);
props.setProperty(OutputKeys.ENCODING, DEFAULT_ENCODE);
tf.setOutputProperties(props);

StringWriter writer = new StringWriter();
tf.transform(new DOMSource(node), new StreamResult(writer));
payload = writer.toString();
payload = payload.replaceAll(REG_INVALID_CHARS, " ");
} catch (TransformerException e) {
throw new XmlException(XmlException.XML_TRANSFORM_ERROR, e);
}

return payload;
}

/**
* Converts the an XML file to XML payload.
*
* @param file the XML file instance
* @return the XML payload representing the XML file
* @throws XmlException problem transforming XML to string
*/
public static String xmlToString(File file) throws XmlException {
Element root = getRootElementFromFile(file);
return nodeToString(root);
}

/**
* Converts the an XML file input stream to XML payload.
*
* @param in the XML file input stream
* @return the payload represents the XML file
* @throws XmlException problem transforming XML to string
*/
public static String xmlToString(InputStream in) throws XmlException {
Element root = getRootElementFromStream(in);
return nodeToString(root);
}

/**
* Saves the node/document/element as XML file.
*
* @param doc the XML node/document/element to save
* @param file the XML file to save
* @throws XmlException problem persisting XML file
*/
public static void saveToXml(Node doc, File file) throws XmlException {
OutputStream out = null;

try {
Transformer tf = TransformerFactory.newInstance().newTransformer();

Properties props = tf.getOutputProperties();
props.setProperty(OutputKeys.METHOD, XMLConstants.XML_NS_PREFIX);
props.setProperty(OutputKeys.INDENT, LOGIC_YES);
tf.setOutputProperties(props);

DOMSource dom = new DOMSource(doc);
out = getOutputStream(file);
Result result = new StreamResult(out);
tf.transform(dom, result);
} catch (TransformerException e) {
throw new XmlException(XmlException.XML_TRANSFORM_ERROR, e);
} finally {
if (out != null) {
try {
out.close();
} catch (IOException e) {
// nothing to do
}
}
}
}

/**
* Validates the element tree context via given XML schema file.
*
* @param doc the XML document to validate
* @param schemaFile the XML schema file instance
* @throws XmlException error occurs if the schema file not exists
*/
public static void validateXml(Node doc, File schemaFile)
throws XmlException {
validateXml(doc, getInputStream(schemaFile));
}

/**
* Validates the element tree context via given XML schema file.
*
* @param doc the XML document to validate
* @param schemaStream the XML schema file input stream
* @throws XmlException error occurs if validation fail
*/
public static void validateXml(Node doc, InputStream schemaStream)
throws XmlException {
try {
Source source = new StreamSource(schemaStream);
Schema schema = SchemaFactory.newInstance(
XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(source);

Validator validator = schema.newValidator();
validator.validate(new DOMSource(doc));
} catch (SAXException e) {
throw new XmlException(XmlException.XML_VALIDATE_ERROR, e);
} catch (IOException e) {
throw new XmlException(XmlException.XML_READ_ERROR, e);
} finally {
if (schemaStream != null) {
try {
schemaStream.close();
} catch (IOException e) {
// nothing to do
}
}
}
}

/**
* Transforms the XML content to XHTML/HTML format string with the XSL.
*
* @param payload the XML payload to convert
* @param xsltFile the XML stylesheet file
* @return the transformed XHTML/HTML format string
* @throws XmlException problem converting XML to HTML
*/
public static String xmlToHtml(String payload, File xsltFile)
throws XmlException {
String result = null;

try {
Source template = new StreamSource(xsltFile);
Transformer transformer = TransformerFactory.newInstance()
.newTransformer(template);

Properties props = transformer.getOutputProperties();
props.setProperty(OutputKeys.OMIT_XML_DECLARATION, LOGIC_YES);
transformer.setOutputProperties(props);

StreamSource source = new StreamSource(new StringReader(payload));
StreamResult sr = new StreamResult(new StringWriter());
transformer.transform(source, sr);

result = sr.getWriter().toString();
} catch (TransformerException e) {
throw new XmlException(XmlException.XML_TRANSFORM_ERROR, e);
}

return result;
}

/**
* Sets the namespace to specific element.
*
* @param element the element to set
* @param namespace the namespace to set
* @param schemaLocation the XML schema file location URI
*/
public static void setNamespace(Element element, String namespace,
String schemaLocation) {
element.setAttributeNS(XMLConstants.XMLNS_ATTRIBUTE_NS_URI,
XMLConstants.XMLNS_ATTRIBUTE, namespace);
element.setAttributeNS(XMLConstants.XMLNS_ATTRIBUTE_NS_URI, XMLNS_XSI,
XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI);
element.setAttributeNS(XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI,
XSI_SCHEMA_LOCATION, schemaLocation);
}

/**
* Encode the XML payload to legality character.
*
* @param payload the XML payload to encode
* @return the encoded XML payload
* @throws XmlException problem encoding the XML payload
*/
public static String encodeXml(String payload) throws XmlException {
Element root = createRootElement(XMLConstants.XML_NS_PREFIX);
root.setTextContent(payload);
return childNodeToString(root.getFirstChild());
}

private static InputStream getInputStream(File file) throws XmlException {
InputStream in = null;

try {
in = new FileInputStream(file);
} catch (FileNotFoundException e) {
throw new XmlException(XmlException.FILE_NOT_FOUND, e);
}

return in;
}

private static OutputStream getOutputStream(File file) throws XmlException {
OutputStream in = null;

try {
in = new FileOutputStream(file);
} catch (FileNotFoundException e) {
throw new XmlException(XmlException.FILE_NOT_FOUND, e);
}

return in;
}

/**
* @Desc 把实体类中有的字段直接转为xml节点
* @author LV_FQ
* @date 2016年12月15日
* @param parent
* @param formMap
* @param fields
*/
public static void entityToXml(Element parent, String... fields){
for(String field : fields){
String temp = "XmlUtils.appendElement(root, \"" + field + "\", decHeadFormMap.getStr(\"field\"));";
System.out.println(temp);

XmlUtils.appendElement(parent, field, "取值");
}
}

/**
* @Desc 根据xml生成java代码
* @author LV_FQ
* @date 2016年12月16日
* @param file xml文件
*/
public static void createJavaCode(File file){
XMLToJavaUtils.createJavaCode(file);
}
}

class XmlException extends RuntimeException {

private static final long serialVersionUID = 381260478228427716L;

public static final String XML_PAYLOAD_EMPTY = "xml.payload.empty";
public static final String XML_ENCODE_ERROR = "xml.encoding.invalid";
public static final String FILE_NOT_FOUND = "xml.file.not.found";
public static final String XML_PARSE_ERROR = "xml.parse.error";
public static final String XML_READ_ERROR = "xml.read.error";
public static final String XML_VALIDATE_ERROR = "xml.validate.error";
public static final String XML_TRANSFORM_ERROR = "xml.transform.error";

public XmlException() {
super();
}

public XmlException(String key, Throwable cause) {
super(key, cause);
}

public XmlException(String key) {
super(key);
}

public XmlException(Throwable cause) {
super(cause);
}
}

/**
* @Desc 根据xml的格式生成xml的对应的java生成代码
* @author LV_FQ
* @date 2016年12月16日 下午2:08:38
* @version 1.0
*
*/
class XMLToJavaUtils {

public static void createJavaCode(File file) {
try {
//File file = new File("C:/Users/SUCCESS/Desktop/temp.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(file);
if (doc.hasChildNodes()) {
printNote(doc.getChildNodes(), null);
}
} catch (Exception e) {
e.printStackTrace();
}
}

private static void printNote(NodeList nodeList, Node parent) {
for (int i = 0; i < nodeList.getLength(); i++) {
Node node = nodeList.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE) {

if(parent == null){
System.out.println("Element "+ getTagName(node.getNodeName())+" = XmlUtils.createRootElement(\""+ node.getNodeName() +"\");");
}else{
String temp = "XmlUtils.appendElement("+getTagName(parent == null? null : parent.getNodeName())+", \"" + node.getNodeName();

if (node.hasChildNodes() && node.getChildNodes().getLength() > 1) {
System.out.println();
//非叶节点把节点的名称加上，以便子节点和父节点做关联
temp = "Element " + getTagName(node.getNodeName()) + " = " + temp + "\");";
}else{
//叶节点把注释加上
//temp += "\", \"value\");//" + node.getTextContent();
temp += "\", \""+ node.getTextContent() +"\");";
}

System.out.println(temp);
}
if (node.hasChildNodes()) {
printNote(node.getChildNodes(), node);
}
}
}
}

/**
* @Desc 把字符串第一个字母转小写
* @author LV_FQ
* @date 2016年12月16日
* @param name
* @return
*/
private static String getTagName(String name){
if(StringUtils.isBlank(name)){
return "";
}
String temp = name;
temp = temp.substring(0, 1).toLowerCase() + temp.substring(1);
return temp;
}
}

测试方法

package com.lfq.createXml;

import java.io.File;

import org.w3c.dom.Element;

public class TestXml {

public static void main(String[] args) {
Element note = XmlUtils.createRootElement("note");
XmlUtils.appendElement(note, "to", "George1");
XmlUtils.appendElement(note, "from", "John2");
XmlUtils.appendElement(note, "heading", "Reminder1");
XmlUtils.appendElement(note, "body", "Don't forget the meeting!");

XmlUtils.saveToXml(note, new File("/home/lv-success/Desktop/temp.xml"));

//使用xml生成工具生成java代码(控制台输出)
File file = new File("/home/lv-success/Desktop/temp.xml");
XmlUtils.createJavaCode(file);
}

}

从test中可以看出，工具类通过已有的操作xml文件的方法读取xml的结构，同时根据读取的节点内容直接把对于生成的方法打印到控制台中，如此嵌套打印，最终打印出这个xml文件的相同java层次结构的代码。

如果对生成的java代码有不同要求，大家可以直接修改工具类中的生成java代码的方法。能生成自己最终要求最接近的代码最好，怎么方便怎么来哈。

说明：其中操作xml的源代码不是我写的，引用的这位网友的代码，可以参考一下，我主要写了生成java代码的方法。参考的链接http://carver.iteye.com/blog/411611