简单实体类和xml文件的相互转换方法

最近写一个题目，要求将一组员工实体类转换成xml文件，或将xml文件转换成一组实体类。题目不难，但写完感觉可以利用泛型和反射将任意一个实体类和xml文件进行转换。于是今天下午立马动手

试了下，做了个简单的模型，可以将简单的实体类和xml文件进行相互转换，但对实体类的属性类型有限制，目前只支持String, Integer, Double三种类型。但是后面可以扩展。

我的大概思路是这样的，只要能拿到实体类的类型信息，我就能拿到实体类的全部字段名称和类型，拼属性的set和get方法更是简单明了，这时候只需要通过方法的反射，将xml文件的数据读取出来给这个反射即可。

反过来只要给我一个任意对象，我就能通过反射拿到该对象所有字段的值，这时候在写xml文件即可。

具体代码如下：

package com.pcq.entity;import java.io.*;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.DocumentHelper;import org.dom4j.Element;import org.dom4j.io.OutputFormat;import org.dom4j.io.SAXReader;import org.dom4j.io.XMLWriter;public class XMLAndEntityUtil { private static Document document = DocumentHelper.createDocument();  /**  * 判断是否是个xml文件,目前类里尚未使用该方法  * @param filePath   * @return  */ @SuppressWarnings("unused") private static boolean isXMLFile(String filePath) {  File file = new File(filePath);  if(!file.exists() || filePath.indexOf(".xml") > -1) {   return false;  }  return true; }  /**  * 将一组对象数据转换成XML文件  * @param list  * @param filePath 存放的文件路径  */ public static <T> void writeXML(List<T> list, String filePath) {  Class<?> c = list.get(0).getClass();  String root = c.getSimpleName().toLowerCase() + "s";  Element rootEle = document.addElement(root);  for(Object obj : list) {   try {    Element e = writeXml(rootEle, obj);    document.setRootElement(e);    writeXml(document, filePath);   } catch (NoSuchMethodException | SecurityException     | IllegalAccessException | IllegalArgumentException     | InvocationTargetException e) {    e.printStackTrace();   }  } } /**  * 通过一个根节点来写对象的xml节点，这个方法不对外开放，主要给writeXML(List<T> list, String filePath)提供服务  * @param root  * @param object  * @return  * @throws NoSuchMethodException  * @throws SecurityException  * @throws IllegalAccessException  * @throws IllegalArgumentException  * @throws InvocationTargetException  */ private static Element writeXml(Element root, Object object) throws NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {  Class<?> c = object.getClass();  String className = c.getSimpleName().toLowerCase();  Element ele = root.addElement(className);  Field[] fields = c.getDeclaredFields();  for(Field f : fields) {   String fieldName = f.getName();   String param = fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);   Element fieldElement = ele.addElement(fieldName);   Method m = c.getMethod("get" + param, null);   String s = "";   if(m.invoke(object, null) != null) {    s = m.invoke(object, null).toString();   }   fieldElement.setText(s);  }  return root; }  /**  * 默认使用utf-8  * @param c  * @param filePath  * @return  * @throws UnsupportedEncodingException  * @throws FileNotFoundException  */ public static <T> List<T> getEntitys(Class<T> c, String filePath) throws UnsupportedEncodingException, FileNotFoundException {  return getEntitys(c, filePath, "utf-8"); } /**  * 将一个xml文件转变成实体类  * @param c  * @param filePath  * @return  * @throws FileNotFoundException   * @throws UnsupportedEncodingException   */ public static <T> List<T> getEntitys(Class<T> c, String filePath, String encoding) throws UnsupportedEncodingException, FileNotFoundException {  File file = new File(filePath);  String labelName = c.getSimpleName().toLowerCase();  SAXReader reader = new SAXReader();  List<T> list = null;   try {   InputStreamReader in = new InputStreamReader(new FileInputStream(file), encoding);   Document document = reader.read(in);   Element root = document.getRootElement();   List elements = root.elements(labelName);   list = new ArrayList<T>();   for(Iterator<Emp> it = elements.iterator(); it.hasNext();) {     Element e = (Element)it.next();     T t = getEntity(c, e);     list.add(t);    }  } catch (DocumentException e) {   e.printStackTrace();  } catch (InstantiationException e1) {   e1.printStackTrace();  } catch (IllegalAccessException e1) {   e1.printStackTrace();  } catch (NoSuchMethodException e1) {   e1.printStackTrace();  } catch (SecurityException e1) {   e1.printStackTrace();  } catch (IllegalArgumentException e1) {   e1.printStackTrace();  } catch (InvocationTargetException e1) {   e1.printStackTrace();  }  return list; }   /**  * 将一种类型 和对应的 xml元素节点传进来，返回该类型的对象,该方法不对外开放  * @param c 类类型  * @param ele 元素节点  * @return 该类型的对象  * @throws InstantiationException  * @throws IllegalAccessException  * @throws NoSuchMethodException  * @throws SecurityException  * @throws IllegalArgumentException  * @throws InvocationTargetException  */ @SuppressWarnings("unchecked") private static <T> T getEntity(Class<T> c, Element ele) throws InstantiationException, IllegalAccessException, NoSuchMethodException, SecurityException, IllegalArgumentException, InvocationTargetException {  Field[] fields = c.getDeclaredFields();  Object object = c.newInstance();//  for(Field f : fields) {   String type = f.getType().toString();//获得字段的类型   String fieldName = f.getName();//获得字段名称   String param = fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);//把字段的第一个字母变成大写   Element e = ele.element(fieldName);   if(type.indexOf("Integer") > -1) {//说明该字段是Integer类型    Integer i = null;    if(e.getTextTrim() != null && !e.getTextTrim().equals("")) {     i = Integer.parseInt(e.getTextTrim());    }    Method m = c.getMethod("set" + param, Integer.class);    m.invoke(object, i);//通过反射给该字段set值   }   if(type.indexOf("Double") > -1) { //说明该字段是Double类型    Double d = null;    if(e.getTextTrim() != null && !e.getTextTrim().equals("")) {     d = Double.parseDouble(e.getTextTrim());    }    Method m = c.getMethod("set" + param, Double.class);    m.invoke(object, d);   }   if(type.indexOf("String") > -1) {//说明该字段是String类型    String s = null;    if(e.getTextTrim() != null && !e.getTextTrim().equals("")) {     s = e.getTextTrim();    }    Method m = c.getMethod("set" + param, String.class);    m.invoke(object, s);   }  }  return (T)object; } /**  * 用来写xml文件  * @param doc Document对象  * @param filePath 生成的文件路径  * @param encoding 写xml文件的编码  */ public static void writeXml(Document doc, String filePath, String encoding) {  XMLWriter writer = null;  OutputFormat format = OutputFormat.createPrettyPrint();  format.setEncoding(encoding);// 指定XML编码    try {   writer = new XMLWriter(new FileWriter(filePath), format);   writer.write(doc);  } catch (IOException e) {   e.printStackTrace();  } finally {   try {    writer.close();   } catch (IOException e) {    e.printStackTrace();   }  } }  /**  * 默认使用utf-8的格式写文件  * @param doc  * @param filePath  */ public static void writeXml(Document doc, String filePath) {  writeXml(doc, filePath, "utf-8"); }}