程序員開發程序的時候都會調用其他平臺接口，它通常都會返回XML數據，那么實體類和xml文件相互轉換的操作方法大家知道嗎？別著急，下面就讓錯新技術頻道小編帶你了解一下吧！
具體代碼如下：
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(); /** * 判斷是否是個xml文件,目前類里尚未使用該方法 * @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; } /** * 將一組對象數據轉換成XML文件 * @param list * @param filePath 存放的文件路徑 */ 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(); } } } /** * 通過一個根節點來寫對象的xml節點，這個方法不對外開放，主要給writeXML(List<T> list, String filePath)提供服務 * @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; } /** * 默認使用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"); } /** * 將一個xml文件轉變成實體類 * @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; } /** * 將一種類型 和對應的 xml元素節點傳進來，返回該類型的對象,該方法不對外開放 * @param c 類類型 * @param ele 元素節點 * @return 該類型的對象 * @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();//獲得字段的類型 String fieldName = f.getName();//獲得字段名稱 String param = fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);//把字段的第一個字母變成大寫 Element e = ele.element(fieldName); if(type.indexOf("Integer") > -1) {//說明該字段是Integer類型 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);//通過反射給該字段set值 } if(type.indexOf("Double") > -1) { //說明該字段是Double類型 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) {//說明該字段是String類型 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; } /** * 用來寫xml文件 * @param doc Document對象 * @param filePath 生成的文件路徑 * @param encoding 寫xml文件的編碼 */ public static void writeXml(Document doc, String filePath, String encoding) { XMLWriter writer = null; OutputFormat format = OutputFormat.createPrettyPrint(); format.setEncoding(encoding);// 指定XML編碼 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(); } } } /** * 默認使用utf-8的格式寫文件 * @param doc * @param filePath */ public static void writeXml(Document doc, String filePath) { writeXml(doc, filePath, "utf-8"); }}假如有個實體類是：
package com.pcq.entity;import java.io.Serializable;public class Emp implements Serializable{ private Integer id; private String name; private Integer deptNo; private Integer age; private String gender; private Integer bossId; private Double salary; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getDeptNo() { return deptNo; } public void setDeptNo(Integer deptNo) { this.deptNo = deptNo; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public Integer getBossId() { return bossId; } public void setBossId(Integer bossId) { this.bossId = bossId; } public Double getSalary() { return salary; } public void setSalary(Double salary) { this.salary = salary; } }那么寫出來的xml文件格式如下：
<?xml version="1.0" encoding="utf-8"?><emps> <emp> <id>1</id> <name>張三</name> <deptNo>50</deptNo> <age>25</age> <gender>男</gender> <bossId>6</bossId> <salary>9000.0</salary> </emp> <emp> <id>2</id> <name>李四</name> <deptNo>50</deptNo> <age>22</age> <gender>女</gender> <bossId>6</bossId> <salary>8000.0</salary> </emp></emps>
假如有個實體類如下：
package com.pcq.entity;public class Student { private Integer id; private String name; private Integer age; private String gender; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } }那么寫出來的xml文件如下
<?xml version="1.0" encoding="utf-8"?><students> <student> <id></id> <name>pcq</name> <age>18</age> <gender>男</gender> </student></students>
讀取也必須讀這種格式的xml文件，才能轉換成實體類，要求是實體類的類類型信息（Class）必須要獲得到。
另外這里的實體類的屬性類型均是Integer,String,Double,可以看到工具類里只對這三種類型做了判斷。而且可以預想的是，如果出現一對多的關系，即一個實體類擁有一組另一個類對象的引用，
那xml和實體類的相互轉換要比上述的情況復雜的多。lz表示短時間內甚至長時間內也不一定能做的出來，歡迎同道高人指點。
以上就是關于實體類和xml文件相互轉換的操作方法介紹了，想要學習的話，上面的操作方法大家都熟悉了嗎。今天的分享就到這兒了，希望想學習的朋友。通過上面的介紹可以幫助到大家。
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