最近寫一個題目，要求將一組員工實體類轉(zhuǎn)換成xml文件，或?qū)ml文件轉(zhuǎn)換成一組實體類。題目不難，但寫完感覺可以利用泛型和反射將任意一個實體類和xml文件進行轉(zhuǎn)換。于是今天下午立馬動手
試了下，做了個簡單的模型，可以將簡單的實體類和xml文件進行相互轉(zhuǎn)換，但對實體類的屬性類型有限制，目前只支持String, Integer, Double三種類型。但是后面可以擴展。
我的大概思路是這樣的，只要能拿到實體類的類型信息，我就能拿到實體類的全部字段名稱和類型，拼屬性的set和get方法更是簡單明了，這時候只需要通過方法的反射，將xml文件的數(shù)據(jù)讀取出來給這個反射即可。
反過來只要給我一個任意對象，我就能通過反射拿到該對象所有字段的值，這時候在寫xml文件即可。
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(shù)據(jù)轉(zhuǎn)換成XML文件
* @param list
* @param filePath 存放的文件路徑
*/
public static T> void writeXML(ListT> 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(jié)點來寫對象的xml節(jié)點，這個方法不對外開放，主要給writeXML(ListT> 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> ListT> getEntitys(ClassT> c, String filePath) throws UnsupportedEncodingException, FileNotFoundException {
return getEntitys(c, filePath, "utf-8");
}
/**
* 將一個xml文件轉(zhuǎn)變成實體類
* @param c
* @param filePath
* @return
* @throws FileNotFoundException
* @throws UnsupportedEncodingException
*/
public static T> ListT> getEntitys(ClassT> c, String filePath, String encoding) throws UnsupportedEncodingException, FileNotFoundException {
File file = new File(filePath);
String labelName = c.getSimpleName().toLowerCase();
SAXReader reader = new SAXReader();
ListT> 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 ArrayListT>();
for(IteratorEmp> 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(jié)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(jié)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(ClassT> 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(zhuǎn)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(xiàn)一對多的關(guān)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(zhuǎn)換要比上述的情況復雜的多。lz表示短時間內(nèi)甚至長時間內(nèi)也不一定能做的出來，歡迎同道高人指點。
以上這篇簡單實體類和xml文件的相互轉(zhuǎn)換方法就是小編分享給大家的全部內(nèi)容了，希望能給大家一個參考，也希望大家多多支持腳本之家。
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