Java uses Xstream to generate and parse xml, knowledge structure:
1. Introduction to Xstream;
Usage Restrictions : JDK version cannot be < 1.5.
While preprocessing annotations is safe, auto-detection annotations may cause race conditions.
Features: simplified API; no mapping files; high performance, low memory footprint; clean XML; no need to modify objects; support for internal private fields, no setter/getter methods, final fields; non-public classes, inner classes; classes do not Requires default constructor, full object graph support. Maintains object reference counts, circular references. i provides serialization interface; custom conversion type strategy; detailed error diagnosis; fast output format; currently supports JSON and morphing.
Use the scene Transport to convert the Persistence persistent object Configuration to configure the Unit Tests unit test
Implicit collection When we use the collection class, we do not want to display the collection, but only the elements inside it. Before using the implicit collection: <list> <element /> <element /> <list> Use the implicit collection: xstream.addImplicitCollection( Person.class, "list"); After using implicit collection: <element /> <element />
2.Xstream注解常用知识：
@XStreamAlias("message") 别名注解
作用目标: 类,字段
@XStreamImplicit 隐式集合
@XStreamImplicit(itemFieldName="part")
作用目标: 集合字段
@XStreamConverter(SingleValueCalendarConverter.class) 注入转换器
作用目标: 对象
@XStreamAsAttribute 转换成属性
作用目标: 字段
@XStreamOmitField 忽略字段
作用目标: 字段
Auto-detect Annotations 自动侦查注解
xstream.autodetectAnnotations(true);
自动侦查注解与XStream.processAnnotations(Class[] cls)的区别在于性能.自动侦查注解将缓存所有类的类型.
3.案例分析： （1）同一标签下多个同名元素；
（2）同一标签下循环多个对象；
maven 依赖：
<dependency> <groupId>com.thoughtworks.xstream</groupId> <artifactId>xstream</artifactId> <version>1.4.8</version> </dependency>
1. [代码]1.实体类：PersonBean
import java.util.List; import com.thoughtworks.xstream.annotations.XStreamAlias; import com.thoughtworks.xstream.annotations.XStreamImplicit; /** *@ClassName:PersonBean *@author: chenyoulong Email: [email protected] *@date :2012-9-28 下午3:10:47 *@Description:TODO */ @XStreamAlias("person") public class PersonBean { @XStreamAlias("firstName") private String firstName; @XStreamAlias("lastName") private String lastName; @XStreamAlias("telphone") private PhoneNumber tel; @XStreamAlias("faxphone") private PhoneNumber fax; //测试一个标签下有多个同名标签 @XStreamAlias("friends") private Friends friend; //测试一个标签下循环对象 @XStreamAlias("pets") private Pets pet; //省略setter和getter }
2. [代码]2.实体类：PhoneNumber
@XStreamAlias("phoneNumber")
public class PhoneNumber{
@XStreamAlias("code")
private int code;
@XStreamAlias("number")
private String number;
//省略setter和getter
}
3. [代码]3.实体类：Friends（一个标签下有多个同名标签 ）
/**
* 用Xstream注解的方式实现：一个标签下有多个同名标签
*@ClassName:Friends
*@author: chenyoulong Email: [email protected]
*@date :2012-9-28 下午4:32:24
*@Description:TODO 5个name 中国，美国，俄罗斯，英国，法国
*http://blog.csdn.net/menhuanxiyou/article/details/5426765
*/
public static class Friends{
@XStreamImplicit(itemFieldName="name") //itemFieldName定义重复字段的名称，
/*<friends> <friends>
<name>A1</name> <String>A1</String>
<name>A2</name> 如果没有，则会变成 =====> <String>A1</String>
<name>A3</name> <String>A1</String>
</friends> </friends>
*/
private List<String> name;
public List<String> getName() {
return name;
}
public void setName(List<String> name) {
this.name = name;
}
}
4. [代码]4.1实体类：Animal（同一标签下循环对象实体1）
/测试同一标签下循环某一对象
public class Animal{
@XStreamAlias("name")
private String name;
@XStreamAlias("age")
private int age;
public Animal(String name,int age){
this.name=name;
this.age=age;
}
//省略setter和getter
}
5. [代码]4.2实体类：Pets（同一标签下循环对象实体2）
/**
* 测试同一标签下循环某一对象
*@ClassName:Pets
*@author: chenyoulong Email: [email protected]
*@date :2012-9-28 下午6:26:01
*@Description:TODO
*/
public class Pets{
@XStreamImplicit(itemFieldName="pet")
private List<Animal> animalList;
public List<Animal> getAnimalList() {
return animalList;
}
public void setAnimalList(List<Animal> animalList) {
this.animalList = animalList;
}
}
6. [代码]5.main函数示例1：toxml
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.json.JsonWriter.Format;
import com.thoughtworks.xstream.io.xml.DomDriver;
/**
*@ClassName:PersonTest
*@author: chenyoulong
*@date :2012-9-28 下午3:25:09
*@Description:TODO
*/
public class PersonTest {
/**
* @Title: main
* @Description: TODO
* @param args
* @return void
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
PersonBean per=new PersonBean();
per.setFirstName("chen");
per.setLastName("youlong");
PhoneNumber tel=new PhoneNumber();
tel.setCode(137280);
tel.setNumber("137280968");
PhoneNumber fax=new PhoneNumber();
fax.setCode(20);
fax.setNumber("020221327");
per.setTel(tel);
per.setFax(fax);
//测试一个标签下有多个同名标签
List<String> friendList=new ArrayList<String>();
friendList.add("A1");
friendList.add("A2");
friendList.add("A3");
Friends friend1=new Friends();
friend1.setName(friendList);
per.setFriend(friend1);
//测试一个标签下循环对象
Animal dog=new Animal("Dolly",2);
Animal cat=new Animal("Ketty",2);
List<Animal> petList=new ArrayList<Animal>();
petList.add(dog);
petList.add(cat);
Pets pet=new Pets();
pet.setAnimalList(petList);
per.setPet(pet);
//java对象转换成xml
String xml=XmlUtil.toXml(per);
System.out.println("xml==="+xml);
}
}
7. [代码]xml效果图
xml===<person>
<firstName>chen</firstName>
<lastName>youlong</lastName>
<telphone>
<code>137280</code>
<number>137280968</number>
</telphone>
<faxphone>
<code>20</code>
<number>020221327</number>
</faxphone>
<friends>
<name>A1</name>
<name>A2</name>
<name>A3</name>
</friends>
<pets>
<pet>
<name>doly</name>
<age>2</age>
</pet>
<pet>
<name>Ketty</name>
<age>2</age>
</pet>
</pets>
</person>
8. [代码]5.2 main函数示例2：toBean
public static void main(String[] args) {
// TODO Auto-generated method stub
//toXml
// String xmlStr=new PersonTest().toXml();
//toBean
// PersonBean per=new PersonTest().toBean();
String xmlStr="<person>"+
"<firstName>chen</firstName>"+
"<lastName>youlong</lastName>"+
"<telphone>"+
"<code>137280</code>"+
"<number>137280968</number>"+
"</telphone>"+
"<faxphone>"+
"<code>20</code>"+
"<number>020221327</number>"+
"</faxphone>"+
"<friends>"+
"<name>A1</name>"+
"<name>A2</name>"+
"<name>A3</name>"+
"</friends>"+
"<pets>"+
"<pet>"+
"<name>doly</name>"+
"<age>2</age>"+
"</pet>"+
"<pet>"+
"<name>Ketty</name>"+
"<age>2</age>"+
"</pet>"+
"</pets>"+
"</person>";
//用泛型的知识
PersonBean person=XmlUtil.toBean(xmlStr, PersonBean.class);
System.out.println("person=firstname=="+person.getFirstName());
System.out.println("person==Friends==name1=="+person.getFriend().getName().get(0));
System.out.println("person==Pets==name2=="+person.getPet().getAnimalList().get(1).getName());
/*
//效果与以下方法类同,(以下代码较为直观)
XStream xstream=new XStream(new DomDriver()); //注意：不是new Xstream(); 否则报错：
xstream.processAnnotations(PersonBean.class);
PersonBean person=(PersonBean)xstream.fromXML(xmlStr);
System.out.println("person=firstname=="+person.getFirstName());
System.out.println("person==Friends==name1=="+person.getFriend().getName().get(0));
System.out.println("person==Pets==name=="+person.getPet().getAnimalList().get(1).getName());
*/
}
9. [代码]6.XmlUtil工具类（toxml（）和toBean（））
/**
* 输出xml和解析xml的工具类
*@ClassName:XmlUtil
*@author: chenyoulong Email: [email protected]
*@date :2012-9-29 上午9:51:28
*@Description:TODO
*/
public class XmlUtil{
/**
* java 转换成xml
* @Title: toXml
* @Description: TODO
* @param obj 对象实例
* @return String xml字符串
*/
public static String toXml(Object obj){
XStream xstream=new XStream();
// XStream xstream=new XStream(new DomDriver()); //直接用jaxp dom来解释
// XStream xstream=new XStream(new DomDriver("utf-8")); //指定编码解析器,直接用jaxp dom来解释
////如果没有这句，xml中的根元素会是<包.类名>；或者说：注解根本就没生效，所以的元素名就是类的属性
xstream.processAnnotations(obj.getClass()); //通过注解方式的，一定要有这句话
return xstream.toXML(obj);
}
/**
* 将传入xml文本转换成Java对象
* @Title: toBean
* @Description: TODO
* @param xmlStr
* @param cls xml对应的class类
* @return T xml对应的class类的实例对象
*
* 调用的方法实例：PersonBean person=XmlUtil.toBean(xmlStr, PersonBean.class);
*/
public static <T> T toBean(String xmlStr,Class<T> cls){
//注意：不是new Xstream(); 否则报错：java.lang.NoClassDefFoundError: org/xmlpull/v1/XmlPullParserFactory
XStream xstream=new XStream(new DomDriver());
xstream.processAnnotations(cls);
T obj=(T)xstream.fromXML(xmlStr);
return obj;
}
/**
* 写到xml文件中去
* @Title: writeXMLFile
* @Description: TODO
* @param obj 对象
* @param absPath 绝对路径
* @param fileName 文件名
* @return boolean
*/
public static boolean toXMLFile(Object obj, String absPath, String fileName ){
String strXml = toXml(obj);
String filePath = absPath + fileName;
File file = new File(filePath);
if(!file.exists()){
try {
file.createNewFile();
} catch (IOException e) {
log.error("创建{"+ filePath +"}文件失败!!!" + Strings.getStackTrace(e));
return false ;
}
}// end if
OutputStream ous = null ;
try {
ous = new FileOutputStream(file);
ous.write(strXml.getBytes());
ous.flush();
} catch (Exception e1) {
log.error("写{"+ filePath +"}文件失败!!!" + Strings.getStackTrace(e1));
return false;
}finally{
if(ous != null )
try {
ous.close();
} catch (IOException e) {
log.error("写{"+ filePath +"}文件关闭输出流异常!!!" + Strings.getStackTrace(e));
}
}
return true ;
}
/**
* 从xml文件读取报文
* @Title: toBeanFromFile
* @Description: TODO
* @param absPath 绝对路径
* @param fileName 文件名
* @param cls
* @throws Exception
* @return T
*/
public static <T> T toBeanFromFile(String absPath, String fileName,Class<T> cls) throws Exception{
String filePath = absPath +fileName;
InputStream ins = null ;
try {
ins = new FileInputStream(new File(filePath ));
} catch (Exception e) {
throw new Exception("读{"+ filePath +"}文件失败！", e);
}
String encode = useEncode(cls);
XStream xstream=new XStream(new DomDriver(encode));
xstream.processAnnotations(cls);
T obj =null;
try {
obj = (T)xstream.fromXML(ins);
} catch (Exception e) {
// TODO Auto-generated catch block
throw new Exception("解析{"+ filePath +"}文件失败！",e);
}
if(ins != null)
ins.close();
return obj;
}
}
来源：https://www.oschina.net/code/snippet_116183_14202