XStream使用详解

1.Xstream介绍

(1)Xstream介绍
Xstream是一种OXMapping 技术，是用来处理XML文件序列化的框架,在将JavaBean序列化，或将XML文件反序列化的时候，不需要其它辅助类和映射文件，使得XML序列化不再繁索。Xstream也可以将JavaBean序列化成Json或反序列化，使用非常方便。
(2)Xstream的简单例子

class Person//JavaBean实体类 { private String name; private int age; public Person(String name,int age) { this.name=name; this.age=age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } } public class Test { public static void main(String[] args) { Person bean=new Person("张三",19); XStream xstream = new XStream(); //XML序列化 String xml = xstream.toXML(bean); System.out.println(xml); //XML反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); xstream = new XStream(new JettisonMappedXmlDriver()); xstream.setMode(XStream.NO_REFERENCES); //Json序列化 String json=xstream.toXML(bean); System.out.println(json); //Json反序列 bean=(Person)xstream.fromXML(json); System.out.println(bean); } }

注意： Xstream序列化XML时需要引用的jar包：xstream-[version].jar、xpp3-[version].jar、xmlpull-[version].jar。Xstream序列化Json需要引用的jar包：jettison-[version].jar。

使用Xstream序列化时，对JavaBean没有任何限制。JavaBean的字段可以是私有的，也可以没有getter或setter方法，还可以没有默认的构造函数。

2.Xstream的基本使用

(1)Xstream序列化XML

Xstream序列化XML时可以允许用户使用不同的XML解析器，用户可以使用一个标准的JAXP DOM解析器或自Java6集成StAX解析器。这样用户就不需要依赖xpp3-[version].jar。

Xstream序列化XML时，也可以对XML节点重命名。

public class Test { public static void main(String[] args) { Person bean=new Person("张三",19); //XStream xstream = new XStream();//需要XPP3库 //XStream xstream = new XStream(new DomDriver());//不需要XPP3库 XStream xstream = new XStream(new StaxDriver());//不需要XPP3库开始使用Java6 xstream.alias("人",Person.class);//为类名节点重命名 //XML序列化 String xml = xstream.toXML(bean); System.out.println(xml); //XML反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

(2)Xstream序列化Json

Xstream序列化Json与序列化XML类似，例如：

public class Test { public static void main(String[] args) { Person bean=new Person("张三",19); XStream xstream = new XStream(new JettisonMappedXmlDriver());//设置Json解析器 xstream.setMode(XStream.NO_REFERENCES);//设置reference模型,不引用 xstream.alias("人",Person.class);//为类名节点重命名 //Json序列化 String xml = xstream.toXML(bean); System.out.println(xml); //Json反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

3.Xstream序列化重命名

(1)为包重命名：Xstream.aliasPackage()方法

public class Test { public static void main(String[] args) { Person bean=new Person("张三",19); XStream xstream = new XStream(); xstream.aliasPackage("com.lzw", "test");//为包名称重命名 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

 (2)为类重命名：Xstream.alias()方法

public class Test { public static void main(String[] args) { Person bean=new Person("张三",19); XStream xstream = new XStream(); xstream.alias("人", Person.class);//为类名节点重命名 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

 (3)为字段重命名：Xstream.aliasField()方法

public class Test { public static void main(String[] args) { Person bean=new Person("张三",19); XStream xstream = new XStream(); xstream.aliasField("姓名", Person.class,"name");//为类的字段节点重命名 xstream.aliasField("年龄", Person.class,"age");//为类的字段节点重命名 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

(4)省略集合根节点：Xstream.addImplicitCollection()方法

class Person { private String name; private int age; private List friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; } } public class Test { public static void main(String[] args) { Person bean =new Person("张三",19,"李四","王五","赵六"); XStream xstream = new XStream(); xstream.addImplicitCollection(Person.class, "friends");//省略集合根节点 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

(5)把字段节点设置成属性：Xstream.useAttributeFor()方法

public class Test { public static void main(String[] args) { Person bean =new Person("张三",19,"李四","王五","赵六"); XStream xstream = new XStream(); xstream.useAttributeFor(Person.class, "name");//把字段节点设置成属性 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

(6)隐藏字段：xstream.omitField()方

public class Test { public static void main(String[] args) { Person bean =new Person("张三",19,"李四","王五","赵六"); XStream xstream = new XStream(); xstream.omitField(Person.class, "friends");//把字段节点隐藏 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

4.Xstream注解的使用

(1)设置Xstream应用注解
使用Xstream注解前需要对Xstream进行配置，可以使用两种方式：应用某个JavaBean类的注解或自动使用JavaBean类的注解。代码如下：

XStream xstream = new XStream(); xstream.processAnnotations(Person.class);//应用Person类的注解 xstream.autodetectAnnotations(true);//自动检测注解

(2)重命名注解：@XStreamAlias()

@XStreamAlias("人") class Person { @XStreamAlias("姓名") private String name; @XStreamAlias("年龄") private int age; @XStreamAlias("朋友") private List friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; } }

(3)省略集合根节点：@XStreamImplicit

class Person { private String name; private int age; //@XStreamImplicit//只隐藏集合根节点 @XStreamImplicit(itemFieldName="朋友")//设置重复的节点名，可能会导致无法反序列化 private List 
  
    friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; } } 
  

(4)把字段节点设置成属性：@XStreamAsAttribute

class Person { @XStreamAsAttribute private String name; @XStreamAsAttribute private int age; private List 
  
    friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; } } 
  

(5)隐藏字段：@XStreamOmitField

class Person { private String name; private int age; @XStreamOmitField private List 
  
    friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; } } 
  

(6)设置转换器：@XStreamConverter()

class Person { private String name; private int age; @XStreamConverter(value=BooleanConverter.class,booleans={false},strings={"男","女"}) private boolean sex; public Person(String name, int age, boolean sex) { this.name = name; this.age = age; this.sex=sex; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", sex=" + sex + "]"; } }

5.Xstream自定义的转换器

(1)Xstream自带的转换器
Xstream内部有许多转换器，用于JavaBean对象到XML或Json之间的转换。这些转换器的详细信息网址：http://xstream.codehaus.org/converters.html
(2)使用自定义的转换器

class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } } public class PersonConverter implements Converter { @Override//定义转换器能转换的JavaBean类型 public boolean canConvert(Class type) { return type.equals(Person.class); } @Override//把对象序列化成XML或Json public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) { Person person = (Person) value; writer.startNode("姓名"); writer.setValue(person.getName()); writer.endNode(); writer.startNode("年龄"); writer.setValue(person.getAge()+""); writer.endNode(); writer.startNode("转换器"); writer.setValue("自定义的转换器"); writer.endNode(); } @Override//把XML或Json反序列化成对象 public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) { Person person = new Person("",-1); reader.moveDown(); person.setName(reader.getValue()); reader.moveUp(); reader.moveDown(); person.setAge(Integer.parseInt(reader.getValue())); reader.moveUp(); return person; } } public class Test { public static void main(String[] args) { Person bean =new Person("张三",19); XStream xstream = new XStream(); xstream.registerConverter(new PersonConverter());//注册转换器 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } } } }

(3)常用的转换器接口与抽象类
SingleValueConverter：单值转换接口
AbstractSingleValueConverter：单值转换抽象类
Converter：常规转换器接口

6.Xstream对象流的使用

(1)Xstream对象输出流

class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } } public class Test { public static void main(String[] args) throws IOException { XStream xstream = new XStream(); ObjectOutputStream out = xstream.createObjectOutputStream(System.out); out.writeObject(new Person("张三",12)); out.writeObject(new Person("李四",19)); out.writeObject("Hello"); out.writeInt(12345); out.close(); } }

注意： XStream对象流是通过标准java.io.ObjectOutputStream和java.io.ObjectInputStream对象。 因为XML文档只能有一个根节点,必须包装在一个序列化的所有元素 额外的根节点。 这个根节点默认 < object-stream >上面的例子所示。
(2)Xstream对象输出流

class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } } public class Test { public static void main(String[] args) throws IOException, ClassNotFoundException { String s=" 
   
    
    
      张三 
     
    
      12 
     
    
   
     12345 
    
  "; StringReader reader = new StringReader(s); XStream xstream = new XStream(); ObjectInputStream in = xstream.createObjectInputStream(reader); System.out.println((Person) in.readObject()); System.out.println(in.readInt()); } } }

7.Xstream持久化API

(1)保存JavaBean对象

class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } } public class Test { public static void main(String[] args) throws IOException, ClassNotFoundException { PersistenceStrategy strategy = new FilePersistenceStrategy(new File("D:\\tmp")); List list = new XmlArrayList(strategy); list.add(new Person("张三",13));//保存数据 list.add(new Person("李四",21)); list.add(new Person("王五",17)); } }

public class Test { public static void main(String[] args) throws IOException, ClassNotFoundException { PersistenceStrategy strategy = new FilePersistenceStrategy(new File("D:\\tmp")); List list = new XmlArrayList(strategy); for (Iterator it = list.iterator(); it.hasNext();) { System.out.println((Person) it.next()); it.remove();//删除对象序列化文件 } } }

8.Xstream操作Json

(1)Xstream序列化Json的重命名

@XStreamAlias("人") class Person { @XStreamAlias("姓名") private String name; @XStreamAlias("年龄") private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } } public class Test { public static void main(String[] args) { Person bean=new Person("张三",19); XStream xstream = new XStream(new JettisonMappedXmlDriver());//设置Json解析器 xstream.autodetectAnnotations(true); //Json序列化 String xml = xstream.toXML(bean); System.out.println(xml); //Json反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); } }

注意： Xstream序列化Json的重命名的方式与其序列化成XML的方式一样！
(2)去掉序列化Json的根节点

class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } } public class Test00 { public static void main(String[] args) { Person bean=new Person("张三",19); XStream xstream = new XStream(new JsonHierarchicalStreamDriver() { public HierarchicalStreamWriter createWriter(Writer writer) { return new JsonWriter(writer, JsonWriter.DROP_ROOT_MODE); } }); //Json序列化 String xml = xstream.toXML(bean); System.out.println(xml); } } }

注意： 去掉根节点后的Json串是不能反序列化的，因为XStream 不知道它的类型。
(3)Json的解析器区别
前面两个例子使用了不同的Json解析器，这里说明他们的不同之处：
JettisonMappedXmlDriver：是支持序列化和反序列化Json的。
JsonHierarchicalStreamDriver：只支持序列化，不支持反序列化。