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 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));
}
}程序运行结果： 如果我们检查D:\tmp目录,有三个文件:[email protected]、[email protected]、[email protected]；每个对象都被序列化到XML文件里。
(2)读取并删除JavaBean对象
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。