(转)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

//JavaBean实体类
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){
        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);
    }
}

程序运行结果：

<test.Person>
  <name>张三</name>
  <age>19</age>
</test.Person>

Person [name=张三, age=19]

{"test.Person":{"name":"张三","age":19}}

Person [name=张三, age=19]

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);
    }
}

程序运行结果：

<?xml version="1.0" ?>
<人>
    <name>张三</name>
    <age>19</age>
</人>

Person [name=张三, age=19]

(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);
    }
}

程序运行结果：

{"人":{"name":"张三","age":19}}

Person [name=张三, age=19]

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);
    }
}

程序运行结果：

<com.lzw.Person>
  <name>张三</name>
  <age>19</age>
</com.lzw.Person>

Person [name=张三, age=19]

(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);
    }
}

程序运行结果：

<人>
  <name>张三</name>
  <age>19</age>
</人>

Person [name=张三, age=19]

(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);
    }
}

程序运行结果：

<test.Person>
  <姓名>张三</姓名>
  <年龄>19</年龄>
</test.Person>

Person [name=张三, age=19]

<test.Person>
    <姓名>张三</姓名>
    <年龄>19</年龄>
</test.Person>

Person [name=张三, age=19]

(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);
    }
}

程序运行结果：

<test.Person>
  <name>张三</name>
  <age>19</age>
  <string>李四</string>
  <string>王五</string>
  <string>赵六</string>
</test.Person>

Person [name=张三, age=19, friends=[李四, 王五, 赵六]]

(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);
    }
}

程序运行结果：

<test.Person name="张三">
  <age>19</age>
  <friends class="java.util.Arrays$ArrayList">
    <a class="string-array">
      <string>李四</string>
      <string>王五</string>
      <string>赵六</string>
    </a>
  </friends>
</test.Person>

Person [name=张三, age=19, friends=[李四, 王五, 赵六]]

(6)隐藏字段：xstream.omitField()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.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);
    }
}

程序运行结果：

<test.Person>
  <name>张三</name>
  <age>19</age>
</test.Person>

Person [name=张三, age=19, friends=null]

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 + "]";
    }
}

程序运行结果：

<人>
  <姓名>张三</姓名>
  <年龄>19</年龄>
  <朋友 class="java.util.Arrays$ArrayList">
    <a class="string-array">
      <string>李四</string>
      <string>王五</string>
      <string>赵六</string>
    </a>
  </朋友>
</人>

Person [name=张三, age=19, friends=[李四, 王五, 赵六]]

(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<String> 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 + "]";
    }
}

程序运行结果：

<test.Person>
  <name>张三</name>
  <age>19</age>
  <朋友>李四</朋友>
  <朋友>王五</朋友>
  <朋友>赵六</朋友>
</test.Person>
Person [name=张三, age=19, friends=[李四, 王五, 赵六]]

(4)把字段节点设置成属性：@XStreamAsAttribute

class Person{
    @XStreamAsAttribute
    private String name;
    @XStreamAsAttribute
    private int age;
    private List<String> 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 + "]";
    }
}

程序运行结果：

<test.Person name="张三" age="19">
  <friends class="java.util.Arrays$ArrayList">
    <a class="string-array">
      <string>李四</string>
      <string>王五</string>
      <string>赵六</string>
    </a>
  </friends>
</test.Person>

Person [name=张三, age=19, friends=[李四, 王五, 赵六]]

(5)隐藏字段：@XStreamOmitField

class Person{
    private String name;
    private int age;
    @XStreamOmitField
    private List<String> 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 + "]";
    }
}

程序运行结果：

<test.Person>
  <name>张三</name>
  <age>19</age>
</test.Person>
Person [name=张三, age=19, friends=null]

(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 + "]";
    }
}

程序运行结果：

<test.Person>
  <name>张三</name>
  <age>19</age>
  <sex>男</sex>
</test.Person>

Person [name=张三, age=19, sex=true]

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);
    }
}

程序运行结果：

test.Person>
  <姓名>张三</姓名>
  <年龄>19</年龄>
  <转换器>自定义的转换器</转换器>
</test.Person>

Person [name=张三, age=19]

(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();
    }
}

程序运行结果：

<object-stream>
  <test.Person>
    <name>张三</name>
    <age>12</age>
  </test.Person>
  <test.Person>
    <name>李四</name>
    <age>19</age>
  </test.Person>
  <string>Hello</string>
  <int>12345</int>
</object-stream>

**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="<object-stream><test.Person><name>张三</name><age>12</age></test.Person><int>12345</int></object-stream>";
        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());
    }
}

程序运行结果：

Person [name=张三, age=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:int@0.xml、int@1.xml、int@2.xml；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
        }
    }
}

程序运行结果：

Person [name=张三, age=13]
Person [name=李四, age=21]
Person [name=王五, age=17]

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);
    }
}

程序运行结果：

{"人":{"姓名":"张三","年龄":19}}

Person [name=张三, age=19]

** 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);
    }
}

程序运行结果：

{ "name": "张三", "age": 19 }

**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：

1. JettisonMappedXmlDriver：是支持序列化和反序列化Json的。
2. JsonHierarchicalStreamDriver：只支持序列化，不支持反序列化。

转载自 : http://www.cnblogs.com/LiZhiW/p/4313493.html