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XStream学习手册

一、前言

1、XStream官网

http://x-stream.github.io

2、XStream是什么

XStream是一个简单的基于Java的类库，用来将Java对象序列化成XML（JSON）或反序列化为对象(即：可以轻易的将Java对象和XML文档相互转换)

3、XSteam能干什么

XStream在运行时使用Java反射机制对要进行序列化的对象树的结构进行探索，并不需要对对象作出修改。XStream可以序列化内部字段，包括私private和final字段，并且支持非公开类以及内部类。

在缺省情况下，XStream不需要配置映射关系，对象和字段将映射为同名XML元素。但是当对象和字段名与XML中的元素名不同时，XStream支持指定别名。XStream支持以方法调用的方式，或是Java 标注的方式指定别名。

XStream在进行数据类型转换时，使用系统缺省的类型转换器。同时，也支持用户自定义的类型转换器。

4、XStream特点

使用方便 - XStream的API提供了一个高层次外观，以简化常用的用例
无需创建映射 - XStream的API提供了默认的映射大部分对象序列化
性能 - XStream快速和低内存占用，适合于大对象图或系统
干净的XML - XStream创建一个干净和紧凑XML结果，这很容易阅读
不需要修改对象 - XStream可序列化的内部字段，如private和final字段，支持非公开类和内部类。默认构造函数不是强制性的要求
完整对象图支持 - XStream允许保持在对象模型中遇到的重复引用，并支持循环引用
可自定义的转换策略 - 定制策略可以允许特定类型的定制被表示为XML的注册
安全框架 - XStream提供了一个公平控制有关解组的类型，以防止操纵输入安全问题
错误消息 - 出现异常是由于格式不正确的XML时，XStream抛出一个统一的例外，提供了详细的诊断，以解决这个问题
另一种输出格式 - XStream支持其它的输出格式，如JSON

5、XStream常见的用途

传输、持久化、配置、单元测试

二、XStream入门

1、添加XSteam依赖

<dependency>
    <groupId>com.thoughtworks.xstream</groupId>
    <artifactId>xstream</artifactId>
    <version>1.4.12</version>
</dependency>
 <dependency>
    <groupId>org.codehaus.jettison</groupId>
    <artifactId>jettison</artifactId>
    <version>1.4.1</version>
</dependency>

2、XStream基本使用

package io.github.xstream.test01;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;
import lombok.AllArgsConstructor;
import lombok.ToString;

public class XStreamTest01 {
    public static void main(String[] args) {
        Student student = new Student("张三", 20);
        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Java 6
        //XML序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
        //XML反序列化
        student = (Student) xStream.fromXML(xml);
        System.out.println(student);

        xStream = new XStream(new JettisonMappedXmlDriver());
        xStream.setMode(XStream.NO_REFERENCES);
        //Json序列化
        String json = xStream.toXML(student);
        System.out.println(json);
        //Json反序列
        student = (Student) xStream.fromXML(json);
        System.out.println(student);
    }
}

@AllArgsConstructor
@ToString
class Student {
    private String name;
    private int age;
}

3、程序运行结果

<io.github.xstream.test01.Student>
  <name>张三</name>
  <age>20</age>
</io.github.xstream.test01.Student>
Security framework of XStream not initialized, XStream is probably vulnerable.
Student(name=张三, age=20)
{"io.github.xstream.test01.Student":{"name":"张三","age":20}}
Student(name=张三, age=20)
Security framework of XStream not initialized, XStream is probably vulnerable.

注意：文中使用到的Lombok注解，Lombok依赖自行添加；XStream序列化XML时需要引用的jar包：xstream-[version].jar、xpp3-[version].jar、xmlpull-[version].jar，当引入xstream依赖后会自动依赖xpp3、xmlpull依赖。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。

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Java 6集成STAX解析器。这样用户就不需要依赖xpp3-[version].jar。

三、XStream混叠

1、混叠是一种技术来定制生成XML或者使用XStream特定的格式化XML。假设，一个下面的XML格式是用于序列化/反序列化Student对象。

<student name="张三">
    <phone>
        <brand>小米</brand>
        <description>小米手机的描述</description>
    </phone>
    <phone>
        <brand>苹果</brand>
        <description>苹果手机的描述</description>
    </phone>
</student>

2、根椐上面的XML格式，我们创建实体类

@AllArgsConstructor
@ToString
class Student {
    private String studentName;
    private List<Phone> phones;
}

@AllArgsConstructor
@ToString
class Phone {
    private String brand;
    private String description;
}

3、执行代码

package io.github.xstream.test02;

import com.thoughtworks.xstream.XStream;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

public class XStreamTest02 {
    public static void main(String[] args) {
        List<Phone> phones = new ArrayList<>();
        phones.add(new Phone("小米手机", "小米手机的描述"));
        phones.add(new Phone("苹果手机", "苹果手机的描述"));
        Student student = new Student("张三", phones);

        XStream xStream = new XStream();//需要XPP3库
        //XML序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
    }
}

@AllArgsConstructor
@ToString
class Student {
    private String studentName;
    private List<Phone> phones;
}

@AllArgsConstructor
@ToString
class Phone {
    private String brand;
    private String description;
}

4、验证输出

<io.github.xstream.test02.Student>
  <studentName>张三</studentName>
  <phones>
    <io.github.xstream.test02.Phone>
      <brand>小米手机</brand>
      <description>小米手机的描述</description>
    </io.github.xstream.test02.Phone>
    <io.github.xstream.test02.Phone>
      <brand>苹果手机</brand>
      <description>苹果手机的描述</description>
    </io.github.xstream.test02.Phone>
  </phones>
</io.github.xstream.test02.Student>

在上面的结果，我们已经看到了Student对象名称是完全合格的。要替换它作为学生的标签，按照四、XStream类混叠的步骤

另外，在上述结果中可以看出，所需studentName要重命名来命名。要替换它，按照五、XStream字段混叠的步骤

在上面的结果，我们可以看到手机标记被添加成为手机列表。替换它，按照六、XStream隐式集合混叠的步骤

在上面的结果，我们可以看到这个名字来作为一个子节点，需要将它作为根节点的属性。替换它，按照七、XStream属性混叠的步骤

四、XStream类混叠

1、类混叠是用来创建一个类的XML完全限定名称的别名。让我们修改XStreamTest02例子，将下面的代码添加到XStreamTest02例子里面

xStream.alias("student", Person02.class);
xStream.alias("phone", Phone.class);

2、执行代码

package io.github.xstream.test02;

import com.thoughtworks.xstream.XStream;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

public class XStreamTest02 {
    public static void main(String[] args) {
        List<Phone> phones = new ArrayList<>();
        phones.add(new Phone("小米手机", "小米手机的描述"));
        phones.add(new Phone("苹果手机", "苹果手机的描述"));
        Student student = new Student("张三", phones);

        XStream xStream = new XStream();//需要XPP3库
        xStream.alias("student", Student.class);
        xStream.alias("phone", Phone.class);

        //XML序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
    }
}

@AllArgsConstructor
@ToString
class Student {
    private String studentName;
    private List<Phone> phones;
}

@AllArgsConstructor
@ToString
class Phone {
    private String brand;
    private String description;
}

3、执行结果

<student>
  <studentName>张三</studentName>
  <phones>
    <phone>
      <brand>小米手机</brand>
      <description>小米手机的描述</description>
    </phone>
    <phone>
      <brand>苹果手机</brand>
      <description>苹果手机的描述</description>
    </phone>
  </phones>
</student>

可以看到<io.github.xstream.test02.Student>和<io.github.xstream.test02.Phone>分别被修改为了<student>和<phone>

五、XStream字段混叠

1、字段混叠用于创建以XML字段的别名。让我们再次修改原来的XStreamTest02例子，将下面的代码添加到XStreamTest02例子里面

xStream.aliasField("name", Student.class, "studentName");

2、执行代码

package io.github.xstream.test02;

import com.thoughtworks.xstream.XStream;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

public class XStreamTest02 {
    public static void main(String[] args) {
        List<Phone> phones = new ArrayList<>();
        phones.add(new Phone("小米手机", "小米手机的描述"));
        phones.add(new Phone("苹果手机", "苹果手机的描述"));
        Student student = new Student("张三", phones);

        XStream xStream = new XStream();//需要XPP3库
        xStream.alias("student", Student.class);
        xStream.alias("phone", Phone.class);
        xStream.aliasField("name", Student.class, "studentName");

        //XML序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
    }
}

@AllArgsConstructor
@ToString
class Student {
    private String studentName;
    private List<Phone> phones;
}

@AllArgsConstructor
@ToString
class Phone {
    private String brand;
    private String description;
}

3、执行结果

<student>
  <name>张三</name>
  <phones>
    <phone>
      <brand>小米手机</brand>
      <description>小米手机的描述</description>
    </phone>
    <phone>
      <brand>苹果手机</brand>
      <description>苹果手机的描述</description>
    </phone>
  </phones>
</student>

可以看到<studentName>被修改为了<name>

六、XStream隐式集合混叠

1、隐式集合混叠时使用的集合是表示在XML无需显示根。例如，在我们的例子中，我们需要一个接一个，但不是在根节点来显示每一个节点。让我们再次修改原来的XStreamTest02例子，将下面的代码添加到XStreamTest02例子里面

xStream.addImplicitCollection(Student.class, "phones");

2、执行代码

package io.github.xstream.test02;

import com.thoughtworks.xstream.XStream;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

public class XStreamTest02 {
    public static void main(String[] args) {
        List<Phone> phones = new ArrayList<>();
        phones.add(new Phone("小米手机", "小米手机的描述"));
        phones.add(new Phone("苹果手机", "苹果手机的描述"));
        Student student = new Student("张三", phones);

        XStream xStream = new XStream();//需要XPP3库
        xStream.alias("student", Student.class);
        xStream.alias("phone", Phone.class);
        xStream.aliasField("name", Student.class, "studentName");
        xStream.addImplicitCollection(Student.class, "phones");

        //XML序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
    }
}

@AllArgsConstructor
@ToString
class Student {
    private String studentName;
    private List<Phone> phones;
}

@AllArgsConstructor
@ToString
class Phone {
    private String brand;
    private String description;
}

3、执行结果

<student>
  <name>张三</name>
  <phone>
    <brand>小米手机</brand>
    <description>小米手机的描述</description>
  </phone>
  <phone>
    <brand>苹果手机</brand>
    <description>苹果手机的描述</description>
  </phone>
</student>

可以看到<phones>被隐藏了

七、XStream属性混叠

1、属性混叠用于创建一个成员变量作为XML属性序列化。让我们再次修改原来的XStreamTest02例子，将下面的代码添加到XStreamTest02例子里面

xStream.useAttributeFor(Student.class, "studentName");

2、执行代码

package io.github.xstream.test02;

import com.thoughtworks.xstream.XStream;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

public class XStreamTest02 {
    public static void main(String[] args) {
        List<Phone> phones = new ArrayList<>();
        phones.add(new Phone("小米手机", "小米手机的描述"));
        phones.add(new Phone("苹果手机", "苹果手机的描述"));
        Student student = new Student("张三", phones);

        XStream xStream = new XStream();//需要XPP3库
        xStream.alias("student", Student.class);
        xStream.alias("phone", Phone.class);
        xStream.aliasField("name", Student.class, "studentName");
        xStream.addImplicitCollection(Student.class, "phones");
        xStream.useAttributeFor(Student.class, "studentName");

        //XML序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
    }
}

@AllArgsConstructor
@ToString
class Student {
    private String studentName;
    private List<Phone> phones;
}

@AllArgsConstructor
@ToString
class Phone {
    private String brand;
    private String description;
}

3、执行结果

<student name="张三">
  <phone>
    <brand>小米手机</brand>
    <description>小米手机的描述</description>
  </phone>
  <phone>
    <brand>苹果手机</brand>
    <description>苹果手机的描述</description>
  </phone>
</student>

可以看到<name>被作为了<student>的属性

八、XStream包混叠

1、包混叠用于创建一个类XML的完全限定名称的别名到一个新的限定名称。让我们再次修改原来的XStreamTest02例子，将下面代码

xStream.alias("student", Student.class);
xStream.alias("phone", Phone.class);

修改为

xStream.aliasPackage("xx.xx.xx.xx", "io.github.xstream.test02");

2、执行代码

package io.github.xstream.test02;

import com.thoughtworks.xstream.XStream;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

public class XStreamTest02 {
    public static void main(String[] args) {
        List<Phone> phones = new ArrayList<>();
        phones.add(new Phone("小米手机", "小米手机的描述"));
        phones.add(new Phone("苹果手机", "苹果手机的描述"));
        Student student = new Student("张三", phones);

        XStream xStream = new XStream();//需要XPP3库
//        xStream.alias("student", Student.class);
//        xStream.alias("phone", Phone.class);
        xStream.aliasPackage("xx.xx.xx.xx", "io.github.xstream.test02");
        xStream.aliasField("name", Student.class, "studentName");
        xStream.addImplicitCollection(Student.class, "phones");
        xStream.useAttributeFor(Student.class, "studentName");

        //XML序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
    }
}

@AllArgsConstructor
@ToString
class Student {
    private String studentName;
    private List<Phone> phones;
}

@AllArgsConstructor
@ToString
class Phone {
    private String brand;
    private String description;
}

3、执行结果

<xx.xx.xx.xx.Student name="张三">
  <xx.xx.xx.xx.Phone>
    <brand>小米手机</brand>
    <description>小米手机的描述</description>
  </xx.xx.xx.xx.Phone>
  <xx.xx.xx.xx.Phone>
    <brand>苹果手机</brand>
    <description>苹果手机的描述</description>
  </xx.xx.xx.xx.Phone>
</xx.xx.xx.xx.Student>

可以看到包名由io.github.xstream.test02替换为了xx.xx.xx.xx

九、XStream注解

1、前面的四、五、六、七、八步骤都是通过代码操作的

//xStream.alias("student", Student.class);
//xStream.alias("phone", Phone.class);
xStream.aliasPackage("xx.xx.xx.xx", "io.github.xstream.test02");
xStream.aliasField("name", Student.class, "studentName");
xStream.addImplicitCollection(Student.class, "phones");
xStream.useAttributeFor(Student.class, "studentName");

2、XStream同时也支持注解，使用注解会变得简单也会达到相同的效果

package io.github.xstream.test03;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.*;
import com.thoughtworks.xstream.converters.basic.BooleanConverter;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

public class XStreamTest03 {
    public static void main(String[] args) {
        List<Phone> phones = new ArrayList<>();
        phones.add(new Phone("小米手机", "小米手机的描述"));
        phones.add(new Phone("苹果手机", "苹果手机的描述"));
        Student student = new Student("张三", phones, 20, true);
        
        XStream xStream = new XStream();//需要XPP3库
        //xStream.processAnnotations(new Class[]{Student.class});
        xStream.autodetectAnnotations(true);
        //XML序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
    }
}

@AllArgsConstructor
@ToString
//别名注解
@XStreamAlias("student")
class Student {
    @XStreamAlias("name")
    //把字段节点设置成属性
    @XStreamAsAttribute
    private String studentName;
    //省略集合根节点
    @XStreamImplicit
    private List<Phone> phones;
    //隐藏字段
    @XStreamOmitField
    private int age;
    //设置转换器
    @XStreamConverter(value = BooleanConverter.class, booleans = {false}, strings = {"男", "女"})
    private boolean sex;
}

@AllArgsConstructor
@ToString
@XStreamAlias("phone")
class Phone {
    private String brand;
    private String description;
}

3、使用注解的话，需要XML序列化之前添加如下代码

xStream.autodetectAnnotations(true);

或者

xStream.processAnnotations(new Class[]{Student.class});

4、执行结果

<student name="张三">
  <phone>
    <brand>小米手机</brand>
    <description>小米手机的描述</description>
  </phone>
  <phone>
    <brand>苹果手机</brand>
    <description>苹果手机的描述</description>
  </phone>
  <sex>男</sex>
</student>

使用注解我们也可以看到也能达到相同的效果

注意：当使用XStream对象处理一个被注解的类型时，XStream对象也会处理所有与其相关的类型的注解信息，即该类型的父类、父接口、所有子类的注解。

十、XStream自定义转换器

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://x-stream.github.io/converters.html

2、使用自定义转换器

package io.github.xstream.test04;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

public class XStreamTest04 {
    public static void main(String[] args) {
        Student student =new Student("张三",19);
        XStream xStream = new XStream();
        //注册转换器
        xStream.registerConverter(new StudentConverter());
        //序列化
        String xml = xStream.toXML(student);
        System.out.println(xml);
        //反序列化
        student=(Student)xStream.fromXML(xml);
        System.out.println(student);
    }
}

@Getter
@Setter
@ToString
@AllArgsConstructor
class Student {
    private String name;
    private int age;
}

自定义转换器

package io.github.xstream.test04;

import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;

public class StudentConverter implements Converter {
    //定义转换器能转换的JavaBean类型
    @Override
    public boolean canConvert(Class type) {
        return type.equals(Student.class);
    }

    //把对象序列化成XML或JSON
    @Override
    public void marshal(Object value, HierarchicalStreamWriter writer,
                        MarshallingContext context) {
        Student student = (Student) value;
        writer.startNode("姓名");
        writer.setValue(student.getName());
        writer.endNode();
        writer.startNode("年龄");
        writer.setValue(student.getAge() + "");
        writer.endNode();
        writer.startNode("转换器");
        writer.setValue("自定义的转换器");
        writer.endNode();
    }

    //把XML或JSON反序列化成对象
    @Override
    public Object unmarshal(HierarchicalStreamReader reader,
                            UnmarshallingContext context) {
        Student student = new Student("", -1);
        reader.moveDown();
        student.setName(reader.getValue());
        reader.moveUp();
        reader.moveDown();
        student.setAge(Integer.parseInt(reader.getValue()));
        reader.moveUp();
        return student;
    }
}

3、执行结果

<student>
  <姓名>张三</姓名>
  <年龄>19</年龄>
  <转换器>自定义的转换器</转换器>
</student>
Security framework of XStream not initialized, XStream is probably vulnerable.
Student(name=张三, age=19)

4、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

十一、XStream对象流

1、对象输出流

package io.github.xstream.test05;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.io.*;

public class XStreamTest05 {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        XStreamTest05 xStreamTest04 = new XStreamTest05();
        String path = "F:\test.txt";
        XStream xStream = new XStream();//需要XPP3库
        xStream.processAnnotations(Student.class);
        xStream.autodetectAnnotations(true);
        xStreamTest04.writeObject(xStream, path);
    }

    //对象输出流方法
    public void writeObject(XStream xStream, String path) throws IOException {
        Student zs = new Student("张三", 20);
        Student ls = new Student("李四", 21);
        Student ww = new Student("王五", 22);
        ObjectOutputStream objectOutputStream = xStream.createObjectOutputStream(new FileOutputStream(path));
        objectOutputStream.writeObject(zs);
        objectOutputStream.writeObject(ls);
        objectOutputStream.writeObject(ww);
        objectOutputStream.writeObject("totalStudent");
        objectOutputStream.writeInt(3);
        objectOutputStream.close();
    }
}

@AllArgsConstructor
@ToString
//别名注解
@XStreamAlias("student")
class Student {
    @XStreamAlias("name")
    //把字段节点设置成属性
    @XStreamAsAttribute
    private String studentName;
    private int age;
}

2、在指定路径中打开test.txt文件，查看执行结果

<object-stream>
  <student name="张三">
    <age>20</age>
  </student>
  <student name="李四">
    <age>21</age>
  </student>
  <student name="王五">
    <age>22</age>
  </student>
  <string>totalStudent</string>
  <int>3</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。这个根节点默认为<object-stream>上面的例子所示。

3、对象输入流

package io.github.xstream.test05;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.io.*;

public class XStreamTest05 {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        XStreamTest05 xStreamTest04 = new XStreamTest05();
        String path = "F:\test.txt";
        XStream xStream = new XStream();//需要XPP3库
        xStream.processAnnotations(Student.class);
        xStream.autodetectAnnotations(true);
        xStreamTest04.readObject(xStream, path);
    }

    //对象输入流方法
    public void readObject(XStream xStream, String path) throws IOException, ClassNotFoundException {
        ObjectInputStream objectInputStream = xStream.createObjectInputStream(new FileInputStream(path));
        System.out.println((Student) objectInputStream.readObject());
        System.out.println((Student) objectInputStream.readObject());
        System.out.println((Student) objectInputStream.readObject());
        System.out.println(objectInputStream.readObject());
        System.out.println(objectInputStream.readInt());
    }
}

@AllArgsConstructor
@ToString
//别名注解
@XStreamAlias("student")
class Student {
    @XStreamAlias("name")
    //把字段节点设置成属性
    @XStreamAsAttribute
    private String studentName;
    private int age;
}

4、执行结果

Student(studentName=张三, age=20)
Student(studentName=李四, age=21)
Student(studentName=王五, age=22)
totalStudent
3

十二、XStream持久化API

1、保存Java对象

package io.github.xstream.test06;

import com.thoughtworks.xstream.persistence.FilePersistenceStrategy;
import com.thoughtworks.xstream.persistence.PersistenceStrategy;
import com.thoughtworks.xstream.persistence.XmlArrayList;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.io.File;
import java.util.List;

public class XStreamTest06 {
    public static void main(String[] args) {
        XStreamTest06 xStreamTest06=new XStreamTest06();
        xStreamTest06.saveObject();
    }

    //保存Java对象
    public void saveObject(){
        PersistenceStrategy strategy = new FilePersistenceStrategy(new File("F:\"));
        List list = new XmlArrayList(strategy);
        list.add(new Student("张三",13));
        list.add(new Student("李四",21));
        list.add(new Student("王五",17));
    }
}

@ToString
@AllArgsConstructor
class Student {
    private String name;
    private int age;
}

2、运行程序结果，在F磁盘的根路径可以看到有三个文件:int@0.xml、int@1.xml、int@2.xml，每个对象都被序列化到XML文件里

3、读取并删除JavaBean对象

package io.github.xstream.test06;

import com.thoughtworks.xstream.persistence.FilePersistenceStrategy;
import com.thoughtworks.xstream.persistence.PersistenceStrategy;
import com.thoughtworks.xstream.persistence.XmlArrayList;
import lombok.AllArgsConstructor;
import lombok.ToString;

import java.io.File;
import java.util.Iterator;
import java.util.List;

public class XStreamTest06 {
    public static void main(String[] args) {
        XStreamTest06 xStreamTest06 = new XStreamTest06();
        xStreamTest06.deleteObject();
    }
    
    //读取并删除Java对象
    public void deleteObject() {
        PersistenceStrategy strategy = new FilePersistenceStrategy(new File("F:\"));
        List list = new XmlArrayList(strategy);
        for (Iterator it = list.iterator(); it.hasNext(); ) {
            System.out.println((Student) it.next());
            //删除对象序列化文件
            it.remove();
        }
    }
}

@ToString
@AllArgsConstructor
class Student {
    private String name;
    private int age;
}

4、运行程序结果，可以看到把F磁盘的根路径int@0.xml、int@1.xml、int@2.xml文件删除了

Security framework of XStream not initialized, XStream is probably vulnerable.
Student(name=张三, age=13)
Student(name=李四, age=21)
Student(name=王五, age=17)

十三、XStream操作JSON

1、XStream序列化JSON的重命名

package io.github.xstream.test07;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;
import io.github.xstream.test04.StudentConverter;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

public class XStreamTest07 {
    public static void main(String[] args) {
        XStreamTest07 xStreamTest07 = new XStreamTest07();
        xStreamTest07.serializeJson();
    }

    public void serializeJson() {
        Student student = new Student("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(student);
        System.out.println(xml);
        //JSON反序列化
        student = (Student) xStream.fromXML(xml);
        System.out.println(student);
    }
}

@ToString
@AllArgsConstructor
@XStreamAlias("人")
class Student {
    @XStreamAlias("姓名")
    private String name;
    @XStreamAlias("年龄")
    private int age;
}

2、运行结果

{"人":{"姓名":"张三","年龄":19}}
Student(name=张三, age=19)
Security framework of XStream not initialized, XStream is probably vulnerable.

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！

3、去掉序列化JSON的根节点

package io.github.xstream.test07;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;
import com.thoughtworks.xstream.io.json.JsonHierarchicalStreamDriver;
import com.thoughtworks.xstream.io.json.JsonWriter;
import io.github.xstream.test04.StudentConverter;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

import java.io.Writer;

public class XStreamTest07 {
    public static void main(String[] args) {
        XStreamTest07 xStreamTest07 = new XStreamTest07();
        xStreamTest07.removeRootNode();
    }

    public void removeRootNode() {
        Student student = new Student("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(student);
        System.out.println(xml);
    }
}

@ToString
@AllArgsConstructor
@XStreamAlias("人")
class Student {
    @XStreamAlias("姓名")
    private String name;
    @XStreamAlias("年龄")
    private int age;
}

4、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。

5、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。

参考：

http://x-stream.github.io

https://www.yiibai.com/xstream

https://www.cnblogs.com/LiZhiW/p/4313493.html

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原文地址：https://www.cnblogs.com/coding-farmer/p/13042646.html