轻松搞定XML和对象之间的互转，就它了！

我会带着你远行 2023-05-22 06:50 17阅读 0赞

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## 前言 ##

在微信订阅号和支付宝生活号日常开发中,我们会涉及到对象和XML之间的相互转换。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L01pbG9nZW5pdXM_size_16_color_FFFFFF_t_70 1]

比如我们可以利用StringBuilder去直接拼接来构造XML

/** * 构造基础的响应消息 * * @return */
        public static String buildBaseAckMsg(String fromUserId) { 
            StringBuilder sb = new StringBuilder();
            sb.append("<XML>");
            sb.append("<ToUserId><![CDATA[" + fromUserId + "]]></ToUserId>");
            sb.append("<AppId><![CDATA[" + AlipayServiceEnvConstants.APP_ID + "]]></AppId>");
            sb.append("<CreateTime>" + Calendar.getInstance().getTimeInMillis() + "</CreateTime>");
            sb.append("<MsgType><![CDATA[ack]]></MsgType>");
            sb.append("</XML>");
            return sb.toString();
        }

作为像我这么懒得程序员,肯定会去找大佬写好的轮子,这就是我和`XStream`相遇的契机。下面我们一起走进`XStream`；

## 一.关于 XStream ##

Xstream 是一个简单的库，用于将对象序列化为 XML 然后再序列化回来。

## 二.简单入门 ##

### 2.1 创建要序列化的类 ###

这里有几个简单的类，XStream 可以将这些类的实例转换为 XML，然后再转换回来。

public class Person { 
      private String firstname;
      private String lastname;
      private PhoneNumber phone;
      private PhoneNumber fax;
      // ... constructors and methods
    }
    
    public class PhoneNumber { 
      private int code;
      private String number;
      // ... constructors and methods
    }

注意: 注意这些字段是私有的。 Xstream 不关心字段的可见性。 不需要`getters or setters`。 此外，XStream 并不限制你拥有一个`默认构造函数`。

### 2.2 初始化 XStream ###

引入依赖

<dependency>
        <groupId>com.thoughtworks.xstream</groupId>
        <artifactId>xstream</artifactId>
        <version>1.4.10</version>
    </dependency>

要使用 XStream，只需实例化 XStream 类:

XStream xstream = new XStream();

### 2.3.将序列化对象转为xml ###

让我们创建一个 Person 实例并填充它的字段:

Person person = new Person("Joe", "milo");
            person.setPhone(new PhoneNumber(123,"1234-456"));
            person.setFax(new PhoneNumber(123,"999-456"));

现在,要将其转换为XML,只需要简单的调用XStream的`toXML()`方法

String xml = xstream.toXML(person);

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L01pbG9nZW5pdXM_size_16_color_FFFFFF_t_70 2]

现在，为了使 XStream 输出的 XML 更简洁，可以为 XML 元素名的自定义类名创建别名。 这是使用 XStream 所需的惟一映射类型，当然这是可选的。

xstream.alias("person",Person.class);

我们会发现XML变得更简洁

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L01pbG9nZW5pdXM_size_16_color_FFFFFF_t_70 3]

### 2.4.将XML反序列化对象 ###

首先,我们重写`Person`对象的`toString()`

@Override
        public String toString() { 
            return "Person{" +
                    "firstname='" + firstname + '\'' +
                    ", lastname='" + lastname + '\'' +
                    ", phone=" + phone +
                    ", fax=" + fax +
                    '}';
        }

要重构一个对象,我们只需调用`fromXML()`方法

XStream xstream = new XStream();
            xstream.alias("person",Person.class);
    		//xml字符串
            String xmldemo = "<?xml version=\"1.0\" ?><person><firstname>Joe</firstname><lastname>milo</lastname><phone><code>123</code><number>1234-456</number></phone><fax><code>123</code><number>999-456</number></fax></person>";
            Person o = (Person)xstream.fromXML(xmldemo);
            System.out.println(o.toString());

![在这里插入图片描述][20200416164419401.png]

关于更多关于Xstream的操作,大家可以阅读[XStream使用详解][XStream]

## 三.高级入门 ##

在高级入门中,我们以支付宝生活号开发为例,采用Xstream的注解开发来完成事件订阅过程中的xml报文相关的操作

### 3.1 项目搭建 ###

首先我们搭建项目`springboot-xstream`,当然你可以在[这里][Link 1]找到源代码,案例位于`springboot-xstream`模块下面。由于案例代码太多,强烈建议大家下载源代码案例自己跑一跑。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L01pbG9nZW5pdXM_size_16_color_FFFFFF_t_70 4]

### 3.2 相关类解释 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L01pbG9nZW5pdXM_size_16_color_FFFFFF_t_70 5]

### 3.3 和XStream相关的类 ###

1.AlipayXmlMessage

package com.milo.xstream.xml;
    
    import com.thoughtworks.xstream.annotations.XStreamAlias;
    import com.thoughtworks.xstream.annotations.XStreamConverter;
    import lombok.Data;
    import lombok.extern.slf4j.Slf4j;
    
    import java.io.InputStream;
    import java.io.Serializable;
    import java.util.Map;
    
    /** * 支付宝生活号推送过来的xml消息 * @author milogenius * @date 2020/4/4 15:29 * */
    @Data
    @Slf4j
    @XStreamAlias("XML")
    public class AlipayXmlMessage implements Serializable { 
      private static final long serialVersionUID = -3586245291677274914L;
    
      /** * 使用dom4j解析的存放所有xml属性和值的map. */
      private Map<String, Object> allFieldsMap;
    
      ///
      // 以下都是支付宝生活号推送过来的消息的xml的element所对应的属性
      ///
    
      /**AppId*/
      //AppId--->xml中的字段
      //appId --->pojo中的字段
      @XStreamAlias("AppId")
      @XStreamConverter(value = XStreamCDataConverter.class)
      private String appId;
    
    
      /**用户userid,用户唯一标识*/
      @XStreamAlias("FromAlipayUserId")
      @XStreamConverter(value = XStreamCDataConverter.class)
      private String fromAlipayUserId;
    
    
      /**消息创建时间*/
      @XStreamAlias("CreateTime")
      private Long createTime;
    
      /**消息类型*/
      @XStreamAlias("MsgType")
      @XStreamConverter(value = XStreamCDataConverter.class)
      private String msgType;
    
    
      /**事件类型*/
      @XStreamAlias("EventType")
      @XStreamConverter(value = XStreamCDataConverter.class)
      private String eventType;
    
      /**用户从特定场景关注,带的自定义参数值*/
      @XStreamAlias("ActionParam")
      @XStreamConverter(value = XStreamCDataConverter.class)
      private String actionParam;
    
      /**支付宝用户信息*/
      @XStreamAlias("UserInfo")
      @XStreamConverter(value = XStreamCDataConverter.class)
      private String userInfo;
    
      /**消息id 用于消息去重*/
      @XStreamAlias("MsgId")
      private String msgId;
    
    
    
    
      public static AlipayXmlMessage fromXml(String xml) { 
        //修改支付宝生活号变态的消息内容格式，方便解析
        xml = xml.replace("<?xml version=\\\"1.0\\\" encoding=\\\"gbk\\\"?>", "");
        final AlipayXmlMessage xmlMessage = XStreamTransformer.fromXml(AlipayXmlMessage.class, xml);
        xmlMessage.setAllFieldsMap(XmlUtils.xml2Map(xml));
        return xmlMessage;
      }
    
      public static AlipayXmlMessage fromXml(InputStream is) { 
        return XStreamTransformer.fromXml(AlipayXmlMessage.class, is);
      }
    
    
    
    }

2.AlipayXmlOutMessage

package com.milo.xstream.outxml;
    
    import com.milo.xstream.builder.AckBuilder;
    import com.milo.xstream.xml.XStreamCDataConverter;
    import com.milo.xstream.xml.XStreamTransformer;
    import com.thoughtworks.xstream.annotations.XStreamAlias;
    import com.thoughtworks.xstream.annotations.XStreamConverter;
    import lombok.Data;
    
    import java.io.Serializable;
    
    /** * 响应XML * @author milogenius * @date 2020/4/4 11:57 * */
    @XStreamAlias("xml")
    @Data
    public abstract class AlipayXmlOutMessage implements Serializable { 
      private static final long serialVersionUID = -381382011286216263L;
    
      /**接受者userid*/
      @XStreamAlias("ToUserId")
      @XStreamConverter(value = XStreamCDataConverter.class)
      protected String toUserId;
    
      /**支付宝生活号appid*/
      @XStreamAlias("AppId")
      @XStreamConverter(value = XStreamCDataConverter.class)
      protected String appId;
    
      /**创建时间*/
      @XStreamAlias("CreateTime")
      protected Long createTime;
    
      /**消息类型*/
      @XStreamAlias("MsgType")
      @XStreamConverter(value = XStreamCDataConverter.class)
      protected String msgType;
    
      @XStreamAlias("response")
      protected Response response;
    
      @XStreamAlias("sign")
      protected String sign;
    
      @XStreamAlias("sign_type")
      protected String signType;
    
      /** * 获得ack builder * @return */
      public static AckBuilder ACK() { 
        return new AckBuilder();
      }
    
    
    
      @SuppressWarnings("unchecked")
      public String toXml() { 
        StringBuilder builder = new StringBuilder();
        String xml = XStreamTransformer.toXml((Class<AlipayXmlOutMessage>) this.getClass(), this);
        builder.append("<?xml version=\"1.0\" encoding=\"gbk\"?>\n");
        builder.append(xml);
        return builder.toString();
      }
    
    }

3.XStreamCDataConverter

package com.milo.xstream.xml;
    
    import com.thoughtworks.xstream.converters.basic.StringConverter;
    /** * 自定义转换器 * @author milogenius * @date 2020/4/4 10:56 * */
    public class XStreamCDataConverter extends StringConverter { 
    
      @Override
      public String toString(Object obj) { 
        return "<![CDATA[" + super.toString(obj) + "]]>";
      }
    
    }

**相关注解说明**

`@XStreamAlias`用于定义`XStream`类或字段别名的注释

`@XStreamConverter`用于声明转换器的注释

### 3.4 测试 ###

`XmlDemoTest`

package com.milo.xstream;
    
    import com.milo.xstream.outxml.AlipayXmlOutMessage;
    import com.milo.xstream.xml.AlipayXmlMessage;
    
    /** * @author milogenius * @date 2020-04-04 11:49 */
    public class XmlDemoTest { 
    
        public static void main(String[] args) { 
            //xml --->pojo
            String bizContent = "<XML>\n" +
                    " <AppId><![CDATA[2014070100171523]]></AppId>\n" +
                    " <FromUserId><![CDATA[20882837462837462837462837461234]]></FromUserId>\n" +
                    " <FromAlipayUserId><![CDATA[2088283746283746]]></FromAlipayUserId>\n" +
                    " <CreateTime><![CDATA[1405943673657]]></CreateTime>\n" +
                    " <MsgType><![CDATA[event]]></MsgType>\n" +
                    " <EventType><![CDATA[follow]]></EventType>\n" +
                    " <ActionParam><![CDATA[{\"scene\":{\"sceneId\": \"1234\"}}]]></ActionParam>\n" +
                    " <AgreementId><![CDATA[]]></AgreementId>\n" +
                    " <AccountNo><![CDATA[]]></AccountNo>\n" +
                    " <UserInfo><![CDATA[{\"logon_id\":\"135****1009\",\"user_name\":\"*iuxu527\"}]]></UserInfo>\n" +
                    "</XML>";
            AlipayXmlMessage alipayXmlMessage = AlipayXmlMessage.fromXml(bizContent);
           // System.out.println(alipayXmlMessage);
    
    
    
            //pojo --->xml
            AlipayXmlOutMessage mpXmlOutMessage = AlipayXmlOutMessage.ACK().toUserId("123456").appId("99999999").build();
            String xml = mpXmlOutMessage.toXml();
            System.out.println(xml);
    
        }
    }

### 3.5测试结果 ###

#### 3.5.1 xml ---->pojo ####

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L01pbG9nZW5pdXM_size_16_color_FFFFFF_t_70 6]

#### 3.5.2 pojo —>xml ####

![在这里插入图片描述][2020041616452312.png]

## 四.总结 ##

通过上面的一些小案例,我们学习Xstream的基本用法和注解用法,文章到此为止,谢谢大家阅读;

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[20200416164419401.png]: /images/20230521/f8d19b67929e4834b13f5de0214c7182.png
[XStream]: https://www.cnblogs.com/jpfss/p/9836465.html
[Link 1]: https://gitee.com/milogenius/milogenius-springboot
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[2020041616452312.png]: /images/20230521/19f025194d464718a501ef6faac64e4a.png