XML序列化和反序列化的学习

1、基本介绍

在工作中，经常为了调通上游接口，从而对请求第三方的参数进行XML序列化，这里常使用的方式就是使用JAVA扩展包中的相关注解和类来实现xml的序列化和反序列化。

2、自定义工具类

java">
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.concurrent.ConcurrentHashMap;/*** 1、实现 对象 转 xml* 2、实现 xml 转对象*/
public class XmlInterfaceUtils {private static final ConcurrentHashMap<Class<?>, JAXBContext> contextMap =new ConcurrentHashMap<>();private static JAXBContext context(Class<?> clazz) {// JAXBContext 是线程安全的，可以在多个线程中复用// computeIfAbsent 方法，如果map集合存在相同的key，则覆盖value值；不存在相同key，则添加到map集合中return contextMap.computeIfAbsent(clazz, cls -> {try {return JAXBContext.newInstance(cls);} catch (JAXBException e) {throw new IllegalStateException(e);}});}public static String convertToXml(Object obj) {StringWriter sw = new StringWriter();JAXBContext context = context(obj.getClass());Marshaller marshaller;try {marshaller = context.createMarshaller();//1.格式化输出，即按标签自动换行，否则就是一行输出marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,Boolean.TRUE);//2.设置编码（默认编码就是utf-8）
//            marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");//3.是否省略xml头信息，默认不省略（false）//   <?xml version="1.0" encoding="UTF-8">  这一句就是"头信息"
//            marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);marshaller.marshal(obj, sw);} catch (JAXBException e) {throw new IllegalStateException(e);}return sw.toString();}/*** xml转object** @param clazz 转换类* @param xml   XML 字符串* @param <T>   对象类型* @return 转换结果*/public static <T> T xmlToObject(Class<T> clazz, String xml) {JAXBContext context = context(clazz);// 每次都创建 UnmarshallerUnmarshaller unmarshaller;try {unmarshaller = context.createUnmarshaller();} catch (JAXBException e) {throw new IllegalStateException(e);}StringReader reader = new StringReader(xml);T message;try {message = (T) unmarshaller.unmarshal(reader);} catch (JAXBException e) {throw new IllegalStateException(e);}return message;}
}

3、模拟请求第三方的请求参数-V1.0

3.1 定义业务实体

Provider类

java">import javax.xml.bind.annotation.*;@XmlRootElement
public class Provider {private User user;private String id;private Integer providerTelephone;private String providerAddress;public String getId() {return id;}public void setId(String id) {this.id = id;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}public Integer getProviderTelephone() {return providerTelephone;}public void setProviderTelephone(Integer providerTelephone) {this.providerTelephone = providerTelephone;}public String getProviderAddress() {return providerAddress;}public void setProviderAddress(String providerAddress) {this.providerAddress = providerAddress;}
}

User类

java">public class User {private String username;private String password;public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}
}

3.2 运行代码

java">
public class Application {public static void main(String[] args) {Provider provider = new Provider();User user = new User();user.setUsername("hu");user.setPassword("123456");provider.setUser(user);provider.setProviderTelephone(4008123);provider.setProviderAddress("BeiJing");provider.setId("No.1");//序列化成xml格式的字符串String xml = XmlInterfaceUtils.convertToXml(provider);System.out.println(xml);//反序列化成对象Provider provider1 = XmlInterfaceUtils.xmlToObject(Provider.class, xml);}
}

控制台打印结果

必须要有一个@XmlRootElement用来标记哪个类作为根节点。否则，反序列化会失败，提示缺少 @XmlRootElement注解。

4、模拟请求第三方的请求参数-V2.0

假如第三方发生改变，要求我们进行适配。

将Provider类原本的id标签设置为根节点的属性，其他标签全部首字母大写，且按照手机号码，地址，用户信息的顺序进行反序列化，而User类的标签仍然是小写开头。

java">mport javax.xml.bind.annotation.*;@XmlType(//指定序列化的时候，生成每个标签的顺序，不指定的话，默认按照从上到下的顺序生成propOrder = {"providerTelephone", "providerAddress", "user","id"}
)
@XmlRootElement(name = "Provider")
@XmlAccessorType(XmlAccessType.FIELD)
public class Provider {@XmlElement(name = "User")private User user;//该字段映射为一个属性@XmlAttribute(name = "id")private String id;@XmlElement(name = "ProviderTelephone")private Integer providerTelephone;@XmlElement(name = "ProviderAddress")private String providerAddress;public String getId() {return id;}public void setId(String id) {this.id = id;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}public Integer getProviderTelephone() {return providerTelephone;}public void setProviderTelephone(Integer providerTelephone) {this.providerTelephone = providerTelephone;}public String getProviderAddress() {return providerAddress;}public void setProviderAddress(String providerAddress) {this.providerAddress = providerAddress;}
}

运行结果如下