jaxb解析xml关于处理list的注解

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在JAXB中(用于JAVA对象和xml之间的转换),经常出现各类的 @XmlElement这样的标记,

下面就来以一个例子小结下,加深学习:

import java.util.*;  import javax.xml.bind.annotation.*;     @XmlRootElement  @XmlAccessorType(XmlAccessType.FIELD)  public class Customer {         private List<String> emailAddresses;             public Customer() {          emailAddresses = new ArrayList<String>();      }         public List<String> getEmailAddresses() {          return emailAddresses;      }         public void setEmailAddresses(List<String> emailAddresses) {          this.emailAddresses = emailAddresses;      }     }

这个是一个典型的POJO了,其中引用了对象emailAddress,是一个List,那么下面演示各类用法:
先看默认的调用代码如下:

import javax.xml.bind.JAXBContext;  import javax.xml.bind.Marshaller;     public class Demo {         public static void main(String[] args) throws Exception {          JAXBContext jc = JAXBContext.newInstance(Customer.class);             Customer customer = new Customer();          customer.getEmailAddresses().add("janed@example.com");          customer.getEmailAddresses().add("jdoe@example.org");             Marshaller marshaller = jc.createMarshaller();          marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);          marshaller.marshal(customer, System.out);      }  }

默认的把这个对象输出为一般的XML:
<customer>
    <emailAddresses>janed@example.com</emailAddresses>
    <emailAddresses>jdoe@example.org</emailAddresses>
</customer>

下面逐一看每个注解的用法
1) @XmlElement

@XmlElement(name="email-address")
    private List<String> emailAddresses;
加上这个注解的话,则按自定义的xml标签名去输出某个属性,如下:
<customer>
    <email-address>janed@example.com</email-address>
    <email-address>jdoe@example.org</email-address>
</customer>

2) @XmlElementWrapper
这个注解等于在最外面再包一层了,
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Customer {

    @XmlElementWrapper(name="email-addresses")
    @XmlElement(name="email-address")
    private List<String> emailAddresses;

}
输出:
<customer>
    <email-addresses>
        <email-address>janed@example.com</email-address>
        <email-address>jdoe@example.org</email-address>
    </email-addresses>
</customer>

3) @XmlList
这个等于是在同一行中,把list中的输出,以空格形式分隔开来,

@XmlRootElement  @XmlAccessorType(XmlAccessType.FIELD)  public class Customer {         @XmlList      private List<String> emailAddresses;     }

输出:
<customer>
    <emailAddresses>janed@example.com jdoe@example.org</emailAddresses>
</customer>

4)
@XmlList和 @XmlAttribute混合使用
      @XmlList
    @XmlAttribute
    private List<String> emailAddresses;

输出:
   <customer
    emailAddresses="janed@example.com jdoe@example.org"/>

看到没?就是同一行中逗号输出,并作为customer的一个属性

5)
@XmlList 和 @XmlValue混用

    @XmlList
    @XmlValue
    private List<String> emailAddresses;


就是把emailAddress的list的值,作为<customer>的value 输出,结果如下:
<customer>janed@example.com jdoe@example.org</customer>

本文来至：http://jackyrong.iteye.com/blog/1890669

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