Java 备忘: Jackson 包的 XML 注解支持

官方文档 https://github.com/FasterXML/jackson-dataformat-xml/wiki/Jackson-XML-annotations 还是有点晦涩的，本文提供注解与其对应的 XML 的预览，便于理解。

典型 XML 如下

<root k6="6">
    <k1>str</k1>
    <k-2>2</k-2>
    <k3>
        <ki>1</ki>
        <ki>2</ki>
    </k3>
    <k4>
        <ka>3</ka>
        <ka>4</ka>
    </k4>
    <k5>5-1</k5>
    <k5>5-2</k5>
    <k7>a7b</k7>
    <k8><a>8</a></k8>
    <k9><![CDATA[中<a>文]]></k9>
</root>

对应于带 Jackson 注解的 JavaBean 如下

import java.util.*;

import com.fasterxml.jackson.dataformat.xml.annotation.*;

import lombok.Data;

@Data
@JacksonXmlRootElement(localName = "root")
public class RootXml {

    private String k1;

    @JacksonXmlProperty(localName = "k-2")
    private Integer k2;

    @JacksonXmlElementWrapper(localName = "k3")
    private Collection<String> ki;

    @JacksonXmlElementWrapper(localName = "k4")
    @JacksonXmlProperty(localName = "ka")
    private Collection<String> k4;

    @JacksonXmlElementWrapper(localName = "k5", useWrapping = false)
    private Collection<String> k5;
    
    @JacksonXmlProperty(isAttribute = true)
    private Integer k6;
    
    @Data
    public static class Value1 {

        @JacksonXmlText
        private String a;
    }

    private Value1 k7;

    @Data
    public static class Value2 {

        @JacksonXmlText(value = false)
        private String a;
    }

    private Value2 k8;

    @JacksonXmlCData(value = true) // 序列化时是否总是使用 CDATA 块
    private String k9;
}