Jackson 在同一个 POJO 中映射不同的展开元素

Question

I am trying to parse some XML to Java, but this XML is a big mess.

So looks like Jackson only read the last object of each type and the array size of each type has only one object.

Edit.: This is what i am trying to do (debug and see the values of form object):

public class Main {

    public static void main(String[] args) throws IOException {
        XmlMapper mapper = new XmlMapper();
        Form form  = mapper.readValue(getXml(), Form.class);
    }

    public static String getXml() {

        return "<forms>\n"
            + "    <circles><x>1</x></circles>\n"
            + "    <squares><x>1</x></squares>\n"
            + "    <squares><x>1</x></squares>\n"
            + "    <circles><x>1</x></circles>\n"
            + "    <squares><x>1</x></squares>\n"
            + "</forms>";

    }

}

@JacksonXmlRootElement(localName = "forms")
class Form {

    @JacksonXmlElementWrapper(useWrapping = false)
    @JacksonXmlProperty(localName = "circles", isAttribute = false)
    private List<Circle> circles;

    @JacksonXmlElementWrapper(useWrapping = false)
    @JacksonXmlProperty(localName = "squares", isAttribute = false)
    private List<Square> squares;

    public List<Circle> getCircles() {
        return circles;
    }

    public void setCircles(List<Circle> circles) {
        this.circles = circles;
    }

    public List<Square> getSquares() {
        return squares;
    }

    public void setSquares(List<Square> squares) {
        this.squares = squares;
    }

}

@JacksonXmlRootElement(localName = "circles")
class Circle {

    @JacksonXmlProperty(isAttribute = false)
    private String x;

    public String getX() {
        return x;
    }

    public void setX(String x) {
        this.x = x;
    }

}

@JacksonXmlRootElement(localName = "squares")
class Square {

    @JacksonXmlProperty(isAttribute = false)
    private String x;

    public String getX() {
        return x;
    }

    public void setX(String x) {
        this.x = x;
    }

}

Answer 1

Initialize the list.

    @JacksonXmlElementWrapper(useWrapping = false)
    @JacksonXmlProperty(localName = "circles", isAttribute = false)
    private final List<Circle> circles = new ArrayList<>();

Rather than replace, add all elements.

    public void setCircles(List<Circle> circles) {
        this.circles.addAll(circles);
    }

This is the trick. Thanks to @StaxMan.

Answer 2

Since lists are non-consecutive, what happens is that they will get separately created, so that last run overrides earlier. You may be able to resolve this by implementing setCircles (etc) to append to List, not replace it.