JAXB java.util.Map 绑定 [英] JAXB java.util.Map binding

问题描述

我有一个 Json 响应，如下所示:

I have a Json response which looks like the following:

{
    "data": [
        {
            "param1": "value1",
            "param2": "value2",
                    .
                    .
                    .
            "paramN": "valueN"
        }
    ]
}

我不知道参数的名称和数量.因此，我需要并希望将所有这些参数绑定到一个由 <"paramX", "valueX"> 元组组成的 java.util.Map 字段.为此，我尝试了以下代码，但parametersMap"字段返回 null.

I don't know the name and the number of the parameters. So, I need and want to bind all these parameters to a java.util.Map field consisting of <"paramX", "valueX"> tuples. To do this, I tried the following code but "parametersMap" field returns null.

@XmlRootElement(name="data")
@XmlAccessorType(XmlAccessType.FIELD)
public class Parameters {
    @XmlElement
    private Map<String,String> parametersMap;

    // Getter and setter for parametersMap
}

如何使用 JAXB 注释实现这种绑定?

How can I achieve such a binding with JAXB annotations?

提前致谢.

推荐答案

基本上你需要一个 xml 适配器.您可以修改 KeyValue 类上的名称以获得所需的特定输出.

Basically you need an xml adapter. You can fiddle with the names on the KeyValue class to get the specific output you desire.

参数.java

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import java.util.Map;

@XmlRootElement(name = "data")
@XmlAccessorType(XmlAccessType.FIELD)
public class Parameters {

    @XmlJavaTypeAdapter(value = Adapter.class)
    private Map<String, String> parametersMap;

    // Getter and setter for parametersMap
}

适配器.java

import javax.xml.bind.annotation.adapters.XmlAdapter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class Adapter extends XmlAdapter<List<KeyValue>, Map<String, String>> {

    @Override
    public Map<String, String> unmarshal(List<KeyValue> v) throws Exception {
        Map<String, String> map = new HashMap<>(v.size());
        for (KeyValue keyValue : v) {
            map.put(keyValue.key, keyValue.value);
        }
        return map;
    }

    @Override
    public List<KeyValue> marshal(Map<String, String> v) throws Exception {
        Set<String> keys = v.keySet();
        List<KeyValue> results = new ArrayList<>(v.size());
        for (String key : keys) {
            results.add(new KeyValue(key, v.get(key)));
        }
        return results;
    }
}

KeyValue.java 在这里放置更好的 JAXB 标签，很明显.

KeyValue.java Put better JAXB tags here, obviously.

import javax.xml.bind.annotation.XmlType;

@XmlType
public class KeyValue {
    public KeyValue() {
    }

    public KeyValue(String key, String value) {
        this.key = key;
        this.value = value;
    }

    //obviously needs setters/getters
    String key;
    String value;
}

这篇关于JAXB java.util.Map 绑定的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！