java - デフォルト値を自動拡張するためのプロパティタイプを判別できませんでした

Question

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豆：

public class JavaBean {

    private NestedBean nested;

}

public class NestedBean {

    private String foo;    
    private List<NestedBean> list;      
    private Map<String, NestedBean> map;

}

練る：

http://localhost:8080/mvc-showcase/convert/bean?nested.foo=bar&nested.list[0].foo=baz&nested.map[key].list[0].foo=bip

例外：

NullValueInNestedPathException: Invalid property 'nested.map[key]' of bean class [org.springframework.samples.mvc.convert.JavaBean]: Could not determine property type for auto-growing a default value

Answer 1

次のように使用LazyMapします。

public class LazyMap<K, V> implements Map<K, V> {

    private Map<K, V> nestedMap;
    private Class<V> valueType;

    public LazyMap(Class<V> valueType) {
        nestedMap = new HashMap<K, V>();
        this.valueType = valueType;
    }

    @Override
    public void clear() {
        nestedMap.clear();
    }

    @Override
    public boolean containsKey(Object key) {
        return nestedMap.containsKey(key);
    }

    @Override
    public boolean containsValue(Object value) {
        return nestedMap.containsValue(value);
    }

    @Override
    public Set<java.util.Map.Entry<K, V>> entrySet() {
        return nestedMap.entrySet();
    }

    @SuppressWarnings("unchecked")
    @Override
    public V get(Object key) {
        if (!containsKey(key)) {
            try {
                put((K) key, valueType.newInstance());
            } catch (Exception e) {
                throw new IllegalArgumentException(e);
            }
        }
        return nestedMap.get(key);
    }

    @Override
    public boolean isEmpty() {
        return nestedMap.isEmpty();
    }

    @Override
    public Set<K> keySet() {
        return nestedMap.keySet();
    }

    @Override
    public V put(K key, V value) {
        return nestedMap.put(key, value);
    }

    @Override
    public void putAll(Map<? extends K, ? extends V> m) {
        nestedMap.putAll(m);
    }

    @Override
    public V remove(Object key) {
        return nestedMap.remove(key);
    }

    @Override
    public int size() {
        return nestedMap.size();
    }

    @Override
    public Collection<V> values() {
        return nestedMap.values();
    }

}

豆：

public class NestedBean {

    private String foo;    
    private List<NestedBean> list;      
    private Map<String, NestedBean> map = new LazyMap<String, NestedBean>(NestedBean.class);

}