com.github.rkmk.mapper.FieldHelper Maven / Gradle / Ivy

Go to download
package com.github.rkmk.mapper;

import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import static java.util.Objects.nonNull;

public class FieldHelper {

    public static void set(Field field, Object object, Object value) {
        field.setAccessible(true);

        try {
            field.set(object, value);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException(String.format("The field %s is not accessible",field.getName()), e);
        }
    }

    public static Object get(Field field, Object object) {
        field.setAccessible(true);

        try {
            return field.get(object);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException(String.format("The field %s is not accessible",field.getName()), e);
        }
    }

    public static  T getInstance(Class type) {
        try {
            return type.newInstance();
        }
        catch (Exception e) {
            throw new IllegalArgumentException(String.format("A bean, %s, was mapped " +
                    "which was not instantiable", type.getName()), e);
        }

    }

    public static Class getParameterisedReturnType(Field field){
        Class result = null ;
        Type genericFieldType = field.getGenericType();
        if(genericFieldType instanceof ParameterizedType){
            ParameterizedType aType = (ParameterizedType) genericFieldType;
            Type[] fieldArgTypes = aType.getActualTypeArguments();
            result = fieldArgTypes.length >0 ? (Class)fieldArgTypes[0] : null ;
        }

        if(nonNull(result)) {
            return result;
        }
        throw new IllegalArgumentException(String.format("The field type %s is not inferrable",field.getName()));
    }

    public static List getFields(Class type) {
        List result = new ArrayList<>();
        Class clazz = type;
        while(clazz.getSuperclass() != null) {
            result.addAll(Arrays.asList(clazz.getDeclaredFields()));
            clazz = clazz.getSuperclass();
        }
        return result;
    }

    public static  Object accessField(String fieldName, O o) {
        Field field = null;
        try {
            field = o.getClass().getDeclaredField(fieldName);
        } catch (NoSuchFieldException e) {
            throw new IllegalArgumentException("The field must not be null");
        }
        if (field == null) {
            throw new IllegalArgumentException("The field must not be null");
        }
        field.setAccessible(true);
        try {
            return field.get(o);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("The field not accessible");
        }
    }


}