/src/main/java/com/alibaba/fastjson/util/FieldInfo.java

package com.alibaba.fastjson.util;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.GenericDeclaration;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;

public class FieldInfo implements Comparable<FieldInfo> {

    private final String   name;
    private final Method   method;
    private final Field    field;

    private final Class<?> fieldClass;
    private final Type     fieldType;
    private final Class<?> declaringClass;
    private boolean        getOnly = false;

    public FieldInfo(String name, Class<?> declaringClass, Class<?> fieldClass, Type fieldType, Method method,
                     Field field){
        this.name = name;
        this.declaringClass = declaringClass;
        this.fieldClass = fieldClass;
        this.fieldType = fieldType;
        this.method = method;
        this.field = field;

        if (method != null) {
            method.setAccessible(true);
        }

        if (field != null) {
            field.setAccessible(true);
        }
    }

    public FieldInfo(String name, Method method, Field field){
        this(name, method, field, null, null);
    }

    public FieldInfo(String name, Method method, Field field, Class<?> clazz, Type type){
        this.name = name;
        this.method = method;
        this.field = field;

        if (method != null) {
            method.setAccessible(true);
        }

        if (field != null) {
            field.setAccessible(true);
        }

        Type fieldType;
        Class<?> fieldClass;
        if (method != null) {
            if (method.getParameterTypes().length == 1) {
                fieldClass = method.getParameterTypes()[0];
                fieldType = method.getGenericParameterTypes()[0];
            } else {
                fieldClass = method.getReturnType();
                fieldType = method.getGenericReturnType();
                getOnly = true;
            }
            this.declaringClass = method.getDeclaringClass();
        } else {
            fieldClass = field.getType();
            fieldType = field.getGenericType();
            this.declaringClass = field.getDeclaringClass();
        }
        
        if (clazz != null && fieldClass == Object.class && fieldType instanceof TypeVariable) {
            TypeVariable<?> tv = (TypeVariable<?>) fieldType;
            Type genericFieldType = getInheritGenericType(clazz, tv);
            if (genericFieldType != null) {
                this.fieldClass = TypeUtils.getClass(genericFieldType);
                this.fieldType = genericFieldType;
                return;
            }
        }

        Type genericFieldType = getFieldType(clazz, type, fieldType);

        if (genericFieldType != fieldType) {
            if (genericFieldType instanceof ParameterizedType) {
                fieldClass = TypeUtils.getClass(genericFieldType);
            } else if (genericFieldType instanceof Class) {
                fieldClass = TypeUtils.getClass(genericFieldType);
            }
        }

        this.fieldType = genericFieldType;
        this.fieldClass = fieldClass;
    }

    public static Type getFieldType(Class<?> clazz, Type type, Type fieldType) {
        if (clazz == null || type == null) {
            return fieldType;
        }

        if (!(type instanceof ParameterizedType)) {
            return fieldType;
        }

        if (fieldType instanceof TypeVariable) {
            ParameterizedType paramType = (ParameterizedType) type;
            TypeVariable<?> typeVar = (TypeVariable<?>) fieldType;

            for (int i = 0; i < clazz.getTypeParameters().length; ++i) {
                if (clazz.getTypeParameters()[i].getName().equals(typeVar.getName())) {
                    fieldType = paramType.getActualTypeArguments()[i];
                    break;
                }
            }
        }

        return fieldType;
    }
    
    public static Type getInheritGenericType(Class<?> clazz, TypeVariable<?> tv) {
        Type type = null;
        GenericDeclaration gd = tv.getGenericDeclaration();
        do {
            type = clazz.getGenericSuperclass();
            if (type == null) {
                return null;
            }
            if (type instanceof ParameterizedType) {
                ParameterizedType ptype = (ParameterizedType) type;
                if (ptype.getRawType() == gd) {
                    TypeVariable<?>[] tvs = gd.getTypeParameters();
                    Type[] types = ptype.getActualTypeArguments();
                    for (int i = 0; i < tvs.length; i++) {
                        if (tvs[i] == tv)
                            return types[i];
                    }
                    return null;
                }
            }
            clazz = TypeUtils.getClass(type);
        } while (type != null);
        return null;
    }

    public String toString() {
        return this.name;
    }

    public Class<?> getDeclaringClass() {
        return declaringClass;
    }

    public Class<?> getFieldClass() {
        return fieldClass;
    }

    public Type getFieldType() {
        return fieldType;
    }

    public String getName() {
        return name;
    }

    public Method getMethod() {
        return method;
    }

    public Field getField() {
        return field;
    }

    public int compareTo(FieldInfo o) {
        return this.name.compareTo(o.name);
    }

    public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
        T annotation = null;
        if (method != null) {
            annotation = method.getAnnotation(annotationClass);
        }

        if (annotation == null) {
            if (field != null) {
                annotation = field.getAnnotation(annotationClass);
            }
        }

        return annotation;
    }

    public Object get(Object javaObject) throws IllegalAccessException, InvocationTargetException {
        if (method != null) {
            Object value = method.invoke(javaObject, new Object[0]);
            return value;
        }

        return field.get(javaObject);
    }

    public void set(Object javaObject, Object value) throws IllegalAccessException, InvocationTargetException {
        if (method != null) {
            method.invoke(javaObject, new Object[] { value });
            return;
        }

        field.set(javaObject, value);
    }

    public void setAccessible(boolean flag) throws SecurityException {
        if (method != null) {
            method.setAccessible(flag);
            return;
        }

        field.setAccessible(flag);
    }

    public boolean isGetOnly() {
        return getOnly;
    }

}