gson和fastjson将json对象转换成javaBean 简单对照

    /**
     * @since 1.2.9
     */
    public <T> T toJavaObject(Class<T> clazz) {
        return TypeUtils.cast(this, clazz, ParserConfig.getGlobalInstance());
    }



    @SuppressWarnings({ "unchecked", "rawtypes" })
    public static <T> T cast(Object obj, Class<T> clazz, ParserConfig config) {
        if (obj == null) {
            return null;
        }

        if (clazz == null) {
            throw new IllegalArgumentException("clazz is null");
        }

        if (clazz == obj.getClass()) {
            return (T) obj;
        }

        if (obj instanceof Map) {
            if (clazz == Map.class) {
                return (T) obj;
            }

            Map map = (Map) obj;
            if (clazz == Object.class && !map.containsKey(JSON.DEFAULT_TYPE_KEY)) {
                return (T) obj;
            }

            return castToJavaBean((Map<String, Object>) obj, clazz, config);
        }

        if (clazz.isArray()) {
            if (obj instanceof Collection) {

                Collection collection = (Collection) obj;
                int index = 0;
                Object array = Array.newInstance(clazz.getComponentType(), collection.size());
                for (Object item : collection) {
                    Object value = cast(item, clazz.getComponentType(), config);
                    Array.set(array, index, value);
                    index++;
                }

                return (T) array;
            }

            if (clazz == byte[].class) {
                return (T) castToBytes(obj);
            }
        }

        if (clazz.isAssignableFrom(obj.getClass())) {
            return (T) obj;
        }

        if (clazz == boolean.class || clazz == Boolean.class) {
            return (T) castToBoolean(obj);
        }

        if (clazz == byte.class || clazz == Byte.class) {
            return (T) castToByte(obj);
        }

        // if (clazz == char.class || clazz == Character.class) {
        // return (T) castToCharacter(obj);
        // }

        if (clazz == short.class || clazz == Short.class) {
            return (T) castToShort(obj);
        }

        if (clazz == int.class || clazz == Integer.class) {
            return (T) castToInt(obj);
        }

        if (clazz == long.class || clazz == Long.class) {
            return (T) castToLong(obj);
        }

        if (clazz == float.class || clazz == Float.class) {
            return (T) castToFloat(obj);
        }

        if (clazz == double.class || clazz == Double.class) {
            return (T) castToDouble(obj);
        }

        if (clazz == String.class) {
            return (T) castToString(obj);
        }

        if (clazz == BigDecimal.class) {
            return (T) castToBigDecimal(obj);
        }

        if (clazz == BigInteger.class) {
            return (T) castToBigInteger(obj);
        }

        if (clazz == Date.class) {
            return (T) castToDate(obj);
        }

        if (clazz == java.sql.Date.class) {
            return (T) castToSqlDate(obj);
        }

        if (clazz == java.sql.Timestamp.class) {
            return (T) castToTimestamp(obj);
        }

        if (clazz.isEnum()) {
            return (T) castToEnum(obj, clazz, config);
        }

        if (Calendar.class.isAssignableFrom(clazz)) {
            Date date = castToDate(obj);
            Calendar calendar;
            if (clazz == Calendar.class) {
                calendar = Calendar.getInstance(JSON.defaultTimeZone, JSON.defaultLocale);
            } else {
                try {
                    calendar = (Calendar) clazz.newInstance();
                } catch (Exception e) {
                    throw new JSONException("can not cast to : " + clazz.getName(), e);
                }
            }
            calendar.setTime(date);
            return (T) calendar;
        }

        if (obj instanceof String) {
            String strVal = (String) obj;

            if (strVal.length() == 0 //
                || "null".equals(strVal) //
                || "NULL".equals(strVal)) {
                return null;
            }

            if (clazz == java.util.Currency.class) {
                return (T) java.util.Currency.getInstance(strVal);
            }
        }

        throw new JSONException("can not cast to : " + clazz.getName());
    }





    @SuppressWarnings({ "unchecked" })
    public static <T> T castToJavaBean(Map<String, Object> map, Class<T> clazz, ParserConfig config) {
        try {
            if (clazz == StackTraceElement.class) {
                String declaringClass = (String) map.get("className");
                String methodName = (String) map.get("methodName");
                String fileName = (String) map.get("fileName");
                int lineNumber;
                {
                    Number value = (Number) map.get("lineNumber");
                    if (value == null) {
                        lineNumber = 0;
                    } else {
                        lineNumber = value.intValue();
                    }
                }

                return (T) new StackTraceElement(declaringClass, methodName, fileName, lineNumber);
            }

            {
                Object iClassObject = map.get(JSON.DEFAULT_TYPE_KEY);
                if (iClassObject instanceof String) {
                    String className = (String) iClassObject;

                    Class<?> loadClazz = (Class<T>) loadClass(className);

                    if (loadClazz == null) {
                        throw new ClassNotFoundException(className + " not found");
                    }

                    if (!loadClazz.equals(clazz)) {
                        return (T) castToJavaBean(map, loadClazz, config);
                    }
                }
            }

            if (clazz.isInterface()) {
                JSONObject object;

                if (map instanceof JSONObject) {
                    object = (JSONObject) map;
                } else {
                    object = new JSONObject(map);
                }

                return (T) Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),
                                                  new Class<?>[] { clazz }, object);
            }

            if (config == null) {
                config = ParserConfig.getGlobalInstance();
            }

            JavaBeanDeserializer javaBeanDeser = null;
            ObjectDeserializer deserizer = config.getDeserializer(clazz);
            if (deserizer instanceof JavaBeanDeserializer) {
                javaBeanDeser = (JavaBeanDeserializer) deserizer;
            }
            
            if (javaBeanDeser == null) {
                throw new JSONException("can not get javaBeanDeserializer");
            }
            
            return (T) javaBeanDeser.createInstance(map, config);
        } catch (Exception e) {
            throw new JSONException(e.getMessage(), e);
        }
    }