Java Converter類代碼示例

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
/**
 * Construct a converter which delegates to the specified
 * {@link Converter} implementation.
 *
 * @param converter The converter to delegate to
 */
public ConverterFacade(final Converter converter) {
    if (converter == null) {
        throw new IllegalArgumentException("Converter is missing");
    }
    this.converter = converter;
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
/**
 * map to bean
 * 轉換過程中，由於屬性的類型不同，需要分別轉換。
 * java 反射機製，轉換過程中屬性的類型默認都是 String 類型，否則會拋出異常，而 BeanUtils 項目，做了大量轉換工作，比 java 反射機製好用
 * BeanUtils 的 populate 方法，對 Date 屬性轉換，支持不好，需要自己編寫轉換器
 *
 * @param map  待轉換的 map
 * @param bean 滿足 bean 格式，且需要有無參的構造方法; bean 屬性的名字應該和 map 的 key 相同
 * @throws IllegalAccessException
 * @throws InvocationTargetException
 */
private static void mapToBean(Map<String, Object> map, Object bean) throws IllegalAccessException, InvocationTargetException {

    //注冊幾個轉換器
    ConvertUtils.register(new SqlDateConverter(null), java.sql.Date.class);
    ConvertUtils.register(new SqlTimestampConverter(null), java.sql.Timestamp.class);
    //注冊一個類型轉換器  解決 common-beanutils 為 Date 類型賦值問題
    ConvertUtils.register(new Converter() {
        //  @Override
        public Object convert(Class type, Object value) { // type : 目前所遇到的數據類型。  value :目前參數的值。
            // System.out.println(String.format("value = %s", value));

            if (value == null || value.equals("") || value.equals("null"))
                return null;
            Date date = null;
            try {
                SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                date = dateFormat.parse((String) value);
            } catch (Exception e) {

                e.printStackTrace();
            }

            return date;
        }

    }, Date.class);

    BeanUtils.populate(bean, map);
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
@Override
public void injectMembers(T t)
{
  try {
    LOG.debug("Processing " + annotation + " for field " + field);
    String value = conf.get(annotation.key());
    if (value == null) {
      if (annotation.optional() == false) {
        throw new IllegalArgumentException("Cannot inject " + annotation);
      }
      return;
    }
    Converter c = converters.lookup(field.getType());
    if (c == null) {
      throw new IllegalArgumentException("Cannot find a converter for: " + field);
    }
    field.set(t, c.convert(field.getType(), value));
  } catch (IllegalAccessException e) {
    throw new RuntimeException(e);
  }
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
/**
 * Construct an <b>array</b> <code>Converter</code> with the specified
 * <b>component</b> <code>Converter</code> that throws a
 * <code>ConversionException</code> if an error occurs.
 *
 * @param defaultType The default array type this
 *  <code>Converter</code> handles
 * @param elementConverter Converter used to convert
 *  individual array elements.
 */
public ArrayConverter(final Class<?> defaultType, final Converter elementConverter) {
    super();
    if (defaultType == null) {
        throw new IllegalArgumentException("Default type is missing");
    }
    if (!defaultType.isArray()) {
        throw new IllegalArgumentException("Default type must be an array.");
    }
    if (elementConverter == null) {
        throw new IllegalArgumentException("Component Converter is missing.");
    }
    this.defaultType = defaultType;
    this.elementConverter = elementConverter;
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
public void translateFromCSVToObject(CsvEntityContext context,
    Map<String, Object> csvValues, BeanWrapper object) {

  if (isMissingAndOptional(csvValues))
    return;

  Converter converter = create(context);
  String entityId = (String) csvValues.get(_csvFieldName);
  Object entity = converter.convert(_objFieldType, entityId);
  object.setPropertyValue(_objFieldName, entity);
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
public static void check()
{
  if (classLoaders.putIfAbsent(Thread.currentThread().getContextClassLoader(), Boolean.TRUE) == null) {
    loadDefaultConverters();
    for (Map.Entry<Class<?>, Class<? extends StringCodec<?>>> entry : codecs.entrySet()) {
      try {
        final StringCodec<?> codecInstance = entry.getValue().newInstance();
        ConvertUtils.register(new Converter()
        {
          @Override
          public Object convert(Class type, Object value)
          {
            return value == null ? null : codecInstance.fromString(value.toString());
          }

        }, entry.getKey());
      } catch (Exception ex) {
        throw new RuntimeException(ex);
      }
    }
  }
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
/**
 * Test of getConverter method, of class UtilsBeanFactory.
 */
@Test
public void testGetConverter() {
    System.out.println("getConverter");
    Class from = TypeHandler.class;
    Class to = Integer.class;
    Converter expResult = null;
    Converter result = UtilsBeanFactory.getConverter(from, to);
    assertNotNull(result);

    result = UtilsBeanFactory.getConverter(Date2.class, String.class);
    String res = result.convert(String.class, Calendar.getInstance().getTime());
    assertNotNull(result);

    result = UtilsBeanFactory.getConverter(Date2.class, UtilsBeanFactoryTest.class);
    assertNull(result);
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
public String convert(Object value)
{
    if(value != null)
    {
        Class class1 = value.getClass();
        if(class1.isEnum() && super.lookup(class1) == null)
            super.register(new EnumConverter(class1), class1);
        else
        if(class1.isArray() && class1.getComponentType().isEnum())
        {
            if(super.lookup(class1) == null)
            {
                ArrayConverter arrayconverter = new ArrayConverter(class1, new EnumConverter(class1.getComponentType()), 0);
                arrayconverter.setOnlyFirstToString(false);
                super.register(arrayconverter, class1);
            }
            Converter converter = super.lookup(class1);
            return (String)converter.convert(String.class, value);
        }
    }
    return super.convert(value);
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
public String[] convertToString(Object[] objects) {
    String[] strings = new String[objects.length];

    int i = 0;
    for (Object object : objects) {
        if (object != null) {
            Converter converter = ConvertUtils.lookup(object.getClass());
            if (converter != null) {
                strings[i++] = converter.convert(object.getClass(), object).toString();
            } else {
                strings[i++] = object.toString();
            }
        } else {
            strings[i++] = "";
        }
    }

    return strings;
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
/**
 * 數據轉換
 * 
 * @param source
 *            源數據
 * 
 * @param targetType
 *            目標類型
 * 
 * @return
 */
public static Object convert(Object source, Class targetType) {
    Object result = source;
    if (null == targetType) {
        return result;
    }
    Converter converter = converterMap.get(targetType);
    if (null != converter) {
        result = converter.convert(targetType, source);
    }
    return result;
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
@Override
public String convert(Object value) {
	if (value != null) {
		Class<?> type = value.getClass();
		if (type.isEnum() && super.lookup(type) == null) {
			super.register(new EnumConverter(type), type);
		} else if (type.isArray() && type.getComponentType().isEnum()) {
			if (super.lookup(type) == null) {
				ArrayConverter arrayConverter = new ArrayConverter(type, new EnumConverter(type.getComponentType()), 0);
				arrayConverter.setOnlyFirstToString(false);
				super.register(arrayConverter, type);
			}
			Converter converter = super.lookup(type);
			return ((String) converter.convert(String.class, value));
		}
	}
	return super.convert(value);
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
/****
 * {@link ConverterFactory}
 ****/

@Override
public Converter create(CsvEntityContext context) {
  GtfsReaderContext ctx = (GtfsReaderContext) context.get(GtfsReader.KEY_CONTEXT);
  return new ConverterImpl(ctx);
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
@Override
public Converter lookup(Class<?> clazz) {
	final Converter converter = super.lookup(clazz);
	if (converter == null && clazz.isEnum()) {
		return ENUM_CONVERTER;
	} else {
		return converter;
	}
}
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
@Override
public Converter lookup(Class clazz) {
   	//如果是枚舉類型則設置為Enum.class
   	if (clazz.isEnum()) {
		clazz = Enum.class;
	}
   	
       return super.lookup(clazz);
   }
 

import org.apache.commons.beanutils.Converter; //導入依賴的package包/類
public static <S, D> D convertType(Object obj, Class<S> srcClass, Class<D> destClass) {
	if (srcClass.equals(destClass)) {
		return (D) JsonUtil.copyObject(obj);
	}
	Converter converter = convertUtils.lookup(srcClass, destClass);
	return converter.convert(destClass, obj);
}