这是将servlet请求参数映射到java类的最佳方法？

Question

可能重复：
Easy way of populating Javabeans based on request parameters

嗨，

我有一组搜索参数，某事物的Java对象。像

public class SearchRequest { 

private String customerName; 
private String city; 
... 
} 

该请求必须由服务请求填写。

但不是写像

代码...

SearchRequest searchRequest = new SearchRequest(); 

if (request.getParameter("customerName") != null) 
{ 
    searchRequest.setCustomerName(request.getParameter("customerName")); 
} 
if (request.getParameter("city") != null) 
{ 
    searchRequest.setCity(request.getParameter("city")); 
} 

... 我正在寻找一个更通用的方法。

我正在检查映射工具Dozer，但没有找到一个好方法来处理这个映射。

现在我认为反思会是一种选择。 这是真的吗？ 如果是的话，任何人都有一个代码sniplet如何可以用反射来完成？

Answer 1

我认罪：

public void save(HttpServletRequest req, Object obj) { 
    Set<String> names = new HashSet<String>(); 
    @SuppressWarnings("unchecked") 
    Enumeration<String> enm = req.getParameterNames(); 
    while (enm.hasMoreElements()) { 
     names.add(enm.nextElement()); 
    } 
    Class clazz = obj.getClass(); 
    while (clazz != Object.class && !names.isEmpty()) { 
     for (Field f: clazz.getDeclaredFields()) { 
      if (!Modifier.isTransient(f.getModifiers())) { 
       String name = f.getName(); 
       if (names.contains(name)) { 
        try { 
         names.remove(name); 
         f.setAccessible(true); 
         Object val = convertValue(req, f.getType(), 
           name); 
         f.set(obj, val); 
        } catch (ParseException ex) { 
         LOG.error("Error assigning field", ex); 
        } catch (IllegalAccessException ex) { 
         LOG.error("Error assigning field", ex); 
        } 
       } 
      } 
     } 
     clazz = clazz.getSuperclass(); 
    } 
} 

private Object convertValue(HttpServletRequest req, Class<?> type, 
     String name) throws ParseException { 
    if (type.isArray()) { 
     Class<?> elemType = type.getComponentType(); 
     String strings[] = req.getParameterValues(name); 
     if (strings == null || strings.length == 0) { 
      return new Object[0]; 
     } 
     Object array = Array.newInstance(elemType, strings.length); 
     for (int i = 0; i < strings.length; ++i) { 
      Object val = parse(elemType, strings[i]); 
      Array.set(array, i, val); 
     } 
     return array; 
    } else { 
     String s = req.getParameter(name); 
     if (s == null) { 
      return null; 
     } 
     return parse(type, s); 
    } 
} 

public static Object parse(Class<?> type, String value) 
     throws ParseException { 
    if (type == String.class) { 
     return value; 
    } else if (value == null || value.length() == 0) { 
     return null; 
    } else if (Enum.class.isAssignableFrom(type)) { 
     @SuppressWarnings("unchecked") 
     Object result = Enum.valueOf((Class<? extends Enum>)type, value); 
     return result; 
    } else if (type == boolean.class || type == Boolean.class) { 
     return "true".equals(value); 
    } else if (type == byte.class || type == Byte.class) { 
     return Byte.valueOf(value); 
    } else if (type == short.class || type == Short.class) { 
     return Short.valueOf(value); 
    } else if (type == int.class || type == Integer.class) { 
     return Integer.valueOf(value); 
    } else if (type == long.class || type == Long.class) { 
     return Long.valueOf(value); 
    } else if (type == float.class || type == Float.class) { 
     return Float.valueOf(value); 
    } else if (type == double.class || type == Double.class) { 
     return Double.valueOf(value); 
    } else if (type == Date.class) { 
      return new SimpleDateFormat("dd/MM/yyyy").parse(value); 
    } else if (type == BigDecimal.class) { 
     DecimalFormat format = getDecimalFormat("0.00"); 
     return format.parse(value); 
    } else { 
     throw new RuntimeException("Cannot convert value of type " + type); 
    } 
} 

private static DecimalFormat getDecimalFormat(String pattern) { 
    DecimalFormatSymbols symbols = new DecimalFormatSymbols(); 
    symbols.setDecimalSeparator('.'); 
    DecimalFormat format = new DecimalFormat(pattern); 
    format.setParseBigDecimal(true); 
    format.setDecimalFormatSymbols(symbols); 
    return format; 
}