别的类型转化成BigDecimal 类型（因为钱的计算用BigDecimal 很合适

public class MathUtils {      public static BigDecimal getBigDecimal( Object value ) {          BigDecimal ret = null;          if( value != null ) {              if( value instanceof BigDecimal ) {                  ret = (BigDecimal) value;              } else if( value instanceof String ) {                  ret = new BigDecimal( (String) value );              } else if( value instanceof BigInteger ) {                  ret = new BigDecimal( (BigInteger) value );              } else if( value instanceof Number ) {                  ret = new BigDecimal( ((Number)value).doubleValue() );              } else {                  throw new ClassCastException("Not possible to coerce ["+value+"] from class "+value.getClass()+" into a BigDecimal.");              }          }          return ret;      }  }