描述：在jsp里用 ${order.isNeedInvoice=='N'? 'checked':''} ，isNeedInvoice 在后台是character类型的。
问题：报错，javax.el.ELException: Cannot convert N of type class java.lang.String to class java.lang.Long
查了资料，发现说EL表达式没有CHAR类型，他会把CHAR转成LONG，
参考：https://bz.apache.org/bugzilla/show_bug.cgi?id=52666，tomcat BUG?
EL官方文档：
A {<,>,<=,>=,lt,gt,le,ge} B
■ If A==B, if operator is <=, le, >=, or ge return true.
■ If A is null or B is null, return false
■ If A or B is BigDecimal, coerce both A and B to BigDecimal and use the return
value of A.compareTo(B).
■ If A or B is Float or Double coerce both A and B to Double apply operator
■ If A or B is BigInteger, coerce both A and B to BigInteger and use the return
value of A.compareTo(B).
Chapter 1 Language Syntax and Semantics 13
■ If A or B is Byte, Short, Character, Integer, or Long coerce both A and B to
Long and apply operator
■ If A or B is String coerce both A and B to String, compare lexically
■ If A is Comparable, then:
■ If A.compareTo(B) throws exception, error.
■ Otherwise use result of A.compareTo(B)
■ If B is Comparable, then:
■ If B.compareTo(A) throws exception, error.
■ Otherwise use result of B.compareTo(A)
■ Otherwise, error
CHAR类型，还是别出现的好，在后台转成String 吧