MyBatis报错：Caused by: java.lang.NumberFormatException: For input string: "XX"

 <select id="sltTreatment" resultType="com.vitaminmd.sunny.core.bo.Treatment">
         select *
         from treatment
         where TRUE
         <if test="index == 'A'">
             AND ensubject IS NOT NULL AND ensubject &lt;&gt; ''
         </if>
     </select>

当使用的index为A时，这段便抛出一个NumberFormatExeption的异常，但是如果index为一个数值比如1时就运行正常。
错误

Caused by: java.lang.NumberFormatException: For input string: "A"
    at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
    at java.lang.Double.parseDouble(Unknown Source)
    at org.apache.ibatis.ognl.OgnlOps.doubleValue(OgnlOps.java:248)
    at org.apache.ibatis.ognl.OgnlOps.compareWithConversion(OgnlOps.java:137)
    at org.apache.ibatis.ognl.OgnlOps.isEqual(OgnlOps.java:178)
    at org.apache.ibatis.ognl.OgnlOps.equal(OgnlOps.java:548)
    at org.apache.ibatis.ognl.ASTEq.getValueBody(ASTEq.java:49)
    at org.apache.ibatis.ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:175)
    at org.apache.ibatis.ognl.SimpleNode.getValue(SimpleNode.java:213)
    at org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:314)
    at org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:394)
    at org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:435)
    at org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:414)
    at org.apache.ibatis.builder.xml.dynamic.ExpressionEvaluator.evaluateBoolean(ExpressionEvaluator.java:17)
    at org.apache.ibatis.builder.xml.dynamic.IfSqlNode.apply(IfSqlNode.java:15)
    at org.apache.ibatis.builder.xml.dynamic.MixedSqlNode.apply(MixedSqlNode.java:14)
    at org.apache.ibatis.builder.xml.dynamic.DynamicSqlSource.getBoundSql(DynamicSqlSource.java:22)
    at org.apache.ibatis.mapping.MappedStatement.getBoundSql(MappedStatement.java:198)
    at org.apache.ibatis.executor.BaseExecutor.createCacheKey(BaseExecutor.java:115)
    at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:90)
    at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:72)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:75)

解决方案：

1.改为：test="param eq 'A'.toString()"
2.原因是OGNL语法的问题：
这里 'A' 将被认为是 char 类型，但是 'AA' 或者 "A" 将被作为 String类型。

所以我们可以用转义：<if test="name == &quot;A&quot;">
3.或者将 <if test="index == 'A'"> 改为 <if test='index == "A"'>。