MyBatis中只传一个String参数时要注意的事项

参数名为_parameter，不需要指定成传入的参数名，参考代码如下：

<select id="getLoop" resultMap="AAA" parameterType="String">     
    SELECT *, ROWNUM RN from tablename
        <where>    
            <choose>    
                <when test="_parameter != null and _parameter == '1'.toString()">    
                    RN &lt;=100000  and RN &gt;=1   
                </when>   
                <when test="_parameter != null and _parameter == '2'.toString()">    
                    RN &lt;=200000  and RN &gt;=100001   
                </when>
                <when test="_parameter != null and _parameter == '3'.toString()">    
                    RN &lt;=300000  and RN &gt;=200001   
                </when>        
                <otherwise>    
                    RN &lt;=1  and RN &gt;=1     
                </otherwise>    
            </choose>    
        </where>   
</select>