mybatis常见错误汇总

###1.没有在configuration.xml配置对应的sql配置文件
错误:

Error updating database. Cause: java.lang.IllegalArgumentException:   
 Mapped Statements collection does not contain value for ***Mapper.***   
  Cause: java.lang.IllegalArgumentException: Mapped Statements collection does 
   not contain value for ***Mapper.***

解决方法:
在configuration.xml配置文件中引用对应的sql配置文件

<mappers>  
    <mapper resource="esd/db/mapper/ResumeMapper.xml" />  
</mappers>  

###2.同一sql配置文件中id重复
错误:

Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: 
java.lang.RuntimeException: Error parsing Mapper XML. Cause: java.lang.IllegalArgumentException: 
Mapped Statements collection already contains value for GeographyMapper.getByCode

两个sql语句的id重复了,就会报这个错.

<select id="getByCode" resultType="Geography"  
    parameterType="java.lang.String">  
    select * from Geography where code = ${code}  
</select>  

<!-- 按地名getByName得到一个对象-->  
<select id="getByCode" resultType="Geography"  
    parameterType="java.lang.String">  
    select * from Geography where fullName = ${fullName}  
</select>  

解决方法:
修改其中的一个id就ok了.
###3.mapper配置文件中为bean类配置的属性没有在对应的bean类中找到对应的字段
错误:

Error updating database.  Cause: org.apache.ibatis.reflection.ReflectionException: 
There is no getter for property named 'education' in 'class esd.bean.Personal'
Cause: org.apache.ibatis.reflection.ReflectionException:
 There is no getter for property named 'education' in 'class esd.bean.Personal'

<!-- 这个属性是多余的，在对应的bean类中没有对应的字段,删除后OK -->  
            <if test="education != null and education != ''">  
                education = #{education},  
            </if>  

解决方法:
在mapper配置文件中删除多配置的属性/或则在自己的bean类中补全该字段
###4.标签中不支持 && 符号
错误:
The entity name must immediately follow the ‘&’ in the entity reference
解析不了 && 是什么东东

<update id="update" parameterType="Geography">  
        update Geography  
        <trim prefix="set" suffixOverrides=",">  
            <if test="code != null && code !=''">  
                code=#{code},  
            </if>  
            <if test="name != null && name != ''">  
                name=#{name},  
            </if>  
        </trim>  
        where id= #{id}  
    </update>  

解决方法:使用正确的语法咯,别用&&,用and

<!-- update -->  
    <update id="update" parameterType="Geography">  
        update Geography  
        <trim prefix="set" suffixOverrides=",">  
            <if test="code != null and code !=''">  
                code=#{code},  
            </if>  
            <if test="name != null and name != ''">  
                name=#{name},  
            </if>  
        </trim>  
        where id= #{id}  
    </update>  

###5.返回结果类型写错
由于我的项目配置原因, debug 输出信息中没有报错, 但是项目就是启动不起来, 所以没能截到错误信息提示, 以后遇到会补上
具体说就是: 如果自定义了返回的结果集, 返回的类型一定要是resultMap类型,(下面是错误示例) 如下

<!-- 查询Area 地名 -->  
    <resultMap id="ResultArea" type="Area">  
        <id column="a_code" property="code" />  
        <result column="a_name" property="name" />  
        <result column="a_pyName" property="pyName" />  
        <result column="a_abbr" property="abbr" />  
        <result column="a_mark" property="mark" />  
    </resultMap>  
      
    <!-- 查询Parameter 地名 -->  
    <resultMap id="ResultParameter" type="Parameter">  
        <id column="p_id" property="id" />  
        <result column="p_name" property="name" />  
        <result column="p_value" property="value" />  
        <result column="p_type" property="type" />  
        <result column="p_mark" property="mark" />  
        <association property="area" javaType="Parameter" resultMap="ResultArea" />  
    </resultMap>  
  
    <!-- get by id -->  
    <select id="getById" resultType="ResultParameter" parameterType="int">  
        select p.id as p_id, p.name as p_name, p.value as p_value, p.type as p_type, p.mark as p_mark,  
                a.code as a_code, a.name as a_name, a.pyname as a_pyName, a.abbr as a_abbr, a.mark as a_mark  
        from parameter as p, area as a   
        where p.acode = a.code and id = #{id}  
    </select>

常用在表连接查询中.
如上例中, 我定义了’ResultParameter’的结果集, 那么下面表连接查询的时候,如果返回的是表连接查询结果, 那么一定要使用 resultMap=“ResultParameter”, 否则万一提示信息中没有显示出来, 要费些时间才能找出来.
###6. 标签顺序写错
错误:
The content of element type “resultMap” must match “(constructor?,id*,result*,association*,collection*,discriminator?)”.
下午的时候无意中遇到这个错误, 下面是错误代码:

<resultMap id="ResultMenu" type="com.esd.hesf.model.Menu">  
    <id column="id" property="id" jdbcType="CHAR" />  
    <result column="text" property="text" jdbcType="VARCHAR" />  
    <result column="iconcls" property="iconcls" jdbcType="VARCHAR" />  
    <association property="permissionType" javaType="com.esd.hesf.model.PermissionType" resultMap="ResultPermissionType"/>  
    <result column="update_time" property="updateTime" jdbcType="TIMESTAMP" />  
</resultMap>  

在<resultMap 处画红线, 原因是: 里面的标签, 一定要放在这组标签最下面. 如下:

<resultMap id="ResultMenu" type="com.esd.hesf.model.Menu">  
    <id column="id" property="id" jdbcType="CHAR" />  
    <result column="text" property="text" jdbcType="VARCHAR" />  
    <result column="iconcls" property="iconcls" jdbcType="VARCHAR" />  
    <result column="update_time" property="updateTime" jdbcType="TIMESTAMP" />  
    <association property="permissionType" javaType="com.esd.hesf.model.PermissionType" resultMap="ResultPermissionType"/>  
</resultMap>  

###7.多写了if判断
错误:

org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'year' in 'class java.lang.String'

下面是代码:
dao层方法
[java] view plain copy
/**
* 查询审核报表情况–按公司类型查
* @return
*/
List retrieveReportByCompanyType(String year);
mapper配置文件

<!-- retrieve report statistics by company type -->  
    <select id="retrieveReportByCompanyType" parameterType="java.lang.String" resultMap="ReportViewModel">  
        select   
            <include refid="report_column_list"/>  
        from audit_company_view   
        <where>  
            <if test="year != null and year != ''">  
                au_year = #{year,jdbcType=CHAR}   
            </if>  
        </where>  
        group by t_id  
    </select>  

一般这个错是指参数parameterType类型的字段 没有get, set方法, 我只是传个String类型的参数, so 刚遇到这个问题的时候, 有点摸不着头脑, 怎么会报这个错呢? 原来问题出现在配置文件中:

<if test="year != null and year != ''">  

mybatis自动将if判断中的字段默认为传进来的parameterType类型的字段了… so…只要将这个if判断去掉即可.

<!-- retrieve report statistics by company type -->  
<select id="retrieveReportByCompanyType" parameterType="java.lang.String" resultMap="ReportViewModel">  
    select   
        <include refid="report_column_list"/>  
    from audit_company_view   
    <where>  
            au_year = #{year,jdbcType=CHAR}   
    </where>  
    group by t_id  
</select>  

那问题出来了, 我怎么判断传进来的单个字符串是否为空值呢? 这是否是mybatis的一个小bug呢? 答案尚在查找中, 有了会第一时间贴上来的.# 欢迎使用Markdown编辑器写博客