Mybatis学习错误之：重复加载mapper.xml

系统管理员 2022-07-16 07:19 198阅读 0赞

学习mybatis的时候，突然遇到测试出错。测试mapper代理失败，现在钻研少了，不喜欢看未知的错误了，立即改正。错误打印说mapper.xml已经注册，仔细查看SQLMapConfig.xml发现确实。修改后正常。

原因是直接复制教学代码，在SqlMapConfig.xml中，配置mappers，加载映射文件，已经配置了加载包文件，然后我自己又添加了单独的mapper。所以出错了，将包注释掉就ok。

测试用例：

1 @Before
     2     public void setUp() throws Exception {
     3         // 创建sqlSessionFactory
     4         // mybatis配置文件
     5         String resource = "SqlMapConfig.xml";
     6         // 得到配置文件流
     7         InputStream inputStream = Resources.getResourceAsStream(resource);
     8         // 创建会话工厂，传入mybatis的配置文件信息
     9         sqlSessionFactory = new SqlSessionFactoryBuilder()
    10                 .build(inputStream);
    11         
    12     }
    13     
    14     @Test
    15     public void testFindUserById() throws Exception{
    16         SqlSession sqlSession = sqlSessionFactory.openSession();
    17         UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    18         User user = userMapper.findUserById(1);
    19         System.out.println(user);
    20     
    21     }

SqlMapConfig.xml

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1 <?xml version="1.0" encoding="UTF-8" ?>
     2 <!DOCTYPE configuration
     3 PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
     4 "http://mybatis.org/dtd/mybatis-3-config.dtd">
     5 <configuration>
     6 
     7     
     8     <properties resource="db.properties">
     9         
    10         
    11     </properties>
    12     
    13     
    16     
    17     
    18     <typeAliases>
    19         
    20         
    24         
    25         
    28         <package name="cn.itcast.mybatis.po"/>
    29         
    30     </typeAliases>
    31     
    32     
    33     <environments default="development">
    34         <environment id="development">
    35         
    36             <transactionManager type="JDBC" />
    37         
    38             <dataSource type="POOLED">
    39                 <property name="driver" value="${jdbc.driver}" />
    40                 <property name="url" value="${jdbc.url}" />
    41                 <property name="username" value="${jdbc.username}" />
    42                 <property name="password" value="${jdbc.password}" />
    43             </dataSource>
    44         </environment>
    45     </environments>
    46     
    47     <mappers>
    48         <mapper resource="sqlmap/User.xml"/>
    49         <mapper resource="mapper/UserMapper.xml"/>
    50         
    51         
    52         
    53         
    54         
    58         
    59         
    60         
    65     
    66 
    67     </mappers>
    68     
    69 </configuration>

UserMapper.xml

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1 <?xml version="1.0" encoding="UTF-8" ?>
     2 <!DOCTYPE mapper
     3 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
     4 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
     5 
     6 
     9 <mapper namespace="cn.mrf.mybatis.mapper.UserMapper">
    10 
    11     
    12     
    13     
    22     <select id="findUserById" parameterType="int" resultType="cn.mrf.mybatis.po.User">
    23         SELECT * FROM USER WHERE id=#{value}
    24     </select>
    25     
    26     
    32     <select id="findUserByName" parameterType="java.lang.String" resultType="cn.mrf.mybatis.po.User">
    33         SELECT * FROM USER WHERE username LIKE '%${value}%'
    34     </select>
    35     
    36     
    40     <insert id="insertUser" parameterType="cn.mrf.mybatis.po.User">
    41         
    50         <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
    51             SELECT LAST_INSERT_ID()
    52         </selectKey>
    53         insert into user(username,birthday,sex,address) value(#{username},#{birthday},#{sex},#{address})
    54         
    60         
    64         
    65         
    66     </insert>
    67     
    68     
    71     <delete id="deleteUser" parameterType="java.lang.Integer">
    72         delete from user where id=#{id}
    73     </delete>
    74     
    75     
    82     <update id="updateUser" parameterType="cn.mrf.mybatis.po.User">
    83         update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} 
    84          where id=#{id}
    85     </update>    
    86     
    87 </mapper>

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