在ssm框架中，mybatis+spring操作数据库报错：org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.binding.BindingException: Parameter 'category' not found. Available parameters are [arg1, arg0, param1, param2]

2021/7/21：其实就是方法参数名，到xml文件识别不了的问题

今天又遇上了，错误点已标出

出错的代码：

• mapper

    //通过书的种类或者书名模糊查询，查找相应的图书总数
    public int queryProductsCount(String name, String category);

• mapper.xml

    <!--通过书的种类或者书名模糊查询，查找相应的图书总数-->
    <select id="queryProductsCount" resultType="int">
        select count(1) as count from itcaststore.products
        <where>
            <if test="category != null">
                category like concat('%',#{category},'%')
            </if>
            <if test="name != null">
                and name like concat('%',#{name},'%')
            </if>
        </where>
    </select>

• service

    public int queryProductsCount(String name,String category);

• serviceImpl

    public int queryProductsCount(String name,String category) {
        return productsMapper.queryProductsCount(name,category);
    }

• test

    @org.junit.Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        ProductsServiceImpl productsServiceImpl = context.getBean("ProductsServiceImpl", ProductsServiceImpl.class);
        System.out.println(productsServiceImpl.queryProductsCount(null,null));
    }

错误原因

mybatis的Mapper接口方法传入了多个参数

还要注意：parameterType是要去掉的，虽然这里的参数全部都是String类型，如果涉及多个类型那就必须去掉

解决方法一：

使用#{arg0}和#{arg1}来告诉mybatis,当前变量使用哪个参数的值

    <select id="queryProductsCount" resultType="int">
        select count(1) as count from itcaststore.products
        <where>
            <if test="category != null">
                category like concat('%',#{arg0},'%')
            </if>
            <if test="name != null">
                and name like concat('%',#{arg1},'%')
            </if>
        </where>
    </select>

但是因为这里有：<if test="category != null">和<if test="name != null">，所以此法对于这种特殊情况无解

解决方法二：（不修改mapper.xml)

使用注解@Param

public int queryProductsCount(@Param("name") String name, @Param("category")String category);

解决方法三：

HashMap类型作为传入类型（不修改mapper.xml)

    public int queryProductsCount1(Map<String,String> map);

• Test

    @org.junit.Test
    public void mapperTest() {
        //获取SqlSessionFactory对象
        String resource = "mybatis-config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            SqlSession sqlSession = sqlSessionFactory.openSession();
            ProductsMapper mapper = sqlSession.getMapper(ProductsMapper.class);
            Map<String,String> map = new HashMap<String,String>();
            map.put("name",null);
            map.put("category",null);
            System.out.println(mapper.queryProductsCount1(map));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }