org.apache.ibatis.binding.BindingException

记录Mybatis的xml中无法直接用对象参数的属性

今天使用mybatis的过程中，在dao有一个查询方法

List<User> selectByNickname(@Param("user") User user);

xml中的配置文件

<select id="selectByNickname" resultMap="User">
    select
    *
    from user
    where  phone = #{phone} and nickname = #{nickname}
</select>

程序报错

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.binding.BindingException: Parameter 'nickname' not found. Available parameters are [user, param1]

	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:77)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)
	at com.sun.proxy.$Proxy55.selectList(Unknown Source)
	at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:230)
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:139)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:76)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)
	at com.sun.proxy.$Proxy59.selectByNickname(Unknown Source)
	at top.kooper.demo.DemoApplicationTests.contextLoads(DemoApplicationTests.java:55)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

解决方法（3种）：

1. 将dao层的方法中@Param注解去掉
2. 将xml改为如下

<select id="selectByNickname" resultMap="User">
    select
    *
    from user
    where  phone = #{user.phone} and nickname = #{user.nickname}
</select>

3. 利用<bind>元素

<select id="selectByNickname" resultMap="User">
	<bind name="nickname" value="user.getNickname()"></bind>
	<bind name="phone" value="user.getPhone()"></bind>
    select
    *
    from user
    where  phone = #{phone} and nickname = #{nickname}
</select>

可以看到，还是第一种比较简单，哈哈😆

当然出现这个异常的情况还有很多，最重要的是要检查dao到xml文件的映射是否正确。