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mybatis中的異常BindingException詳解

更新時(shí)間：2024年01月18日 08:58:51 作者：小白不很白

這篇文章主要介紹了mybatis中的異常BindingException詳解,此異常是mybatis中拋出的,意思是使用的這個(gè)方法找到,但是因?yàn)閙apperScan()已經(jīng)掃描到了Mapper類了,在綁定Mapper.xml時(shí)沒有綁定到導(dǎo)致的,需要的朋友可以參考下

BindingException異常

此異常是mybatis中拋出的。

意思是使用的這個(gè)方法找到,但是因?yàn)閙apperScan()已經(jīng)掃描到了Mapper類了，在綁定Mapper.xml時(shí)沒有綁定到導(dǎo)致的。

具體異常信息

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.xxx.xxx.xxx.dao.mapper.PageTemplateMapper.findPageTemplateBasicInfoList
   at org.apache.ibatis.binding.MapperMethod$SqlCommand.<init>(MapperMethod.java:227)
   at org.apache.ibatis.binding.MapperMethod.<init>(MapperMethod.java:49)
   at org.apache.ibatis.binding.MapperProxy.cachedMapperMethod(MapperProxy.java:65)
   at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:58)
   at com.sun.proxy.$Proxy202.findPageTemplateBasicInfoList(Unknown Source)
.....

使用mybatis的步驟

首先要?jiǎng)?chuàng)建一個(gè)interface接口Mapper類。

package com.xiaobai.front.cms.dao.mapper;
public interface PageTemplateMapper {
     List<PageTemplateBasicInfo> findPageTemplateBasicInfoList(PageTemplateQueryDto pageTemplateQueryDto);
}

在啟動(dòng)類或者配置類加掃描Mapper類的路徑。使用的是@MapperScan注解。里面配置的是Mapper類的包路徑。

@Configuration
@MapperScan("com.xiaobai.front.cms.dao.mapper")
public class MybatisConfig {
}

在資源文件夾下配置對(duì)應(yīng)mapper.xml文件，并且寫對(duì)應(yīng)上面方法(findPageTemplateBasicInfoList)的sql。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.xiaobai.front.cms.dao.mapper.PageTemplateMapper">
  <select id="findPageTemplateBasicInfoList" resultType="com.dffl.front.cms.domain.response.PageTemplateBasicInfo">
    .......
  </select>
</mapper>

在配置文件中配置mybatis掃描mapper.xml的路徑

mybatis:
  # 配置mapper的掃描，找到所有的mapper.xml映射文件
  mapperLocations: classpath*:mapper/**/*Mapper.xml

出現(xiàn)BindingException原因分析

第一種

如果mapper.xml中沒有寫對(duì)應(yīng)的方法在啟動(dòng)項(xiàng)目的時(shí)候不會(huì)拋出該異常。而在用到該方法時(shí)會(huì)拋出異常

public SqlCommand(Configuration configuration, Class<?> mapperInterface, Method method) {
      final String methodName = method.getName();
      final Class<?> declaringClass = method.getDeclaringClass();
      MappedStatement ms = resolveMappedStatement(mapperInterface, methodName, declaringClass,
          configuration);
      if (ms == null) {
        if (method.getAnnotation(Flush.class) != null) {
          name = null;
          type = SqlCommandType.FLUSH;
        } else {
          throw new BindingException("Invalid bound statement (not found): "
              + mapperInterface.getName() + "." + methodName);
        }
      } else {
        name = ms.getId();
        type = ms.getSqlCommandType();
        if (type == SqlCommandType.UNKNOWN) {
          throw new BindingException("Unknown execution method for: " + name);
        }
      }
    }
private MappedStatement resolveMappedStatement(Class<?> mapperInterface, String methodName,
        Class<?> declaringClass, Configuration configuration) {
      String statementId = mapperInterface.getName() + "." + methodName;
      if (configuration.hasStatement(statementId)) {
        return configuration.getMappedStatement(statementId);
      } else if (mapperInterface.equals(declaringClass)) {
        return null;
      }
      for (Class<?> superInterface : mapperInterface.getInterfaces()) {
        if (declaringClass.isAssignableFrom(superInterface)) {
          MappedStatement ms = resolveMappedStatement(superInterface, methodName,
              declaringClass, configuration);
          if (ms != null) {
            return ms;
          }
        }
      }
      return null;
    }

configuration 對(duì)象是里面有很多的map。其中一個(gè)就是掃描mapper類和mapper.xml文件生成的每個(gè)方法對(duì)應(yīng)的sql數(shù)據(jù)。mappedStatements key對(duì)應(yīng)的是mapper類里面的全路徑方法名比如：com.xiaobai.front.cms.dao.mapper.PageTemplateMapper.findPageTemplateBasicInfoList。value對(duì)應(yīng)的就是mapper.xml的信息對(duì)象。
當(dāng)在調(diào)用這個(gè)findPageTemplateBasicInfoList方法的時(shí)候由于mapper.xml中沒有對(duì)應(yīng)的綁定這個(gè)方法，mappedStatements中就獲取不到數(shù)據(jù)。
因?yàn)閙appedStatements沒有數(shù)據(jù)所以resolveMappedStatement方法返回null。
所以最后會(huì)拋出throw new BindingException("Invalid bound statement (not found): "
mapperInterface.getName() + “.” + methodName);

第二種

沒有配置@MapperScan(“com.xiaobai.front.cms.dao.mapper”)執(zhí)行某方法時(shí)也會(huì)拋出此異常

 public Resource[] resolveMapperLocations() {
    ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
    List<Resource> resources = new ArrayList<Resource>();
    if (this.mapperLocations != null) {
      for (String mapperLocation : this.mapperLocations) { 
        try {
          Resource[] mappers = resourceResolver.getResources(mapperLocation);
          resources.addAll(Arrays.asList(mappers));
        } catch (IOException e) {
          // ignore
        }
      }
    }
    return resources.toArray(new Resource[resources.size()]);
  }