MyBatis-Plus TypeHander不生效的问题解决_Java

1 现象

mysql 使用json类型字段存储list<string>，java类属性使用typehandler 没有生效。

代码如下

实体类

import com.baomidou.mybatisplus.annotation.tablefield;
import com.baomidou.mybatisplus.extension.handlers.fastjsontypehandler;
public class messagedo {
        @tablefield(typehandler = fastjsontypehandler.class)
        private list<string> notifytype;
   
    }

service 层

@override
public void messageupdate(messageupdatereqdto reqdto) {
    lambdaupdate()
            .set(partnerdo::getwxnotifytype,reqdto.getwxnotifytype())
            .eq(partnerdo::getcompanyid,reqdto.getcompanyid())
            .update();
}

报错如下

关键信息：data truncation: cannot create a json value from a string with character set 'binary'.

 cause: com.mysql.cj.jdbc.exceptions.mysqldatatruncation: data truncation: cannot create a json value from a string with character set 'binary'.
; data truncation: cannot create a json value from a string with character set 'binary'.; nested exception is com.mysql.cj.jdbc.exceptions.mysqldatatruncation: data truncation: cannot create a json value from a string with character set 'binary'.
	at org.springframework.jdbc.support.sqlstatesqlexceptiontranslator.dotranslate(sqlstatesqlexceptiontranslator.java:104)
	at org.springframework.jdbc.support.abstractfallbacksqlexceptiontranslator.translate(abstractfallbacksqlexceptiontranslator.java:72)
	at org.springframework.jdbc.support.abstractfallbacksqlexceptiontranslator.translate(abstractfallbacksqlexceptiontranslator.java:81)
	at org.springframework.jdbc.support.abstractfallbacksqlexceptiontranslator.translate(abstractfallbacksqlexceptiontranslator.java:81)
	at org.mybatis.spring.mybatisexceptiontranslator.translateexceptionifpossible(mybatisexceptiontranslator.java:88)
	at org.mybatis.spring.sqlsessiontemplate$sqlsessioninterceptor.invoke(sqlsessiontemplate.java:440)
	at com.sun.proxy.$proxy146.update(unknown source)
	at org.mybatis.spring.sqlsessiontemplate.update(sqlsessiontemplate.java:287)
	at com.baomidou.mybatisplus.core.override.mybatismappermethod.execute(mybatismappermethod.java:64)
	at com.baomidou.mybatisplus.core.override.mybatismapperproxy$plainmethodinvoker.invoke(mybatismapperproxy.java:148)
	at com.baomidou.mybatisplus.core.override.mybatismapperproxy.invoke(mybatismapperproxy.java:89)
	at com.sun.proxy.$proxy238.update(unknown source)
	at com.baomidou.mybatisplus.extension.conditions.update.chainupdate.update(chainupdate.java:45)
	at com.baomidou.mybatisplus.extension.conditions.update.chainupdate.update(chainupdate.java:35)

令人疑惑，我明明配置typehandler，但是没有生效，在 com.baomidou.mybatisplus.extension.handlers.fastjsontypehandler#tojson 的方法打了断点，还是没有进入断点。

2.源码分析

typehandler的源码

com.baomidou.mybatisplus.core.mybatisparameterhandler#setparameters

public void setparameters(preparedstatement ps) {
    errorcontext.instance().activity("setting parameters").object(this.mappedstatement.getparametermap().getid());
    list<parametermapping> parametermappings = this.boundsql.getparametermappings();
    if (parametermappings != null) {
        for (int i = 0; i < parametermappings.size(); i++) {
            parametermapping parametermapping = parametermappings.get(i);
            if (parametermapping.getmode() != parametermode.out) {
                object value;
                string propertyname = parametermapping.getproperty();
                if (this.boundsql.hasadditionalparameter(propertyname)) { // issue #448 ask first for additional params
                    value = this.boundsql.getadditionalparameter(propertyname);
                } else if (this.parameterobject == null) {
                    value = null;
                } else if (this.typehandlerregistry.hastypehandler(this.parameterobject.getclass())) {
                    value = parameterobject;
                } else {
                    metaobject metaobject = this.configuration.newmetaobject(this.parameterobject);
                    value = metaobject.getvalue(propertyname);
                }
                typehandler typehandler = parametermapping.gettypehandler();
                jdbctype jdbctype = parametermapping.getjdbctype();
                if (value == null && jdbctype == null) {
                    jdbctype = this.configuration.getjdbctypefornull();
                }
                try {
                    typehandler.setparameter(ps, i + 1, value, jdbctype);
                } catch (typeexception | sqlexception e) {
                    throw new typeexception("could not set parameters for mapping: " + parametermapping + ". cause: " + e, e);
                }
            }
        }
    }
}

debug了一下，发现根本没有解析出typehandler

parametermapping 解析

org.apache.ibatis.builder.sqlsourcebuilder#parse

public staticsqlsource(configuration configuration, string sql, list<parametermapping> parametermappings) {
  this.sql = sql;
  this.parametermappings = parametermappings;
  this.configuration = configuration;
}

@override
public boundsql getboundsql(object parameterobject) {
  return new boundsql(configuration, sql, parametermappings, parameterobject);
}

org.apache.ibatis.builder.sqlsourcebuilder#parse

public sqlsource parse(string originalsql, class<?> parametertype, map<string, object> additionalparameters) {
  parametermappingtokenhandler handler = new parametermappingtokenhandler(configuration, parametertype, additionalparameters);
  generictokenparser parser = new generictokenparser("#{", "}", handler);
  string sql = parser.parse(originalsql);
  return new staticsqlsource(configuration, sql, handler.getparametermappings());
}

org.apache.ibatis.builder.sqlsourcebuilder.parametermappingtokenhandler#buildparametermapping

private parametermapping buildparametermapping(string content) {
  map<string, string> propertiesmap = parseparametermapping(content);
  string property = propertiesmap.get("property");
  class<?> propertytype;
  if (metaparameters.hasgetter(property)) { // issue #448 get type from additional params
    propertytype = metaparameters.getgettertype(property);
  } else if (typehandlerregistry.hastypehandler(parametertype)) {
    propertytype = parametertype;
  } else if (jdbctype.cursor.name().equals(propertiesmap.get("jdbctype"))) {
    propertytype = java.sql.resultset.class;
  } else if (property == null || map.class.isassignablefrom(parametertype)) {
    propertytype = object.class;
  } else {
    metaclass metaclass = metaclass.forclass(parametertype, configuration.getreflectorfactory());
    if (metaclass.hasgetter(property)) {
      propertytype = metaclass.getgettertype(property);
    } else {
      propertytype = object.class;
    }
  }
  parametermapping.builder builder = new parametermapping.builder(configuration, property, propertytype);
  class<?> javatype = propertytype;
  string typehandleralias = null;
  for (map.entry<string, string> entry : propertiesmap.entryset()) {
    string name = entry.getkey();
    string value = entry.getvalue();
    if ("javatype".equals(name)) {
      javatype = resolveclass(value);
      builder.javatype(javatype);
    } else if ("jdbctype".equals(name)) {
      builder.jdbctype(resolvejdbctype(value));
    } else if ("mode".equals(name)) {
      builder.mode(resolveparametermode(value));
    } else if ("numericscale".equals(name)) {
      builder.numericscale(integer.valueof(value));
    } else if ("resultmap".equals(name)) {
      builder.resultmapid(value);
    } else if ("typehandler".equals(name)) {
      typehandleralias = value;
    } else if ("jdbctypename".equals(name)) {
      builder.jdbctypename(value);
    } else if ("property".equals(name)) {
      // do nothing
    } else if ("expression".equals(name)) {
      throw new builderexception("expression based parameters are not supported yet");
    } else {
      throw new builderexception("an invalid property '" + name + "' was found in mapping #{" + content + "}.  valid properties are " + parameter_properties);
    }
  }
  if (typehandleralias != null) {
    builder.typehandler(resolvetypehandler(javatype, typehandleralias));
  }
  return builder.build();
}

lambdaupdate set源码

查看api，发现可以传入mapping参数，指定typehandler。

com.baomidou.mybatisplus.core.conditions.update.update#set(r, java.lang.object)

default children set(r column, object val) {
    return set(true, column, val);
}
default children set(boolean condition, r column, object val) {
    return set(condition, column, val, null);
}
/**
 * 设置 更新 sql 的 set 片段
 *
 * @param condition 是否加入 set
 * @param column    字段
 * @param val       值
 * @param mapping   例: javatype=int,jdbctype=numeric,typehandler=xxx.xxx.mytypehandler
 * @return children
 */
children set(boolean condition, r column, object val, string mapping);

3.解决方法

1 手动转为字符串

lambdaupdate()
        .set(partnerdo::getwxnotifytype,json.tojsonstring(reqdto.getwxnotifytype()))
        .eq(partnerdo::getcompanyid,reqdto.getcompanyid()) .update();

2 添加typehandler

lambdaupdate()
.set(partnerdo::getwxnotifytype,reqdto.getwxnotifytype(),"typehandler=com.baomidou.mybatisplus.extension.handlers.fastjsontypehandler")
        .eq(partnerdo::getcompanyid,reqdto.getcompanyid())
        .update();

4.环境

mybatis-plus

<!--mybatis-plus-->
<dependency>
    <groupid>com.baomidou</groupid>
    <artifactid>mybatis-plus-boot-starter</artifactid>
    <version>3.4.3.4</version>
</dependency>

5.总结

mybatis-plus 使用 lambdaupdate更新某个属性，该属性的typehandler无效，需要手动转化或传入typehandler。

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MyBatis-Plus TypeHander不生效的问题解决

2025年08月05日 • Java •我要评论