背景:最近一个使用SQLServer的项目,业务量太大,开始对业务有影响了,因此用户要求升级改造,技术上采用shardingsphere进行分库分表。
经过一系列调研,设计。。。哐哐一顿操作之后开始动刀改造。pom依赖如下:
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<!--sharding--> < dependency > < groupId >org.apache.shardingsphere</ groupId > < artifactId >sharding-jdbc-spring-boot-starter</ artifactId > < version >4.0.1</ version > </ dependency > < dependency > < groupId >com.alibaba</ groupId > < artifactId >druid-spring-boot-starter</ artifactId > < version >1.2.8</ version > </ dependency > |
改造后查询和写入都各种报错:
Caused by: org.apache.ibatis.type.TypeException: Error setting non null for parameter #2 with JdbcType NVARCHAR . Try setting a different JdbcType for this parameter or a different configuration property. Cause: java.sql.SQLFeatureNotSupportedException: setNString
at org.apache.ibatis.type.BaseTypeHandler.setParameter(BaseTypeHandler.java:75)
at org.apache.ibatis.scripting.defaults.DefaultParameterHandler.setParameters(DefaultParameterHandler.java:87)
... 47 common frames omitted
Caused by: java.sql.SQLFeatureNotSupportedException: setNString
at org.apache.shardingsphere.shardingjdbc.jdbc.unsupported.AbstractUnsupportedOperationPreparedStatement.setNString(AbstractUnsupportedOperationPreparedStatement.java:57)
at org.apache.ibatis.type.NStringTypeHandler.setNonNullParameter(NStringTypeHandler.java:31)
at org.apache.ibatis.type.NStringTypeHandler.setNonNullParameter(NStringTypeHandler.java:26)
at org.apache.ibatis.type.BaseTypeHandler.setParameter(BaseTypeHandler.java:73)
... 48 common frames omitted
核心错误:Caused by: java.sql.SQLFeatureNotSupportedException: setNString
问题分析:
网上寻了千百度,蓦然回首,还是没有找到问题,(┭┮﹏┭┮) 最后debug断点跟了源码发现:
操作数据库的PreparedStatement 是ShardingPreparedStatement
然后setNString支持SQLServerPreparedStatement 不支持ShardingPreparedStatement(改造前没问题,改造后出问题的原因)
问题解决:
找到问题了,下面就是解决问题了,既然没有setNString的实现,那就实现一个呗;
第一步 实现NVarcharTypeHandler:
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package cn.preserve.config.mybatis; import org.apache.ibatis.type.BaseTypeHandler; import org.apache.ibatis.type.JdbcType; import org.apache.ibatis.type.MappedJdbcTypes; import org.apache.ibatis.type.TypeException; import java.sql.CallableStatement; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; /** * 将 nvarchar 转成 varchar sharingJDBC不支持nvarchar * 主要是NStringTypeHandler中,没有setNString() */ @MappedJdbcTypes (JdbcType.NVARCHAR) public class NVarcharTypeHandler extends BaseTypeHandler<String> { @Override public void setParameter(PreparedStatement ps, int i, String parameter, JdbcType jdbcType) throws SQLException { if (parameter == null ) { if (jdbcType == null ) { throw new TypeException( "JDBC requires that the JdbcType must be specified for all nullable parameters." ); } try { ps.setNull(i, jdbcType.TYPE_CODE); } catch (SQLException var7) { throw new TypeException( "Error setting null for parameter #" + i + " with JdbcType " + jdbcType + " . " + "Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. " + "Cause: " + var7, var7); } } else { try { this .setNonNullParameter(ps, i, parameter, jdbcType); } catch (Exception var6) { throw new TypeException( "Error setting non null for parameter #" + i + " with JdbcType " + jdbcType + " . " + "Try setting a different JdbcType for this parameter or a different configuration property. " + "Cause: " + var6, var6); } } } /** * 这里使用setNString而不是setString * @param ps * @param i * @param parameter * @param jdbcType * @throws SQLException */ @Override public void setNonNullParameter(PreparedStatement ps, int i, String parameter, JdbcType jdbcType) throws SQLException { ps.setString(i, parameter); } @Override public String getNullableResult(ResultSet rs, String columnName) throws SQLException { return rs.getString(columnName); } @Override public String getNullableResult(ResultSet rs, int columnIndex) throws SQLException { return rs.getString(columnIndex); } @Override public String getNullableResult(CallableStatement cs, int columnIndex) throws SQLException { return cs.getString(columnIndex); } } |
第二步 实现加入数据库配置:
由于我是代理实现的数据库,所有在代码中加入即可
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@Configuration public class DataSourceConfig { @Bean (name = "sqlSessionFactory" ) @Primary public SqlSessionFactory memberDb1SqlSessionFactory(DataSource dataSource) throws Exception { SqlSessionFactoryBean bean = getSqlSessionFactoryBean(dataSource); bean.setTypeHandlers( new TypeHandler[] { new NVarcharTypeHandler()}); return bean.getObject(); } // ******* 其他实现 } |
PS:如果是配置只修要在mybatis-config.xml中配置一下
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< typeHandlers > < typeHandler handler = "cn.preserve.config.mybatis.NVarcharTypeHandler" /> </ typeHandlers > |
配置完成后,测试以前功能全部正常(#^.^#)
如果嫌麻烦,有另外一种解决方案:将mapper.xml中的NVARCHAR替换从VARCHAR也可以哦
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原文链接:https://blog.csdn.net/idto315/article/details/122414787