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报错现象

oracle表中存在TIMESTAMP类型的列时，jdbc查出来做序列化时报错

报错内容

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class java.io.ByteArrayInputStream]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class java.io.ByteArrayInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.oxye.ResMsg["data"]->com.oxye.base.dto.BaseResponse["columns"]->java.util.ArrayList[0]->java.util.ArrayList[10]->oracle.sql.TIMESTAMP["stream"])
---
Caused by: org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class java.io.ByteArrayInputStream]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class java.io.ByteArrayInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.oxye.ResMsg["data"]->com.oxye.base.dto.BaseResponse["columns"]->java.util.ArrayList[0]->java.util.ArrayList[10]->oracle.sql.TIMESTAMP["stream"])
---
Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class java.io.ByteArrayInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.oxye.ResMsg["data"]->com.oxye.base.dto.BaseResponse["columns"]->java.util.ArrayList[0]->java.util.ArrayList[10]->oracle.sql.TIMESTAMP["stream"])

处理方法

任选其一，目的就是设置一个变量：
1.项目启动时设置一行代码 System.setProperty(“oracle.jdbc.J2EE13Compliant”, “true”);

2.jar启动命令增加 -Doracle.jdbc.J2EE13Compliant=true

3.oracle连接串中增加属性oracle.jdbc.J2EE13Compliant=true

Oracle驱动源码

版本

	<dependency><groupId>com.oracle.database.jdbc</groupId><artifactId>ojdbc8</artifactId><version>21.9.0.0</version></dependency>

oracle.jdbc.driver.GeneratedPhysicalConnection类有属性j2ee13Compliant，可以看到
readConnectionProperties中会从多处寻找属性oracle.jdbc.J2EE13Compliant，找不到默认是false

/***/
abstract class GeneratedPhysicalConnection extends OracleConnection {boolean j2ee13Compliant;/***/protected void readConnectionProperties(String var1, @Blind(PropertiesBlinder.class) Properties var2, @Blind(PropertiesBlinder.class) Properties var3) throws SQLException {/***/var4 = null;if (var2 != null) {var4 = var2.getProperty("oracle.jdbc.J2EE13Compliant");}if (var4 == null) {var4 = getSystemProperty("oracle.jdbc.J2EE13Compliant", (String)null);}if (var4 == null && var3 != null) {var4 = var3.getProperty("oracle.jdbc.J2EE13Compliant");}if (var4 == null) {var4 = "false";}this.j2ee13Compliant = var4 != null && var4.equalsIgnoreCase("true");/***/

oracle.jdbc.driver.TimestampAccessor的getObject方法中，会根据属性j2ee13Compliant选择获取时间的方式

/***/
class TimestampAccessor extends DateTimeCommonAccessor {/***/Object getObject(int var1) throws SQLException {if (!this.isUseLess && !this.isNull(var1)) {if (this.externalType == 0) {return this.statement.connection.j2ee13Compliant ? this.getTimestamp(var1) : this.getTIMESTAMP(var1);} else {switch (this.externalType) {case 93:return this.getTimestamp(var1);default:throw (SQLException)((SQLException)DatabaseError.createSqlException(this.getConnectionDuringExceptionHandling(), 4).fillInStackTrace());}}} else {return null;}}/***/

oracle.jdbc.driver.DateTimeCommonAccessor有两个方法getTimestamp和getTIMESTAMP，j2ee13Compliant为true时用getTimestamp获得java.sql.Timestamp，false获取oracle.sql.TIMESTAMP

/***/
import java.sql.Timestamp;
/***/
import oracle.sql.TIMESTAMP;
/***/
abstract class DateTimeCommonAccessor extends Accessor {/***/Timestamp getTimestamp(int var1) throws SQLException {return this.getTimestamp(var1, (Calendar)null);}/***/TIMESTAMP getTIMESTAMP(int var1) throws SQLException {return this.isNull(var1) ? null : new TIMESTAMP(this.getBytesInternal(var1));}/***/

总结

通过设置属性oracle.jdbc.J2EE13Compliant=true，可以时oracle的timestamp以oracle.sql.TIMESTAMP类型返回，不设置时默认false，返回oracle.sql.TIMESTAMP，可能会导致序列化时类型转换失败等问题