【Error_SpringBoot】Duplicate entry ‘测试‘ for key ‘idx_username‘ ＞ ### The error may e违反了数据库的唯一约束Unique

Problems

主要问题
违反了数据库的唯一约束Unique

### Error updating database.  Cause: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '测试' for key 'idx_username'
### The error may exist in com/sky/mapper/EmployeeMapper.java (best guess)### The error may 
involve com.sky.mapper.EmployeeMapper.insert-Inline
### The error occurred while setting parameters
### SQL: insert into employee ( name, username, password, phone, sex, id_number, status, create_time, update_time, create_user,
update_user)values (?, ?,?, ?, ?, ?, ?, ?, ?, ?, ?)
### Cause: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '测试' for key 'idx_username' ; Duplicate entry '测试' for
key 'idx_username'; nested exception is
java.sql.SQLIntegrityConstraintViolationException: Duplicate entry
'测试' for key 'idx_username'] with root cause

java.sql.SQLIntegrityConstraintViolationException: Duplicate entry
'测试' for key 'idx_username'

2023-07-09 11:27:58.701 ERROR 27008 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.DuplicateKeyException: 
### Error updating database.  Cause: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '测试' for key 'idx_username'
### The error may exist in com/sky/mapper/EmployeeMapper.java (best guess)
### The error may involve com.sky.mapper.EmployeeMapper.insert-Inline
### The error occurred while setting parameters
### SQL: insert into employee ( name, username, password, phone, sex, id_number, status, create_time, update_time, create_user, update_user)values (?, ?,?, ?, ?, ?, ?, ?, ?, ?, ?)
### Cause: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '测试' for key 'idx_username'
; Duplicate entry '测试' for key 'idx_username'; nested exception is java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '测试' for key 'idx_username'] with root cause

java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '测试' for key 'idx_username'
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:117) ~[mysql-connector-java-8.0.30.jar:8.0.30]
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) ~[mysql-connector-java-8.0.30.jar:8.0.30]
	at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:916) ~[mysql-connector-java-8.0.30.jar:8.0.30]
	at com.mysql.cj.jdbc.ClientPreparedStatement.execute(ClientPreparedStatement.java:354) ~[mysql-connector-java-8.0.30.jar:8.0.30]
	at com.alibaba.druid.pool.DruidPooledPreparedStatement.execute(DruidPooledPreparedStatement.java:497) ~[druid-1.2.1.jar:1.2.1]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_301]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_301]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_301]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_301]
	at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59) ~[mybatis-3.5.7.jar:3.5.7]
	at com.sun.proxy.$Proxy104.execute(Unknown Source) ~[na:na]
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:47) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76) ~[mybatis-3.5.7.jar:3.5.7]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_301]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_301]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_301]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_301]
	at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:64) ~[mybatis-3.5.7.jar:3.5.7]
	at com.sun.proxy.$Proxy102.update(Unknown Source) ~[na:na]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:194) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:181) ~[mybatis-3.5.7.jar:3.5.7]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_301]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_301]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_301]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_301]
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:427) ~[mybatis-spring-2.0.6.jar:2.0.6]
	at com.sun.proxy.$Proxy79.insert(Unknown Source) ~[na:na]
	at org.mybatis.spring.SqlSessionTemplate.insert(SqlSessionTemplate.java:272) ~[mybatis-spring-2.0.6.jar:2.0.6]
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:62) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.binding.MapperProxy$PlainMethodInvoker.invoke(MapperProxy.java:145) ~[mybatis-3.5.7.jar:3.5.7]
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:86) ~[mybatis-3.5.7.jar:3.5.7]
	at com.sun.proxy.$Proxy80.insert(Unknown Source) ~[na:na]
	at com.sky.service.impl.EmployeeServiceImpl.save(EmployeeServiceImpl.java:101) ~[classes/:na]
	at com.sky.controller.admin.EmployeeController.save(EmployeeController.java:99) ~[classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_301]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_301]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_301]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_301]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1070) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:681) ~[tomcat-embed-core-9.0.65.jar:4.0.FR]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.65.jar:4.0.FR]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.22.jar:5.3.22]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1789) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_301]

analysis

该用户已存在，违反了数据库的唯一约束。抛出的一场未作处理。

solution

处理异常。
我们可以通过全局异常处理器，处理。
Duplicate entry ‘测试’ for key ‘idx_username’。
获取错误信息，
若信息中包含（Duplicate entry ）
则返回错误信息msg= “'测试 ” + “已存在”
否则 ----> “未知错误”