本来是mssql+hibernate+native SQL 应用的很和谐
但是到了把mssql换成mysql,就出了错(同样的数据结构和数据)。
查询方法是:
[java] view plaincopy
String sql =
"select id XXX_ID from t_tab";
List<Map> list = session.createSQLQuery(sql)
.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP)
.list();
错误信息:
[css] view plaincopy
org.hibernate.exception.SQLGrammarException: could not execute query
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:90)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.loader.Loader.doList(Loader.java:2231)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2125)
at org.hibernate.loader.Loader.list(Loader.java:2120)
at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:312)
at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1722)
at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:165)
at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:175)
at com.exsun.common.dao.BasDaoImpl.findBySql(BasDaoImpl.java:173)
at com.exsun.arms.service.EmployeesalaryService.getList(EmployeesalaryService.java:32)
at com.exsun.arms.service.EmployeesalaryService$$FastClassByCGLIB$$2d81000f.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:700)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:635)
at com.exsun.arms.service.EmployeesalaryService$$EnhancerByCGLIB$$1e3e6d9f.getList(<generated>)
at com.exsun.arms.action.EmployeesalaryAction.getList(EmployeesalaryAction.java:110)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:269)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:170)
at org.springframework.web.struts.DelegatingActionProxy.execute(DelegatingActionProxy.java:110)
at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:627)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at com.exsun.common.util.MenuFilter.doFilter(MenuFilter.java:103)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:96)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.sql.SQLException: Column 'id' not found.
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1072)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:986)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:981)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
at com.mysql.jdbc.ResultSetImpl.findColumn(ResultSetImpl.java:1144)
at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5616)
at org.hibernate.type.StringType.get(StringType.java:41)
at org.hibernate.type.NullableType.nullSafeGet(NullableType.java:184)
at org.hibernate.type.NullableType.nullSafeGet(NullableType.java:210)
at org.hibernate.loader.custom.CustomLoader$ScalarResultColumnProcessor.extract(CustomLoader.java:497)
at org.hibernate.loader.custom.CustomLoader$ResultRowProcessor.buildResultRow(CustomLoader.java:443)
at org.hibernate.loader.custom.CustomLoader.getResultColumnOrRow(CustomLoader.java:340)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:629)
at org.hibernate.loader.Loader.doQuery(Loader.java:724)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
at org.hibernate.loader.Loader.doList(Loader.java:2228)
... 62 more
看到最后Caused by: java.sql.SQLException:
所以我试试用JDBC连接
[java] view plaincopy
public class TestMySqlJDBC {
public static void main(String[] args) throws Exception, IllegalAccessException, ClassNotFoundException {
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con=java.sql.DriverManager.getConnection("jdbc:mysql://localhost:3306/arms?useUnicode=true&characterEncoding=utf8&","root","");
Statement stmt=con.createStatement();
ResultSet rs=stmt.executeQuery("select id XXX_ID,name from t_tab");
while(rs.next())
{
System.out.printf("id:%s___name:%s/n",rs.getString("XXX_ID"),rs.getString("name"));
}
rs.close();
stmt.close();
con.close();
}
}
可以很正常的运行。
后来仔细又看了一下hibernate的执行错误
Caused by: java.sql.SQLException: Column 'id' not found.
是ID 找不到 不是XXX_ID 找不到。这意思貌似hibernate就没按别名alias 来取值
跟踪了一下hibernate
其中在Customer里发现的这一段
[java] view plaincopy
public class ScalarResultColumnProcessor implements ResultColumnProcessor {
private int position = -1;
private String alias;
private Type type;
public ScalarResultColumnProcessor(int position) {
this.position = position;
}
public ScalarResultColumnProcessor(String alias, Type type) {
this.alias = alias;
this.type = type;
}
//这个方法中的alias 为"id"而不是XXX_ID
public Object extract(
Object[] data,
ResultSet resultSet,
SessionImplementor session) throws SQLException, HibernateException {
return type.nullSafeGet( resultSet, alias, session, null );
}
...........
...........
...........
hibernate是按照select id,name from tab来解释
而不是 select id XXX_ID , name from tab
这里跟到的数据果然是Hibernate把alias给忽略了。。。
-------------------------------------
继续跟踪hibernate代码.根据调用栈,单步跟踪很快找到
org.hibernate.loader.custom.CustomLoader$ScalarResultColumnProcessor 里面的
[java] view plaincopy
public void performDiscovery(Metadata metadata, List types, List aliases) throws SQLException {
if ( alias == null ) {
alias = metadata.getColumnName( position );
}
else if ( position < 0 ) {
position = metadata.resolveColumnPosition( alias );
}
if ( type == null ) {
type = metadata.getHibernateType( position );
}
types.add( type );
aliases.add( alias );
}
这里就是拼装将来要根据列名get出来的结果的地方
alias = metadata.getColumnName( position )
getColumnName 跟进去就是JDBC的实现.
跟踪可以看到.从这里get出来的alias不是真正的aliasName,而是originalColumnName原始列名.
后来试着修改了hibernate各种方言的设置:MySQLDialect,MySQL5Dialect,MySQL5InnoDBDialect等等还是不行。
我用JDBC试了下
mysql-connector-java-5.1.9-bin.jar
mysql-connector-java-5.1.10-bin.jar
mysql-connector-java-5.1.11-bin.jar
[java] view plaincopy
ResultSet rs=stmt.executeQuery(sql);
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
List<String> columnName = new ArrayList();
for (int i = 1; i <= columnCount; i++) {
String tmp = rsmd.getColumnName(i) + "___" + rsmd.getColumnLabel(i);
System.out.println(tmp);
}
三个实现,结果都是一样的.
mysql的JDBC要获取alias只能用getColumnLable,不能用getColumnName
而Hibernate取字段名称的时候就只用 getColumnName.
解决办法有两个,一个是改hibernate,再不就得改mysql.
怕Hibernate对别的数据库实现有影响
所以就拿mysql的JDBC驱动开刀了.
把com.mysql.jdbc.ResultSetMetaData
中的
[java] view plaincopy
public String getColumnName(int column) throws SQLException {
if (this.useOldAliasBehavior) {
return getField(column).getName();
}
String name = getField(column).getNameNoAliases();
if (name != null && name.length() == 0) {
return getField(column).getName();
}
return name;
}
修改为:
[java] view plaincopy
public String getColumnName(int column) throws SQLException {
return getColumnLable(column);
}
然后把JDBC重新打包一下
再运行就OK了.
--转自