Cannot unwrap to requested type [javax.sql.DataSource]

本文介绍在Hibernate配置文件中如何正确设置hibernate.connection.provider_class属性,并使用C3P0连接池。通过示例代码展示如何配置,并强调了需要导入对应的hibernate-c3p0 jar包。

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hibernate配置文件中必须指定hibernate.connection.provider_class属性,
Java code
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<property name= "connection.provider_class" >
         org.hibernate.connection.C3P0ConnectionProvider
     </property>
,然后倒入hibernate-c3p0的jar包..我也碰到这样的问题,这样解决的.具体原理我也不懂,希望高手解答.
联邦SQL测试失败: Error while executing SQL "select u."user_id", t."task_name" from MYSQL."sys_user" u join PGSQL."ops_task" t on u."user_id" = t."task_id" limit 1": Error while compiling generated Java code: public org.apache.calcite.linq4j.Enumerable bind(final org.apache.calcite.DataContext root) { final org.apache.calcite.runtime.ResultSetEnumerable enumerable = org.apache.calcite.runtime.ResultSetEnumerable.of((javax.sql.DataSource) root.getRootSchema().getSubSchema("MYSQL").unwrap(javax.sql.DataSource.class), "SELECT `user_id`\r\nFROM `sys_user`\r\nORDER BY `user_id` IS NULL, `user_id`", new org.apache.calcite.linq4j.function.Function1() { public org.apache.calcite.linq4j.function.Function0 apply(final java.sql.ResultSet resultSet) { return new org.apache.calcite.linq4j.function.Function0() { public Object apply() { try { final Object value; value = resultSet.getLong(1); if (resultSet.wasNull()) { value = null; } return value; } catch (java.sql.SQLException e) { throw new RuntimeException( e); } } } ; } public Object apply(final Object resultSet) { return apply( (java.sql.ResultSet) resultSet); } } ); enumerable.setTimeout(root); final org.apache.calcite.runtime.ResultSetEnumerable enumerable0 = org.apache.calcite.runtime.ResultSetEnumerable.of((javax.sql.DataSource) root.getRootSchema().getSubSchema("PGSQL").unwrap(javax.sql.DataSource.class), "SELECT \"task_name\", CAST(\"task_id\" AS BIGINT) AS \"task_id0\"\r\nFROM \"ops_task\"\r\nORDER BY 2", new org.apache.calcite.linq4j.function.Function1() { public org.apache.calcite.linq4j.function.Function0 apply(final java.sql.ResultSet resultSet) { return new org.apache.calcite.linq4j.function.Function0() { public Object apply() { try { final Object[] values = new Object[2]; values[0] = resultSet.getObject(1); values[1] = resultSet.getLong(2); if (resultSet.wasNull()) { values[1] = null; } return values; } catch (java.sql.SQLException e) { throw new RuntimeException( e); } } } ; } public Object apply(final Object resultSet) { return apply( (java.sql.ResultSet) resultSet); } } ); enumerable0.setTimeout(root); final org.apache.calcite.linq4j.Enumerable _inputEnumerable = org.apache.calcite.linq4j.EnumerableDefaults.mergeJoin(enumerable, enumerable0, new org.apache.calcite.linq4j.function.Function1() { public long apply(long left) { return left; } public Object apply(Long left) { return apply( left.longValue()); } public Object apply(Object left) { return apply( (Long) left); } } , new org.apache.calcite.linq4j.function.Function1() { public long apply(Object[] right) { return org.apache.calcite.runtime.SqlFunctions.toLong(right[1]); } public Object apply(Object right) { return apply( (Object[]) right); } } , null, new org.apache.calcite.linq4j.function.Function2() { public Object[] apply(Long left, Object[] right) { return new Object[] { left, right[0], right[1]}; } public Object[] apply(Object left, Object right) { return apply( (Long) left, (Object[]) right); } } , org.apache.calcite.linq4j.JoinType.INNER, new java.util.Comparator(){ public int compare(Long v0, Long v1) { final int c; c = org.apache.calcite.runtime.Utilities.compare(v0, v1); if (c != 0) { return c; } return 0; } public int compare(Object o0, Object o1) { return this.compare((Long) o0, (Long) o1); } }, null).take(1); return new org.apache.calcite.linq4j.AbstractEnumerable(){ public org.apache.calcite.linq4j.Enumerator enumerator() { return new org.apache.calcite.linq4j.Enumerator(){ public final org.apache.calcite.linq4j.Enumerator inputEnumerator = _inputEnumerable.enumerator(); public void reset() { inputEnumerator.reset(); } public boolean moveNext() { return inputEnumerator.moveNext(); } public void close() { inputEnumerator.close(); } public Object current() { final Object[] current = (Object[]) inputEnumerator.current(); final Object input_value = current[0]; final Object input_value0 = current[1]; return new Object[] { input_value, input_value0}; } }; } }; } public Class getElementType() { return java.lang.Object[].class; }
最新发布
08-02
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