private void pagination(Invocation invocation, StatementHandler target) throws SQLException {
final MetaObject metaStatementHandler = getMetaObject(target);
final BoundSql boundSql = target.getBoundSql();
Page<?> page = PAGE_THREAD_LOCAL.get();
if (page == null) {
page = findPageParameter(boundSql.getParameterObject());
}
// 如果传入的参数中有分页对象且sql语句中有select，才做分页处理
String sql = boundSql.getSql().toLowerCase();
if (sql.startsWith("select") && page != null) {
// 采用物理分页后，就不需要mybatis的内存分页了，所以重置下面的两个参数
metaStatementHandler.setValue("delegate.rowBounds.offset", RowBounds.NO_ROW_OFFSET);
metaStatementHandler.setValue("delegate.rowBounds.limit", RowBounds.NO_ROW_LIMIT);
// 设置分页对象里的总记录数和总页数
Connection connection = (Connection) invocation.getArgs()[0];
MappedStatement mappedStatement =
(MappedStatement) metaStatementHandler.getValue("delegate.mappedStatement");
if (page.isCountTotal()) {
int recordsTotal = getTotalCount(sql, connection, mappedStatement, boundSql);
page.setTotalNum(recordsTotal);
}
// 最后重写sql
String pageSql = buildPageSql(sql, page);
metaStatementHandler.setValue("delegate.boundSql.sql", pageSql);
}
}
@SuppressWarnings({"rawtypes", "unchecked"})
@Override
public Object intercept(Invocation invocation) throws Throwable {
final String name = invocation.getMethod().getName();
final Object target = invocation.getTarget();
if (target instanceof StatementHandler) {
pagination(invocation, (StatementHandler) target);
} else if (target instanceof Executor) {
autoMap(invocation, name);
} else if (target instanceof ResultSetHandler) {
Object result = invocation.proceed();
if (result instanceof List) {
Page page = PAGE_THREAD_LOCAL.get();
if (page != null) {
page.addAll((List) result);
PAGE_THREAD_LOCAL.remove();
return page;
}
}
return result;
}
return invocation.proceed();
}
/**
* 从传递的参数中找Page对象，并返回
*
* @param paramObj
* @return
*/
public Page<?> findPageParameter(Object paramObj) {
Page<?> page = null;
if (paramObj instanceof Page) {
page = (Page<?>) paramObj;
} else if (paramObj instanceof Map) {
Map<?, ?> m = (Map<?, ?>) paramObj;
for (Object o : m.values()) {
if (o instanceof Page) {
page = (Page<?>) o;
break;
}
}
}
if (page != null) {
PAGE_THREAD_LOCAL.set(page);
}
return page;
}