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);
}
}
/**
* 生成特定数据库的分页语句
*
* @param sql
* @param page
* @return
*/
private String buildPageSql(String sql, Page<?> page) {
if (page == null || dialect == null || dialect.equals("")) {
return sql;
}
StringBuilder sb = new StringBuilder();
int startRow = page.getOffset();
if ("mysql".equals(dialect)) {
sb.append(sql);
sb.append(" limit ").append(startRow).append(",").append(page.getLimit());
} else if ("hsqldb".equals(dialect)) {
sb.append("select limit ");
sb.append(startRow);
sb.append(" ");
sb.append(page.getLimit());
sb.append(" ");
sb.append(sql.substring(6));
} else if ("oracle".equals(dialect)) {
sb.append("select * from (select tmp_tb.*,ROWNUM row_id from (");
sb.append(sql);
sb.append(") tmp_tb where ROWNUM<=");
sb.append(startRow + page.getLimit());
sb.append(") where row_id>");
sb.append(startRow);
} else {
throw new IllegalArgumentException("SelectInterceptor error:does not support " + dialect);
}
return sb.toString();
}
@SuppressWarnings({"rawtypes", "unchecked"})
private void autoMap(Invocation invocation, String name) throws ClassNotFoundException {
final Object[] queryArgs = invocation.getArgs();
final MappedStatement ms = (MappedStatement) queryArgs[0];
final Object parameter = queryArgs[1];
String statementId = ms.getId();
MapperMeta meta = getMapperMeta(ms.getConfiguration(), statementId);
if (meta.isFillEntity()) {
// 将泛型类加入到参数中供CrudTemplate使用
if (parameter != null) {
Map map;
if (parameter instanceof Map) {
map = (HashMap) parameter;
map.put(CrudProvider.CLASS_KEY, meta.getEntity());
} else {
map = new HashMap();
map.put(CrudProvider.PARA_KEY, parameter);
map.put(CrudProvider.CLASS_KEY, meta.getEntity());
}
queryArgs[1] = map;
} else {
queryArgs[1] = meta.getEntity();
}
}
if (meta.isFillResultMap()) {
MetaObject metaMappedStatement = getMetaObject(ms);
metaMappedStatement.setValue("resultMaps", meta.getResultMaps());
}
if (name.equals("query")) {
final RowBounds rowBounds = (RowBounds) queryArgs[2];
if (rowBounds == null || rowBounds == RowBounds.DEFAULT) {
Page p = findPageParameter(queryArgs[1]);
if (p != null) {
queryArgs[2] = new RowBounds(p.getOffset(), p.getLimit());
}
}
}
}
@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();
}