iBatis大数据量分页查询的性能问题分析及改进
感谢 http://www.iteye.com/topic/544765；http://www.iteye.com/topic/566605
首先看一下iBatis的分页代码是怎么执行的
iBatis中，具体负责执行sql的类是 com.ibatis.sqlmap.engine.execution.SqlExecutor。
负责分页查询的方法是executeQuery —>handleMultipleResults —> handleResults。handleResults方法的源码如下：
private void handleResults(RequestScope request, ResultSet rs, int skipResults, int maxResults, RowHandlerCallback callback) throws SQLException {
try {
request.setResultSet(rs);
ResultMap resultMap = request.getResultMap();
if (resultMap != null) {
// Skip Results
if (rs.getType() != ResultSet.TYPE_FORWARD_ONLY) {
if (skipResults > 0) {
rs.absolute(skipResults);
}
} else {
for (int i = 0; i < skipResults; i++) {
if (!rs.next()) {
return;
}
}
}
// Get Results
int resultsFetched = 0;
while ((maxResults == SqlExecutor.NO_MAXIMUM_RESULTS || resultsFetched < maxResults) && rs.next()) {
Object[] columnValues = resultMap.resolveSubMap(request, rs).getResults(request, rs);
callback.handleResultObject(request, columnValues, rs);
resultsFetched++;
}
}
} finally {
request.setResultSet(null);
}
}
从代码中可以看出iBatis分页查询的逻辑是首先判断ResulteSet的类型，
如果ResultSet的类型是 ResultSet.TYPE_FORWARD_ONLY，则使用ResultSet对象的next()方法，一步一步地移动游标到要取的第一条记录的位置，然后再采用next()方法取出一页的数据；
如果ResultSet的类型不是ResultSet.TYPE_FORWARD_ONLY，则采用 ResultSet对象的absolute()方法，移动游标到要取的第一条记录的位置，然后再采用next()方法取出一页的数据。
ResultSet的类型，是在iBatis的配置文件中配置的，如：
<select id="queryAllUser" resultMap="user" resultSetType="FORWARD_ONLY">
select id,name from user_tab
</select>
其中resultSetType的可选值为FORWARD_ONLY | SCROLL_INSENSITIVE | SCROLL_SENSITIVE，
如果没有配置，默认值为FORWARD_ONLY，FORWARD_ONLY类型的ResultSet 不支持absolute方法，所以是通过next方法定位的。
一般情况下，我们都使用FORWARD_ONLY类型的ResultSet，SCROLL类型ResultSet的优点是可向前，向后滚动，并支持精确定位（absolute）,但缺点是把结果集全部加载进缓存（如果查询是从100万条数据开始取100条，会把前100万条数据也加载进缓存），容易造成内存溢出，性能也很差，除非必要，一般不使用。
可见，iBatis的分页完全依赖于JDBC ResultSet的next方法或absolute方法来实现。
而Hibernate在分页查询方面，比iBatis要好很多，Hibernate可以根据不同的数据库，对sql做不同的优化加工，然后再执行优化后的sql。
比如，对于Oracle数据库来说，原始sql为select * form user_tab, 从1000001条开始取100条，则hibernate加工后的sql为：
select *
from (select row_.*, rownum rownum_
from (SELECT * FROM user_tab) row_
where rownum <= 1000100)
where rownum_ > 1000000
写一个程序，对比一下两种方式下的查询效率。程序如下：
public class Test{
public static void main(String[] args) throws Exception {
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:db", "db",
"xwdb");
long a = System.currentTimeMillis();
testIbatisPageQuery(conn);
//testHibernatePageQuery(conn);
long b = System.currentTimeMillis();
System.out.println(b-a);
}
public static void testIbatisPageQuery(Connection conn) throws Exception{
String sql = "SELECT * FROM user_tab ";
Statement stmt = conn.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
ResultSet rs = stmt.executeQuery(sql);
int j=0;
//游标移动到1000001条数据的位置
while(rs.next() && j++<1000000){
}
int i=0;
//依次取出100条数据
while(rs.next() && i++<100){
}
}
public static void testHibernatePageQuery(Connection conn) throws Exception{
String sql = "SELECT * FROM user_tab ";
StringBuffer pagingSelect = new StringBuffer( sql.length()+100 );
pagingSelect.append("select * from ( select row_.*, rownum rownum_ from ( ");
pagingSelect.append(sql);
pagingSelect.append(" ) row_ where rownum <= 1000100) where rownum_ > 1000000");
Statement stmt = conn.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
ResultSet rs = stmt.executeQuery(pagingSelect.toString());
while(rs.next()){
}
}
}
发现testIbatisPageQuery需要执行十几秒，而testHibernatePageQuery仅需要执行零点几秒，差异很大。
而如果改成从1000条开始取100条，甚至更靠前，则2者的差别是非常小的。
综上所述，如果系统中查询的数据量很大，并且用户会选择查询非常靠后的数据，那么我们就应该替换iBatis的分页实现，如果不存在这种情况，那我们就不需要替换iBatis的分页实现，一般情况下，用户不可能去查询那么靠后的页，这也是iBatis一直不修改分页实现的原因吧。
如果我们选择替换的话，有三种办法，
一种是自己写一个类，继承iBatis的SqlExecutor,然后把这个类注入到 com.ibatis.sqlmap.engine.impl.ExtendedSqlMapClient中，由于SqlExecutor是 ExtendedSqlMapClient的私有变量，没有public类型的set方法，所以需要采用reflect机制注入；
第二种办法是弃用iBatis的分页查询方法 queryForList(String sql,Object obj,int maxResult,int skipResult)，而用普通查询方法，queryForList(String sql,Object obj)。只不过把maxResult和skipResult都作为obj的变量传到sql里去。如下：
<select id="queryAllUser" resultMap="user">
select *
from (select row_.*, rownum rownum_
from (SELECT * FROM user_tab) row_
where rownum <= #_maxResult#)
where rownum_ > #_skipResult#
</select>
第三种方法是在自己的工程里写一个和iBatis的SqlExecutor的包名和类名完全一样的类，web工程中，WEB-INF/classes下的java类，先于 WEB-INF/lib下jar包的加载，所以就巧妙了覆盖了iBatis的SqlExecutor类；
这种方式可行是因为
1、JVM类的加载是通过Class.forName(String cls)来实现，根据这个原理可以自己写一个与com.ibatis.sqlmap.engine.execution.SqlExecutor同名类；
2、java web类的加载顺序是：首先是web容器的相关类与jar包，然后是web工程下面WEB-INF/classes/下的所有类，最后才是WEB-INF/lib下的所有jar包；
有了以上的先决条件就好办了，可以在你的项目src目录下建包com.ibatis.sqlmap.engine.execution，然后在此包下建类 SqlExecutor，然后把iBatis包下的这个类的源码复制进来后做小小改动，原来的executeQuery方法改成私有、换名，换成什么名称随便，然后新建一个公有的executeQuery方法，分页功能就在这个方法体内实现；
这样一来，web容器首会找到WEB-INF/classes下的 com.ibatis.sqlmap.engine.execution.SqlExecutor这个类，因而会忽略掉在ibatis包中的这个类，即实现了自定义的分页功能，又不用去破坏ibatis的包；
还有一点，也可以将自定义的这个类打成jar包放到lib中去，不过这时就要注意了，jar包的名称一定要在ibatis包的名称之前，也就是说 ibatis-2.3.4.726.jar，那么这个jar就可以写成ibatis-2.3.4.725.jar，或者字母在ibatis这几个字母之前，这样才能正确加载自己写的那个类。
SqlExecutor.java
/*
* Copyright 2004 Clinton Begin
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.ibatis.sqlmap.engine.execution;
import java.sql.BatchUpdateException;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Types;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.ibatis.sqlmap.engine.impl.SqlMapClientImpl;
import com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate;
import com.ibatis.sqlmap.engine.mapping.parameter.ParameterMap;
import com.ibatis.sqlmap.engine.mapping.parameter.ParameterMapping;
import com.ibatis.sqlmap.engine.mapping.result.ResultMap;
import com.ibatis.sqlmap.engine.mapping.result.ResultObjectFactoryUtil;
import com.ibatis.sqlmap.engine.mapping.statement.DefaultRowHandler;
import com.ibatis.sqlmap.engine.mapping.statement.MappedStatement;
import com.ibatis.sqlmap.engine.mapping.statement.RowHandlerCallback;
import com.ibatis.sqlmap.engine.scope.ErrorContext;
import com.ibatis.sqlmap.engine.scope.SessionScope;
import com.ibatis.sqlmap.engine.scope.StatementScope;
/**
* Class responsible for executing the SQL
*/
@SuppressWarnings ("unchecked")
public class SqlExecutor {
private static final Log log = LogFactory.getLog(SqlExecutor.class);
//
// Constants
//
/**
* Constant to let us know not to skip anything
*/
public static final int NO_SKIPPED_RESULTS = 0;
/**
* Constant to let us know to include all records
*/
public static final int NO_MAXIMUM_RESULTS = -999999;
public SqlExecutor() {
log.info("Custom class 'SqlExecutor' Initialization");
}
//
// Public Methods
//
/**
* Execute an update
*
* @param statementScope
* - the request scope
* @param conn
* - the database connection
* @param sql
* - the sql statement to execute
* @param parameters
* - the parameters for the sql statement
* @return - the number of records changed
* @throws SQLException
* - if the update fails
*/
public int executeUpdate(StatementScope statementScope, Connection conn,
String sql, Object[] parameters) throws SQLException {
ErrorContext errorContext = statementScope.getErrorContext();
errorContext.setActivity("executing update");
errorContext.setObjectId(sql);
PreparedStatement ps = null;
setupResultObjectFactory(statementScope);
int rows = 0;
try {
errorContext
.setMoreInfo("Check the SQL Statement (preparation failed).");
ps = prepareStatement(statementScope.getSession(), conn, sql);
setStatementTimeout(statementScope.getStatement(), ps);
errorContext
.setMoreInfo("Check the parameters (set parameters failed).");
statementScope.getParameterMap().setParameters(statementScope, ps,
parameters);
errorContext.setMoreInfo("Check the statement (update failed).");
ps.execute();
rows = ps.getUpdateCount();
} finally {
closeStatement(statementScope.getSession(), ps);
}
return rows;
}
/**
* Adds a statement to a batch
*
* @param statementScope
* - the request scope
* @param conn
* - the database connection
* @param sql
* - the sql statement
* @param parameters
* - the parameters for the statement
* @throws SQLException
* - if the statement fails
*/
public void addBatch(StatementScope statementScope, Connection conn,
String sql, Object[] parameters) throws SQLException {
Batch batch = (Batch) statementScope.getSession().getBatch();
if (batch == null) {
batch = new Batch();
statementScope.getSession().setBatch(batch);
}
batch.addBatch(statementScope, conn, sql, parameters);
}
/**
* Execute a batch of statements
*
* @param sessionScope
* - the session scope
* @return - the number of rows impacted by the batch
* @throws SQLException
* - if a statement fails
*/
public int executeBatch(SessionScope sessionScope) throws SQLException {
int rows = 0;
Batch batch = (Batch) sessionScope.getBatch();
if (batch != null) {
try {
rows = batch.executeBatch();
} finally {
batch.cleanupBatch(sessionScope);
}
}
return rows;
}
/**
* Execute a batch of statements
*
* @param sessionScope
* - the session scope
* @return - a List of BatchResult objects (may be null if no batch has been
* initiated). There will be one BatchResult object in the list for
* each sub-batch executed
* @throws SQLException
* if a database access error occurs, or the drive does not
* support batch statements
* @throws BatchException
* if the driver throws BatchUpdateException
*/
public List executeBatchDetailed(SessionScope sessionScope)
throws SQLException, BatchException {
List answer = null;
Batch batch = (Batch) sessionScope.getBatch();
if (batch != null) {
try {
answer = batch.executeBatchDetailed();
} finally {
batch.cleanupBatch(sessionScope);
}
}
return answer;
}
/**
* Long form of the method to execute a query
*
* @param statementScope
* - the request scope
* @param conn
* - the database connection
* @param sql
* - the SQL statement to execute
* @param parameters
* - the parameters for the statement
* @param skipResults
* - the number of results to skip
* @param maxResults
* - the maximum number of results to return
* @param callback
* - the row handler for the query
* @throws SQLException
* - if the query fails
*/
//------------------------------- 分页代码重写(start) ------------------------------------//
//重写executeQuery方法，首先判断是否分页查询，分页查询先将分页SQL语句构建，然后执行iBatis默认的查询
public void executeQuery(StatementScope statementScope, Connection conn,
String sql, Object[] parameters, int skipResults, int maxResults,
RowHandlerCallback callback) throws SQLException {
//取数据库产品名称
String dbName = conn.getMetaData().getDatabaseProductName();
int len = sql.length();
//判断是否分页
if ((skipResults != NO_SKIPPED_RESULTS || maxResults != NO_MAXIMUM_RESULTS)) {
//根据数据库产品名称取对应的分页SQL语句
sql = Dialect.getLimitString(dbName, sql, skipResults, maxResults);
//分页语句是否存在
if (sql.length() != len) {
skipResults = NO_SKIPPED_RESULTS;
maxResults = NO_MAXIMUM_RESULTS;
}
}
iBatisExecuteQuery(statementScope, conn, sql, parameters, skipResults,
maxResults, callback);
}
//iBatis包中默认的executeQuery方法
private void iBatisExecuteQuery(StatementScope statementScope,
Connection conn, String sql, Object[] parameters, int skipResults,
int maxResults, RowHandlerCallback callback) throws SQLException {
ErrorContext errorContext = statementScope.getErrorContext();
errorContext.setActivity("executing query");
errorContext.setObjectId(sql);
PreparedStatement ps = null;
ResultSet rs = null;
setupResultObjectFactory(statementScope);
try {
errorContext
.setMoreInfo("Check the SQL Statement (preparation failed).");
Integer rsType = statementScope.getStatement().getResultSetType();
if (rsType != null) {
ps = prepareStatement(statementScope.getSession(), conn, sql,
rsType);
} else {
ps = prepareStatement(statementScope.getSession(), conn, sql);
}
setStatementTimeout(statementScope.getStatement(), ps);
Integer fetchSize = statementScope.getStatement().getFetchSize();
if (fetchSize != null) {
ps.setFetchSize(fetchSize.intValue());
}
errorContext
.setMoreInfo("Check the parameters (set parameters failed).");
statementScope.getParameterMap().setParameters(statementScope, ps,
parameters);
errorContext.setMoreInfo("Check the statement (query failed).");
ps.execute();
errorContext
.setMoreInfo("Check the results (failed to retrieve results).");
// Begin ResultSet Handling
rs = handleMultipleResults(ps, statementScope, skipResults,
maxResults, callback);
// End ResultSet Handling
} finally {
try {
closeResultSet(rs);
} finally {
closeStatement(statementScope.getSession(), ps);
}
}
}
//-------------------- 分页代码重写(end) -------------------------------------//
/**
* Execute a stored procedure that updates data
*
* @param statementScope
* - the request scope
* @param conn
* - the database connection
* @param sql
* - the SQL to call the procedure
* @param parameters
* - the parameters for the procedure
* @return - the rows impacted by the procedure
* @throws SQLException
* - if the procedure fails
*/
public int executeUpdateProcedure(StatementScope statementScope,
Connection conn, String sql, Object[] parameters)
throws SQLException {
ErrorContext errorContext = statementScope.getErrorContext();
errorContext.setActivity("executing update procedure");
errorContext.setObjectId(sql);
CallableStatement cs = null;
setupResultObjectFactory(statementScope);
int rows = 0;
try {
errorContext
.setMoreInfo("Check the SQL Statement (preparation failed).");
cs = prepareCall(statementScope.getSession(), conn, sql);
setStatementTimeout(statementScope.getStatement(), cs);
ParameterMap parameterMap = statementScope.getParameterMap();
ParameterMapping[] mappings = parameterMap.getParameterMappings();
errorContext
.setMoreInfo("Check the output parameters (register output parameters failed).");
registerOutputParameters(cs, mappings);
errorContext
.setMoreInfo("Check the parameters (set parameters failed).");
parameterMap.setParameters(statementScope, cs, parameters);
errorContext
.setMoreInfo("Check the statement (update procedure failed).");
cs.execute();
rows = cs.getUpdateCount();
errorContext
.setMoreInfo("Check the output parameters (retrieval of output parameters failed).");
retrieveOutputParameters(statementScope, cs, mappings, parameters,
null);
} finally {
closeStatement(statementScope.getSession(), cs);
}
return rows;
}
/**
* Execute a stored procedure
*
* @param statementScope
* - the request scope
* @param conn
* - the database connection
* @param sql
* - the sql to call the procedure
* @param parameters
* - the parameters for the procedure
* @param skipResults
* - the number of results to skip
* @param maxResults
* - the maximum number of results to return
* @param callback
* - a row handler for processing the results
* @throws SQLException
* - if the procedure fails
*/
public void executeQueryProcedure(StatementScope statementScope,
Connection conn, String sql, Object[] parameters, int skipResults,
int maxResults, RowHandlerCallback callback) throws SQLException {
ErrorContext errorContext = statementScope.getErrorContext();
errorContext.setActivity("executing query procedure");
errorContext.setObjectId(sql);
CallableStatement cs = null;
ResultSet rs = null;
setupResultObjectFactory(statementScope);
try {
errorContext
.setMoreInfo("Check the SQL Statement (preparation failed).");
Integer rsType = statementScope.getStatement().getResultSetType();
if (rsType != null) {
cs = prepareCall(statementScope.getSession(), conn, sql, rsType);
} else {
cs = prepareCall(statementScope.getSession(), conn, sql);
}
setStatementTimeout(statementScope.getStatement(), cs);
Integer fetchSize = statementScope.getStatement().getFetchSize();
if (fetchSize != null) {
cs.setFetchSize(fetchSize.intValue());
}
ParameterMap parameterMap = statementScope.getParameterMap();
ParameterMapping[] mappings = parameterMap.getParameterMappings();
errorContext
.setMoreInfo("Check the output parameters (register output parameters failed).");
registerOutputParameters(cs, mappings);
errorContext
.setMoreInfo("Check the parameters (set parameters failed).");
parameterMap.setParameters(statementScope, cs, parameters);
errorContext
.setMoreInfo("Check the statement (update procedure failed).");
cs.execute();
errorContext
.setMoreInfo("Check the results (failed to retrieve results).");
// Begin ResultSet Handling
rs = handleMultipleResults(cs, statementScope, skipResults,
maxResults, callback);
// End ResultSet Handling
errorContext
.setMoreInfo("Check the output parameters (retrieval of output parameters failed).");
retrieveOutputParameters(statementScope, cs, mappings, parameters,
callback);
} finally {
try {
closeResultSet(rs);
} finally {
closeStatement(statementScope.getSession(), cs);
}
}
}
private ResultSet handleMultipleResults(PreparedStatement ps,
StatementScope statementScope, int skipResults, int maxResults,
RowHandlerCallback callback) throws SQLException {
ResultSet rs;
rs = getFirstResultSet(statementScope, ps);
if (rs != null) {
handleResults(statementScope, rs, skipResults, maxResults, callback);
}
// Multiple ResultSet handling
if (callback.getRowHandler() instanceof DefaultRowHandler) {
MappedStatement statement = statementScope.getStatement();
DefaultRowHandler defaultRowHandler = ((DefaultRowHandler) callback
.getRowHandler());
if (statement.hasMultipleResultMaps()) {
List multipleResults = new ArrayList();
multipleResults.add(defaultRowHandler.getList());
ResultMap[] resultMaps = statement.getAdditionalResultMaps();
int i = 0;
while (moveToNextResultsSafely(statementScope, ps)) {
if (i >= resultMaps.length)
break;
ResultMap rm = resultMaps[i];
statementScope.setResultMap(rm);
rs = ps.getResultSet();
DefaultRowHandler rh = new DefaultRowHandler();
handleResults(statementScope, rs, skipResults, maxResults,
new RowHandlerCallback(rm, null, rh));
multipleResults.add(rh.getList());
i++;
}
defaultRowHandler.setList(multipleResults);
statementScope.setResultMap(statement.getResultMap());
} else {
while (moveToNextResultsSafely(statementScope, ps))
;
}
}
// End additional ResultSet handling
return rs;
}
private ResultSet getFirstResultSet(StatementScope scope, Statement stmt)
throws SQLException {
ResultSet rs = null;
boolean hasMoreResults = true;
while (hasMoreResults) {
rs = stmt.getResultSet();
if (rs != null) {
break;
}
hasMoreResults = moveToNextResultsIfPresent(scope, stmt);
}
return rs;
}
private boolean moveToNextResultsIfPresent(StatementScope scope,
Statement stmt) throws SQLException {
boolean moreResults;
// This is the messed up JDBC approach for determining if there are more
// results
moreResults = !(((moveToNextResultsSafely(scope, stmt) == false) && (stmt
.getUpdateCount() == -1)));
return moreResults;
}
private boolean moveToNextResultsSafely(StatementScope scope, Statement stmt)
throws SQLException {
if (forceMultipleResultSetSupport(scope)
|| stmt.getConnection().getMetaData()
.supportsMultipleResultSets()) {
return stmt.getMoreResults();
}
return false;
}
private boolean forceMultipleResultSetSupport(StatementScope scope) {
return ((SqlMapClientImpl) scope.getSession().getSqlMapClient())
.getDelegate().isForceMultipleResultSetSupport();
}
private void handleResults(StatementScope statementScope, ResultSet rs,
int skipResults, int maxResults, RowHandlerCallback callback)
throws SQLException {
try {
statementScope.setResultSet(rs);
ResultMap resultMap = statementScope.getResultMap();
if (resultMap != null) {
// Skip Results
if (rs.getType() != ResultSet.TYPE_FORWARD_ONLY) {
if (skipResults > 0) {
rs.absolute(skipResults);
}
} else {
for (int i = 0; i < skipResults; i++) {
if (!rs.next()) {
return;
}
}
}
// Get Results
int resultsFetched = 0;
while ((maxResults == SqlExecutor.NO_MAXIMUM_RESULTS || resultsFetched < maxResults)
&& rs.next()) {
Object[] columnValues = resultMap.resolveSubMap(
statementScope, rs).getResults(statementScope, rs);
callback.handleResultObject(statementScope, columnValues,
rs);
resultsFetched++;
}
}
} finally {
statementScope.setResultSet(null);
}
}
private void retrieveOutputParameters(StatementScope statementScope,
CallableStatement cs, ParameterMapping[] mappings,
Object[] parameters, RowHandlerCallback callback)
throws SQLException {
for (int i = 0; i < mappings.length; i++) {
ParameterMapping mapping = ((ParameterMapping) mappings[i]);
if (mapping.isOutputAllowed()) {
if ("java.sql.ResultSet".equalsIgnoreCase(mapping
.getJavaTypeName())) {
ResultSet rs = (ResultSet) cs.getObject(i + 1);
ResultMap resultMap;
if (mapping.getResultMapName() == null) {
resultMap = statementScope.getResultMap();
handleOutputParameterResults(statementScope, resultMap,
rs, callback);
} else {
SqlMapClientImpl client = (SqlMapClientImpl) statementScope
.getSession().getSqlMapClient();
resultMap = client.getDelegate().getResultMap(
mapping.getResultMapName());
DefaultRowHandler rowHandler = new DefaultRowHandler();
RowHandlerCallback handlerCallback = new RowHandlerCallback(
resultMap, null, rowHandler);
handleOutputParameterResults(statementScope, resultMap,
rs, handlerCallback);
parameters[i] = rowHandler.getList();
}
rs.close();
} else {
parameters[i] = mapping.getTypeHandler().getResult(cs,
i + 1);
}
}
}
}
private void registerOutputParameters(CallableStatement cs,
ParameterMapping[] mappings) throws SQLException {
for (int i = 0; i < mappings.length; i++) {
ParameterMapping mapping = ((ParameterMapping) mappings[i]);
if (mapping.isOutputAllowed()) {
if (null != mapping.getTypeName()
&& !mapping.getTypeName().equals("")) { // @added
cs.registerOutParameter(i + 1, mapping.getJdbcType(),
mapping.getTypeName());
} else {
if (mapping.getNumericScale() != null
&& (mapping.getJdbcType() == Types.NUMERIC || mapping
.getJdbcType() == Types.DECIMAL)) {
cs.registerOutParameter(i + 1, mapping.getJdbcType(),
mapping.getNumericScale().intValue());
} else {
cs.registerOutParameter(i + 1, mapping.getJdbcType());
}
}
}
}
}
private void handleOutputParameterResults(StatementScope statementScope,
ResultMap resultMap, ResultSet rs, RowHandlerCallback callback)
throws SQLException {
ResultMap orig = statementScope.getResultMap();
try {
statementScope.setResultSet(rs);
if (resultMap != null) {
statementScope.setResultMap(resultMap);
// Get Results
while (rs.next()) {
Object[] columnValues = resultMap.resolveSubMap(
statementScope, rs).getResults(statementScope, rs);
callback.handleResultObject(statementScope, columnValues,
rs);
}
}
} finally {
statementScope.setResultSet(null);
statementScope.setResultMap(orig);
}
}
/**
* Clean up any batches on the session
*
* @param sessionScope
* - the session to clean up
*/
public void cleanup(SessionScope sessionScope) {
Batch batch = (Batch) sessionScope.getBatch();
if (batch != null) {
batch.cleanupBatch(sessionScope);
sessionScope.setBatch(null);
}
}
private PreparedStatement prepareStatement(SessionScope sessionScope,
Connection conn, String sql, Integer rsType) throws SQLException {
SqlMapExecutorDelegate delegate = ((SqlMapClientImpl) sessionScope
.getSqlMapExecutor()).getDelegate();
if (sessionScope.hasPreparedStatementFor(sql)) {
return sessionScope.getPreparedStatement((sql));
} else {
PreparedStatement ps = conn.prepareStatement(sql,
rsType.intValue(), ResultSet.CONCUR_READ_ONLY);
sessionScope.putPreparedStatement(delegate, sql, ps);
return ps;
}
}
private CallableStatement prepareCall(SessionScope sessionScope,
Connection conn, String sql, Integer rsType) throws SQLException {
SqlMapExecutorDelegate delegate = ((SqlMapClientImpl) sessionScope
.getSqlMapExecutor()).getDelegate();
if (sessionScope.hasPreparedStatementFor(sql)) {
return (CallableStatement) sessionScope.getPreparedStatement((sql));
} else {
CallableStatement cs = conn.prepareCall(sql, rsType.intValue(),
ResultSet.CONCUR_READ_ONLY);
sessionScope.putPreparedStatement(delegate, sql, cs);
return cs;
}
}
private static PreparedStatement prepareStatement(
SessionScope sessionScope, Connection conn, String sql)
throws SQLException {
SqlMapExecutorDelegate delegate = ((SqlMapClientImpl) sessionScope
.getSqlMapExecutor()).getDelegate();
if (sessionScope.hasPreparedStatementFor(sql)) {
return sessionScope.getPreparedStatement((sql));
} else {
PreparedStatement ps = conn.prepareStatement(sql);
sessionScope.putPreparedStatement(delegate, sql, ps);
return ps;
}
}
private CallableStatement prepareCall(SessionScope sessionScope,
Connection conn, String sql) throws SQLException {
SqlMapExecutorDelegate delegate = ((SqlMapClientImpl) sessionScope
.getSqlMapExecutor()).getDelegate();
if (sessionScope.hasPreparedStatementFor(sql)) {
return (CallableStatement) sessionScope.getPreparedStatement((sql));
} else {
CallableStatement cs = conn.prepareCall(sql);
sessionScope.putPreparedStatement(delegate, sql, cs);
return cs;
}
}
private static void closeStatement(SessionScope sessionScope,
PreparedStatement ps) {
if (ps != null) {
if (!sessionScope.hasPreparedStatement(ps)) {
try {
ps.close();
} catch (SQLException e) {
// ignore
}
}
}
}
/**
* @param rs
*/
private static void closeResultSet(ResultSet rs) {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
// ignore
}
}
}
private static void setStatementTimeout(MappedStatement mappedStatement,
Statement statement) throws SQLException {
if (mappedStatement.getTimeout() != null) {
statement.setQueryTimeout(mappedStatement.getTimeout().intValue());
}
}
//
// Inner Classes
//
private static class Batch {
private String currentSql;
private List statementList = new ArrayList();
private List batchResultList = new ArrayList();
private int size;
/**
* Create a new batch
*/
public Batch() {
this.size = 0;
}
/**
* Getter for the batch size
*
* @return - the batch size
*/
public int getSize() {
return size;
}
/**
* Add a prepared statement to the batch
*
* @param statementScope
* - the request scope
* @param conn
* - the database connection
* @param sql
* - the SQL to add
* @param parameters
* - the parameters for the SQL
* @throws SQLException
* - if the prepare for the SQL fails
*/
public void addBatch(StatementScope statementScope, Connection conn,
String sql, Object[] parameters) throws SQLException {
PreparedStatement ps = null;
if (currentSql != null && currentSql.equals(sql)) {
int last = statementList.size() - 1;
ps = (PreparedStatement) statementList.get(last);
} else {
ps = prepareStatement(statementScope.getSession(), conn, sql);
setStatementTimeout(statementScope.getStatement(), ps);
currentSql = sql;
statementList.add(ps);
batchResultList.add(new BatchResult(statementScope
.getStatement().getId(), sql));
}
statementScope.getParameterMap().setParameters(statementScope, ps,
parameters);
ps.addBatch();
size++;
}
/**
* TODO (Jeff Butler) - maybe this method should be deprecated in some
* release, and then removed in some even later release.
* executeBatchDetailed gives much more complete information. <p/>
* Execute the current session's batch
*
* @return - the number of rows updated
* @throws SQLException
* - if the batch fails
*/
public int executeBatch() throws SQLException {
int totalRowCount = 0;
for (int i = 0, n = statementList.size(); i < n; i++) {
PreparedStatement ps = (PreparedStatement) statementList.get(i);
int[] rowCounts = ps.executeBatch();
for (int j = 0; j < rowCounts.length; j++) {
if (rowCounts[j] == Statement.SUCCESS_NO_INFO) {
// do nothing
} else if (rowCounts[j] == Statement.EXECUTE_FAILED) {
throw new SQLException(
"The batched statement at index " + j
+ " failed to execute.");
} else {
totalRowCount += rowCounts[j];
}
}
}
return totalRowCount;
}
/**
* Batch execution method that returns all the information the driver
* has to offer.
*
* @return a List of BatchResult objects
* @throws BatchException
* (an SQLException sub class) if any nested batch fails
* @throws SQLException
* if a database access error occurs, or the drive does not
* support batch statements
* @throws BatchException
* if the driver throws BatchUpdateException
*/
public List executeBatchDetailed() throws SQLException, BatchException {
List answer = new ArrayList();
for (int i = 0, n = statementList.size(); i < n; i++) {
BatchResult br = (BatchResult) batchResultList.get(i);
PreparedStatement ps = (PreparedStatement) statementList.get(i);
try {
br.setUpdateCounts(ps.executeBatch());
} catch (BatchUpdateException e) {
StringBuffer message = new StringBuffer();
message.append("Sub batch number ");
message.append(i + 1);
message.append(" failed.");
if (i > 0) {
message.append(" ");
message.append(i);
message
.append(" prior sub batch(s) completed successfully, but will be rolled back.");
}
throw new BatchException(message.toString(), e, answer, br
.getStatementId(), br.getSql());
}
answer.add(br);
}
return answer;
}
/**
* Close all the statements in the batch and clear all the statements
*
* @param sessionScope
*/
public void cleanupBatch(SessionScope sessionScope) {
for (int i = 0, n = statementList.size(); i < n; i++) {
PreparedStatement ps = (PreparedStatement) statementList.get(i);
closeStatement(sessionScope, ps);
}
currentSql = null;
statementList.clear();
batchResultList.clear();
size = 0;
}
}
private void setupResultObjectFactory(StatementScope statementScope) {
SqlMapClientImpl client = (SqlMapClientImpl) statementScope
.getSession().getSqlMapClient();
ResultObjectFactoryUtil.setResultObjectFactory(client
.getResultObjectFactory());
ResultObjectFactoryUtil.setStatementId(statementScope.getStatement()
.getId());
}
}
Dialect.java
package com.ibatis.sqlmap.engine.execution;
public class Dialect {
private static final String SQL_END_DELIMITER = ";";
public static String getLimitString(String dbName, String sql, int offset,
int limit) {
String limitString = sql;
if (dbName.toLowerCase().indexOf("mysql") != -1) {
limitString = getMysqlLimitString(sql, offset, limit);
}
if (dbName.toLowerCase().indexOf("microsoft sql server") != -1) {
limitString = getMssqlLimitString(sql, offset, limit);
}
if (dbName.toLowerCase().indexOf("oracle") != -1) {
limitString = getOracleLimitString(sql, offset, limit);
}
if (dbName.toLowerCase().indexOf("db2") != -1) {
limitString = getDB2LimitString(sql, offset, limit);
}
return limitString;
}
private static String getMysqlLimitString(String sql, int offset, int limit) {
sql = trim(sql);
StringBuffer sb = new StringBuffer(sql.length() + 20);
sb.append(sql);
if (offset > 0) {
sb.append(" limit ").append(offset).append(',').append(limit);
} else {
sb.append(" limit ").append(limit);
}
return sb.toString();
}
private static String getOracleLimitString(String sql, int offset, int limit) {
sql = trim(sql);
StringBuffer sb = new StringBuffer(sql.length() + 100);
if (offset > 0) {
sb.append("select * from ( select row_.*, rownum rownum_ from ( ")
.append(sql).append(" ) row_ where rownum <= ").append(
offset + limit).append(") where rownum_ > ")
.append(offset);
} else {
sb.append("select * from ( ").append(sql).append(
" ) where rownum <= ").append(limit);
}
return sb.toString();
}
private static String getMssqlLimitString(String sql, int offset, int limit) {
return null;
}
private static String getDB2LimitString(String sql, int offset, int limit) {
return null;
}
private static String trim(String sql) {
sql = sql.trim();
if (sql.endsWith(SQL_END_DELIMITER)) {
sql = sql.substring(0, sql.length() - 1
- SQL_END_DELIMITER.length());
}
return sql;
}
}