对spring JdbcTemplate的一个扩展(使其支持单Connection)

关键字: Spring   sping    

对spring JdbcTemplate的一个扩展(使其支持单Connection). 不怕大家笑话,以前一直没怎么使用过spring jdbc template, 印象中只用过 public List queryForList(String sql, Object[] args) public Map queryForMap(String sql, Object[] args) 和SqlFunction 在orm大行其道,spring诞生快一个实际的今天,再来探讨jdbc的一些封装实在不知道有没有意义. 不过还是想把刚刚弄出来的一点东西和大家分享. 看了一下 JdbcTemplate, 发现起核心是那几个 execute 方法. 而那几个execute方法的机构大概是这样(重点讨论Connection,所以其他地方从简)   代码 execute方法开始 Connection con = DataSourceUtils.getConnection(getDataSource()); // 做一些数据库操作 DataSourceUtils.releaseConnection(con, getDataSource()); execute方法结束 <script>render_code();</script>   当你要批量执行一些操作时(不是 每个操作使用不同的sql,或者是其他不适合 addBatch的情形). 如下: 代码 JdbcTemplate jdbcTemplate=new JdbcTemplate(ds); jdbcTemplate.query(sql_1, args_1,rch_1); jdbcTemplate.query(sql_2, args_2,rch_2); jdbcTemplate.query(sql_3, args_3,rch_3); jdbcTemplate.query(sql_4, args_4,rch_4); ...... <script>render_code();</script>   此时,在内部实际上执行了,n次 getConnection,releaseConnection. 而这些操作,在很多时候,是可以通过一个Connection来完成的. 我的扩展就是实现了这个功能.   代码 JdbcTemplatePlus jdbcTemplate=new JdbcTemplatePlus(ds); // 内部使用一个唯一的Connection jdbcTemplate.setUseOneConnection(true); jdbcTemplate.query(sql_1, args_1,rch_1); jdbcTemplate.query(sql_2, args_2,rch_2); jdbcTemplate.query(sql_3, args_3,rch_3); jdbcTemplate.query(sql_4, args_4,rch_4); ...... // 最后调用该方法 释放那个内部唯一的Connection // 虽然我在finalize 里调用了,不过finalize毕竟不是总能在正确的时间被正确的调用 jdbcTemplate.releaseConnection(); <script>render_code();</script>   我们系统中,有大量的嵌套查询.使用该JdbcTemplatePlus的唯一Connection特性后,类似的操作速度提升明显. (不过可能我们原先的做法不对,也许 spring内部已经实现这个机制了 这些我就不明白了,欢迎大家来指正) 我们原先的做法(伪代码): 代码 public List queryNsubQueryUserList(Map param){ // 外层查询 final String bsql="select * from ......"; final JdbcTemplate jdbcTemplate=createJdbcTemplate(); // 子查询相关 final String subSql="select ............ "; final JdbcTemplate subJdbcTemplate=createJdbcTemplate(); List rslist=jdbcTemplate.query(bsql.toString(),sqlArg, new ResultSetHandler(){ public void processRow(ResultSet rs) throws SQLException { final 一个VO recordObj=new 一个VO(); // 子查询 subJdbcTemplate.query(subSql, subQueryArgs, new ResultSetHandler(){ public void processRow(ResultSet rs) throws SQLException { // 一些操作........ } } ); // 一些操作........ recordObj.setXXXXX(rs.getString("XXXXX")); ......... // 将记录放入集合 addRecord(recordObj); } } ); return rslist; } } <script>render_code();</script> 在使用 JdbcTemplatePlus 代替 JdbcTemplate,并设置.setUseOneConnection(true)后, 耗时变为原先的1/8左右.   扩展的 JdbcTemplatePlus 代码如下,欢迎大家拍砖,挑错. 对 execute方法的修改如下: 把所有的 this.ativeJdbcExtractor换成 getNativeJdbcExtractor(), 这个是必须的 呵呵. 把所有 Connection con = DataSourceUtils.getConnection(getDataSource()); 换成 Connection con = tryGetConnection(); 把所有 DataSourceUtils.releaseConnection(con, getDataSource()); 换成 tryReleaseConnection(con);   代码 package com.neusoft.tdframework.dao; import java.sql.CallableStatement; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.SQLException; import java.sql.Statement; import javax.sql.DataSource; import org.springframework.dao.DataAccessException; import org.springframework.jdbc.core.CallableStatementCallback; import org.springframework.jdbc.core.CallableStatementCreator; import org.springframework.jdbc.core.ConnectionCallback; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.jdbc.core.ParameterDisposer; import org.springframework.jdbc.core.PreparedStatementCallback; import org.springframework.jdbc.core.PreparedStatementCreator; import org.springframework.jdbc.core.SqlProvider; import org.springframework.jdbc.core.StatementCallback; import org.springframework.jdbc.datasource.DataSourceUtils; import org.springframework.jdbc.support.JdbcUtils; import org.springframework.util.Assert; public class JdbcTemplatePlus extends JdbcTemplate { private Connection connection=null; private boolean useOneConnection=false; public JdbcTemplatePlus() { super(); } public JdbcTemplatePlus(DataSource dataSource) { super(dataSource); } public JdbcTemplatePlus(DataSource dataSource, boolean lazyInit) { super(dataSource,lazyInit); } private Connection tryGetConnection(){ if (useOneConnection){ if (connection==null){ connection= DataSourceUtils.getConnection(getDataSource()); } return connection; } return DataSourceUtils.getConnection(getDataSource()); } private void tryReleaseConnection(Connection con){ if (!useOneConnection){ DataSourceUtils.releaseConnection(con, getDataSource()); } } public Connection getConnection(){ return connection; } public void setConnection(Connection connection){ this.connection=connection; } public boolean isUseOneConnection() { return useOneConnection; } public void setUseOneConnection(boolean useOneConnection) { this.useOneConnection = useOneConnection; } public void releaseConnection(){ DataSourceUtils.releaseConnection(connection, getDataSource()); } // 不明白这个方法为什么spring不把他弄成 protected 或 public, // 导致我要重写execute方法时还必须要重写这个方法 <img src="/images/forum/smiles/icon_sad.gif"/> public static String getSql(Object sqlProvider) { if (sqlProvider instanceof SqlProvider) { return ((SqlProvider) sqlProvider).getSql(); } else { return null; } } /* 对 execute方法的修改如下: 把所有的 this.ativeJdbcExtractor换成 getNativeJdbcExtractor(), 这个是必须的 呵呵. 把所有 Connection con = DataSourceUtils.getConnection(getDataSource()); 换成 Connection con = tryGetConnection(); 把所有 DataSourceUtils.releaseConnection(con, getDataSource()); 换成 tryReleaseConnection(con); */ public Object execute(ConnectionCallback action) throws DataAccessException { Assert.notNull(action, "Callback object must not be null"); Connection con = tryGetConnection(); try { Connection conToUse = con; if (getNativeJdbcExtractor() != null) { conToUse = getNativeJdbcExtractor().getNativeConnection(con); } else { conToUse = createConnectionProxy(con); } return action.doInConnection(conToUse); } catch (SQLException ex) { tryReleaseConnection(con); con = null; throw getExceptionTranslator().translate("ConnectionCallback", getSql(action), ex); } finally { tryReleaseConnection(con); } } public Object execute(StatementCallback action) throws DataAccessException { Assert.notNull(action, "Callback object must not be null"); Connection con = tryGetConnection(); Statement stmt = null; try { Connection conToUse = con; if (getNativeJdbcExtractor() != null && getNativeJdbcExtractor() .isNativeConnectionNecessaryForNativeStatements()) { conToUse = getNativeJdbcExtractor().getNativeConnection(con); } stmt = conToUse.createStatement(); applyStatementSettings(stmt); Statement stmtToUse = stmt; if (getNativeJdbcExtractor() != null) { stmtToUse = getNativeJdbcExtractor().getNativeStatement(stmt); } Object result = action.doInStatement(stmtToUse); handleWarnings(stmt.getWarnings()); return result; } catch (SQLException ex) { JdbcUtils.closeStatement(stmt); stmt = null; tryReleaseConnection(con); con = null; throw getExceptionTranslator().translate("StatementCallback", getSql(action), ex); } finally { JdbcUtils.closeStatement(stmt); tryReleaseConnection(con); } } public Object execute(PreparedStatementCreator psc, PreparedStatementCallback action) throws DataAccessException { Assert.notNull(psc, "PreparedStatementCreator must not be null"); Assert.notNull(action, "Callback object must not be null"); if (logger.isDebugEnabled()) { String sql = getSql(psc); logger.debug("Executing prepared SQL statement" + (sql != null ? " [" + sql + "]" : "")); } Connection con = tryGetConnection(); PreparedStatement ps = null; try { Connection conToUse = con; if (getNativeJdbcExtractor() != null && getNativeJdbcExtractor() .isNativeConnectionNecessaryForNativePreparedStatements()) { conToUse = getNativeJdbcExtractor().getNativeConnection(con); } ps = psc.createPreparedStatement(conToUse); applyStatementSettings(ps); PreparedStatement psToUse = ps; if (getNativeJdbcExtractor() != null) { psToUse = getNativeJdbcExtractor() .getNativePreparedStatement(ps); } Object result = action.doInPreparedStatement(psToUse); handleWarnings(ps.getWarnings()); return result; } catch (SQLException ex) { if (psc instanceof ParameterDisposer) { ((ParameterDisposer) psc).cleanupParameters(); } String sql = getSql(psc); psc = null; JdbcUtils.closeStatement(ps); ps = null; tryReleaseConnection(con); con = null; throw getExceptionTranslator().translate( "PreparedStatementCallback", sql, ex); } finally { if (psc instanceof ParameterDisposer) { ((ParameterDisposer) psc).cleanupParameters(); } JdbcUtils.closeStatement(ps); tryReleaseConnection(con); } } public Object execute(CallableStatementCreator csc, CallableStatementCallback action) throws DataAccessException { Assert.notNull(csc, "CallableStatementCreator must not be null"); Assert.notNull(action, "Callback object must not be null"); if (logger.isDebugEnabled()) { String sql = getSql(csc); logger.debug("Calling stored procedure" + (sql != null ? " [" + sql + "]" : "")); } Connection con = tryGetConnection(); CallableStatement cs = null; try { Connection conToUse = con; if (getNativeJdbcExtractor() != null) { conToUse = getNativeJdbcExtractor().getNativeConnection(con); } cs = csc.createCallableStatement(conToUse); applyStatementSettings(cs); CallableStatement csToUse = cs; if (getNativeJdbcExtractor() != null) { csToUse = getNativeJdbcExtractor() .getNativeCallableStatement(cs); } Object result = action.doInCallableStatement(csToUse); handleWarnings(cs.getWarnings()); return result; } catch (SQLException ex) { // Release Connection early, to avoid potential connection pool // deadlock // in the case when the exception translator hasn't been initialized // yet. if (csc instanceof ParameterDisposer) { ((ParameterDisposer) csc).cleanupParameters(); } String sql = getSql(csc); csc = null; JdbcUtils.closeStatement(cs); cs = null; tryReleaseConnection(con); con = null; throw getExceptionTranslator().translate( "CallableStatementCallback", sql, ex); } finally { if (csc instanceof ParameterDisposer) { ((ParameterDisposer) csc).cleanupParameters(); } JdbcUtils.closeStatement(cs); tryReleaseConnection(con); } } protected void finalize() throws Throwable{ super.finalize(); releaseConnection(); } }