\u672c\u6587\u4e3b\u8981\u7814\u7a76\u4e00\u4e0bmysql jdbc\u7684prepareStatement<\/p>\n
java\/sql\/Connection.java<\/p>\n
\/**\n * Creates a <code>PreparedStatement<\/code> object for sending\n * parameterized SQL statements to the database.\n * <P>\n * A SQL statement with or without IN parameters can be\n * pre-compiled and stored in a <code>PreparedStatement<\/code> object. This\n * object can then be used to efficiently execute this statement\n * multiple times.\n *\n * <P><B>Note:<\/B> This method is optimized for handling\n * parametric SQL statements that benefit from precompilation. If\n * the driver supports precompilation,\n * the method <code>prepareStatement<\/code> will send\n * the statement to the database for precompilation. Some drivers\n * may not support precompilation. In this case, the statement may\n * not be sent to the database until the <code>PreparedStatement<\/code>\n * object is executed. This has no direct effect on users; however, it does\n * affect which methods throw certain <code>SQLException<\/code> objects.\n * <P>\n * Result sets created using the returned <code>PreparedStatement<\/code>\n * object will by default be type <code>TYPE_FORWARD_ONLY<\/code>\n * and have a concurrency level of <code>CONCUR_READ_ONLY<\/code>.\n * The holdability of the created result sets can be determined by\n * calling {@link #getHoldability}.\n *\n * @param sql an SQL statement that may contain one or more '?' IN\n * parameter placeholders\n * @return a new default <code>PreparedStatement<\/code> object containing the\n * pre-compiled SQL statement\n * @exception SQLException if a database access error occurs\n * or this method is called on a closed connection\n *\/\n PreparedStatement prepareStatement(String sql)\n throws SQLException;<\/code><\/pre>\njava.sql.Connection\u5b9a\u4e49\u4e86prepareStatement\u65b9\u6cd5\uff0c\u6839\u636esql\u521b\u5efaPreparedStatement<\/p><\/blockquote>\n
ConnectionImpl<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/ConnectionImpl.java<\/p>\n
\/**\n * A SQL statement with or without IN parameters can be pre-compiled and\n * stored in a PreparedStatement object. This object can then be used to\n * efficiently execute this statement multiple times.\n * <p>\n * <B>Note:<\/B> This method is optimized for handling parametric SQL\n * statements that benefit from precompilation if the driver supports\n * precompilation. In this case, the statement is not sent to the database\n * until the PreparedStatement is executed. This has no direct effect on\n * users; however it does affect which method throws certain\n * java.sql.SQLExceptions\n * <\/p>\n * <p>\n * MySQL does not support precompilation of statements, so they are handled\n * by the driver.\n * <\/p>\n * \n * @param sql\n * a SQL statement that may contain one or more '?' IN parameter\n * placeholders\n * @return a new PreparedStatement object containing the pre-compiled\n * statement.\n * @exception SQLException\n * if a database access error occurs.\n *\/\n public java.sql.PreparedStatement prepareStatement(String sql)\n throws SQLException {\n return prepareStatement(sql, DEFAULT_RESULT_SET_TYPE,\n DEFAULT_RESULT_SET_CONCURRENCY);\n }<\/code><\/pre>\nmysql jdbc\u7684ConnectionImpl\u5b9e\u73b0\u4e86prepareStatement\u65b9\u6cd5\uff0c\u6839\u636e\u6ce8\u91ca\uff0c\u9884\u7f16\u8bd1\u4e3b\u8981\u662fdriver\u6765\u5904\u7406<\/p><\/blockquote>\n
prepareStatement<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/ConnectionImpl.java<\/p>\n
\/**\n * JDBC 2.0 Same as prepareStatement() above, but allows the default result\n * set type and result set concurrency type to be overridden.\n * \n * @param sql\n * the SQL query containing place holders\n * @param resultSetType\n * a result set type, see ResultSet.TYPE_XXX\n * @param resultSetConcurrency\n * a concurrency type, see ResultSet.CONCUR_XXX\n * @return a new PreparedStatement object containing the pre-compiled SQL\n * statement\n * @exception SQLException\n * if a database-access error occurs.\n *\/\n public synchronized java.sql.PreparedStatement prepareStatement(String sql,\n int resultSetType, int resultSetConcurrency) throws SQLException {\n checkClosed();\n\n \/\/\n \/\/ FIXME: Create warnings if can't create results of the given\n \/\/ type or concurrency\n \/\/\n PreparedStatement pStmt = null;\n \n boolean canServerPrepare = true;\n \n String nativeSql = getProcessEscapeCodesForPrepStmts() ? nativeSQL(sql): sql;\n \n if (this.useServerPreparedStmts && getEmulateUnsupportedPstmts()) {\n canServerPrepare = canHandleAsServerPreparedStatement(nativeSql);\n }\n \n if (this.useServerPreparedStmts && canServerPrepare) {\n if (this.getCachePreparedStatements()) {\n synchronized (this.serverSideStatementCache) {\n pStmt = (com.mysql.jdbc.ServerPreparedStatement)this.serverSideStatementCache.remove(sql);\n \n if (pStmt != null) {\n ((com.mysql.jdbc.ServerPreparedStatement)pStmt).setClosed(false);\n pStmt.clearParameters();\n }\n\n if (pStmt == null) {\n try {\n pStmt = ServerPreparedStatement.getInstance(getLoadBalanceSafeProxy(), nativeSql,\n this.database, resultSetType, resultSetConcurrency);\n if (sql.length() < getPreparedStatementCacheSqlLimit()) {\n ((com.mysql.jdbc.ServerPreparedStatement)pStmt).isCached = true;\n }\n \n pStmt.setResultSetType(resultSetType);\n pStmt.setResultSetConcurrency(resultSetConcurrency);\n } catch (SQLException sqlEx) {\n \/\/ Punt, if necessary\n if (getEmulateUnsupportedPstmts()) {\n pStmt = (PreparedStatement) clientPrepareStatement(nativeSql, resultSetType, resultSetConcurrency, false);\n \n if (sql.length() < getPreparedStatementCacheSqlLimit()) {\n this.serverSideStatementCheckCache.put(sql, Boolean.FALSE);\n }\n } else {\n throw sqlEx;\n }\n }\n }\n }\n } else {\n try {\n pStmt = ServerPreparedStatement.getInstance(getLoadBalanceSafeProxy(), nativeSql,\n this.database, resultSetType, resultSetConcurrency);\n \n pStmt.setResultSetType(resultSetType);\n pStmt.setResultSetConcurrency(resultSetConcurrency);\n } catch (SQLException sqlEx) {\n \/\/ Punt, if necessary\n if (getEmulateUnsupportedPstmts()) {\n pStmt = (PreparedStatement) clientPrepareStatement(nativeSql, resultSetType, resultSetConcurrency, false);\n } else {\n throw sqlEx;\n }\n }\n }\n } else {\n pStmt = (PreparedStatement) clientPrepareStatement(nativeSql, resultSetType, resultSetConcurrency, false);\n }\n \n return pStmt;\n }<\/code><\/pre>\nprepareStatement\u9996\u5148\u6839\u636euseServerPreparedStmts\u4ee5\u53cagetEmulateUnsupportedPstmts\u6765\u5224\u65ad\u662f\u5426\u8981\u901a\u8fc7canHandleAsServerPreparedStatement\u5224\u65adcanServerPrepare\uff1b\u4e4b\u540e\u5728useServerPreparedStmts\u53cacanServerPrepare\u4e3atrue\u65f6\uff0c\u6839\u636ecachePreparedStatements\u505aServerPreparedStatement\u7684\u5904\u7406\uff1b\u5982\u679c\u4e0d\u5f00\u542fserverPrepare\u5219\u6267\u884cclientPrepareStatement<\/p><\/blockquote>\n
canHandleAsServerPreparedStatement<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/ConnectionImpl.java<\/p>\n
private boolean canHandleAsServerPreparedStatement(String sql) \n throws SQLException {\n if (sql == null || sql.length() == 0) {\n return true;\n }\n\n if (!this.useServerPreparedStmts) {\n return false;\n }\n \n if (getCachePreparedStatements()) {\n synchronized (this.serverSideStatementCheckCache) {\n Boolean flag = (Boolean)this.serverSideStatementCheckCache.get(sql);\n \n if (flag != null) {\n return flag.booleanValue();\n }\n \n boolean canHandle = canHandleAsServerPreparedStatementNoCache(sql);\n \n if (sql.length() < getPreparedStatementCacheSqlLimit()) {\n this.serverSideStatementCheckCache.put(sql, \n canHandle ? Boolean.TRUE : Boolean.FALSE);\n }\n \n return canHandle;\n }\n }\n \n return canHandleAsServerPreparedStatementNoCache(sql);\n }<\/code><\/pre>\ncanHandleAsServerPreparedStatement\u9996\u5148\u5224\u65aduseServerPreparedStmts\uff0c\u4e4b\u540e\u82e5cachePreparedStatements\u4e3atrue\u5219\u505aserverSideStatementCheckCache\u5224\u65ad\uff0c\u6700\u540e\u90fd\u4f1a\u901a\u8fc7canHandleAsServerPreparedStatementNoCache\u8fdb\u884c\u5224\u65ad<\/p><\/blockquote>\n
canHandleAsServerPreparedStatementNoCache<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/ConnectionImpl.java<\/p>\n
private boolean canHandleAsServerPreparedStatementNoCache(String sql) \n throws SQLException {\n \n \/\/ Can't use server-side prepare for CALL\n if (StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql, "CALL")) {\n return false;\n }\n \n boolean canHandleAsStatement = true;\n \n if (!versionMeetsMinimum(5, 0, 7) && \n (StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql, "SELECT")\n || StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql,\n "DELETE")\n || StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql,\n "INSERT")\n || StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql,\n "UPDATE")\n || StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql,\n "REPLACE"))) {\n\n \/\/ check for limit ?[,?]\n\n \/*\n * The grammar for this (from the server) is: ULONG_NUM | ULONG_NUM\n * ',' ULONG_NUM | ULONG_NUM OFFSET_SYM ULONG_NUM\n *\/\n\n int currentPos = 0;\n int statementLength = sql.length();\n int lastPosToLook = statementLength - 7; \/\/ "LIMIT ".length()\n boolean allowBackslashEscapes = !this.noBackslashEscapes;\n char quoteChar = this.useAnsiQuotes ? '"' : '\/'';\n boolean foundLimitWithPlaceholder = false;\n\n while (currentPos < lastPosToLook) {\n int limitStart = StringUtils.indexOfIgnoreCaseRespectQuotes(\n currentPos, sql, "LIMIT ", quoteChar,\n allowBackslashEscapes);\n\n if (limitStart == -1) {\n break;\n }\n\n currentPos = limitStart + 7;\n\n while (currentPos < statementLength) {\n char c = sql.charAt(currentPos);\n\n \/\/\n \/\/ Have we reached the end\n \/\/ of what can be in a LIMIT clause?\n \/\/\n\n if (!Character.isDigit(c) && !Character.isWhitespace(c)\n && c != ',' && c != '?') {\n break;\n }\n\n if (c == '?') {\n foundLimitWithPlaceholder = true;\n break;\n }\n\n currentPos++;\n }\n }\n\n canHandleAsStatement = !foundLimitWithPlaceholder;\n } else if (StringUtils.startsWithIgnoreCaseAndWs(sql, "CREATE TABLE")) {\n canHandleAsStatement = false;\n } else if (StringUtils.startsWithIgnoreCaseAndWs(sql, "DO")) {\n canHandleAsStatement = false;\n } else if (StringUtils.startsWithIgnoreCaseAndWs(sql, "SET")) {\n canHandleAsStatement = false;\n }\n\n \n \n return canHandleAsStatement;\n }<\/code><\/pre>\ncanHandleAsServerPreparedStatementNoCache\u65b9\u6cd5\u9488\u5bf9call\u3001create table\u3001do\u3001set\u8fd4\u56defalse\uff0c\u5176\u4ed6\u7684\u9488\u5bf9\u5c0f\u4e8e5.0.7\u7248\u672c\u7684\u505a\u7279\u6b8a\u5224\u65ad\uff0c\u5176\u4f59\u7684\u9ed8\u8ba4\u8fd4\u56detrue<\/p><\/blockquote>\n
clientPrepareStatement<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/ConnectionImpl.java<\/p>\n
\/** A cache of SQL to parsed prepared statement parameters. *\/\n private CacheAdapter<String, ParseInfo> cachedPreparedStatementParams;\n\n public java.sql.PreparedStatement clientPrepareStatement(String sql,\n int resultSetType, int resultSetConcurrency, \n boolean processEscapeCodesIfNeeded) throws SQLException {\n checkClosed();\n\n String nativeSql = processEscapeCodesIfNeeded && getProcessEscapeCodesForPrepStmts() ? nativeSQL(sql): sql;\n \n PreparedStatement pStmt = null;\n\n if (getCachePreparedStatements()) {\n PreparedStatement.ParseInfo pStmtInfo = this.cachedPreparedStatementParams.get(nativeSql);\n \n if (pStmtInfo == null) {\n pStmt = com.mysql.jdbc.PreparedStatement.getInstance(getLoadBalanceSafeProxy(), nativeSql,\n this.database);\n\n this.cachedPreparedStatementParams.put(nativeSql, pStmt\n .getParseInfo());\n } else {\n pStmt = new com.mysql.jdbc.PreparedStatement(getLoadBalanceSafeProxy(), nativeSql,\n this.database, pStmtInfo);\n }\n } else {\n pStmt = com.mysql.jdbc.PreparedStatement.getInstance(getLoadBalanceSafeProxy(), nativeSql,\n this.database);\n }\n\n pStmt.setResultSetType(resultSetType);\n pStmt.setResultSetConcurrency(resultSetConcurrency);\n\n return pStmt;\n }<\/code><\/pre>\nclientPrepareStatement\u5728cachePreparedStatements\u4e3atrue\u65f6\u4f1a\u4ececachedPreparedStatementParams(\u7f13\u5b58\u7684key\u4e3anativeSql\uff0cvalue\u4e3aParseInfo<\/code>)\u53bb\u83b7\u53d6ParseInfo\uff0c\u83b7\u53d6\u4e0d\u5230\u5219\u6267\u884ccom.mysql.jdbc.PreparedStatement.getInstance\u518d\u653e\u5165\u7f13\u5b58\uff0c\u83b7\u53d6\u5230ParseInfo\u5219\u901a\u8fc7com.mysql.jdbc.PreparedStatement(getLoadBalanceSafeProxy(), nativeSql,this.database, pStmtInfo)\u521b\u5efaPreparedStatement\uff1b\u5982\u679c\u4e3afalse\u5219\u76f4\u63a5\u901a\u8fc7com.mysql.jdbc.PreparedStatement.getInstance\u6765\u521b\u5efa<\/p><\/blockquote>\nPreparedStatement.getInstance<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/PreparedStatement.java<\/p>\n
\/**\n * Creates a prepared statement instance -- We need to provide factory-style\n * methods so we can support both JDBC3 (and older) and JDBC4 runtimes,\n * otherwise the class verifier complains when it tries to load JDBC4-only\n * interface classes that are present in JDBC4 method signatures.\n *\/\n\n protected static PreparedStatement getInstance(MySQLConnection conn, String sql,\n String catalog) throws SQLException {\n if (!Util.isJdbc4()) {\n return new PreparedStatement(conn, sql, catalog);\n }\n\n return (PreparedStatement) Util.handleNewInstance(\n JDBC_4_PSTMT_3_ARG_CTOR, new Object[] { conn, sql, catalog }, conn.getExceptionInterceptor());\n }<\/code><\/pre>\ngetInstance\u65b9\u6cd5\u5bf9\u4e8e\u975ejdbc4\u7684\u76f4\u63a5new\u4e00\u4e2aPreparedStatement\uff0c\u82e5\u4f7f\u7528\u4e86jdbc4\u5219\u901a\u8fc7Util.handleNewInstance\u4f7f\u7528JDBC_4_PSTMT_3_ARG_CTOR\u7684\u6784\u9020\u5668\u53cd\u5c04\u521b\u5efa<\/p><\/blockquote>\n
JDBC_4_PSTMT_3_ARG_CTOR<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/PreparedStatement.java<\/p>\n
public class PreparedStatement extends com.mysql.jdbc.StatementImpl implements\n java.sql.PreparedStatement {\n private static final Constructor<?> JDBC_4_PSTMT_2_ARG_CTOR;\n private static final Constructor<?> JDBC_4_PSTMT_3_ARG_CTOR;\n private static final Constructor<?> JDBC_4_PSTMT_4_ARG_CTOR;\n \n static {\n if (Util.isJdbc4()) {\n try {\n JDBC_4_PSTMT_2_ARG_CTOR = Class.forName(\n "com.mysql.jdbc.JDBC4PreparedStatement")\n .getConstructor(\n new Class[] { MySQLConnection.class, String.class });\n JDBC_4_PSTMT_3_ARG_CTOR = Class.forName(\n "com.mysql.jdbc.JDBC4PreparedStatement")\n .getConstructor(\n new Class[] { MySQLConnection.class, String.class,\n String.class });\n JDBC_4_PSTMT_4_ARG_CTOR = Class.forName(\n "com.mysql.jdbc.JDBC4PreparedStatement")\n .getConstructor(\n new Class[] { MySQLConnection.class, String.class,\n String.class, ParseInfo.class });\n } catch (SecurityException e) {\n throw new RuntimeException(e);\n } catch (NoSuchMethodException e) {\n throw new RuntimeException(e);\n } catch (ClassNotFoundException e) {\n throw new RuntimeException(e);\n }\n } else {\n JDBC_4_PSTMT_2_ARG_CTOR = null;\n JDBC_4_PSTMT_3_ARG_CTOR = null;\n JDBC_4_PSTMT_4_ARG_CTOR = null;\n }\n }\n\n \/\/......\n} <\/code><\/pre>\ncom.mysql.jdbc.PreparedStatement\u5728static\u65b9\u6cd5\u521d\u59cb\u5316\u4e86JDBC_4_PSTMT_3_ARG_CTOR\uff0c\u5176\u6784\u9020\u5668\u6709\u4e09\u4e2a\u53c2\u6570\uff0c\u5206\u522b\u662fMySQLConnection.class, String.class,String.class\uff0c\u4f7f\u7528\u7684\u7c7b\u662fcom.mysql.jdbc.JDBC4PreparedStatement<\/p><\/blockquote>\n
JDBC4PreparedStatement<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/JDBC4PreparedStatement.java<\/p>\n
public class JDBC4PreparedStatement extends PreparedStatement {\n\n public JDBC4PreparedStatement(MySQLConnection conn, String catalog) throws SQLException {\n super(conn, catalog);\n }\n \n public JDBC4PreparedStatement(MySQLConnection conn, String sql, String catalog)\n throws SQLException {\n super(conn, sql, catalog);\n }\n \n public JDBC4PreparedStatement(MySQLConnection conn, String sql, String catalog,\n ParseInfo cachedParseInfo) throws SQLException {\n super(conn, sql, catalog, cachedParseInfo);\n }\n\n public void setRowId(int parameterIndex, RowId x) throws SQLException {\n JDBC4PreparedStatementHelper.setRowId(this, parameterIndex, x);\n }\n \n \/**\n * JDBC 4.0 Set a NCLOB parameter.\n * \n * @param i\n * the first parameter is 1, the second is 2, ...\n * @param x\n * an object representing a NCLOB\n * \n * @throws SQLException\n * if a database error occurs\n *\/\n public void setNClob(int parameterIndex, NClob value) throws SQLException {\n JDBC4PreparedStatementHelper.setNClob(this, parameterIndex, value);\n }\n\n public void setSQLXML(int parameterIndex, SQLXML xmlObject)\n throws SQLException {\n JDBC4PreparedStatementHelper.setSQLXML(this, parameterIndex, xmlObject);\n }\n} <\/code><\/pre>\nJDBC4PreparedStatement\u7684\u4e09\u4e2a\u53c2\u6570\u6784\u9020\u5668\u4e3b\u8981\u662f\u8c03\u7528\u4e86\u7236\u7c7bPreparedStatement\u7684\u5bf9\u5e94\u7684\u6784\u9020\u5668\uff1bJDBC4PreparedStatement\u4e3b\u8981\u662f\u652f\u6301\u4e86setNClob\u3001setSQLXML<\/p><\/blockquote>\n
new PreparedStatement<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/PreparedStatement.java<\/p>\n
\/**\n * Constructor for the PreparedStatement class.\n * \n * @param conn\n * the connection creating this statement\n * @param sql\n * the SQL for this statement\n * @param catalog\n * the catalog\/database this statement should be issued against\n * \n * @throws SQLException\n * if a database error occurs.\n *\/\n public PreparedStatement(MySQLConnection conn, String sql, String catalog)\n throws SQLException {\n super(conn, catalog);\n\n if (sql == null) {\n throw SQLError.createSQLException(Messages.getString("PreparedStatement.0"), \/\/$NON-NLS-1$\n SQLError.SQL_STATE_ILLEGAL_ARGUMENT, getExceptionInterceptor());\n }\n\n detectFractionalSecondsSupport();\n this.originalSql = sql;\n\n if (this.originalSql.startsWith(PING_MARKER)) {\n this.doPingInstead = true;\n } else {\n this.doPingInstead = false;\n }\n \n this.dbmd = this.connection.getMetaData();\n\n this.useTrueBoolean = this.connection.versionMeetsMinimum(3, 21, 23);\n\n this.parseInfo = new ParseInfo(sql, this.connection, this.dbmd,\n this.charEncoding, this.charConverter);\n\n initializeFromParseInfo();\n \n this.compensateForOnDuplicateKeyUpdate = this.connection.getCompensateOnDuplicateKeyUpdateCounts();\n \n if (conn.getRequiresEscapingEncoder())\n charsetEncoder = Charset.forName(conn.getEncoding()).newEncoder();\n }<\/code><\/pre>\n\u8fd9\u91cc\u4e3b\u8981\u662f\u7528\u4e86connection\u7684metaData\u3001\u4ee5\u53ca\u6784\u9020ParseInfo<\/p><\/blockquote>\n
StatementImpl<\/h2>\n
mysql-connector-java-5.1.21-sources.jar!\/com\/mysql\/jdbc\/StatementImpl.java<\/p>\n
public StatementImpl(MySQLConnection c, String catalog) throws SQLException {\n if ((c == null) || c.isClosed()) {\n throw SQLError.createSQLException(\n Messages.getString("Statement.0"), \/\/$NON-NLS-1$\n SQLError.SQL_STATE_CONNECTION_NOT_OPEN, null); \/\/$NON-NLS-1$ \/\/$NON-NLS-2$\n }\n\n this.connection = c;\n this.connectionId = this.connection.getId();\n this.exceptionInterceptor = this.connection\n .getExceptionInterceptor();\n\n this.currentCatalog = catalog;\n this.pedantic = this.connection.getPedantic();\n this.continueBatchOnError = this.connection.getContinueBatchOnError();\n this.useLegacyDatetimeCode = this.connection.getUseLegacyDatetimeCode();\n \n if (!this.connection.getDontTrackOpenResources()) {\n this.connection.registerStatement(this);\n }\n\n \/\/\n \/\/ Adjust, if we know it\n \/\/\n\n if (this.connection != null) {\n this.maxFieldSize = this.connection.getMaxAllowedPacket();\n\n int defaultFetchSize = this.connection.getDefaultFetchSize();\n\n if (defaultFetchSize != 0) {\n setFetchSize(defaultFetchSize);\n }\n \n if (this.connection.getUseUnicode()) {\n this.charEncoding = this.connection.getEncoding();\n\n this.charConverter = this.connection.getCharsetConverter(this.charEncoding);\n }\n \n \n\n boolean profiling = this.connection.getProfileSql()\n || this.connection.getUseUsageAdvisor() || this.connection.getLogSlowQueries();\n\n if (this.connection.getAutoGenerateTestcaseScript() || profiling) {\n this.statementId = statementCounter++;\n }\n\n if (profiling) {\n this.pointOfOrigin = new Throwable();\n this.profileSQL = this.connection.getProfileSql();\n this.useUsageAdvisor = this.connection.getUseUsageAdvisor();\n this.eventSink = ProfilerEventHandlerFactory.getInstance(this.connection);\n }\n\n int maxRowsConn = this.connection.getMaxRows();\n\n if (maxRowsConn != -1) {\n setMaxRows(maxRowsConn);\n }\n \n this.holdResultsOpenOverClose = this.connection.getHoldResultsOpenOverStatementClose();\n }\n \n version5013OrNewer = this.connection.versionMeetsMinimum(5, 0, 13);\n }<\/code><\/pre>\n\u8fd9\u91cc\u4f1a\u83b7\u53d6connection\u7684\u4e00\u7cfb\u5217\u914d\u7f6e\uff0c\u540c\u65f6\u5bf9\u4e8e\u9700\u8981trackOpenResources\u7684\u4f1a\u6267\u884cregisterStatement(\u8fd9\u4e2a\u5728realClose\u7684\u65f6\u5019\u4f1aunregister<\/code>)<\/p><\/blockquote>\n\u53c2\u6570\u503c<\/h2>\nisJdbc4<\/h3>\n
com\/mysql\/jdbc\/Util.java<\/p>\n
private static boolean isJdbc4 = false;\n\n try {\n Class.forName("java.sql.NClob");\n isJdbc4 = true;\n } catch (Throwable t) {\n isJdbc4 = false;\n }<\/code><\/pre>\nisJdbc4\u9ed8\u8ba4\u4e3afalse\uff0c\u5728\u68c0\u6d4b\u5230java.sql.NClob\u7c7b\u7684\u65f6\u5019\u4e3atrue\uff1bjdk8\u7248\u672c\u652f\u6301jdbc4<\/p><\/blockquote>\n
useServerPreparedStmts<\/h3>\n
com\/mysql\/jdbc\/ConnectionPropertiesImpl.java<\/p>\n
private BooleanConnectionProperty detectServerPreparedStmts = new BooleanConnectionProperty(\n "useServerPrepStmts", \/\/$NON-NLS-1$\n false,\n Messages.getString("ConnectionProperties.useServerPrepStmts"), \/\/$NON-NLS-1$\n "3.1.0", MISC_CATEGORY, Integer.MIN_VALUE); \/\/$NON-NLS-1$<\/code><\/pre>\nuseServerPreparedStmts\u9ed8\u8ba4\u4e3afalse<\/p><\/blockquote>\n
cachePrepStmts<\/h3>\n
com\/mysql\/jdbc\/ConnectionPropertiesImpl.java<\/p>\n
private BooleanConnectionProperty cachePreparedStatements = new BooleanConnectionProperty(\n "cachePrepStmts", \/\/$NON-NLS-1$\n false,\n Messages.getString("ConnectionProperties.cachePrepStmts"), \/\/$NON-NLS-1$\n "3.0.10", PERFORMANCE_CATEGORY, Integer.MIN_VALUE); \/\/$NON-NLS-1$<\/code><\/pre>\ncachePrepStmts\u9ed8\u8ba4\u4e3afalse<\/p><\/blockquote>\n
\u5c0f\u7ed3<\/h2>\n\n- mysql\u7684jdbc driver\u7684prepareStatement\u9996\u5148\u6839\u636euseServerPreparedStmts\u4ee5\u53cagetEmulateUnsupportedPstmts\u6765\u5224\u65ad\u662f\u5426\u8981\u901a\u8fc7canHandleAsServerPreparedStatement\u5224\u65adcanServerPrepare\uff1b\u4e4b\u540e\u5728useServerPreparedStmts\u53cacanServerPrepare\u4e3atrue\u65f6\uff0c\u6839\u636ecachePreparedStatements\u505aServerPreparedStatement\u7684\u5904\u7406\uff1b\u5982\u679c\u4e0d\u5f00\u542fserverPrepare\u5219\u6267\u884cclientPrepareStatement(
useServerPreparedStmts\u53cacachePrepStmts\u53c2\u6570\u9ed8\u8ba4\u4e3afalse<\/code>)<\/li>\n- clientPrepareStatement\u5728cachePreparedStatements\u4e3atrue\u65f6\u4f1a\u4ececachedPreparedStatementParams(
\u7f13\u5b58\u7684key\u4e3anativeSql\uff0cvalue\u4e3aParseInfo<\/code>)\u53bb\u83b7\u53d6ParseInfo\uff0c\u83b7\u53d6\u4e0d\u5230\u5219\u6267\u884ccom.mysql.jdbc.PreparedStatement.getInstance\u518d\u653e\u5165\u7f13\u5b58\uff0c\u83b7\u53d6\u5230ParseInfo\u5219\u901a\u8fc7com.mysql.jdbc.PreparedStatement(getLoadBalanceSafeProxy(), nativeSql,this.database, pStmtInfo)\u521b\u5efaPreparedStatement\uff1b\u5982\u679c\u4e3afalse\u5219\u76f4\u63a5\u901a\u8fc7com.mysql.jdbc.PreparedStatement.getInstance\u6765\u521b\u5efa<\/li>\n- useServerPreparedStmts\u4e3atrue\u65f6\uff0c\u521b\u5efa\u7684\u662fServerPreparedStatement(
\u521b\u5efa\u7684\u65f6\u5019\u4f1a\u89e6\u53d1prepare\u64cd\u4f5c\uff0c\u5f80mysql\u670d\u52a1\u7aef\u53d1\u9001COM_PREPARE\u6307\u4ee4<\/code>)\uff0c\u672c\u5730\u901a\u8fc7serverSideStatementCache\u7c7b\u6765\u7f13\u5b58ServerPreparedStatement\uff0ckey\u4e3asql<\/li>\n<\/ul>\ndoc<\/h2>\n