目录
java.sql.Driver
java.sql.DriverManager
java.sql.Connection
Statement createStatement()
PreparedStatement prepareStatement(String sql)
CallableStatement prepareCall(String sql)
java.sql.Statement
ResultSet executeQuery(String sql)
int executeUpdate(String sql)
boolean execute(String sql)
java.sql.PreparedStatement
ResultSet executeQuery()
int executeUpdate()
boolean execute()
void setInt(int parameterIndex, int x)
void setString(int parameterIndex, String x)
java.sql.ResultSet
boolean next()
String getString(int columnIndex)
String getString(int columnLabel)
例，从user表中查询name为张三的用户信息：
String url = "jdbc:mysql://localhost:3306/mail_manager?useUnicode=true&characterEncoding=utf8&useSSL=false&allowPublicKeyRetrieval=true";String user = "root";String password = "root";Connection conn = null;try { Class.forName("com.mysql.jdbc.Driver"); conn = DriverManager.getConnection(url, username, password); PreparedStatement ps = conn.prepareStatement("select name, email from user where name=?"); ps.setString(1, "张三"); ResultSet rs = ps.executeQuery(); while(rs.next()){ String username = rs.getString("name"); String email = rs.getString("email"); System.out.println(username); System.out.println(email); }}catch (ClassNotFoundException ignored){}com.mysql.jdbc.NonRegisteringDriver
// com.mysql.jdbc.NonRegisteringDriverpublic Connection connect(String url, Properties info) { // ... com.mysql.jdbc.Connection newConn = ConnectionImpl.getInstance(this.host(props), this.port(props), props, this.database(props), url); // ...}protected static Connection getInstance(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url) throws SQLException { return (Connection)(!Util.isJdbc4() ? new ConnectionImpl(hostToConnectTo, portToConnectTo, info, databaseToConnectTo, url) : (Connection)Util.handleNewInstance(JDBC_4_CONNECTION_CTOR, new Object[]{hostToConnectTo, portToConnectTo, info, databaseToConnectTo, url}, (ExceptionInterceptor)null));}com.mysql.jdbc.ConnectionImpl
// com.mysql.jdbc.ConnectionImplpublic ConnectionImpl(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url) throws SQLException { // ... this.createNewIO(false); // ...}public void createNewIO(boolean isForReconnect) throws SQLException { synchronized(this.getConnectionMutex()) { Properties mergedProps = this.exposeAsProperties(this.props); if (!this.getHighAvailability()) { this.connectOneTryOnly(isForReconnect, mergedProps); } else { this.connectWithRetries(isForReconnect, mergedProps); } }}private void connectOneTryOnly(boolean isForReconnect, Properties mergedProps) throws SQLException { // ... this.coreConnect(mergedProps); // ...}private void coreConnect(Properties mergedProps) throws SQLException, IOException { // ... this.io = new MysqlIO(newHost, newPort, mergedProps, this.getSocketFactoryClassName(), this.getProxy(), this.getSocketTimeout(), this.largeRowSizeThreshold.getValueAsInt()); this.io.doHandshake(this.user, this.password, this.database); // ...}com.mysql.jdbc.MysqlIO
通过Socket与MysqlServer通信，通过mysqlInput与mysqlOutput传输数据
// com.mysql.jdbc.MysqlIOpublic MysqlIO(String host, int port, Properties props, String socketFactoryClassName, MySQLConnection conn, int socketTimeout, int useBufferRowSizeThreshold) throws IOException, SQLException { // ... this.mysqlConnection = this.socketFactory.connect(this.host, this.port, props); this.mysqlConnection = this.socketFactory.beforeHandshake(); if (this.connection.getUseReadAheadInput()) { this.mysqlInput = new ReadAheadInputStream(this.mysqlConnection.getInputStream(), 16384, this.connection.getTraceProtocol(), this.connection.getLog()); } else if (this.connection.useUnbufferedInput()) { this.mysqlInput = this.mysqlConnection.getInputStream(); } else { this.mysqlInput = new BufferedInputStream(this.mysqlConnection.getInputStream(), 16384); } this.mysqlOutput = new BufferedOutputStream(this.mysqlConnection.getOutputStream(), 16384); // ...}com.mysql.jdbc.PreparedStatement
通过发送和接受Packet完成数据库查询
// com.mysql.jdbc.PreparedStatementpublic ResultSet executeQuery() throws SQLException { synchronized(this.checkClosed().getConnectionMutex()) { // ... Buffer sendPacket = this.fillSendPacket(); // ... this.results = this.executeInternal(this.maxRows, sendPacket, this.createStreamingResultSet(), true, metadataFromCache, false); // ... return this.results; }}protected ResultSetInternalMethods executeInternal(int maxRowsToRetrieve, Buffer sendPacket, boolean createStreamingResultSet, boolean queryIsSelectOnly, Field[] metadataFromCache, boolean isBatch) throws SQLException { synchronized(this.checkClosed().getConnectionMutex()) { // ... ResultSetInternalMethods rs; rs = locallyScopedConnection.execSQL(this, (String)null, maxRowsToRetrieve, sendPacket, this.resultSetType, this.resultSetConcurrency, createStreamingResultSet, this.currentCatalog, metadataFromCache, isBatch); // ... }}com.mysql.jdbc.ConnectionImpl
// com.mysql.jdbc.ConnectionImplpublic ResultSetInternalMethods execSQL(StatementImpl callingStatement, String sql, int maxRows, Buffer packet, int resultSetType, int resultSetConcurrency, boolean streamResults, String catalog, Field[] cachedMetadata, boolean isBatch) throws SQLException { synchronized(this.getConnectionMutex()) { // ... ResultSetInternalMethods var36 = this.io.sqlQueryDirect(callingStatement, (String)null, (String)null, packet, maxRows, resultSetType, resultSetConcurrency, streamResults, catalog, cachedMetadata); // ... }}com.mysql.jdbc.MysqlIO
通过Socket与MysqlServer通信，通过mysqlInput与mysqlOutput传输数据
// com.mysql.jdbc.MysqlIOfinal ResultSetInternalMethods sqlQueryDirect(StatementImpl callingStatement, String query, String characterEncoding, Buffer queryPacket, int maxRows, int resultSetType, int resultSetConcurrency, boolean streamResults, String catalog, Field[] cachedMetadata) throws Exception { // ... this.sendPacket.writeByte((byte)3); if (characterEncoding != null) { if (this.platformDbCharsetMatches) { this.sendPacket.writeStringNoNull(query, characterEncoding, this.connection.getServerCharset(), this.connection.parserKnowsUnicode(), this.connection); } else if (StringUtils.startsWithIgnoreCaseAndWs(query, "LOAD DATA")) { this.sendPacket.writeBytesNoNull(StringUtils.getBytes(query)); } else { this.sendPacket.writeStringNoNull(query, characterEncoding, this.connection.getServerCharset(), this.connection.parserKnowsUnicode(), this.connection); } } else { this.sendPacket.writeStringNoNull(query); } Buffer resultPacket = this.sendCommand(3, (String)null, queryPacket, false, (String)null, 0); // ...}final Buffer sendCommand(int command, String extraData, Buffer queryPacket, boolean skipCheck, String extraDataCharEncoding, int timeoutMillis) throws SQLException { // ... this.send(this.sendPacket, this.sendPacket.getPosition()); // ...}private final void send(Buffer packet, int packetLen) throws SQLException { // ... Buffer packetToSend = packet; packet.setPosition(0); packet.writeLongInt(packetLen - 4); packet.writeByte(this.packetSequence); // ... this.mysqlOutput.write(packetToSend.getByteBuffer(), 0, packetLen); this.mysqlOutput.flush(); // ... }参考https://dev.mysql.com/doc/internals/en/mysql-server.html#mysqld_stmt_fetch
