MySQL driver read------Connection connection, based on JDBC-----5.1.26

Programs that generally get database connections

Class.forName ("Com.mysql.jdbc.Driver"), final Connection Connection = (Connection) drivermanager.getconnection ("jdbc : Mysql://localhost:3306/testdb "," guoxiaoming "," guoxiaoming ");

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Register MySQL driver class next time, we are now focusing on the establishment of connection

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Public interface Connection  extends Wrapper {

The JDK's connection provides a standard, connection (session) to a particular database. Executes the SQL statement in the connection context and returns the result.

The connection interface is implemented by the database-driven class, which holds the IO class in the database connection.

The DriverManager class in JDBC encapsulates a unified approach to acquiring connection objects

public static Connection getconnection (string url, string user, String password) throws SQLException {        Java.util.Prop Erties info = new Java.util.Properties ();        Gets the ClassLoader of the code that called this method, May//IS NULL. ClassLoader CALLERCL = Drivermanager.getcallerclassloader (), if (user! = null) {    info.put ("user", user);} if (password! = null) {    info.put ("password", password);}        Return (getconnection (URL, info, CALLERCL));}

Enter the getconnection (URL,INFO,CALLERCL) method to see what you can see,

Connection result = Di.driver.connect (URL, info);

The code eventually gets the connection object

The corresponding driver driver class is implemented in JDBC

public class Nonregisteringreplicationdriver extends Nonregisteringdriver {public nonregisteringreplicationdriver () Throws SQLException {super ();} /* * (NON-JAVADOC) * *  @see java.sql.driver#connect (java.lang.String, java.util.Properties) */public Connection Connect (String URL, Properties info) throws SQLException {return connectreplicationconnection (URL, info);}}

See the Connectreplicationconnection (Url,info) method in the parent class Nonregisteringdriver class

return new Replicationconnection (Masterprops, slavesprops);

See the class

Public replicationconnection (Properties masterproperties,properties slaveproperties) throws SQLException { This.driver = new Nonregisteringdriver (); this.slaveproperties = Slaveproperties;this.masterproperties = masterproperties;        This.initializemasterconnection ();        This.initializeslaveconnection ();        This.currentconnection = this.masterconnection;}

Initialized two links, one is masterconnection and the other is slaveconnection

See notes

/** * Connection that opens the connections, one, one, replication Master, and * another to one or more slaves, and decide s to use master when the connection * are not read-only, and use slave (s) if the connection is read-only. *  * @version $Id: replicationconnection.java,v 1.1.2.1 2005/05/13 18:58:38 *          mmatthews EXP $ */

We finally saw in the Connectionimpl class

protected static Connection getinstance (String hosttoconnectto,int porttoconnectto, Properties info, string Databasetoconnectto,string URL) throws SQLException {if (! UTIL.ISJDBC4 ()) {return new Connectionimpl (Hosttoconnectto, Porttoconnectto, Info,databasetoconnectto, URL);} Return (Connection) util.handlenewinstance (jdbc_4_connection_ctor,new object[] {hosttoconnectto, integer.valueof ( Porttoconnectto), Info,databasetoconnectto, url}, null);}

Instantiate a subclass of the class

By constructing a method

Public Jdbc4connection (string hosttoconnectto, int porttoconnectto, Properties info, string Databasetoconnectto, String URL) throws SQLException {super (Hosttoconnectto, Porttoconnectto, info, databasetoconnectto, URL);//TODO auto-generated constructor stub}

In its parent class

Protected Connectionimpl (String hosttoconnectto, int porttoconnectto, Properties info,string Databasetoconnectto, String URL) throws SQLException {This.connectioncreationtimemillis = System.currenttimemillis (); if ( Databasetoconnectto = = null) {Databasetoconnectto = "";}

Emphasis on methods

public void Createnewio (Boolean isforreconnect) throws SQLException {synchronized (Getconnectionmutex ()) {// Synchronization not needed for *new* connections, but defintely for//connections going through fail-over, since we might Get the//New connection up and running *enough* to start sending//cached or Still-open server-side prepared statements O ver//to the backend before we get a chance to re-prepare them ... Properties mergedprops  = exposeasproperties (This.props), if (!gethighavailability ()) {connectonetryonly ( Isforreconnect, mergedprops); return;} Connectwithretries (Isforreconnect, Mergedprops);}}

In the end we see concrete links implemented in the Coreconnect method.

private void Coreconnect (Properties mergedprops) throws sqlexception,ioexception {int newPort = 3306; String newhost = "localhost"; String protocol = mergedprops.getproperty (Nonregisteringdriver.protocol_property_key), if (protocol! = NULL) {//"new" Style Urlif ("TCP". Equalsignorecase (protocol)) {newhost = Normalizehost (Mergedprops.getproperty ( Nonregisteringdriver.host_property_key)); newPort = Parseportnumber (Mergedprops.getproperty ( Nonregisteringdriver.port_property_key, "3306"));} else if ("pipe". Equalsignorecase (protocol)) {Setsocketfactoryclassname (NamedPipeSocketFactory.class.getName ()); String path = Mergedprops.getproperty (Nonregisteringdriver.path_property_key), if (path! = null) { Mergedprops.setproperty (namedpipesocketfactory.named_pipe_prop_name, Path);}} else {//normalize for all unknown Protocolsnewhost = Normalizehost (Mergedprops.getproperty (nonregisteringdriver.host_ Property_key)); newPort = Parseportnumber (Mergedprops.getproperty (Nonregisteringdriver.port_property_key, "3306"));}} else {string[] Parsedhostportpair = Nonregisteringdriver.parsehostportpair (this.hostportpair); newHost = Parsedhostportpair[nonregisteringdriver.host_name_index];newhost = Normalizehost (newHost); if (parsedHostPortPair[ NONREGISTERINGDRIVER.PORT_NUMBER_INDEX]! = null) {NewPort = Parseportnumber (parsedhostportpair[ Nonregisteringdriver.port_number_index]);}} This.port = Newport;this.host = Newhost;this.io = new Mysqlio (Newhost, Newport,mergedprops, Getsocketfactoryclassname () , GetProxy (), Getsockettimeout (), this.largeRowSizeThreshold.getValueAsInt ()); This.io.doHandshake (This.user, This.password,this.database);}

Implemented in the construction method of the new Mysqlio class

 Public Mysqlio (string host, int port, Properties props, String socketfactoryclassname, Mysqlconnection conn,                int sockettimeout, int usebufferrowsizethreshold) throws IOException, SQLException {this.connection = conn; if (This.connection.getEnablePacketDebug ()) {This.packetdebugringbuffer = new linkedlist<string        Buffer> ();                } This.traceprotocol = This.connection.getTraceProtocol ();                This.useautoslowlog = This.connection.getAutoSlowLog ();        This.usebufferrowsizethreshold = Usebufferrowsizethreshold;        This.usedirectrowunpack = This.connection.getUseDirectRowUnpack ();        This.logslowqueries = This.connection.getLogSlowQueries ();        This.reusablepacket = new Buffer (initial_packet_size);        This.sendpacket = new Buffer (initial_packet_size);        This.port = port;        This.host = host;        This.socketfactoryclassname = Socketfactoryclassname; This.socketfactory = CREAtesocketfactory ();                This.exceptioninterceptor = This.connection.getExceptionInterceptor ();                try {this.mysqlconnection = This.socketFactory.connect (This.host, this.port, props);        if (sockettimeout! = 0) {try {this.mysqlConnection.setSoTimeout (sockettimeout); } catch (Exception ex) {/* Ignore if the platform does not support it */}} This.mysqlconnec        tion = This.socketFactory.beforeHandshake (); if (This.connection.getUseReadAheadInput ()) {this.mysqlinput = new Readaheadinputstream (this.mysqlConnection.getIn        Putstream (), 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);        This.isinteractiveclient = This.connection.getInteractiveClient ();        This.profilesql = THIS.CONNECTION.GETPROFILESQL ();        This.autogeneratetestcasescript = This.connection.getAutoGenerateTestcaseScript ();        This.needtograbqueryfrompacket = (This.profilesql | |        this.logslowqueries | |        This.autogeneratetestcasescript); if (This.connection.getUseNanosForElapsedTime () && util.nanotimeavailable ()) {this.usenanosforelapsedtime = True;this.querytimingunits = messages.getstring ("nanoseconds");} else {this.querytimingunits = messages.getstring ("Milliseconds");}        if (This.connection.getLogSlowQueries ()) {calculateslowquerythreshold ();} } catch (IOException Ioex) {throw sqlerror.createcommunicationsexception (this.connection, 0, 0, Ioex, getexception        Interceptor ()); }    }

This.mysqlconnection = This.socketFactory.connect (this.host,this.port, props);
This returns the socket object

Among the Standardsocketfactory classes

if (this.host! = null) {if (!) ( Wantslocalbind | | Wantstimeout | | Needsconfigurationbeforeconnect)) {inetaddress[] possibleaddresses = Inetaddress.getallbyname (this.host); Throwable caughtwhileconnecting = null;//need to loop through all possible addresses, in case//someone have IPV6 Configur Ed (SuSE, for example ...) for (int i = 0; i < possibleaddresses.length; i++) {try {this.rawsocket = new Socket (possibleaddresses[i],port); Configu Resocket (this.rawsocket, props); catch (Exception ex) {caughtwhileconnecting = ex;}} if (Rawsocket = = null) {Unwrapexceptiontoproperclassandthrowit (caughtwhileconnecting);}} else {//must explicitly state-due to ClassLoader issues//when running on older JVMs:(try {inetaddress[] Possiblead Dresses = Inetaddress.getallbyname (this.host); Throwable caughtwhileconnecting = Null;object localsockaddr = null; Class<?> inetsocketaddressclass = null; Constructor<?> Addrconstructor = null;try {inetsocketaddressclass = Class.forName ("Java.net.InetSocketAddress ") Addrconstructor = Inetsocketaddressclass.getconstructor (new class[] {inetaddress.class, Integer.type}), if (wantslocalbind) {localsockaddr = Addrconstructor.newinstance (new object[] {inetaddress.getbyname ( Localsockethostname), new Integer (0/* * Use ephemeral * port */)});}} catch (Throwable ex) {Unwrapexceptiontoproperclassandthrowit (ex);} Need to loop through all possible addresses, in case//someone have IPV6 configured (SuSE, for example ...) for (int i = 0; i < possibleaddresses.length; i++) {try {this.rawsocket = new Socket (); Configuresocket (This.rawsocket, props); Object sockaddr = Addrconstructor.newinstance (new object[] {possibleaddresses[i],integer.valueof (port)});// Bind to the local port if not using the ephemeral portif (localsockaddr! = null) {Socketbindmethod.invoke (rawsocket,new Ob Ject[] {localsockaddr});} Connectwithtimeoutmethod.invoke (rawsocket,new object[] {sockaddr,integer.valueof (connectTimeout)}); catch (Exception ex) {this.rawsocket = Null;caughtwhileconnecting = ex;}} if (This.rawsocket = = null) {Unwrapexceptiontoproperclassandthrowit (caughtwhileconnecting);}} catch (Throwable t) {Unwrapexceptiontoproperclassandthrowit (t);}} return this.rawsocket;}

The possibility of multiple IPs for host may be connected to one of the IPs, then break exits

MySQL driver read------Connection connection, based on JDBC-----5.1.26