trunk/tools/MySQLConnection.java

package tools;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.StringTokenizer;
import java.io.IOException;
import java.util.ArrayList;

public class MySQLConnection {

        /*--------------------- constants -----------------------*/
        
    // -- constants for database connection --
    static final String    HOST =                       "white";        
    static final String    USER =                   "";
    static final String    PASSWORD =           "nieve";
        
        /*------------------- member variables --------------------*/
        
        public Connection conn; 
        private String host;
        private String user;
        private String password=PASSWORD;
        private String port;
        private String dbname;
        
        /*-------------------- constructors -----------------------*/

        /** 
         * Connect to database using the given server, user and password
         * @param dbServer
         * @param dbUserName
         * @param dbPassword
         * @throws SQLException 
         */
        public MySQLConnection(String dbServer, String dbUserName, String dbPassword) throws SQLException {
                loadMySQLDriver();
                host=dbServer;
                user=dbUserName;
                password=dbPassword;
                port="";
                dbname="";              
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;

                conn = DriverManager.getConnection(connStr, user, password);
        }

        /**
         * Connect to database using the given server, user, password and dbname.
         * Please always use this constructor in preference rather than constructing without specifying a database
         * @param dbServer
         * @param dbUserName
         * @param dbPassword
         * @param dbName 
         * @throws SQLException 
         */
        public MySQLConnection(String dbServer, String dbUserName, String dbPassword, String dbName) throws SQLException {
                loadMySQLDriver(); 
                host=dbServer;
                user=dbUserName;
                password=dbPassword;
                port="";
                dbname=dbName;          
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;

                conn = DriverManager.getConnection(connStr, user, password);
        }

        /**
         * Connect to database using the given server and dbName
         * Password taken from default, user name from unix user name
         * @param dbServer
         * @param dbName
         * @throws SQLException 
         */
        public MySQLConnection(String dbServer, String dbName) throws SQLException {
                loadMySQLDriver(); 
                host=dbServer;
                user=getUserName();
                port="";
                dbname=dbName;
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;

                conn = DriverManager.getConnection(connStr, user, password);
        }

        /**
         * Connect to database using the given server, user, password, dbname and port
         * Only needed if mysql server uses a port different from the standard 3306
         * @param dbServer
         * @param dbUserName
         * @param dbPassword
         * @param dbName
         * @param portNum
         * @throws SQLException 
         */
        public MySQLConnection(String dbServer, String dbUserName, String dbPassword, String dbName, int portNum) throws SQLException {
                loadMySQLDriver();
                host=dbServer;
                user=dbUserName;
                password=dbPassword;
                port=":"+portNum;
                dbname=dbName;          
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;

                conn = DriverManager.getConnection(connStr, user, password);
        }
                
        /**
         * Connect to database giving a connection file
         * @param connFile the connection file's name
         * @throws SQLException 
         */
        public MySQLConnection(String connFile) throws SQLException {
                loadMySQLDriver();
                readConnectionFile(connFile);
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;

                conn = DriverManager.getConnection(connStr, user, password);
        }
        
        
        /*---------------------- methods -------------------------*/
        
        /** get user name from operating system (for use as database username) */
        public static String getUserName() {
                String user = null;
                user = System.getProperty("user.name");
                if(user == null) {
                        System.err.println("Could not get user name from operating system. Exiting");
                        System.exit(1);
                }
                return user;
        }
        
        public static void loadMySQLDriver() {
                try {
                        Class.forName("com.mysql.jdbc.Driver").newInstance();
                }
                catch(IllegalAccessException e) {
                        e.printStackTrace();
                        System.err.println("An exception occurred while loading the mysql jdbc driver, exiting.");
                        System.exit(1);
                }
                catch(InstantiationException e) {
                        e.printStackTrace();
                        System.err.println("An exception occurred while loading the mysql jdbc driver, exiting.");
                        System.exit(1);                 
                }
                catch(ClassNotFoundException e) {
                        e.printStackTrace();
                        System.err.println("An exception occurred while loading the mysql jdbc driver, exiting.");
                        System.exit(1);                 
                }
                catch(Exception e) {
                        e.printStackTrace();
                        System.err.println("An exception occurred while loading the mysql jdbc driver, exiting.");
                        System.exit(1);                 
                }               
        }

        /**
         * Used in the constructor that gets a connFile as argument. To read the connection parameters from a connection file.
         * @param connFile
         */
        private void readConnectionFile(String connFile) {
                // reads the values of the connFile into the static variables; 
                String homedir = System.getProperty("user.home"); 
                if (connFile.length()==0) { // no file was specified
                        connFile=homedir+"/.my.cnf"; // assume default configuration file 
                }               
                // else the location of the connection file was given           
                // Open the configuration file          
                BufferedReader fileIn = null;
                StringTokenizer str;
                String item, oneLine;
                // to control if the minimum mandatory 4 parameters are given in file
                int paramCount=0; 
                // setting default blank values for port and dbname, they are set to blank unless fields specified in file
                port="";
                dbname="";
                // list the entries in the file and decompose them 
                try {
                        fileIn = new BufferedReader(new FileReader(new File(connFile))); // open BufferedReader to file connFile 
                        while ((oneLine = fileIn.readLine()) != null ) {
                                // Construct a stringTokenizer for the line that we read with : delimited
                                str = new StringTokenizer(oneLine, "="); // true sets returnDelimiters flag 
                                while ( str.hasMoreTokens()) {
                                        item = str.nextToken();
                                        if( item.equals("host")) { // mandatory parameter
                                                host=str.nextToken();
                                                paramCount++;
                                                break; 
                                        } // end if host 
                                        if( item.equals("port")) { // optional parameter
                                                port=":"+str.nextToken();
                                                break; 
                                        } // end if port
                                        if( item.equals("user")) { // mandatory parameter
                                                user=str.nextToken();
                                                paramCount++;
                                                break; 
                                        } // end if password 
                                        if( item.equals("password")) { // mandatory parameter
                                                password=str.nextToken();
                                                paramCount++;
                                                break; 
                                        } // end if password
                                        if( item.equals("database")) { // mandatory parameter
                                                dbname=str.nextToken();
                                                paramCount++;
                                                break; 
                                        } // end if password                                    
                                } // next token in this line 
                        } // next line in the file
                        if (paramCount<4){
                                System.err.println("Not all mandatory parameters are given in connection file "+connFile+". Can't connect to mysql server, exiting.");
                                System.exit(1);
                        }                       
                } 
                catch (IOException e) {
                        System.err.println("Couldn't open file "+connFile);                     
                        e.printStackTrace();
                        System.exit(1);
                }  
                
                try { // closing the file
                        if (fileIn != null) fileIn.close();                     
                } catch (IOException e) {
                        System.err.println("Couldn't close file "+connFile);
                        e.printStackTrace(); 
                }
                
        }

        public String getDbname() {
                return dbname;
        }

        public void setDbname(String dbname) {
                this.dbname = dbname;
        }

        public String getHost() {
                return host;
        }

        public void setHost(String host) {
                this.host = host;
        }

        public String getPassword() {
                return password;
        }

        public void setPassword(String password) {
                this.password = password;
        }

        public String getUser() {
                return user;
        }

        public void setUser(String user) {
                this.user = user;
        }

        public Statement createStatement() throws SQLException {
                return this.conn.createStatement();
        }
        
        public void executeSql(String query) throws SQLException{
                Statement stmt;         
                stmt = conn.createStatement();  
                stmt.execute(query);
                stmt.close();               
        }
                
        /** 
         * @param query
         * @return the first column of the first row of the result of the given query as a string
         * or null if no results were returned
         * TODO: How to figure out whether a database error occured?
         */     
        public String getStringFromDb(String query) {
                Statement    stmt;
                ResultSet    rs;
                String       result = null;
                
                try { 
                        
                    stmt = conn.createStatement();
                    rs = stmt.executeQuery(query);
                    if(rs.next()) {
                        result = rs.getString(1);
                    }
                    rs.close();
                    stmt.close(); 
                    
                } // end try
                catch (SQLException e) {
                    System.err.println("SQLException: " + e.getMessage());
                    System.err.println("SQLState:     " + e.getSQLState());
                    System.err.println("VendorError:  " + e.getErrorCode());
                    e.printStackTrace();
                } // end catch                          
                
                return result;
        }
        
        /** 
         * @param query
         * @return the first column of the first row of the result of the given query as an integer
         * or -1 if no results were returned
         */
        public int getIntFromDb(String query) {
                Statement    stmt;
                ResultSet    rs;
                int          result = -1;

                try { 
                        
                    stmt = conn.createStatement();
                    rs = stmt.executeQuery(query);
                    if(rs.next()) {
                        result = rs.getInt(1);
                    }
                    rs.close();
                    stmt.close(); 
                    
                } // end try
                catch (SQLException e) {
                    System.err.println("SQLException: " + e.getMessage());
                    System.err.println("SQLState:     " + e.getSQLState());
                    System.err.println("VendorError:  " + e.getErrorCode());
                    e.printStackTrace();
                } // end catch                  
                
                return result;
        }
        
        public void close() {
                
                try {
                        conn.close();
            } catch (SQLException e) {
                        System.err.println("SQLException: " + e.getMessage());
                        System.err.println("SQLState:     " + e.getSQLState());
                        System.err.println("VendorError:  " + e.getErrorCode());
                        e.printStackTrace();
            } // end try/catch connection 
        }
        
        /**
         * Get the actual Connection object within this MySQLConnection. In case that an external library need a Connection object
         * @return
         */
        public Connection getConnectionObject() {
                return this.conn;
        }

    /**
     * To print the db size info for the given db of this MySQLConnection.
     * @param dbName
     */
        public void printDbSizeInfo (String dbName) {
                double data = 0, index = 0, table_data = 0, table_index = 0, GB = Math.pow(2, 30);
                String Query = null, table = null;
                Statement Stmt = null;
                ResultSet RS = null;            
                try {
                    Query = "SHOW TABLE STATUS FROM "+dbName;
                    Stmt = this.conn.createStatement();
                    RS = Stmt.executeQuery(Query);
                    while (RS.next()) {
                                table = RS.getString("Name");
                                table_data = RS.getDouble("Data_length");
                                table_index = RS.getDouble("Index_length");
                                data += RS.getDouble("Data_length");
                                index += RS.getDouble("Index_length");
                                System.out.println("Table "+table+"##data:"+table_data+", index:"+table_index);
                    }
                    RS.close();
                    Stmt.close();       
                    System.out.println("Database "+dbName+" needs "+((data+index)/GB)+ " GB (data:"+(data/GB)+", index:"+(index/GB)+").");
                } 
                catch (SQLException e) {
                    System.err.println("SQLException: " + e.getMessage());
                    System.err.println("SQLState:     " + e.getSQLState());
                    System.err.println("VendorError:  " + e.getErrorCode());
                    e.printStackTrace();
                } // end try/catch connection
    }

    /**
     * To get range of a column from a table in this MySQLConnection. Note that if the connection was created without pointing 
     * to a particular database then the argument table must be specified as dbname.tablename.
     * @param table
     * @param column
     * @return
     */
    public double[] getRange(String table, String column) {
        String query = "";
        Statement S;
        ResultSet R;
        double[] range = new double[2];
        try { 
            query = "SELECT MIN("+column+"), MAX("+column+") FROM "+table+";";
            S = this.conn.createStatement();
            R = S.executeQuery(query);          
            if (R.next()) {
                        range[0] = R.getDouble(1);
                        range[1] = R.getDouble(2);
            } 
            R.close();
            S.close();
        } // end try
        catch (SQLException e) {
            System.err.println("SQLException: " + e.getMessage());
            System.err.println("SQLState:     " + e.getSQLState());
            System.err.println("VendorError:  " + e.getErrorCode());
            e.printStackTrace();
        } // end catch          
        return range;           
    }

    /**
     * To get range of a column from a table in this MySQLConnection using a given WHERE condition. Note that if 
     * the connection was created without pointing to a particular database then the argument table must 
     * be specified as dbname.tablename.
     * @param table
     * @param column
     * @param whereStr
     * @return
     */
    public double[] getRange(String table, String column, String whereStr) {
        String query = "";
        Statement S;
        ResultSet R;
        double[] range = new double[2];
        try { 
            query = "SELECT MIN("+column+"), MAX("+column+") FROM "+table+" WHERE ("+whereStr+");";
            S = this.conn.createStatement();
            R = S.executeQuery(query);          
            if (R.next()) {
                        range[0] = R.getDouble(1);
                        range[1] = R.getDouble(2);
            } 
            R.close();
            S.close();
        } // end try
        catch (SQLException e) {
            System.err.println("SQLException: " + e.getMessage());
            System.err.println("SQLState:     " + e.getSQLState());
            System.err.println("VendorError:  " + e.getErrorCode());
            e.printStackTrace();
        } // end catch          
        return range;           
    }
        
    /**
     * To get all indexes names for a certain table. Note the MySQLConnection object must be created with a non-blank database.
     * Using INFORMATION_SCHEMA db, only works from mysql 5.0
     * @param table
     * @return
     */
    public String[] getAllIndexes4Table(String table) {
        ArrayList<String> indexesAL=new ArrayList<String>();
        String query;
        Statement S;
        ResultSet R;
        try { 
            query = "SELECT DISTINCT INDEX_NAME FROM INFORMATION_SCHEMA.STATISTICS WHERE TABLE_SCHEMA='"+dbname+"' AND TABLE_NAME='"+table+"';";
            S = this.conn.createStatement();
            R = S.executeQuery(query);          
            while (R.next()) {
                        indexesAL.add(R.getString(1));                  
            } 
            R.close();
            S.close();
        } // end try                    
        catch (SQLException e) {
            System.err.println("SQLException: " + e.getMessage());
            System.err.println("SQLState:     " + e.getSQLState());
            System.err.println("VendorError:  " + e.getErrorCode());
            e.printStackTrace();
        } // end catch
        String[] indexes=new String[indexesAL.size()];
        int i=0;
        for (String index:indexesAL) {
                indexes[i]=index;
                i++;
        }
        return indexes;
    }
    
    /**
     * Gets an array of Strings with all queries necessary to create all the indexes for a certain table 
     * @param table
     * @return
     */
    public String[] getCreateIndex4Table(String table){
        String[] indexes=this.getAllIndexes4Table(table);
        String[] createIndexQueries=new String[indexes.length];         
        for (int i=0;i<indexes.length;i++){
                String index=indexes[i];
                try { 
                        Statement S;
                        ResultSet R;
                    String query = "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.STATISTICS " +
                                                "WHERE TABLE_SCHEMA='"+dbname+"' AND TABLE_NAME='"+table+"' AND INDEX_NAME='"+index+"' " +
                                                                "ORDER BY SEQ_IN_INDEX;";
                    S = this.conn.createStatement();
                    R = S.executeQuery(query);
                    String createIndexStr="CREATE INDEX "+index+" ON "+table+" (";
                    while (R.next()) {
                        String colName = R.getString(1);
                        createIndexStr+=colName+",";
                    }
                    createIndexStr=createIndexStr.substring(0,createIndexStr.lastIndexOf(","));
                    createIndexStr+=");";
                    createIndexQueries[i]=createIndexStr;
                    R.close();
                    S.close();
                } // end try                    
                catch (SQLException e) {
                    System.err.println("SQLException: " + e.getMessage());
                    System.err.println("SQLState:     " + e.getSQLState());
                    System.err.println("VendorError:  " + e.getErrorCode());
                    e.printStackTrace();
                } // end catch                  
        }
        return createIndexQueries;
    }
    
    /**
     * To get the column type for a certain column and table
     * @param table
     * @param column
     * @return
     */
    public String getColumnType(String table,String column){
        String query = "SELECT COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS " +
                                        "WHERE TABLE_SCHEMA='"+this.dbname+"' AND TABLE_NAME='"+table+"' AND COLUMN_NAME='"+column+"';";
        String colType = this.getStringFromDb(query);
        return colType;
    }
    
    /**
     * To findout whether a key (i.e. column) is numeric-based or text-based
     * @param table
     * @param key
     * @return true if is numeric-based, false if is text-based
     */
    public boolean isKeyNumeric(String table, String key){
        boolean isNumeric = false;
        String colType = getColumnType(table,key);
        if (colType.contains("int") || colType.contains("INT")){
                isNumeric = true;
        }
        else if (colType.contains("char") || colType.contains("CHAR")){
                isNumeric = false;
        }
        else {
                System.err.println("The key '"+key+"' from table '"+table+"' is neither numeric-based (int) nor text-based (char/varchar). Check what's wrong!");
        }
        return isNumeric;
    }
    
    /**
     * To get all tables for this MySQLConnection's database.
     * @return an array of String with all table names
     */
        public String[] getTables4Db(){
                String[] tables=null;
                ArrayList<String> tablesAL=new ArrayList<String>();
                String query="SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='"+dbname+"' ORDER BY TABLE_NAME DESC;";
                try {                   
                        Statement S = this.conn.createStatement();
                        ResultSet R=S.executeQuery(query);
                        while (R.next()){
                                tablesAL.add(R.getString(1));
                        }
                        S.close();
                        R.close();
                        tables=new String[tablesAL.size()];
                        for (int i=0;i<tablesAL.size();i++) {
                                tables[i]=tablesAL.get(i);
                        }
                }
                catch(SQLException e){                  
                        System.err.println("Couldn't get table names from "+host+" for db="+dbname);
            System.err.println("SQLException: " + e.getMessage());
            System.err.println("SQLState:     " + e.getSQLState());
            System.err.println("VendorError:  " + e.getErrorCode());
                        e.printStackTrace();
                }
                return tables;
        }
        
        /** 
         * To get all distinct ordered ids from a certain key and table from this MySQLConnection
         * @param key the key name
         * @param table the table name
         * @return int array containing all ids 
         */
        public Integer[] getAllNumIds4KeyAndTable(String key, String table){
                Integer[] allIds=null;          
                try {
                        Statement S=conn.createStatement();
                        String query="SELECT DISTINCT "+key+" FROM "+table+" ORDER BY "+key+";";
                        ResultSet R=S.executeQuery(query);
                        ArrayList<Integer> idsAL=new ArrayList<Integer>();
                        while (R.next()){
                                idsAL.add(R.getInt(1));
                        }
                        allIds=new Integer[idsAL.size()];
                        for (int i=0;i<idsAL.size();i++) {
                                allIds[i]=idsAL.get(i);
                        }
                        R.close();
                        S.close();
                }
                catch (SQLException e){
                        e.printStackTrace();
                }
                return allIds;
        }

        /** 
         * To get all distinct ordered text (i.e. char/varchar column) ids from a certain key and table from this MySQLConnection
         * @param key the key name
         * @param table the table name
         * @return int array containing all ids 
         */
        public String[] getAllTxtIds4KeyAndTable(String key, String table){
                String[] allIds=null;           
                try {
                        Statement S=conn.createStatement();
                        String query="SELECT DISTINCT "+key+" FROM "+table+" ORDER BY "+key+";";
                        ResultSet R=S.executeQuery(query);
                        ArrayList<String> idsAL=new ArrayList<String>();
                        while (R.next()){
                                idsAL.add(R.getString(1));
                        }
                        allIds=new String[idsAL.size()];
                        for (int i=0;i<idsAL.size();i++) {
                                allIds[i]=idsAL.get(i);
                        }
                        R.close();
                        S.close();
                }
                catch (SQLException e){
                        e.printStackTrace();
                }
                return allIds;
        }

        /** 
         * To get all distinct ordered ids from a certain key and table from this MySQLConnection
         * @param key the key name
         * @param table the table name
         * @return int array containing all ids 
         */
        public Object[] getAllIds4KeyAndTable(String key, String table){
                Object[] allIds=null;
                try {
                        Statement S=conn.createStatement();
                        String query="SELECT DISTINCT "+key+" FROM "+table+" ORDER BY "+key+";";
                        ResultSet R=S.executeQuery(query);
                        ArrayList<String> idsAL=new ArrayList<String>();
                        while (R.next()){
                                idsAL.add(R.getString(1));
                        }
                        if (isKeyNumeric(table,key)){
                                allIds=new Integer[idsAL.size()];
                                for (int i=0;i<idsAL.size();i++) {
                                        allIds[i]=Integer.parseInt(idsAL.get(i));
                                }
                        } else {
                                allIds=new String[idsAL.size()];
                                for (int i=0;i<idsAL.size();i++){
                                        allIds[i]=idsAL.get(i);
                                }
                        }
                        R.close();
                        S.close();
                }
                catch (SQLException e){
                        e.printStackTrace();
                }
                return allIds;
        }

    /**
     * To set the sql_mode of this connection. 
     * @param sqlmode either NO_UNSIGNED_SUBTRACTION or blank
     */
    public void setSqlMode(String sqlmode) {
        String query="SET SESSION sql_mode='"+sqlmode+"';";
        try {
                this.executeSql(query);
        }
        catch (SQLException e){
                System.err.println("Couldn't change the sql mode to "+sqlmode);
            System.err.println("SQLException: " + e.getMessage());
            System.err.println("SQLState:     " + e.getSQLState());
            System.err.println("VendorError:  " + e.getErrorCode());
            e.printStackTrace();                
        }
    }
    
}
Revision:	350
Committed:	Thu Oct 11 12:38:07 2007 UTC (17 years, 4 months ago) by stehr
File size:	22037 byte(s)
Log Message:	Machine: added main and some other methods; MySQLConnection: added explicit handling of some exceptions