field.java

在资料浩瀚的互联网中

/*
      Copyright (C) 2002-2004 MySQL AB

      This program is free software; you can redistribute it and/or modify
      it under the terms of version 2 of the GNU General Public License as 
      published by the Free Software Foundation.

      There are special exceptions to the terms and conditions of the GPL 
      as it is applied to this software. View the full text of the 
      exception in file EXCEPTIONS-CONNECTOR-J in the directory of this 
      software distribution.

      This program is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU General Public License for more details.

      You should have received a copy of the GNU General Public License
      along with this program; if not, write to the Free Software
      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



 */
package com.mysql.jdbc;

import java.io.UnsupportedEncodingException;
import java.sql.SQLException;
import java.sql.Types;


/**
 * Field is a class used to describe fields in a
 * ResultSet
 *
 * @author Mark Matthews
 * @version $Id: Field.java,v 1.15.4.24 2005/02/17 21:42:27 mmatthews Exp $
 */
public class Field {
    //~ Static fields/initializers ---------------------------------------------

    private static final int AUTO_INCREMENT_FLAG = 512;
    private static final int NO_CHARSET_INFO = -1;

    //~ Instance fields --------------------------------------------------------

    private Connection connection = null;
    private String charsetName = null;
    private String databaseName = null;
    private String fullName = null;
    private String fullOriginalName = null;
    private String name; // The Field name
    private String originalColumnName = null;
    private String originalTableName = null;
    private String tableName; // The Name of the Table
    private byte[] buffer;
    private int charsetIndex = 0;
    private int colDecimals;
    private int databaseNameLength = -1;

    // database name info
    private int databaseNameStart = -1;
    private int defaultValueLength = -1;

    // default value info - from COM_LIST_FIELDS execution
    private int defaultValueStart = -1;
    private int length; // Internal length of the field;
    private int mysqlType = -1; // the MySQL type
    private int nameLength;
    private int nameStart;
    private int originalColumnNameLength = -1;

    // column name info (before aliasing)
    private int originalColumnNameStart = -1;
    private int originalTableNameLength = -1;

    // table name info (before aliasing)
    private int originalTableNameStart = -1;
    private int precisionAdjustFactor = 0;
    private int sqlType = -1; // the java.sql.Type
    private int tableNameLength;
    private int tableNameStart;
    private short colFlag;
    
    private String collationName = null;

    //~ Constructors -----------------------------------------------------------

    /**
    * Constructor used by DatabaseMetaData methods.
    */
    Field(String tableName, String columnName, int jdbcType, int length) {
        this.tableName = tableName;
        this.name = columnName;
        this.length = length;
        this.sqlType = jdbcType;
        this.colFlag = 0;
        this.colDecimals = 0;
    }

    /**
     * Constructor used when communicating with pre 4.1 servers
     */
    Field(Connection conn, byte[] buffer, int nameStart, int nameLength,
        int tableNameStart, int tableNameLength, int length, int mysqlType,
        short colFlag, int colDecimals) throws SQLException {
        this(conn, buffer, -1, -1, tableNameStart, tableNameLength, -1, -1,
            nameStart, nameLength, -1, -1, length, mysqlType, colFlag,
            colDecimals, -1, -1, NO_CHARSET_INFO);
    }

    /**
     * Constructor used when communicating with 4.1 and newer
     * servers
     */
    Field(Connection conn, byte[] buffer, int databaseNameStart,
        int databaseNameLength, int tableNameStart, int tableNameLength,
        int originalTableNameStart, int originalTableNameLength, int nameStart,
        int nameLength, int originalColumnNameStart,
        int originalColumnNameLength, int length, int mysqlType, short colFlag,
        int colDecimals, int defaultValueStart, int defaultValueLength,
        int charsetIndex) throws SQLException {
        this.connection = conn;
        this.buffer = buffer;
        this.nameStart = nameStart;
        this.nameLength = nameLength;
        this.tableNameStart = tableNameStart;
        this.tableNameLength = tableNameLength;
        this.length = length;
        this.colFlag = colFlag;
        this.colDecimals = colDecimals;
        this.mysqlType = mysqlType;

        // 4.1 field info...
        this.databaseNameStart = databaseNameStart;
        this.databaseNameLength = databaseNameLength;

        this.originalTableNameStart = originalTableNameStart;
        this.originalTableNameLength = originalTableNameLength;

        this.originalColumnNameStart = originalColumnNameStart;
        this.originalColumnNameLength = originalColumnNameLength;

        this.defaultValueStart = defaultValueStart;
        this.defaultValueLength = defaultValueLength;

        // Re-map to 'real' blob type, if we're a BLOB

        if (this.mysqlType == MysqlDefs.FIELD_TYPE_BLOB) {
        	setBlobTypeBasedOnLength();
        }
        
        // Map MySqlTypes to java.sql Types
        this.sqlType = MysqlDefs.mysqlToJavaType(this.mysqlType);
        
        if (this.sqlType == Types.TINYINT && this.length == 1 
        		&& this.connection.getTinyInt1isBit()) {
        	this.sqlType = Types.BIT;
        }
        
        if (this.mysqlType == MysqlDefs.FIELD_TYPE_BIT) {
        	if (this.length == 0) {
        		this.sqlType = Types.BIT;
        	} else {
        		this.sqlType = Types.VARBINARY;
        		this.colFlag |= 128; // we need to pretend this is a full
        		this.colFlag |= 16; // binary blob
        	}
        }

	
        // If we're not running 4.1 or newer, use the connection's
        // charset
        this.charsetIndex = charsetIndex;
        
        this.charsetName = this.connection.getCharsetNameForIndex(this.charsetIndex);

		
        boolean isBinary = isBinary();

        //
        // Handle TEXT type (special case), Fix proposed by Peter McKeown
        //
        if ((this.sqlType == java.sql.Types.LONGVARBINARY) && !isBinary) {
            this.sqlType = java.sql.Types.LONGVARCHAR;
        } else if ((this.sqlType == java.sql.Types.VARBINARY) && !isBinary) {
            this.sqlType = java.sql.Types.VARCHAR;
        }

        //
        // Handle odd values for 'M' for floating point/decimal numbers
        //
        if (!isUnsigned()) {
            switch (this.mysqlType) {
            case MysqlDefs.FIELD_TYPE_DECIMAL:
                this.precisionAdjustFactor = -1;

                break;

            case MysqlDefs.FIELD_TYPE_DOUBLE:
            case MysqlDefs.FIELD_TYPE_FLOAT:
                this.precisionAdjustFactor = 1;

                break;
            }
        } else {
            switch (this.mysqlType) {
            case MysqlDefs.FIELD_TYPE_DOUBLE:
            case MysqlDefs.FIELD_TYPE_FLOAT:
                this.precisionAdjustFactor = 1;

                break;
            }
        }
    }

    //~ Methods ----------------------------------------------------------------

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public boolean isAutoIncrement() {
        return ((this.colFlag & AUTO_INCREMENT_FLAG) > 0);
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public boolean isBinary() {
        return ((this.colFlag & 128) > 0);
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public boolean isBlob() {
        return ((this.colFlag & 16) > 0);
    }

    /**
     * Returns the character set (if known) for this
     * field.
     *
     * @return the character set
     */
    public String getCharacterSet() {
        return this.charsetName;
    }
    
    public int getMaxBytesPerCharacter() throws SQLException {
    	return this.connection.getMaxBytesPerChar((String)CharsetMapping.JAVA_TO_MYSQL_CHARSET_MAP.get(getCharacterSet()));
    }
    
    public synchronized String getCollation() throws SQLException {
    	if (this.collationName == null) {
    		if (this.connection != null) {
    			if (this.connection.versionMeetsMinimum(4, 1, 0)) {
    				java.sql.DatabaseMetaData dbmd = this.connection.getMetaData();
    			
    				String quotedIdStr = dbmd.getIdentifierQuoteString();
    			
    				if (" ".equals(quotedIdStr)) { //$NON-NLS-1$
    					quotedIdStr = ""; //$NON-NLS-1$
    				}
    				
    				String csCatalogName = getDatabaseName();
    				String csTableName = getOriginalTableName();
    				String csColumnName = getOriginalName();
    				
    				if (csCatalogName != null && csCatalogName.length() != 0
    						&& csTableName != null && csTableName.length() != 0
    						&& csColumnName != null && csColumnName.length() != 0) {
    					StringBuffer queryBuf = new StringBuffer(csCatalogName.length() + csTableName.length() + 28);
    					queryBuf.append("SHOW FULL COLUMNS FROM "); //$NON-NLS-1$
    					queryBuf.append(quotedIdStr);
    					queryBuf.append(csCatalogName);
    					queryBuf.append(quotedIdStr);
    					queryBuf.append("."); //$NON-NLS-1$
    					queryBuf.append(quotedIdStr);
    					queryBuf.append(csTableName);
						queryBuf.append(quotedIdStr);

						java.sql.Statement collationStmt = null;
						java.sql.ResultSet collationRs = null;

						try {
							collationStmt = this.connection.createStatement();
							
							collationRs = collationStmt.executeQuery(queryBuf.toString());

							while (collationRs.next()) {
								if (csColumnName.equals(collationRs.getString("Field"))) { //$NON-NLS-1$
									this.collationName = collationRs.getString("Collation"); //$NON-NLS-1$

									break;
								}
							}
						} finally {
							if (collationRs != null) {
								collationRs.close();
								collationRs = null;
							}

							if (collationStmt != null) {
								collationStmt.close();
								collationStmt = null;
							}
						}

    				}
    			}
    			
    		}
    		
    	}
    	
    	return this.collationName;
    }

    /**
     * DOCUMENT ME!
     *
     * @param conn DOCUMENT ME!
     */
    public void setConnection(Connection conn) {
        this.connection = conn;
        
		this.charsetName = this.connection.getEncoding();
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public String getDatabaseName() {
        if ((this.databaseName == null) && (this.databaseNameStart != -1)
                && (this.databaseNameLength != -1)) {