java执行sql处理类，包括CLOB，Blob字段的处理

import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.Reader;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Types;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class ExeSqlDAO {
private Log log = LogFactory.getLog(this.getClass().getName());

private int rows, cols;
/**
     * 执行数据库的更新操作
     *
     * @param sql SQL语句
     * @param con 数据库连接对象
     * @exception java.sql.SQLException
     */
    //do update
    public void update(String sql, Connection con) throws SQLException {
    log.info("JDBC SQL: "+sql);
            PreparedStatement pstmt = con.prepareStatement(sql);
            pstmt.executeUpdate();
            pstmt.close();


    }
    /**
     * 批量执行数据库操作
     *
     * @param sql
     * @param con
     * @throws SQLException
     */
    public void muchUpdate(String[] sql, Connection con) throws SQLException {
    for (int i=0;i<sql.length;i++){
    if (sql[i]!=null&&sql[i].length()>0&&!sql[i].equals("")){
    update(sql[i],con);
    }
    }

}
    /**
     * 执行查询数据库操作
     *
     * @param sql SQL语句
     * @param con 数据库连接对象
     * @return Result对象
     * @exception java.sql.SQLException
     */
    //do select
    public Resultobj queryExecute(String sql, Connection con) throws SQLException {
            Statement stmt = null;
            Resultobj result = new Resultobj();
            rows = 0;
            stmt = con.createStatement();
            log.info("JDBC SQL: "+sql);
            ResultSet rs = stmt.executeQuery(sql);
            ResultSetMetaData rsmd = rs.getMetaData();
            cols = rsmd.getColumnCount();
            String s[] = new String[cols];
            for (int i = 1; i <= cols; i++) {
                    s[i - 1] = rsmd.getColumnLabel(i);
            }
            result.add(s);
            rows++;
          if(rs==null){
          System.out.println("#############");
          }
            while (rs.next()) {
                    s = new String[cols];
                    for (int i = 1; i <= cols; i++) {
                            s[i - 1] = helper(rs, rsmd.getColumnType(i), i);
                           
                    }
                    result.add(s);
                    rows++;
            }

            result.setCols(cols);
            result.setRows(rows);

            rs.close();
            stmt.close();
            return (result);

    }

/**
     * 执行查询数据库操作
     * @param sql SQL语句
     * @param con 数据库连接对象
     * @param maxRow 取得最大记录个数
     * @return Result对象
     * @exception java.sql.SQLException
     */
    //do select
    public Resultobj queryByMaxRow(String sql, Connection con,int intMaxRows) throws SQLException {

            Statement stmt = null;
            Resultobj result = new Resultobj();
            rows = 0;
            stmt = con.createStatement();
            stmt.setMaxRows(intMaxRows);
            log.info("JDBC SQL: "+sql);
            ResultSet rs = stmt.executeQuery(sql);
            ResultSetMetaData rsmd = rs.getMetaData();
            cols = rsmd.getColumnCount();
            String s[] = new String[cols];
            for (int i = 1; i <= cols; i++) {
                    s[i - 1] = rsmd.getColumnLabel(i);
            }
            result.add(s);
            rows++;

            while (rs.next()) {
                    s = new String[cols];
                    for (int i = 1; i <= cols; i++) {
                            s[i - 1] = helper(rs, rsmd.getColumnType(i), i);
                          
                    }
                    result.add(s);
                    rows++;
            }
            result.setCols(cols);
            result.setRows(rows);
            //System.out.print("cols"+cols);
            //System.out.print("rows"+rows);
            rs.close();
            stmt.close();
            return (result);
    }
    /**
     * 对记录中的字段的类型转换
     * @param rs
     * @param dataType
     * @param col
     * @return
     * @throws SQLException
     */
    public String helper(ResultSet rs, int dataType, int col) throws SQLException {
            String retValue = null;
            Integer intObj;
            // ask for data depending on the datatype
            switch (dataType) {

                    case Types.DATE :
                            java.sql.Date date = rs.getDate(col);
                            if (date != null)
                                    retValue = date.toString();
                            break;
                    case Types.TIME :
                            java.sql.Time time = rs.getTime(col);
                            if (time != null)
                                    retValue = time.toString();
                            break;
                    case Types.TIMESTAMP :
                            java.sql.Timestamp timestamp = rs.getTimestamp(col);
                            if (timestamp != null)
                                    retValue = timestamp.toString();
                            break;
                    case Types.CHAR :
                    case Types.VARCHAR :
                    case Types.LONGVARCHAR :
                            retValue = rs.getString(col);
                            break;
                    case Types.NUMERIC :
                    case Types.DECIMAL ://zhanpeng 修改了不建议使用的api
                            java.math.BigDecimal numeric = rs.getBigDecimal(col);
                            if (numeric != null)
                                    retValue = numeric.toString();
                            break;
                    case Types.BIT :
                            boolean bit = rs.getBoolean(col);
                            Boolean boolObj = new Boolean(bit);
                            retValue = boolObj.toString();
                            break;
                    case Types.TINYINT :
                            byte tinyint = rs.getByte(col);
                            intObj = new Integer(tinyint);
                            retValue = intObj.toString();
                            break;
                    case Types.SMALLINT :
                            short smallint = rs.getShort(col);
                            intObj = new Integer(smallint);
                            retValue = intObj.toString();
                            break;
                    case Types.INTEGER :
                            int integer = rs.getInt(col);
                            intObj = new Integer(integer);
                            retValue = intObj.toString();
                            break;
                    case Types.BIGINT :
                            long bigint = rs.getLong(col);
                            Long longObj = new Long(bigint);
                            retValue = longObj.toString();
                            break;
                    case Types.REAL :
                            float real = rs.getFloat(col);
                            Float floatObj = new Float(real);
                            retValue = floatObj.toString();
                            break;
                    case Types.FLOAT :
                    case Types.DOUBLE :
                            double longreal = rs.getDouble(col);
                            Double doubleObj = new Double(longreal);
                            retValue = doubleObj.toString();
                            break;
                    case Types.BINARY :
                    case Types.VARBINARY :
                    case Types.LONGVARBINARY :
                            byte[] binary = rs.getBytes(col);
                            if (binary != null)
                                    retValue = new String(binary);
                            break;
                    case Types.CLOB :
                   
                    if(rs.getClob(col)!=null){
                    try {
Clob cBlob =(Clob)rs.getClob(col);
retValue=readClob(cBlob);
} catch (IOException e) {

}
                    }
                        break;       
            }
            if (retValue==null) {
            retValue = "";
            }
            return retValue;
    }
    //处理Clob字段
    public  String readClob(Clob cBlob)throws java.sql.SQLException, java.io.IOException {
    Reader r = cBlob.getCharacterStream();
    char[] b = new char[1024 * 3];
    int i = 0;
    CharArrayWriter caw = new CharArrayWriter();
    while ((i = r.read(b)) > 0) {
    caw.write(b, 0, i);
    }
   
    b = caw.toCharArray();
    String result = new String(b);
    return result;
    }

public Resultobj queryExecute (ResultSet rs) throws SQLException{
   
    Resultobj result = new Resultobj();
    ResultSetMetaData rsmd = rs.getMetaData();
    int rows = 0;
    int cols = rsmd.getColumnCount();
    String s[] = new String[cols];
    for(int i = 1;i<=cols;i++){
    s[i-1] = rsmd.getColumnLabel(i);
    }
    result.add(s);
    rows++;
    while(rs.next()){
    s = new String[cols];
    for(int i =1;i<=cols;i++){
    s[i-1]=helper(rs,rsmd.getColumnType(i),i);
    }
    result.add(s);
    rows++;
    }
    result.setCols(cols);
    result.setRows(rows);
    return result;
    }
}