本文通过简单的JAVA程序来说明如何操作（读取、复制表、写文件）GBase 8t大对象数据类型。GBase 8t大对象数据类型包括：简单大对象类型（byte,text）和智能大对象（blob,clob）类型。

准备工作：

数据库环境变量
export INFORMIXSERVER=gbaseserver
export INFORMIXDIR=/home/gbase
export ONCONFIG=onconfig.gbaseserver
export INFORMIXSQLHOSTS=$INFORMIXDIR/etc/sqlhosts.gbaseserver
export PATH=$INFORMIXDIR/bin:/usr/bin:${PATH}:.
export GL_DATE="%m/%d/%iy"
export DATETIME="%iY-%m-%d %H:%M:%S"
export DB_LOCALE=zh_CN.GB18030-2000
export CLIENT_LOCALE=zh_CN.GB18030-2000

数据库实例创建sbspace空间。

创建测试表：

drop table demo1_1;
create table demo1_1(c1 int,col1 byte,col2 text,col3 blob, col4 clob);
create index idx_demo1_1 on demo1_1(c1);


drop table demo1_2;
create table demo1_2(c1 int,col1 byte,col2 text,col3 blob, col4 clob);
create index idx_demo1_2 on demo1_2(c1);

先运行 java demo1程序向表demo1_1插入记录。
http://www.informixchina.net/Article/38149

JAVA示例程序

本示例程序读取表demo1_1记录，将记录复制到表demo1_2，并将读取的文件写入到文件中。
GBase 8t JDBC驱动提供标准的处理API接口。

JAVA环境变量
export JAVA_HOME=/home/informix/jdk1.8.0_111
export PATH=${PATH}:/home/informix/jdk1.8.0_111/bin
export CLASSPATH=.:/home/informix/jdk1.8.0_111/lib/tools.jar:/home/informix/jdk1.8.0_111/lib/dt.jar
export CLASSPATH=${CLASSPATH}:/home/gbase/jdbc/lib/ifxjdbc.jar

vi demo2.java

import java.util.*;
import java.sql.*;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.FileNotFoundException;
import java.io.Reader;
import java.sql.Blob;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.StringTokenizer;

public class demo2{
     private static String URL_STRING = "jdbc:informix-sqli://192.168.18.110:9088/demodb:INFORMIXSERVER=gbaseserver;CLIENT_LOCALE=zh_CN.GB18030-2000;DB_LOCALE=zh_CN.GB18030-2000;";
     private static String user = "informix";
     private static String password = "informix";
     static Statement         stmt;
     static PreparedStatement pstmt  = null;
     static Connection        conn = null;
     public static void main(String args[]) 
     { 
       try {
            Class.forName("com.informix.jdbc.IfxDriver");
        } catch (Exception e) {
            System.out.println("FAILED: failed to load Informix JDBC driver.");
            return;
        }
       try {
           conn = DriverManager.getConnection(URL_STRING,user, password);
           if (!conn.isClosed())
                         System.out.println("connect successfully"); 
           conn.setAutoCommit(true); 
        } catch (SQLException e) {
            System.out.println("FAILED: failed to connect: " + e.toString());
            return;
        }
        System.out.println("doing ........"); 
        

     System.out.println("Reading from demo1_1 and copying to demo1_2 ..\\n");
     System.out.println("Writing to files ..\\n");
        try {
            int row = 0;
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("Select c1,col1 ,col2 ,col3 , col4 from demo1_1");
            pstmt = conn.prepareStatement("insert into demo1_2(c1,col1 ,col2 ,col3 , col4) values (?, ?, ?, ?, ?)");
            while (rs.next()) {
                row++;
                int c1 = rs.getInt(1);
        byte[] b = null;
                b =rs.getBytes(2);
                Blob col1 = rs.getBlob(2);
                Clob col2 = rs.getClob(3);
                Blob col3 = rs.getBlob(4);
                Clob col4 = rs.getClob(5);
                pstmt.setInt(1,c1);
                pstmt.setBlob(2, col1);
                pstmt.setClob(3, col2);
                pstmt.setBlob(4, col3);
                pstmt.setClob(5, col4);
                pstmt.executeUpdate();
                //begin to write to files 
                byteToFile(b,"test"+row+".jpg");

            }
            rs.close();
            stmt.close();
            pstmt.close();
        } catch (SQLException e) {
            System.out.println("FAILED: Select Failed ...\\n");
            e.printStackTrace();
        }


         
      try {
            conn.close();
        } catch (SQLException e) {
        }


   }

    static void byteToFile(byte buf[] ,String filename){
        try{
          FileOutputStream fos = null;
          BufferedOutputStream bos = null;
      File file = new File(filename);  
      fos = new FileOutputStream(file);
      bos = new BufferedOutputStream(fos); 
      bos.write(buf);
          bos.flush();
    } catch (FileNotFoundException e) {
       e.printStackTrace();
        } catch (IOException e) { 
       e.printStackTrace();
        } 
    }  

}