Oracle8i对Blob和Clob类型的操作

环境：
JDK:1.4
Database: Oracle 9i
App Server: Apache Tomcat 5.0
表结构：
CREATE TABLE TESTBLOB (ID Int, NAME Varchar2(20), BLOBATTR Blob)
CREATE TABLE TESTBLOB (ID Int, NAME Varchar2(20), CLOBATTR Clob)
说明：
JAVA可以通过JDBC，也可以通过JNDI访问并操作数据库，这两种方式的具体操作存在着一些差异，由于通过App Server的数据库连接池JNDI获得的数据库连接提供的java.sql.Blob和java.sql.Clob实现类与JDBC方式提供的不同，因此在入库操作的时候需要分别对待；出库操作没有这种差异，因此不用单独对待。

一、BLOB操作

1、入库(JDBC方式)
package test;
import java.sql.*;
import java.io.*;
public class BlobTest1 {
public static void main(String[] args) throws ClassNotFoundException, SQLException, IOException {
Class.forName("oracle.jdbc.driver.OracleDriver");
     Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "hr", "oracle");
     con.setAutoCommit(false);
     Statement st = con.createStatement();
     //插入一个空对象empty_blob()
     st.executeUpdate("insert into TESTBLOB (ID, NAME, BLOBATTR) values (1, 'thename', empty_blob())");
     //锁定数据行进行更新，注意"for update"语句
     ResultSet rs = st.executeQuery("select BLOBATTR from TESTBLOB where ID=1 for update");
     long sum=0;
     if (rs.next())
     {
         //得到java.sql.Blob对象后强制转换为oracle.sql.BLOB
         oracle.sql.BLOB blob = (oracle.sql.BLOB) rs.getBlob("BLOBATTR");
         OutputStream outStream = blob.getBinaryOutputStream();
        
         InputStream in = new FileInputStream("d:/aaa.rar");
         byte[] data = new byte[1024*4];
         //in.read(data);输入流读取数据，返回读取字节数
         int len;
         //data是传入的byte(字节)数组，定义：byte[] data
         while((len = in.read(data))!=-1){
        sum=sum+len;
         outStream.write(data, 0, len);//输出流写入数据库
         outStream.flush();
         }
         System.out.println();
         outStream.close();
     }
    
     con.commit();
     con.close();
     System.out.println("写入完毕\n文件大小"+sum+"字节");
}
}

2、出库(JDBC方式)
package test;
import java.sql.*;
import java.io.*;
public class BlobTest2 {
public static void main(String[] args) throws ClassNotFoundException, SQLException, IOException {
Class.forName("oracle.jdbc.driver.OracleDriver");
    Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "hr", "oracle");
    con.setAutoCommit(false);
    Statement st = con.createStatement();
    //不需要"for update"
    ResultSet rs = st.executeQuery("select BLOBATTR from TESTBLOB where ID=1");
    con.commit();
    long sum=0;//存放文件大小的变量
    if (rs.next())
    {
        java.sql.Blob blob = rs.getBlob("BLOBATTR");
        InputStream inStream = blob.getBinaryStream();
        byte[] data = new byte[1024*4];//data是读出并需要返回的数据，类型是byte[]
        FileOutputStream outStream = new FileOutputStream("d:/bbb.rar");
        int len;
        while((len = inStream.read(data))!=-1){
        sum+=len;
            outStream.write(data, 0, len);
            outStream.flush();
            }
        System.out.println();
        outStream.close();
        inStream.close();
    }
    con.close();
    System.out.println("读出完毕\n文件大小:"+sum+"字节");
}
}

3、入库(JNDI方式)
待整理……
4、出库(JNDI方式)
待整理……


二、CLOB操作

1、入库(JDBC方式)
package test;

import java.sql.*;
import java.io.*;

public class ClobTest1 {
public static void main(String[] args) throws ClassNotFoundException,
    SQLException, IOException {
   Class.forName("oracle.jdbc.driver.OracleDriver");
   Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "hr", "oracle");
   con.setAutoCommit(false);
   Statement st = con.createStatement();
   // 插入一个空对象empty_clob()
   st.executeUpdate("insert into TESTCLOB (ID, NAME, CLOBATTR) values (1, 'thename', empty_clob())");
   // 锁定数据行进行更新，注意"for update"语句
   ResultSet rs = st.executeQuery("select CLOBATTR from TESTCLOB where ID=1 for update");
   if (rs.next()) {
    // 得到java.sql.Clob对象后强制转换为oracle.sql.CLOB
    oracle.sql.CLOB clob = (oracle.sql.CLOB) rs.getClob("CLOBATTR");
    Writer outStream = clob.getCharacterOutputStream();

    Reader in = new FileReader("d:/aaa.txt");
    if (in.ready()) {
     int len = 0;
     int sum = 0;
     char[] c = new char[1024*2];
     while ((len = in.read(c)) != -1) {
      sum+=len;
      outStream.write(c, 0, len);
      outStream.flush();
     }
     System.out.println("总共" + c.length + "个字符");
   
     /*
     String data;//data是传入的字符串，定义：String data.若是jsp文本域内容，可直接用data接收request.getParameter("mytxtarea")
     data="不抛弃，不放弃！";//假设Servlet取到了
     char[] ch = data.toCharArray();
     outStream.write(ch, 0, ch.length);
     outStream.flush();
     System.out.println("总共" + ch.length + "个字符");
     outStream.close();
     */
    }
   }
   con.commit();
   con.close();
}

}

2、出库(JDBC方式)
package test;

import java.io.IOException;
import java.io.Reader;
import java.sql.*;

public class ClobTest2 {
public static void main(String[] args) throws ClassNotFoundException,
    SQLException, IOException {
   Class.forName("oracle.jdbc.driver.OracleDriver");
   Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "hr", "oracle");
   con.setAutoCommit(false);
   Statement st = con.createStatement();
   // 不需要"for update"
   ResultSet rs = st.executeQuery("select CLOBATTR from TESTCLOB where ID=1");
   if (rs.next()) {
    java.sql.Clob clob = rs.getClob("CLOBATTR");
    Reader inStream = clob.getCharacterStream();
    char[] c = new char[(int) clob.length()];
    inStream.read(c);
    // data是读出并需要返回的数据，类型是String
    String data = new String(c);
    inStream.close();
    System.out.println(data);
   }
   con.commit();
   con.close();
}

}