Java访问Oracle的Clob、Blob字段

在使用Java访问Oracle的Clob或Blob字段时，大家常常会碰到很多问题，利用Oracle的新的更新方式可以解决

/* 
 *  Oracle 测试表 
 */
CREATE TABLE T_Demo( 
    id integer primary key, 
    content clob
); 

/* 
 *  实体Bean 
 */
package com.utsun.common.demo; 
  public class DemoBean{ 
    private int id; 
    private String content; 
    public int getId(){ 
       return this.id; 
    } 

    public String getConent(){ 
       return this.content; 
    }

    public void setId(int id){ 
       this.id = id; 
    }

    public void setContent(String content){ 
       this.content = content; 
    }
}

/* 
 *  Action Bean 
 */
package com.utsun.common.demo;  

import java.sql.*;
import java.text.SimpleDateFormat;
import tellhow.commonweb.db.*;
import oracle.sql.*;
import oracle.jdbc.driver.*;
import java.io.*;

public class DemoActionBean{ 
    DBConnectionManager dbcm = DBConnectionManager.getInstance(); 
    Connection connection = null; 
    DBAccess dba = null;  

     void init() throws Exception{ 
       try{ 
           connection = dbcm.getConnection(); 
           dba = new DBAccess(connection); 
       } 
       catch (Exception s){ 
           dispose(); 
           throw e; 
       } 
    } 

    void dispose() throws Exception{ 
       try{ 
           dbcm.freeConnection(connection); 
       } 
       catch (Exception e){ 
           throw e; 
       } 
    }  

    public BulletinBean fetch(int keyid) throws Exception{ 
       DemoBean bean = new DemoBean(); 
       bean.setBtID(keyid); 

       String sql = "SELECT * FROM T_Demo WHERE id=" + Integer.toString(keyid); 
       String line = ""; 
       String text = ""; 
       ResultSet rs = null; 
       try{ 
           init(); 
           rs = dba.openSelect(sql); 
           try{ 
              while (rs.next()){ 
                  CLOB clob = (oracle.sql.CLOB)rs.getClob("Content"); 
                  if (clob != null){ 
                     BufferedReader in = new BufferedReader(clob.getCharacterStream()); 
                     while ((line = in.readLine()) != null) 
                         text += line + "\n"; 
                     in.close(); 
                  } 
                  bean.setContent(text); 
                  break; 
              } 
           } 
           finally{ 
              rs.close(); 
           } 
       } 
       catch (Exception e){ 
           throw e; 
       } 
       finally{ 
           dispose(); 
       } 
       return bean; 
    } 
     public boolean insert(DemoBean bean) throws Exception   { 
       boolean result = true; 
       try { 
           init(); 
           int maxID = 1; 
           ResultSet rs = dba.openSelect("SELECT NVL(Max(id),0) FROM T_Demo"); 
           while (rs.next()) 
              maxID = rs.getInt(1) + 1; 
           rs.close();  

           StringBuffer sqlBT = new StringBuffer(); 
           sqlBT.append("BEGIN "); 
           sqlBT.append("  INSERT INTO T_Demo (id, content) "); 
           sqlBT.append("  VALUES (?,EMPTY_CLOB())"); 
           sqlBT.append("    RETURN content INTO ?; "); 
           sqlBT.append("END;"); 

           connection.setAutoCommit(false); 
           OracleCallableStatement ocs = (OracleCallableStatement)connection.prepareCall(sqlBT.toString()); 
           ocs.setInt(1, maxID); 
           ocs.registerOutParameter(2, OracleTypes.CLOB); 
           ocs.executeUpdate();

           CLOB clob = ocs.getCLOB(2); 
           clob.putString(1, bean.getContent()); 
           ocs.close(); 
           connection.commit(); 
       } 
       catch (Exception e) { 
           connection.rollback(); 
           throw e; 
       } 
       finally    { 
           dispose(); 
       } 
       return result; 
    }

    public boolean update(DemoBean bean) throws Exception   { 
       boolean result = true; 
       try { 
           init();  

           StringBuffer sqlBT = new StringBuffer(); 
           sqlBT.append("BEGIN "); 
           sqlBT.append("  UPDATE T_Demo SET content=EMPTY_CLOB() WHERE id=? "); 
           sqlBT.append("  RETURN content INTO ?; "); 
           sqlBT.append("END;");  

           connection.setAutoCommit(false); 
           OracleCallableStatement ocsBT = (OracleCallableStatement)connection.prepareCall(sqlBT.toString()); 
           ocsBT.setInt(2, bean.getID()); 
           ocsBT.registerOutParameter(1, OracleTypes.CLOB); 
           ocsBT.executeUpdate(); 
           CLOB clob = ocsBT.getCLOB(1); 
           clob.putString(1, content); 
           ocsBT.close(); 
           connection.commit(); 
       } 
       catch (Exception e)  {
......