详解jdbc实现对CLOB和BLOB数据类型的操作

详解jdbc实现对CLOB和BLOB数据类型的操作

1、 读取操作

CLOB 

//获得数据库连接    
  Connection con = ConnectionFactory.getConnection();    
  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    
    data = new String(c);    
    inStream.close();    
  }    
  inStream.close();    
  con.commit();    
  con.close();   

BLOB

//获得数据库连接    
  Connection con = ConnectionFactory.getConnection();    
  con.setAutoCommit(false);    
  Statement st = con.createStatement();    
  //不需要“for update”    
  ResultSet rs = st.executeQuery("select BLOBATTR from TESTBLOB where ID=1");    
  if (rs.next())    
  {    
    java.sql.Blob blob = rs.getBlob("BLOBATTR");    
    InputStream inStream = blob.getBinaryStream();    
    //data是读出并需要返回的数据，类型是byte[]    
    data = new byte[input.available()];    
    inStream.read(data);    
    inStream.close();    
  }    
  inStream.close();    
  con.commit();    
  con.close();  

2、写入操作

CLOB

//获得数据库连接    
  Connection con = ConnectionFactory.getConnection();    
  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();    
    //data是传入的字符串，定义：String data    
    char[] c = data.toCharArray();    
    outStream.write(c, 0, c.length);    
  }    
  outStream.flush();    
  outStream.close();    
  con.commit();    
  con.close();  
  

BLOB

//获得数据库连接    
  Connection con = ConnectionFactory.getConnection();    
  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");    
  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();    
    //data是传入的byte数组，定义：byte[] data   
    outStream.write(data, 0, data.length);    
  }    
  outStream.flush();    
  outStream.close();    
  con.commit();    
  con.close();    

3、读写CLOB/BLOB数据到文件

TNS：

# tnsnames.ora Network Configuration File: d:\oracle\product\10.2.0\client_1\NETWORK\ADMIN\tnsnames.ora  
 # Generated by Oracle configuration tools.  
 
 ORADB =  
   (DESCRIPTION =  
     (ADDRESS_LIST =  
       (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.100)(PORT = 1521))  
     )  
     (CONNECT_DATA =  
       (SID = ORCL)  
     )  
   )  
 
 MYORCL =  
   (DESCRIPTION =  
     (ADDRESS_LIST =  
       (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.100)(PORT = 1521))  
     )  
     (CONNECT_DATA =  
       (SERVICE_NAME = myorcl)  
     )  
   )  

Table：

create table TEST_ORALOB  
 (  
   ID     VARCHAR2(20),  
   TSBLOB BLOB not null,  
   TSCLOB CLOB not null  
 ) 

测试代码：

package lavasoft.oralob.common;  
 
import oracle.sql.BLOB;  
 
import java.io.*;  
import java.sql.*;  
 
/**  
 * JDBC读写Oracle10g的CLOB、BLOB  
 *  
 */  
public class TestOraLob {  
 
     public static void main(String[] args) {  
         insertBlob();  
         queryBlob();  
     }  
 
     public static void insertBlob() {  
         Connection conn = DBToolkit.getConnection();  
         PreparedStatement ps = null;  
         try {  
             String sql = "insert into test_oralob (ID, TSBLOB, TSCLOB) values (?, ?, ?)";  
             ps = conn.prepareStatement(sql);  
             ps.setString(1, "100");  
             //设置二进制BLOB参数  
             File file_blob = new File("C:\\a.jpg");  
             InputStream in = new BufferedInputStream(new FileInputStream(file_blob));  
             ps.setBinaryStream(2, in, (int) file_blob.length());  
             //设置二进制CLOB参数  
             File file_clob = new File("c:\\a.txt");  
             InputStreamReader reader = new InputStreamReader(new FileInputStream(file_clob));  
             ps.setCharacterStream(3, reader, (int) file_clob.length());  
             ps.executeUpdate();  
             in.close();  
         } catch (IOException e) {  
             e.printStackTrace();  
         } catch (SQLException e) {  
             e.printStackTrace();  
         } finally {  
             DBToolkit.closeConnection(conn);  
         }  
     }  
 
     public static void queryBlob() {  
         Connection conn = DBToolkit.getConnection();  
         PreparedStatement ps = null;  
         Statement stmt = null;  
         ResultSet rs = null;  
         try {  
             String sql = "select TSBLOB from TEST_ORALOB where id ='100'";  
             stmt = conn.createStatement();  
             rs = stmt.executeQuery(sql);  
             if (rs.next()) {  
                 //读取Oracle的BLOB字段  
                 InputStream in = rs.getBinaryStream(1);  
                 File file = new File("c:\\a1.jpg");  
                 OutputStream out = new BufferedOutputStream(new FileOutputStream(file));  
                 byte[] buff1 = new byte[1024];  
                 for (int i = 0; (i = in.read(buff1)) > 0;) {  
                     out.write(buff1, 0, i);  
                 }  
                 out.flush();  
                 out.close();  
                 in.close();  
                 //读取Oracle的CLOB字段  
                 char[] buff2 = new char[1024];  
                 File file_clob = new File("c:\\a1.txt");  
                 OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(file_clob));  
                 Reader reader = rs.getCharacterStream(1);  
                 for (int i = 0; (i = reader.read(buff2)) > 0;) {  
                     writer.write(buff2, 0, i);  
                 }  
                 writer.flush();  
                 writer.close();  
                 reader.close();  
             }  
             rs.close();  
             stmt.close();  
         } catch (IOException e) {  
             e.printStackTrace();  
         } catch (SQLException e) {  
             e.printStackTrace();  
         } finally {  
             DBToolkit.closeConnection(conn);  
         }  
     }  
 } 

注：如果是具体的字符串写入CLOB字段，简化写法：

//设置二进制CLOB参数   
 String xxx = "abcdefg";  
 ps.setCharacterStream(3, new StringReader(xxx), xxx.getBytes("GBK").length);   
 ps.executeUpdate();   
 in.close(); 

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