JDBC操作Oracle CLOB对象

把C:\TEMP\cbr_order_version_exp.log内容存入CLOB字段中，并将内容从数据库又读入C:\temp\retrieved\cbr_order_version_exp.log文件中

---创建表

SQL>create table clob_content(file_name varchar2(40) not null, clob_column clob not null);

---确认文件

C:\TEMP>dir cbr_order*.log

Volume in drive C is OS

Volume Serial Number is 94D2-727F

Directory of C:\TEMP

02/06/2012 06:03 PM 1,309 cbr_order_version_exp.log

---java代码

package com.ssgm.jyu.jdbc; import java.sql.*; import java.io.*; import oracle.sql.*; import oracle.jdbc.*; public class JdbcClob { public static void main(String[] args){ Connection conn = null; Statement stmt = null; try{ Class.forName("oracle.jdbc.driver.OracleDriver"); } catch(ClassNotFoundException e){ e.printStackTrace(); } try{ conn = DriverManager.getConnection("jdbc:oracle:thin:@hostname:1521:SID","username","password"); stmt = conn.createStatement(); conn.setAutoCommit(false); String sourceDir = "C:\\temp\\"; String targetDir = "C:\\temp\\retrieved\\"; String fileName = "cbr_order_version_exp.log"; System.out.println("Writing CLOB from "+sourceDir+fileName+" to table clob_content"); writeCLOB(stmt,sourceDir+fileName); System.out.println("Reading CLOB from table clob_content to "+targetDir+fileName); readCLOB(stmt, fileName, sourceDir, targetDir); } catch(SQLException e){ e.printStackTrace(); } finally{ try{ stmt.close(); conn.close(); } catch(SQLException e){ e.printStackTrace(); } } } public static void writeCLOB(Statement stmt, String fullName){ ResultSet clobRS = null; try{ String sqlInsert = "INSERT INTO CLOB_CONTENT VALUES('"+fullName+"',EMPTY_CLOB())"; //step1: initialize LOB column to set the LOB locator stmt.executeUpdate(sqlInsert); //step2: retrieve the row containing the LOB locator clobRS = stmt.executeQuery("SELECT clob_column FROM clob_content WHERE file_name='"+fullName+"' FOR UPDATE"); clobRS.next(); //step3: create a LOB obj and read the LOB locator CLOB myClob = ((OracleResultSet) clobRS).getCLOB("clob_column"); //step4: get the chunk size of the LOB from the LOB object int chunkSize = myClob.getChunkSize(); //step5: create a buffer to hold a block of data from the file char[] textBuffer = new char[chunkSize]; //step6: create a file object File file = new File(fullName); //step7: create input stream objects to read the file contents FileInputStream in = new FileInputStream(file); InputStreamReader reader = new InputStreamReader(in); BufferedReader br = new BufferedReader(reader); //step8: read the file contents and write it to the LOB long position = 1; int charsRead; while((charsRead = br.read(textBuffer)) != -1){ //write the buffer contents to myClob myClob.putChars(position, textBuffer); position = position + charsRead; } //step9: perform a commit stmt.execute("COMMIT"); //step10: close the objects used to read the file br.close(); reader.close(); in.close(); System.out.println("Wrote content from "+fullName+" to CLOB"); } catch(SQLException e){ System.out.println("Error Code: "+e.getErrorCode()); System.out.println("Error Message: "+e.getMessage()); e.printStackTrace(); } catch(IOException e){ System.out.println("Error Message: "+e.getMessage()); e.printStackTrace(); } } public static void readCLOB( Statement stmt, String fileName, String sourceDir, String targetDir){ String sqlSelect = "SELECT clob_column FROM clob_content WHERE file_name='" +sourceDir+fileName+"'"; ResultSet clobRS = null; try{ //step1: retrieve the row containing the LOB locator clobRS = stmt.executeQuery(sqlSelect); clobRS.next(); //step2: create a LOB obj and read the LOB locator CLOB myClob = ((OracleResultSet) clobRS).getCLOB("clob_column"); //step3: get the chunk size of the LOB from the LOB object int chunkSize = myClob.getChunkSize(); //step4: create a buffer to hold a chunk of data //retrieved from the LOB object char[] textBuffer = new char[chunkSize]; //step5: create a file object String saveFile = targetDir+"retrievedCLOB"+fileName; File file = new File(saveFile); //step6: create output stream obj to write the LOB //contents to the new file FileOutputStream out = new FileOutputStream(file); OutputStreamWriter writer = new OutputStreamWriter(out); BufferedWriter bw = new BufferedWriter(writer); //step7: get the length of the LOB contents from the LOB obj long clobLength = myClob.getLength(); //step8: while the end of the LOB contents have not been reached, //read a chunk of data from LOB to buffer, //then write the buffer contents to the file for(long position = 1; position <=clobLength; position+=chunkSize){ //read a chunk of data from myClob //and store it in the buffer int charsRead = myClob.getChars(position, chunkSize, textBuffer); //write the buffer contents to file bw.write(textBuffer); } //step9: close the stream objects bw.close(); writer.close(); out.close(); System.out.println("Read CLOB and save file" + saveFile ); } catch(SQLException e){ System.out.println("Error Code: "+e.getErrorCode()); System.out.println("Error Message: "+e.getMessage()); e.printStackTrace(); } catch(IOException e){ System.out.println("Error Message: "+e.getMessage()); e.printStackTrace(); } } }

---运行屏幕显示

Writing CLOB from C:\temp\cbr_order_version_exp.log to table clob_content

Wrote content from C:\temp\cbr_order_version_exp.log to CLOB

Reading CLOB from table clob_content to C:\temp\retrieved\cbr_order_version_exp.log

Read CLOB and save fileC:\temp\retrieved\retrievedCLOBcbr_order_version_exp.log

---数据库验证

SQL> select * from clob_content;

FILE_NAME

--------------------------------------------------------------------------------

CLOB_COLUMN

--------------------------------------------------------------------------------

C:\temp\cbr_order_version_exp.log

;;;

Export: Release 10.2.0.4.0 - 64bit Production on Monday, 06 February, 2012

---操作系统验证

C:\TEMP>cd retrieved

C:\TEMP\retrieved>dir

Volume in drive C is OS

Volume Serial Number is 94D2-727F

Directory of C:\TEMP\retrieved

02/08/2012 03:45 PM <DIR> .

02/08/2012 03:45 PM <DIR> ..

02/08/2012 03:45 PM 8,132 retrievedCLOBcbr_order_version_exp.log

1 File(s) 8,132 bytes

2 Dir(s) 22,748,835,840 bytes free