import java.sql.*;
import java.io.*;
import oracle.jdbc.driver.OracleResultSet;
import oracle.sql.CLOB;

public class TestOracleClob implements Serializable{

public static void main(String[] args) {

//create table test (id integer,content clob);
System.out.println("-------------------insert -----------------");

try{
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection con=DriverManager.getConnection("jdbc:oracle:thin:@fangm:1521:LICSFC","SFC","SFC");

//con.setAutoCommit(false);
//Ok 1
String sql="insert into test values(1,empty_clob())";
Statement stmt=con.createStatement();
ResultSet rs=stmt.executeQuery(sql);
String sqll="select content from test where id=1 for update";
ResultSet rss=stmt.executeQuery(sqll);

if(rss.next()){
         CLOB clob = ((OracleResultSet)rss).getCLOB(1);
        clob.putString(1,"ddddddddddddddddddddddddddddddddddd");
        sql="update test set content=? where id=1";
         PreparedStatement pstmt=con.prepareStatement(sql);
         pstmt.setClob(1,clob);
         pstmt.executeUpdate();
         pstmt.close();
}

//Ok 2
//String sql1="insert into test values(2,empty_clob())";
//ResultSet rs3=stmt.executeQuery(sql1);
String sql12="insert into test values(?,?)";
PreparedStatement pstmt1=con.prepareStatement(sql12);
pstmt1.setInt(1,2);
pstmt1.setClob(2,oracle.sql.CLOB.empty_lob());
pstmt1.executeUpdate();
String sqll2="select content from test where id=2 for update";
ResultSet rss2=stmt.executeQuery(sqll2);
if(rss2.next()){
CLOB clob = ((OracleResultSet)rss2).getCLOB(1);
clob.putString(1,"affffffffffdfdfdfdddddddffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffdddfff");
String sql1="update test set content=? where id=2";
PreparedStatement pstmt=con.prepareStatement(sql1);
pstmt.setClob(1,clob);
pstmt.executeUpdate();
pstmt.close();
}
//con.commit();

rss.close();
rss2.close();
pstmt1.close();
rs.close();
stmt.close();
con.close();
System.out.println("-------------insert ok-------------");
}catch(Exception e){
System.out.println("insert:"+e);
}

System.out.println("-------------------query -----------------");
try{
String content="";
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection con=DriverManager.getConnection("jdbc:oracle:thin:@fangm:1521:LICSFC","SFC","SFC");
Statement stmt=con.createStatement();
String sql="select content from test where id=1";
ResultSet rs=stmt.executeQuery(sql);
if(rs.next()){
CLOB clob = ((OracleResultSet)rs).getCLOB(1);
if(clob!=null){
Reader is=clob.getCharacterStream();
BufferedReader br=new BufferedReader(is);
String s=br.readLine();
while(s!=null){
content+=s+",";
s=br.readLine();
}
}
}

rs.close();

stmt.close();
con.close();
System.out.println("clob:"+content);
System.out.println("-------------query ok-------------");
}catch(Exception ee){
System.out.println("query:"+ee);
}

}
}

【注】
1.insert 可以直接插入字符串，但是有个数限制。
   如果开始插入empty_clob()，后面再update，则没有了限制。


2.如果后面有update，则在select时候必须lock（for update）