之前在学校的时候做的都是练习，小儿科，遇到的情况完全都在自己的设想范围内。最近老是遇到字段溢出的情况，但是varchar2好像最长也只有4000个字符。所以不得不另辟蹊径，就找上了clob字段。

package test;import java.io.BufferedReader;import java.io.IOException;import java.io.Writer;import java.sql.Clob;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import oracle.sql.CLOB;public class ClobTest {	 private static Connection conn;       	    static {  	        try {  	            Class.forName("oracle.jdbc.driver.OracleDriver");  	            conn = DriverManager.getConnection(  	                    "jdbc:oracle:thin:@localhost:1521:orcl","wch","wch123");  	        } catch (ClassNotFoundException e) {  	            e.printStackTrace();  	        } catch (SQLException e) {  	            e.printStackTrace();  	        }  	    }  	      	    public static void main(String[] args) throws SQLException, IOException {  	      //  testInsert();  	       // testUpdate();  	        testRead();  	    }  	  	    private static void testInsert() throws SQLException {  	        String sql = "insert into CLOBTEST values(1, empty_clob(),empty_clob())";  	        Statement stm = conn.createStatement();  	        stm.execute(sql);  	    }  	      	    private static void testUpdate() throws SQLException, IOException {  	        String sql = "select context,c2 from CLOBTEST where id = 1 for update";  	        Statement stm = conn.createStatement();  	        ResultSet rs = stm.executeQuery(sql);  	        while (rs.next()) {  	            oracle.sql.CLOB c = (CLOB) rs.getClob(1);  	            Writer w = c.setCharacterStream(1);	            w.write("wchwchwch\r\n");	            w.write("哈哈哈\r\n哈哈哈ds", 2, 5);	            w.flush();	            w.close();	            c = (CLOB) rs.getClob(2);	            w = c.setCharacterStream(1);	            w.write("dingsen");	            w.flush();	            w.close();	        }	        conn.commit(); 	    }  	      	    private static void testRead() throws SQLException, IOException {  	        String sql = "select context,c2 from CLOBTEST where id = 1";  	        PreparedStatement pstm = conn.prepareStatement(sql);  	        ResultSet rs = pstm.executeQuery();  	        System.out.println("-----------------------------------");	        while (rs.next()) {  	            Clob clob = rs.getClob(1);  	            BufferedReader r = new BufferedReader(clob.getCharacterStream());  	            char[] cs = new char[10]; 	            int total = 0;	            StringBuilder sb = new StringBuilder();	            while ((total = r.read(cs)) != -1) {  	                sb.append(cs,0,total);	            }  	            System.out.println(sb.toString());	        }  	    }  }