CLOB字段的插入以及更新操作 .

1.  插入方法，首先需要先插入一个空的CLOB对象，之后查询出该条对象，并进行更新操作：

@Override
public void add(Object obj) throws DAOException {

    Connection conn = null;
    PreparedStatement pst = null;
    try {
        conn = getJdbcTemplate().getDataSource().getConnection();
        conn.setAutoCommit(false);
        //获得一个主键
        String seqSql ="select cms.SEQ_TERMSERVICE_ID.nextval from dual";
        Long id = this.getJdbcTemplate().queryForLong(seqSql);
        //执行插入操作
        Statement st = conn.createStatement();
        String sql1 = "insert into cms.s_termservice(TERMSERVICE_ID,CREATETIME,UPDATETIME,CONTENT) values(" + id + ",sysdate,sysdate,empty_clob())";
        st.executeUpdate(sql1);
        //从数据库中重新获取CLOB对象写入数据
        String sql2 = "select CONTENT from cms.s_termservice where TERMSERVICE_ID=" + id + " for update";
        //锁定数据行进行更新，注意“for update”语句
        ResultSet rs = st.executeQuery(sql2);
        while(rs.next()) {
            CLOB clob = (CLOB)rs.getClob("CONTENT");
            clob.putString(1, ((TermService)obj).getContent());
            String sql3 = "update cms.s_termservice set CONTENT=? where TERMSERVICE_ID=" + id;
            pst = conn.prepareStatement(sql3);
            pst.setClob(1, clob);
            pst.execute();
        }
           //最后一步自己提交
           conn.commit();
           conn.setAutoCommit(true);
    } catch (SQLException e) {
        logger.error("in TermserviceDaoImpl,add fail, e is " + e.getMessage());
    } finally {
           try {
            if(conn != null) {
                   conn.close();
            }
            if(pst != null) {
                pst.close();
            }
           } catch (SQLException e1) {
            logger.error("in TermserviceDaoImpl,add fail, e1 is " + e1.getMessage());
           }
    }
}

@Override public void add(Object obj) throws DAOException { Connection conn = null; PreparedStatement pst = null; try { conn = getJdbcTemplate().getDataSource().getConnection(); conn.setAutoCommit(false); //获得一个主键 String seqSql ="select cms.SEQ_TERMSERVICE_ID.nextval from dual"; Long id = this.getJdbcTemplate().queryForLong(seqSql); //执行插入操作 Statement st = conn.createStatement(); String sql1 = "insert into cms.s_termservice(TERMSERVICE_ID,CREATETIME,UPDATETIME,CONTENT) values(" + id + ",sysdate,sysdate,empty_clob())"; st.executeUpdate(sql1); //从数据库中重新获取CLOB对象写入数据 String sql2 = "select CONTENT from cms.s_termservice where TERMSERVICE_ID=" + id + " for update"; //锁定数据行进行更新，注意“for update”语句 ResultSet rs = st.executeQuery(sql2); while(rs.next()) { CLOB clob = (CLOB)rs.getClob("CONTENT"); clob.putString(1, ((TermService)obj).getContent()); String sql3 = "update cms.s_termservice set CONTENT=? where TERMSERVICE_ID=" + id; pst = conn.prepareStatement(sql3); pst.setClob(1, clob); pst.execute(); } //最后一步自己提交 conn.commit(); conn.setAutoCommit(true); } catch (SQLException e) { logger.error("in TermserviceDaoImpl,add fail, e is " + e.getMessage()); } finally { try { if(conn != null) { conn.close(); } if(pst != null) { pst.close(); } } catch (SQLException e1) { logger.error("in TermserviceDaoImpl,add fail, e1 is " + e1.getMessage()); } } }
2. 更新操作，我个人是先置空CLOB字段，在从新更新该字段，如果没这样做，在更新时，如果更新数据比数据库中的数据短时，并不能完全更新，本人是这样操作的

以下是代码：

@Override
public void update(Object obj) throws DAOException {

    Connection conn = null;
    PreparedStatement pst = null;
    try {
        conn = getJdbcTemplate().getDataSource().getConnection();
        conn.setAutoCommit(false);
        Statement st = conn.createStatement();
        int id = ((TermService)obj).getTermserviceId();
        //从数据库中重新获取CLOB对象写入数据
        String sql1 = "update cms.s_termservice s set s.CONTENT=' ' where TERMSERVICE_ID=" + id; //这边需要设置一个空的字段，后面就不会出现空指针
        st.execute(sql1);
        String sql2 = "select CONTENT from cms.s_termservice s where s.TERMSERVICE_ID=" + id;
        //锁定数据行进行更新，注意“for update”语句
        ResultSet rs = st.executeQuery(sql2);
        while(rs.next()) {
            CLOB clob = (CLOB)rs.getClob("CONTENT");
            if(clob != null) {
                clob.putString(1, ((TermService)obj).getContent());
                String sql3 = "update cms.s_termservice set CONTENT=?,UPDATETIME=sysdate where TERMSERVICE_ID=" + id;
                pst = conn.prepareStatement(sql3);
                pst.setClob(1, clob);
                pst.execute();
            }
        }
           //最后一步自己提交
           conn.commit();
           conn.setAutoCommit(true);
    } catch (SQLException e) {
        logger.error("in TermserviceDaoImpl,add fail, e is " + e.getMessage());
    } finally {
           try {
            if(conn != null) {
                   conn.close();
            }
            if(pst != null) {
                pst.close();
            }
           } catch (SQLException e1) {
            logger.error("in TermserviceDaoImpl,add fail, e1 is " + e1.getMessage());
           }
    }
}

@Override public void update(Object obj) throws DAOException { Connection conn = null; PreparedStatement pst = null; try { conn = getJdbcTemplate().getDataSource().getConnection(); conn.setAutoCommit(false); Statement st = conn.createStatement(); int id = ((TermService)obj).getTermserviceId(); //从数据库中重新获取CLOB对象写入数据 String sql1 = "update cms.s_termservice s set s.CONTENT=' ' where TERMSERVICE_ID=" + id; //这边需要设置一个空的字段，后面就不会出现空指针 st.execute(sql1); String sql2 = "select CONTENT from cms.s_termservice s where s.TERMSERVICE_ID=" + id; //锁定数据行进行更新，注意“for update”语句 ResultSet rs = st.executeQuery(sql2); while(rs.next()) { CLOB clob = (CLOB)rs.getClob("CONTENT"); if(clob != null) { clob.putString(1, ((TermService)obj).getContent()); String sql3 = "update cms.s_termservice set CONTENT=?,UPDATETIME=sysdate where TERMSERVICE_ID=" + id; pst = conn.prepareStatement(sql3); pst.setClob(1, clob); pst.execute(); } } //最后一步自己提交 conn.commit(); conn.setAutoCommit(true); } catch (SQLException e) { logger.error("in TermserviceDaoImpl,add fail, e is " + e.getMessage()); } finally { try { if(conn != null) { conn.close(); } if(pst != null) { pst.close(); } } catch (SQLException e1) { logger.error("in TermserviceDaoImpl,add fail, e1 is " + e1.getMessage()); } } }
3.  获取CLOB，并进行STRING的转化

private RowMapper showTSMapper = new RowMapper() {
    public Object mapRow(ResultSet rs, int rowNum) throws SQLException {
        TermService termService = new TermService();
        termService.setTermserviceId(rs.getInt("TERMSERVICE_ID"));
        termService.setCreatetime(rs.getDate("CREATETIME"));
        termService.setUpdatetime(rs.getDate("UPDATETIME"));
        StringBuffer sb = new StringBuffer();
           try {
            CLOB clob = (CLOB)rs.getClob("CONTENT");
            if(clob != null) {
                    Reader is = clob.getCharacterStream();
                    BufferedReader br = new BufferedReader(is);
                    String s = br.readLine();
                    while (s != null) {
                        sb.append(s);
                        s = br.readLine();
                    }
            }
            if(sb.length()>10) {
                termService.setContent(sb.substring(0,10) + ".......");
            } else {
                termService.setContent(sb.toString());
            }
        } catch (IOException e) {
            logger.error("in TermserviceDaoImpl.showTSMapper fail, e is " + e.getMessage());
        }
        return termService;
    }
};

private RowMapper modifyMapper = new RowMapper() {
    public Object mapRow(ResultSet rs, int rowNum) throws SQLException {
        TermService termService = new TermService();
        termService.setTermserviceId(rs.getInt("TERMSERVICE_ID"));
        termService.setCreatetime(rs.getDate("CREATETIME"));
        termService.setUpdatetime(rs.getDate("UPDATETIME"));
        StringBuffer sb = new StringBuffer();
           try {
            CLOB clob = (CLOB)rs.getClob("CONTENT");
            if(clob != null) {
                    Reader is = clob.getCharacterStream();
                    BufferedReader br = new BufferedReader(is);
                    String s = br.readLine();
                    while (s != null) {
                        sb.append(s);
                        s = br.readLine();
                    }
            }
            termService.setContent(sb.toString());
        } catch (IOException e) {
            logger.error("in TermserviceDaoImpl.tsMapper fail, e is " + e.getMessage());
        }
        return termService;
    }
};