mybatis 解决Druid设置Oracle的Clob字段时的小坑

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">http://blog.csdn.net/renfufei/article/details/44887371</span>

mybatis 插入读取clob类型，之前使用类型转换器的方式，但是不好使，不能读取，

    <result property="message" column="message" jdbcType="CLOB"       javaType = "java.lang.String"  typeHandler ="examples.service.OracleClobTypeHandler"/>

package examples.service;import java.sql.CallableStatement;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import oracle.sql.CLOB;import org.apache.ibatis.type.JdbcType;import org.apache.ibatis.type.TypeHandler;public class OracleClobTypeHandler implements TypeHandler<Object> {    public Object valueOf(String param) {    return null;  }  @Override  public Object getResult(ResultSet arg0, String arg1) throws SQLException {    CLOB clob = (CLOB) arg0.getClob(arg1);    return (clob == null || clob.length() == 0) ? null : clob.getSubString((long) 1, (int) clob.length());  }  @Override  public Object getResult(ResultSet arg0, int arg1) throws SQLException {    return null;  }  @Override  public Object getResult(CallableStatement arg0, int arg1) throws SQLException {    return null;  }  @Override  public void setParameter(PreparedStatement arg0, int arg1, Object arg2, JdbcType arg3) throws SQLException {    CLOB clob = CLOB.empty_lob();    clob.setString(1, (String) arg2);    arg0.setClob(arg1, clob);  }}

后面看到这个帖子，

众所周知，Oracle有很多坑, 所以才有了去IOE。

在使用Druid做数据库连接池后，其实偶尔也会碰到小坑，这就是使用开源项目所必须去填平的。【如果使用不开源的产品，那就不是坑，而是陷阱了，你都不知道怎么去填坑】

用Druid连接池，通过JDBC往Oracle数据库的Clob字段插入数据，或者更新数据时，一个问题出现了。

类似于这样:

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">Caused by: java<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.lang</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ClassCastException</span>: <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.alibaba</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.druid</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.proxy</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.jdbc</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ClobProxyImpl</span> cannot be cast to oracle<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.sql</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.CLOB</span>at oracle<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.jdbc</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.driver</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.OraclePreparedStatement</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setClob</span>(OraclePreparedStatement<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.java</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">7919</span>)at <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.alibaba</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.druid</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.filter</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.FilterChainImpl</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.preparedStatement</span>_setClob(FilterChainImpl<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.java</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2978</span>)at <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.alibaba</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.druid</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.filter</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.FilterAdapter</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.preparedStatement</span>_setClob(FilterAdapter<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.java</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1178</span>)at <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.alibaba</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.druid</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.filter</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.FilterChainImpl</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.preparedStatement</span>_setClob(FilterChainImpl<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.java</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2975</span>)at <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.alibaba</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.druid</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.filter</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.FilterAdapter</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.preparedStatement</span>_setClob(FilterAdapter<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.java</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1178</span>)at <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.alibaba</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.druid</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.filter</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.FilterChainImpl</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.preparedStatement</span>_setClob(FilterChainImpl<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.java</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2975</span>)at <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.alibaba</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.druid</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.proxy</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.jdbc</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.PreparedStatementProxyImpl</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setClob</span>(PreparedStatementProxyImpl<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.java</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>)at <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.alibaba</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.druid</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.pool</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.DruidPooledPreparedStatement</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setClob</span>(DruidPooledPreparedStatement<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.java</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">588</span>)... <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">63</span> more</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

然后, 参考网上的文章，切换成 StringReader 以后又出现了字符串过长的问题,只好断点调试找BUG了，然后发现了一个方法:

<code class="hljs bash has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">ClobProxyImpl<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#getRawClob()</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

那么问题来了,也解决了。 代码贴出来如下所示:

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.cncounter.util.solution.processor;<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.sql.Clob;<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.sql.PreparedStatement;<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.sql.SQLException;<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ClobProcessor</span> {</span>  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String JDBC_TYPE_CLOB = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"clob"</span>;  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">processSolutionType</span>(PreparedStatement statement, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> order,      String jdbcType, Object paramValue) {    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> result = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span> == statement || order < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>){      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> result;    }    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//</span>    String value = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span> != paramValue){      value = paramValue.toString();    }    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//</span>    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(JDBC_TYPE_CLOB.trim().equalsIgnoreCase(jdbcType)){        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//</span>        Clob clob = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(paramValue <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">instanceof</span> Clob){          clob = (Clob)paramValue;        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {          clob = statement.getConnection().createClob();          <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 从 1 开始</span>          clob.setString(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, value);        }        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 阿里巴巴的坑</span>        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(clob <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">instanceof</span> com.alibaba.druid.proxy.jdbc.ClobProxyImpl){          com.alibaba.druid.proxy.jdbc.ClobProxyImpl impl = (com.alibaba.druid.proxy.jdbc.ClobProxyImpl)clob;          clob = impl.getRawClob(); <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 获取原生的这个 Clob</span>        }        statement.setClob(order, clob);        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//</span>        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 请注意, StringReader有坑,字段超过5万或者多少之后,就报错了. 所以注释了</span>        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// MyBatis的Clob类型也是这个BUG，如果不使用Clob,直接默认String,则Mybatis不报错</span>        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//StringReader reader = new StringReader(value);</span>        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//Reader reader = clob.getCharacterStream();</span>        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 设置输出流</span>        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//statement.setCharacterStream(order, reader, value.length());</span>      } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {        statement.setString(order, value);      }      result = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;    } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (SQLException e) {      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throw</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RuntimeException(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"设置["</span>+jdbcType+<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"]类型出错!"</span>, e);    }    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//</span>    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> result;  }}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li></ul>

分析了下原因，大概Druid是因为Clob有什么需要处理的，就增加了一个代理类:com.alibaba.druid.proxy.jdbc.ClobProxyImpl ; Blob就没有。 
然后呢，Oracle也比较粗暴，setClob() 里面直接强转为 oracle.sql.CLOB。于是问题就出现了。

另外值得一提的是MyBatis的Clob类型有BUG，在上面的代码注释之中也提醒了，属于是 StringReader 的坑，反正谁用谁知道。 我们的处理策略是， 在 xml 之中不指定 jdbcType，由MyBatis自己判断，当成String处理就不报错，然后也就不管了。

作者: 铁锚 http://blog.csdn.net/renfufei

日期: 2015年04月05日

把clob直接配置成varchar,插入和读取都没有问题，测试过10万字节的数据，可以正常插入和读取

   ggg LONG NULL,    之前对应longvarchar
   hhh CLOB NULL    之前对应clob

   

<span style="color:#ff0000;"> <result column="ggg" property="ggg" jdbcType="VARCHAR"/>      <result column="hhh" property="hhh" jdbcType="VARCHAR"/></span>