Java更新Oracle的clob类型字段

1.查询该clob字段

<select id="selectItsmTask" resultType="java.util.HashMap"
parameterType="java.util.HashMap">
select a.task_oid,a.task_history from itsm_task a where a.task_oid = #{REQ_TASK_OID,jdbcType=VARCHAR}
</select>


2.处理该clob字段查询结果

/**
* Clob类型 转String
*
* @param clob
* @return
*/
private String ClobToString(Clob clob) {
String ret = "";
try {
Reader read = clob.getCharacterStream();
BufferedReader br = new BufferedReader(read);
String s;
s = br.readLine();
StringBuffer sb = new StringBuffer();
while (s != null) {
sb.append(s);
s = br.readLine();
}
ret = sb.toString();
if (br != null) {
br.close();
}
if (read != null) {
read.close();
}
} catch (SQLException e) {
logger.error("Clob转String失败(sql)：" + e);
} catch (IOException e) {
logger.error("Clob转String失败：" + e);
}
return ret;
}
/**
* 修改clob字段内容
*
* @param map
* @return
*/
private void updateClob(Map<String, Object> map) {
Map<String, Object> updateInfo = new HashMap<String, Object>();
updateInfo.put("reqTaskOid", map.get("REQ_TASK_OID"));
// 获取itsm_task中的task_history字段内容
Map<String, Object> result = fieldsModifyMapper.selectItsmTask(map);
Clob columnClob = (Clob) result.get("TASK_HISTORY");
String taskHistory = ClobToString(columnClob);
// 修改itsm_task中的task_history字段内容
// 创建xml的Document对象
try {
Document document = DocumentHelper.parseText(taskHistory);
List lists = document.selectNodes("/workflow/node/fields/field");//寻找field节点
Iterator iter = lists.iterator();
while (iter.hasNext()) {
Element fieldElement = (Element) iter.next();
if (fieldElement.attributes().size() > 0) {
Attribute attr = (Attribute) fieldElement.attributes().get(0);
if (attr.getValue().equals("hope_finish_date")) {
fieldElement.setText("<![CDATA["+String.valueOf(map.get("FLD_HOPE_FINISH_DATE_NEW"))+"]]>");
}
if (attr.getValue().equals("software_req_content")) {
fieldElement.setText("<![CDATA["+String.valueOf(map.get("FLD_SOFTWARE_REQ_CONTENT_NEW"))+"]]>");
}
if (attr.getValue().equals("req_complexity")) {
fieldElement.setText("<![CDATA["+String.valueOf(map.get("FLD_REQ_COMPLEXITY_NEW_ID"))+"]]>");
}
if (attr.getValue().equals("is_dev_assessment")) {
fieldElement.setText("<![CDATA["+String.valueOf(map.get("FLD_IS_DEV_ASSESSMENT_NEW_ID"))+"]]>");
}
}
}
updateInfo.put("taskHistory", StringEscapeUtils.unescapeXml(document.asXML()));
} catch (DocumentException e) {
e.printStackTrace();
}
fieldsModifyMapper.updateItsmTask(updateInfo);
}


3.更新该clob字段查询结果

<update id="updateItsmTask" parameterType="java.util.HashMap">
update itsm_task a
<set>
<if test="taskHistory != null">
a.task_history =#{taskHistory,jdbcType=CLOB}
</if>
</set>
where a.task_oid = #{reqTaskOid,jdbcType=VARCHAR}
</update>


**注意：**使用StringEscapeUtils.unescapeXml(String str）方法，防止标签符号在存入Oracle数据库的时候被转义。