MyBatis中參數是List類型時怎麼處理?大家都知道MyBatis批處理大量數據是很難做到事務回滾的(事務由Spring管理),都將邏輯寫在存儲中又是及其頭疼的一件事(參數長度也有限制),那麼我想的是將參數在後臺封裝爲單個或多個list集合,直接通過MyBatis將此參數傳到數據庫存儲過程中,一來擺脫了MyBatis批量插入數據的諸多限制(例如:不能實時返回主鍵、foreach標籤循環集合長度有限制),二來就是在存儲中靈活的控制事務,但是這又會涉及兩個問題,MyBatis的xml文件中該怎麼封裝,利用BaseTypeHandler嗎?
對於這個問題,經過一天的研究終於算是跑通了,說一下解決辦法:
1.建立數據庫表,大家應該都有自己的庫表了,所以這一步基本上就可以跳過了。我之所以在這裏把庫表貼出來是爲了讓大家對應裏面的參數。
數據庫表:
- create table ZD_UNIT_MENU
- (
- unit_id VARCHAR2(32),
- menu_id VARCHAR2(32)
- )
2.在數據庫中建立相應的java對象(Oracle中的類型)和數組:
- CREATE OR REPLACE TYPE unit_menu_obj AS OBJECT(
- unitId VARCHAR2(32),
- menuId VARCHAR2(32)
- );
- CREATE OR REPLACE TYPE unit_menu_table AS table OF unit_menu_obj;
3.存儲過程:
- create or replace procedure save_unit_power(list0 in unit_menu_table,result0 out int) as
- sql_bind varchar(200);
- begin
- FOR i IN 1 .. list0.count LOOP
- sql_bind := 'insert into ZD_UNIT_MENU(UNIT_ID,MENU_ID) values('''||list0(i).unitId||''', '''||list0(i).menuId||''' )';
- execute immediate sql_bind;
- end loop;
-
- commit;
-
- result0 := 1;
-
- EXCEPTION
- WHEN OTHERS THEN
- result0 := -1;
- ROLLBACK;
- end save_unit_power;
4.再看看mybatis的配置吧:
- <parameterMap type="java.util.Map" id="_map">
- <parameter property="list0" jdbcType="ARRAY"
- javaType="java.util.List" mode="IN" typeHandler="com.zd.util.ListHandler"/>
- <parameter property="result0" jdbcType="DECIMAL"
- javaType="java.lang.Integer" mode="OUT" />
- </parameterMap>
- <select id="addUnitPower" statementType="CALLABLE" parameterMap="_map">
- <![CDATA[
- CALL save_unit_power(?,?)
- ]]>
- </select>
5.看看我是如何調用的?我直接貼我的server代碼了,dao層的就沒必要了:
- List<UnitMenu> list = new ArrayList<UnitMenu>();
- Map<String, Object> _map = new HashMap<String, Object>();
- String[] menuIds = menuTreeIds.split(",");
- JSONObject job = new JSONObject();
- int result = -1;
- for(int i = 0; i < menuIds.length; i++){
- UnitMenu um = new UnitMenu();
- um.setMenuId(menuIds[i]);
- um.setUnitId(unitId);
- list.add(um);
- }
- _map.put("list0", list);
- _map.put("result0", "");
- unitMenuMapper.addUnitPower(_map);
- System.out.println("================================================_map = "+_map.toString());
- result = (Integer)_map.get("result0");
- System.out.println("================================================result = "+result);
6.非常關鍵的一點兒,細心的人應該會注意到,在mapper.xml配置中,有typeHandler配置,裏面配置的實際上是我寫的一個類,這個類的作用就是講java中的list轉換成數據庫中我們建立的對象和數組,看代碼吧:
- package com.zd.util;
-
- import java.sql.CallableStatement;
- import java.sql.Connection;
- import java.sql.DriverManager;
- import java.sql.ResultSet;
- import java.sql.SQLException;
- import java.util.ArrayList;
- import java.util.List;
-
- import oracle.sql.ARRAY;
- import oracle.sql.ArrayDescriptor;
- import oracle.sql.STRUCT;
- import oracle.sql.StructDescriptor;
-
- import org.apache.ibatis.type.BaseTypeHandler;
- import org.apache.ibatis.type.JdbcType;
-
- import com.zd.model.system.UnitMenu;
-
- public class ListHandler extends BaseTypeHandler{
-
- @Override
- public Object getNullableResult(ResultSet arg0, String arg1)
- throws SQLException {
-
- return null;
- }
-
- @Override
- public Object getNullableResult(CallableStatement arg0, int arg1)
- throws SQLException {
-
- return null;
- }
-
- @SuppressWarnings("unchecked")
- @Override
- public void setNonNullParameter(java.sql.PreparedStatement parameterSetter, int i,
- Object o, JdbcType jdbcType) throws SQLException {
- Connection conn = null;
- try {
- if(null != o){
- List<UnitMenu> list = (ArrayList<UnitMenu>) o;
- conn = DriverManager.getConnection("jdbc:oracle:thin:@192.168.1.88:1521:orcl", "tctscm", "tctscm");
-
- ARRAY array = getArray(conn, "UNIT_MENU_OBJ", "UNIT_MENU_TABLE", list);
- parameterSetter.setArray(i, array);
- }
- } catch (Exception e) {
- e.printStackTrace();
- } finally{
- if(null != conn){
- conn.close();
- }
- }
-
- }
-
- @SuppressWarnings("rawtypes")
- private ARRAY getArray(Connection con,String OracleObj, String Oraclelist, List<UnitMenu> listData) throws Exception {
- ARRAY array = null;
- ArrayDescriptor desc = ArrayDescriptor.createDescriptor(Oraclelist, con);
- STRUCT[] structs = new STRUCT[listData.size()];
- if (listData != null && listData.size() > 0){
- StructDescriptor structdesc = new StructDescriptor(OracleObj, con);
- for (int i = 0; i < listData.size(); i++){
- Object[] result = {listData.get(i).getUnitId(),listData.get(i).getMenuId()};
- structs[i] = new STRUCT(structdesc, con, result);
- }
- array = new ARRAY(desc, con, structs);
- }else{
- array = new ARRAY(desc, con, structs);
- }
- return array;
- }
-
- }