DELIMITER $ 
CREATE PROCEDURE mybatis.ges_user_count(IN age INT, OUT user_count INT) 
BEGIN 
SELECT COUNT(*) FROM users WHERE users.age=age INTO user_count; 
END 
$

這個(gè)存儲(chǔ)過程的含義其實(shí)比較簡(jiǎn)單的，就是輸入age，然后執(zhí)行select count(*) from users where users.age = age into user_count；獲得年齡等于age的人數(shù)賦值給user_count，還是比較簡(jiǎn)單的。

接下來是存儲(chǔ)過程的調(diào)用，執(zhí)行如下命令就可以完成存儲(chǔ)過程的調(diào)用。

接下來我們看看利用Mybatis是如何調(diào)用存儲(chǔ)過程的。

userMapper.xml添加存儲(chǔ)過程調(diào)用配置：

<select id="count" statementType="CALLABLE" parameterMap="getUserCountMap"> 
  CALL mybatis.ges_user_count(?,?) 
</select>

Main函數(shù)：

public class Learn1Main { 
 public static void main(String [] args){ 
  //mybatis的配置文件 
  String resource = "learn/mybatis-config.xml"; 
  //使用類加載器加載mybatis的配置文件（它也加載關(guān)聯(lián)的映射文件） 
  InputStream is = Learn1Main.class.getClassLoader().getResourceAsStream(resource); 
  //構(gòu)建sqlSession的工廠 
  SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is); 
  SqlSession session = sessionFactory.openSession(); 
  Map<String, Integer> parameterMap = new HashMap<String, Integer>(); 
  parameterMap.put("age", 12); 
  parameterMap.put("user_count", -1); 
  session.selectOne("com.tianjunwei.learn.learn1.entity.User.count", parameterMap); 
  Integer result = parameterMap.get("user_count"); 
  System.out.println(result); 
 } 
}

運(yùn)行結(jié)果：

其最終的執(zhí)行過程在DefaultResultSetHandler中，調(diào)用普通的sql和存儲(chǔ)過程之間還是有所區(qū)別的，Sql語句的執(zhí)行是使用CallableStatement。

// 
// HANDLE OUTPUT PARAMETER 
// 
//調(diào)用存儲(chǔ)過程返回結(jié)果，將結(jié)果值放在參數(shù)中 
@Override 
public void handleOutputParameters(CallableStatement cs) throws SQLException { 
 final Object parameterObject = parameterHandler.getParameterObject(); 
 final MetaObject metaParam = configuration.newMetaObject(parameterObject); 
 final List<ParameterMapping> parameterMappings = boundSql.getParameterMappings(); 
/循環(huán)處理每個(gè)參數(shù) 
 for (int i = 0; i < parameterMappings.size(); i++) { 
 final ParameterMapping parameterMapping = parameterMappings.get(i); 
 //判斷參數(shù)的模式 
 if (parameterMapping.getMode() == ParameterMode.OUT || parameterMapping.getMode() == ParameterMode.INOUT) { 
  if (ResultSet.class.equals(parameterMapping.getJavaType())) { 
  handleRefCursorOutputParameter((ResultSet) cs.getObject(i + 1), parameterMapping, metaParam); 
  } else { 
  final TypeHandler<?> typeHandler = parameterMapping.getTypeHandler(); 
  metaParam.setValue(parameterMapping.getProperty(), typeHandler.getResult(cs, i + 1)); 
  } 
 } 
 } 
} 
private void handleRefCursorOutputParameter(ResultSet rs, ParameterMapping parameterMapping, MetaObject metaParam) throws SQLException { 
 try { 
 final String resultMapId = parameterMapping.getResultMapId(); 
 final ResultMap resultMap = configuration.getResultMap(resultMapId); 
 final DefaultResultHandler resultHandler = new DefaultResultHandler(objectFactory); 
 final ResultSetWrapper rsw = new ResultSetWrapper(rs, configuration); 
 handleRowValues(rsw, resultMap, resultHandler, new RowBounds(), null); 
 metaParam.setValue(parameterMapping.getProperty(), resultHandler.getResultList()); 
 } finally { 
 // issue #228 (close resultsets) 
 closeResultSet(rs); 
 } 
}