ibatis和mybatis中的BatchExecutor

ibatis中的的处理方法

spring集成了ibatis的批量提交的功能，我们只要调用API就可以了
首先在你的dao中需要继承org.springframework.orm.ibatis.support.SqlMapClientDaoSupport
然后在代码中调用getSqlMapClientTemplate方法，获取SqlMapClientTemplate对象，然后做处理

public void insertInfos(List<Info> records) {
       if (null == records || records.size() == 0) {
           return;
       }
       // 执行回调
       SqlMapClientTemplate sqlMapClientTemplate = iBatisDaoLS13.getSqlMapClientTemplate();
       sqlMapClientTemplate.execute(new SqlMapClientCallback() {
           // 实现回调接口
           public Object doInSqlMapClient(SqlMapExecutor executor) throws SQLException {
               // 开始批处理, for循环里面的sql必须一致，否则会创建新的PreparedStatement
               executor.startBatch();
               for (Info info : records) {
                   executor.insert(NAMESPACE + "insertAInfo", info);
               }
               // 执行批处理
               executor.executeBatch();
               return null;
           }
       });
   }

mybatis中的的处理方法

在程序中，有时候我们需要批量的去操作一些数据，批量的新增、修改、删除，如果是通过for循环一条记录一条记录的去更新无疑效率会比较慢。更佳的做法无疑是采用JDBC对批处理的支持。Mybatis基于JDBC对批处理的支持，也提供了进行数据的批量操作的API，BatchExecutor。下面是一段JDBC进行批量操作的示例代码。

@Test

public void testJDBCBatch() throws SQLException {

String sql = "insert into t_user(name, mobile, email) values(?,?,?)";

try (Connection conn = dataSource.getConnection(); PreparedStatement pstmt = conn.prepareStatement(sql);) {

List<User> users = this.getUsers();

for (User user : users) {

pstmt.setString(1, user.getName());

pstmt.setString(2, user.getMobile());

pstmt.setString(3, user.getEmail());

pstmt.addBatch();

}

pstmt.executeBatch();

conn.commit();

}

在每一次调用的时候是调用Statement.addBatch()方法，最终所有的参数都传递完了，没有更多的参数时调用Statement.executeBatch()方法进行批量操作。在上一篇博文中我们查看了BatchExecutor的源码，它的核心代码doUpdate()方法，每次被调用的时候都是以handler.batch()结束，而handler.batch()对应的底层代码是调用对应的Statement的addBatch()方法。那它是在什么时候执行executeBatch()呢？

@Override

public int doUpdate(MappedStatement ms, Object parameterObject) throws SQLException {

final Configuration configuration = ms.getConfiguration();

final StatementHandler handler = configuration.newStatementHandler(this, ms, parameterObject, RowBounds.DEFAULT, null, null);

final BoundSql boundSql = handler.getBoundSql();

final String sql = boundSql.getSql();

final Statement stmt;

if (sql.equals(currentSql) && ms.equals(currentStatement)) {

intlast = statementList.size() - 1;

stmt = statementList.get(last);

handler.parameterize(stmt);//fix Issues 322

BatchResult batchResult = batchResultList.get(last);

batchResult.addParameterObject(parameterObject);

} else {

Connection connection = getConnection(ms.getStatementLog());

stmt = handler.prepare(connection);

handler.parameterize(stmt); //fix Issues 322

currentSql = sql;

currentStatement = ms;

statementList.add(stmt);

batchResultList.add(new BatchResult(ms, sql, parameterObject));

}

// handler.parameterize(stmt);

handler.batch(stmt);

return BATCH_UPDATE_RETURN_VALUE;

}

它的executeBatch()是在doFlushStatements()方法调用中调用的，它会在当前Executor进行commit时调用，也会在当前Executor第一次执行doQuery()时调用，在这个时候都会调用Executor的flushStatements()方法，而BaseExecutor在执行flushStatements()时最终会调用其doFlushStatements()方法。当然，我们也可以手动的调用SqlSession的flushStatements()方法，其底层实现也会调用对应的BaseExecutor的flushStatements()方法。

@Override

public List<BatchResult> doFlushStatements(boolean isRollback) throws SQLException {

try {

List<BatchResult> results = new ArrayList<BatchResult>();

if (isRollback) {

return Collections.emptyList();

}

for (int i = 0, n = statementList.size(); i < n; i++) {

Statement stmt = statementList.get(i);

BatchResult batchResult = batchResultList.get(i);

try {

batchResult.setUpdateCounts(stmt.executeBatch());

MappedStatement ms = batchResult.getMappedStatement();

List<Object> parameterObjects = batchResult.getParameterObjects();

KeyGenerator keyGenerator = ms.getKeyGenerator();

if (Jdbc3KeyGenerator.class.equals(keyGenerator.getClass())) {

Jdbc3KeyGenerator jdbc3KeyGenerator = (Jdbc3KeyGenerator) keyGenerator;

jdbc3KeyGenerator.processBatch(ms, stmt, parameterObjects);

} else if (!NoKeyGenerator.class.equals(keyGenerator.getClass())) { //issue #141

for (Object parameter : parameterObjects) {

keyGenerator.processAfter(this, ms, stmt, parameter);

}

} catch (BatchUpdateException e) {

StringBuilder message = new StringBuilder();

message.append(batchResult.getMappedStatement().getId())

.append(" (batch index #")

.append(i + 1)

.append(")")

.append(" failed.");

if (i > 0) {

message.append(" ")

.append(i)

.append(" prior sub executor(s) completed successfully, but will be rolled back.");

}

throw new BatchExecutorException(message.toString(), e, results, batchResult);

}

results.add(batchResult);

}

return results;

} finally {

for (Statement stmt : statementList) {

closeStatement(stmt);

}

currentSql = null;

statementList.clear();

batchResultList.clear();

}

下面是一个使用Mybatis的BatchExecutor进行批量操作的示例。在示例中我们创建了一个使用BatchExecutor的SqlSession，也可以是SqlSessionTemplate，其实现了SqlSession接口，底层通过一个SqlSession代理进行相应的操作。然后在循环中一次调用对应Mapper的新增操作，相当于调用BatchExecutor的doUpdate()，最后调用SqlSession的commit()方法提交事务，在SqlSession的commit()中会调用Executor的commit()，从而导致了executeBatch()的发生。

@Test

public void testExecutor() {

SqlSession session = this.sessionFactory.openSession(ExecutorType.BATCH);

UserMapper mapper = session.getMapper(UserMapper.class);

User user = null;

for (inti = 0; i < 10; i++) {

user = new User();

user.setName("Name_" + i);

user.setEmail("email");

mapper.insert(user);

}

// 批量插入User

session.commit();// 提交事务时批量操作才会写入数据库

session.close();

}