目标：

1. mybatis-plus批处理的原理和过程
2. 验证的技术方案
3. 性能评估方案
4. 最佳实践（应用规范）

   1. 批处理的核心逻辑

   com.baomidou.mybatisplus.core.executor.MybatisBatchExecutor#doFlushStatements

   @Override
    public List<BatchResult> doFlushStatements(boolean isRollback) throws SQLException {
        try {
            List<BatchResult> results = new ArrayList<>();
            if (isRollback) {
                return Collections.emptyList();
            }
            for (int i = 0, n = statementList.size(); i < n; i++) {
                Statement stmt = statementList.get(i);
                applyTransactionTimeout(stmt);
                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);
                        }
                    }
                    // Close statement to close cursor #1109
                    closeStatement(stmt);
                } 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();
        }
    }