擴展MybatisPlus批量插入（忽略唯一索引衝突行）

一、背景

1. 再數據同步或者冪等場景下，常常需要設置唯一索引來避免重複請求，select and update效率低，且併發時還是會報錯，並不友好，那麼可以用Mysql的Insert ignore語法來優化。
2. MybatisPlus官方並沒有針此處場景進行支持

二、環境

<dependency>
	<groupId>com.baomidou</groupId>
	<artifactId>mybatis-plus-boot-starter</artifactId>
	<version>3.2.0</version>
	<exclusions>
		<exclusion>
			<groupId>com.baomidou</groupId>
			<artifactId>mybatis-plus-generator</artifactId>
		</exclusion>
	</exclusions>
</dependency>

三、注入自定義批量插入sql

因爲只需要改造insertBatchSomeColumn方法，那直接CV就好

insertBatchSomeColumn方法屬於mybatis plus官方擴展包中

1. sql模板

public class InsertIgnoreBatchAllColumn extends AbstractMethod {

    /**
     * mapper 對應的方法名
     */
    private static final String MAPPER_METHOD = "insertIgnoreBatchAllColumn";

    /**
     * 字段篩選條件
     */
    @Setter
    @Accessors(chain = true)
    private Predicate<TableFieldInfo> predicate;

    @SuppressWarnings("Duplicates")
    @Override
    public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
        KeyGenerator keyGenerator = new NoKeyGenerator();
        SqlMethod sqlMethod = SqlMethod.INSERT_ONE;
        String sqlTemplate = "<script>\nINSERT IGNORE INTO %s %s VALUES %s\n</script>";

        List<TableFieldInfo> fieldList = tableInfo.getFieldList();
        String insertSqlColumn = tableInfo.getKeyInsertSqlColumn(false) +
            this.filterTableFieldInfo(fieldList, predicate, TableFieldInfo::getInsertSqlColumn, EMPTY);
        String columnScript = LEFT_BRACKET + insertSqlColumn.substring(0, insertSqlColumn.length() - 1) + RIGHT_BRACKET;
        String insertSqlProperty = tableInfo.getKeyInsertSqlProperty(ENTITY_DOT, false) +
            this.filterTableFieldInfo(fieldList, predicate, i -> i.getInsertSqlProperty(ENTITY_DOT), EMPTY);
        insertSqlProperty = LEFT_BRACKET + insertSqlProperty.substring(0, insertSqlProperty.length() - 1) + RIGHT_BRACKET;
        String valuesScript = SqlScriptUtils.convertForeach(insertSqlProperty, "list", null, ENTITY, COMMA);
        String keyProperty = null;
        String keyColumn = null;
        // 表包含主鍵處理邏輯,如果不包含主鍵當普通字段處理
        if (StringUtils.isNotEmpty(tableInfo.getKeyProperty())) {
            if (tableInfo.getIdType() == IdType.AUTO) {
                /* 自增主鍵 */
                keyGenerator = new Jdbc3KeyGenerator();
                keyProperty = tableInfo.getKeyProperty();
                keyColumn = tableInfo.getKeyColumn();
            } else {
                if (null != tableInfo.getKeySequence()) {
                    keyGenerator = TableInfoHelper.genKeyGenerator(tableInfo, builderAssistant, sqlMethod.getMethod(), languageDriver);
                    keyProperty = tableInfo.getKeyProperty();
                    keyColumn = tableInfo.getKeyColumn();
                }
            }
        }
        String sql = String.format(sqlTemplate, tableInfo.getTableName(), columnScript, valuesScript);
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, modelClass);
        return this.addInsertMappedStatement(mapperClass, modelClass, MAPPER_METHOD, sqlSource, keyGenerator, keyProperty, keyColumn);
    }
}

2. 注入sql

public class CustomerSqlInjector extends DefaultSqlInjector {

    @Override
    public List<AbstractMethod> getMethodList(Class<?> mapperClass) {
        List<AbstractMethod> methodList = super.getMethodList(mapperClass);
        methodList.add(new InsertIgnoreBatchAllColumn());
        return methodList;
    }
}

3. 通用mapper

public interface CommonMapper<T> extends BaseMapper<T> {

    /**
     * 全量插入,等價於insert，忽略唯一索引衝突的行
     * {@link InsertIgnoreBatchAllColumn}
     *
     * @param entityList
     * @return
     */
    int insertIgnoreBatchAllColumn(List<T> entityList);

}

4. 通用Service

public class CommonServiceImpl<M extends CommonMapper<T>, T> extends ServiceImpl<M, T> {

    @Transactional(rollbackFor = Exception.class)
    public boolean fastSaveIgnoreBatch(List<T> list, int batchSize) {
        if(CollectionUtils.isEmpty(list)) {
            return true;
        }

        batchSize = batchSize < 1 ? BATCH_SIZE : batchSize;

        if(list.size() <= batchSize) {
            return retBool(baseMapper.insertIgnoreBatchAllColumn(list));
        }

        for (int fromIdx = 0 , endIdx = batchSize ; ; fromIdx += batchSize, endIdx += batchSize) {
            if(endIdx > list.size()) {
                endIdx = list.size();
            }
            baseMapper.insertIgnoreBatchAllColumn(list.subList(fromIdx, endIdx));
            if(endIdx == list.size()) {
                return true;
            }
        }
    }
	
	@Transactional(rollbackFor = Exception.class)
    public boolean fastSaveIgnoreBatch(List<T> list) {
        return fastSaveIgnoreBatch(list, BATCH_SIZE);
    }

}