思路：
（1）使用JDBC的batchUpdate实现批量更新。
（2）对原集合进行指定数量的切割处理（例如：原集合有10万数据量，切割数据量是一万，需切割十次），切割方法参考java.util.List的subList方法。
（3）使用Java线程池执行操作。

1. batchUpdate批量处理

1.1 引入JDBC的maven依赖

点击查看代码 
<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

1.2使用JdbcTemplate 操作

点击查看代码 
public  void batchUpdate(List<User> entities) {
        String sql = "UPDATE User SET cloum1 = ?, cloum2 = ?, " +
                "time = now() WHERE id = ?";
        jdbcTemplate.batchUpdate(sql, new BatchPreparedStatementSetter() {
            @Override
            public void setValues(PreparedStatement ps, int i) throws SQLException {
                User entity = entities.get(i);
                ps.setString(1, entity.getCloum1);
                ps.setString(2, entity.getCloum2);
                ps.setInt(3, entity.getId());
            }
            @Override
            public int getBatchSize() {
                return entities.size();
            }
        });
    }

2. 分批次处理

示例如下：

点击查看代码 
    public static final int BATCH_SIZE = 1000;
    @Autowired
    private JdbcTemplate jdbcTemplate;
    @Autowired
    private AsyncConfig asyncConfig;

    public void updateQaInBatches(List<User> repeatList) {
        int size = repeatList.size();
        int times = (size + BATCH_SIZE - 1) / BATCH_SIZE; // 计算需要循环的次数，向上取整

        for (int i = 0; i < times; i++) {
            int fromIndex = i * BATCH_SIZE;
            int toIndex = Math.min(size, (i + 1) * BATCH_SIZE);
            List<User> batchList = repeatList.subList(fromIndex, toIndex);
            asyncConfig.getAsyncExecutor().execute(new Thread(new Runnable(){
                @Override
                public void run() {
                    // 执行批量更新
                    batchUpdate(batchList);
                }
            }));
        }
    }

3. Java线程池

示例如下：

点击查看代码 
@Configuration
@EnableAsync
public class AsyncConfig implements AsyncConfigurer {

    @Override
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
        taskExecutor.setCorePoolSize(8);
        taskExecutor.setMaxPoolSize(16);
        taskExecutor.setQueueCapacity(1024);
        taskExecutor.initialize();
        return taskExecutor;
    }
}