使用JdbcTemplate的BatchPreparedStatementSetter批量插入数据

记录：397

场景：使用JdbcTemplate从一个数据库批量查出数据存放在List<Map<String, Object>>中，把查出的结果数据批量写入到另一个数据库。

版本：JDK 1.8,SpringBoot 2.6.3

关键类01：org.springframework.jdbc.core.JdbcTemplate

关键类02：org.springframework.jdbc.core.BatchPreparedStatementSetter

1.批量查询和批量写入

public static void main(String[] args) {
  // 1.获取两个数据库的JdbcTemplate
  JdbcTemplate db01 = getJdbcTemplateDb01();
  JdbcTemplate db02 = getJdbcTemplateDb02();
  // 2.查询SQL和插入SQL
  String db01SelectSQL = getSelectSQL();
  String db02InsertSQL = getInsertSQL();
  // 3.批量查询
  List<Map<String, Object>> db01Result = db01.queryForList(db01SelectSQL);
  // 4.批量写入
  db02.batchUpdate(db02InsertSQL, new BatchPreparedStatementSetter() {
    @Override
    public void setValues(PreparedStatement ps, int i) throws SQLException {
      Map<String, Object> oneRow = db01Result.get(i);
      ps.setObject(1, oneRow.get("CITY_ID"));
      ps.setObject(2, oneRow.get("CITY_NAME"));
      ps.setObject(3, oneRow.get("LAND_AREA"));
      ps.setObject(4, oneRow.get("POPULATION"));
      ps.setObject(5, oneRow.get("GROSS"));
      ps.setObject(6, oneRow.get("CITY_DESCRIBE"));
      ps.setObject(7, oneRow.get("DATA_YEAR"));
      ps.setObject(8, oneRow.get("UPDATE_TIME"));
    }
    @Override
    public int getBatchSize() {
        // 必须有值,一般是需要写入的数量
        return db01Result.size();
    }
  });
}

2.查询SQL和写入SQL

// 查询SQL
public static String getSelectSQL() {
  String selectSQL = "SELECT CITY_ID,CITY_NAME,LAND_AREA,POPULATION, " +
          "  GROSS,CITY_DESCRIBE,DATA_YEAR,UPDATE_TIME " +
          "FROM t_city ";
  return selectSQL;
}
// 插入SQL
public static String getInsertSQL() {
  String insertSQL = "INSERT INTO t_city (\n" +
          "  CITY_ID,CITY_NAME,LAND_AREA,POPULATION,\n" +
          "  GROSS,CITY_DESCRIBE,DATA_YEAR,UPDATE_TIME)\n" +
          "VALUES (?, ?, ?, ?, ?, ?, ?, ?)";
  return insertSQL;
}

3.获取JdbcTemplate

// 操作数据库hub_a_db的JdbcTemplate
public static JdbcTemplate getJdbcTemplateDb01() {
  String username = "hub_a";
  String password = "12345678";
  String jdbcUrl = "jdbc:mysql://127.0.0.1:3306/hub_a_db";
  String driverName = "com.mysql.jdbc.Driver";
  // com.alibaba.druid.pool.DruidDataSource
  DruidDataSource dataSource = new DruidDataSource();
  // 设置数据源属性参数
  dataSource.setPassword(password);
  dataSource.setUrl(jdbcUrl);
  dataSource.setUsername(username);
  dataSource.setDriverClassName(driverName);
  // 获取spring的JdbcTemplate
  JdbcTemplate jdbcTemplate = new JdbcTemplate();
  // 设置数据源
  jdbcTemplate.setDataSource(dataSource);
  return jdbcTemplate;
}
// 操作数据库hub_b_db的JdbcTemplate
public static JdbcTemplate getJdbcTemplateDb02() {
  String username = "hub_b";
  String password = "12345678";
  String jdbcUrl = "jdbc:mysql://127.0.0.1:3306/hub_b_db";
  String driverName = "com.mysql.jdbc.Driver";
  // com.alibaba.druid.pool.DruidDataSource
  DruidDataSource dataSource = new DruidDataSource();
  // 设置数据源属性参数
  dataSource.setPassword(password);
  dataSource.setUrl(jdbcUrl);
  dataSource.setUsername(username);
  dataSource.setDriverClassName(driverName);
  // 获取spring的JdbcTemplate
  JdbcTemplate jdbcTemplate = new JdbcTemplate();
  // 设置数据源
  jdbcTemplate.setDataSource(dataSource);
  return jdbcTemplate;
}

4.建表语句

CREATE TABLE t_city (
  CITY_ID BIGINT(16) NOT NULL COMMENT '唯一标识',
  CITY_NAME VARCHAR(64) COLLATE utf8_bin NOT NULL COMMENT '城市名',
  LAND_AREA DOUBLE DEFAULT NULL COMMENT '城市面积',
  POPULATION BIGINT(16) DEFAULT NULL COMMENT '城市人口',
  GROSS DOUBLE DEFAULT NULL COMMENT '生产总值',
  CITY_DESCRIBE VARCHAR(512) COLLATE utf8_bin DEFAULT NULL COMMENT '城市描述',
  DATA_YEAR VARCHAR(16) COLLATE utf8_bin DEFAULT NULL COMMENT '数据年份',
  UPDATE_TIME DATETIME DEFAULT NULL COMMENT '更新时间'
) ENGINE=INNODB DEFAULT CHARSET=utf8 COLLATE=utf8_bin COMMENT='城市信息表';

5.建数据库语句

// 创建数据库hub_a_db和用户hub_a
USE mysql;
CREATE DATABASE hub_a_db DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE USER hub_a@'%' IDENTIFIED BY '12345678';
GRANT ALL ON hub_a_db.* TO 'hub_a'@'%' IDENTIFIED BY '12345678';
FLUSH PRIVILEGES;
// 创建数据库hub_b_db和用户hub_b
USE mysql;
CREATE DATABASE hub_b_db DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE USER hub_b@'%' IDENTIFIED BY '12345678';
GRANT ALL ON hub_b_db.* TO 'hub_b'@'%' IDENTIFIED BY '12345678';
FLUSH PRIVILEGES;

6.在MySQL中查询一张表的全部字段SQL

SELECT
  COLUMN_NAME
FROM
  INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 't_city';

7.BatchPreparedStatementSetter的getBatchSize说明

BatchPreparedStatementSetter的getBatchSize需要返回值原因是JdbcTemplate的batchUpdate在执行前，会先调用getBatchSize获取值，做后续判断。源码如下：

public int[] batchUpdate(String sql, final BatchPreparedStatementSetter pss) throws DataAccessException {
  if (this.logger.isDebugEnabled()) {
      this.logger.debug("Executing SQL batch update [" + sql + "]");
  }
  int[] result = (int[])this.execute(sql, (ps) -> {
    try {
        int batchSize = pss.getBatchSize();
        InterruptibleBatchPreparedStatementSetter ipss = pss instanceof InterruptibleBatchPreparedStatementSetter ? (InterruptibleBatchPreparedStatementSetter)pss : null;
        if (!JdbcUtils.supportsBatchUpdates(ps.getConnection())) {
            List<Integer> rowsAffected = new ArrayList();
            int ix = 0;
            while(true) {
                if (ix < batchSize) {
                    pss.setValues(ps, ix);
                    if (ipss == null || !ipss.isBatchExhausted(ix)) {
                        rowsAffected.add(ps.executeUpdate());
                        ++ix;
                        continue;
                    }
                }
                int[] rowsAffectedArray = new int[rowsAffected.size()];
  
                for(int ixx = 0; ixx < rowsAffectedArray.length; ++ixx) {
                    rowsAffectedArray[ixx] = (Integer)rowsAffected.get(ixx);
                }
                int[] var13 = rowsAffectedArray;
                return var13;
            }
        } else {
            int i = 0;
            while(true) {
                if (i < batchSize) {
                    pss.setValues(ps, i);
                    if (ipss == null || !ipss.isBatchExhausted(i)) {
                        ps.addBatch();
                        ++i;
                        continue;
                    }
                }
  
                int[] var10 = ps.executeBatch();
                return var10;
            }
        }
    } finally {
        if (pss instanceof ParameterDisposer) {
            ((ParameterDisposer)pss).cleanupParameters();
        }
    }
  });
  Assert.state(result != null, "No result array");
  return result;
}

以上，感谢。

2023年4月10日