java实现不同数据库之间数据的迁移

1，导入数据库依赖

        <!--MySQL连接包-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.11</version>
        </dependency>
        <!--postgresql-->
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.1.1</version>
        </dependency>

我这里一个是把pg库里面的数据迁移到mysql数据库，所以引入的是pg和mysql的依赖，你们根据实际使用情况进行导入

2，DataMigration.java

package com.myqxin.sx.common.utils;

import java.sql.*;

/**
 * @author: myqxin
 * @Desc:
 * @create: 2021-09-18 10:31
 **/
public class DataMigration {

    /**
     * 数据源
     *
     * @return
     */
    private Connection formConn() {
        try {
            Class.forName("org.postgresql.Driver");
            return DriverManager.getConnection("jdbc:postgresql://localhost:5432/dw", "用户名", "密码!");
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 目标库
     *
     * @return
     */
    private Connection toDestination() {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            return DriverManager.getConnection("jdbc:mysql://localhost:3306/intellect_masterdata?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai", "用户名", "密码");
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    public void transfer() throws SQLException {
        //获取源数据库
        Connection formConn = formConn();
        Statement statement = formConn.createStatement();
        ResultSet resultSet = statement.executeQuery("select * from mdata.v_pharmacy_info");

        //结果集获取到的长度
        int size = resultSet.getMetaData().getColumnCount();
        //比较懒，拼接insert into 语句
        StringBuffer sbf = new StringBuffer();
        sbf.append("inster into sync_master_data_base_info values (");
        String link = "";
        for (int i = 0; i < size; i++) {
            sbf.append(link).append("?");
            link = ",";
        }
        sbf.append(")");
        //要存入的数据库
        Connection connection = toDestination();
        PreparedStatement preparedStatement = connection.prepareStatement(sbf.toString());

        //取出结果集并向目标数据库插入数据 ( 使用批处理 )
        //完成条数
        int count = 0;
        int num = 0;
        //取消事务(不写入日志)
        connection.setAutoCommit(false);
        long start = System.currentTimeMillis();
        while (resultSet.next()) {
            ++count;
            for (int i = 1; i <= size; i++) {
                preparedStatement.setObject(i, resultSet.getObject(i));
            }

            //将预先语句存储起来，这里还没有向数据库插入
            preparedStatement.addBatch();
            //当count 到达 1000条时 向数据库提交
            if (count % 1000 == 0) {
                ++num;
                preparedStatement.executeBatch();
                System.out.println("第" + num + "次提交,耗时:" + (System.currentTimeMillis() - start) / 1000.0 + "s");
            }
        }
        //防止有数据未提交
        preparedStatement.executeBatch();
        //提交
        connection.commit();
        System.out.println("完成 " + count + " 条数据,耗时:" + (System.currentTimeMillis() - start) / 1000.0 + "s");
        //恢复事务
        // mysqlconn.setAutoCommit(true);

        //关闭资源
        close(connection, preparedStatement, null);
        close(formConn, statement, resultSet);

    }

    public void close(Connection conn, Statement stmt, ResultSet rs) {

        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (stmt != null) {
            try {
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        DataMigrationUtil dataMigrationUtil = new DataMigrationUtil();
        try {
            dataMigrationUtil.transfer();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

}

3，调用

    public static void main(String[] args) {
        DataMigration dataMigration = new DataMigration();
        try {
            dataMigration.transfer();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

如果是做定时任务的，避免重复的数据插入，可以使用replace into，如果存在primary key 或者 unique相同的记录，则先删除掉，再插入新的记录

        sbf.append("replace into test_user values (");

参考来自：https://www.cnblogs.com/oukele/p/9626006.html
注意事项：要保证操作的两张表，字段个数是一致的（类型可以不一致），不然会抛出异常，可以在拼接？的那里做修改，具体看你们实际情况使用