openGauss学习笔记-165 openGauss 数据库运维-备份与恢复-导入数据-使用COPY FROM STDIN导入数据-通过本地文件导入导出数据

165.1 示例1：通过本地文件导入导出数据

在使用JAVA语言基于openGauss进行二次开发时，可以使用CopyManager接口，通过流方式，将数据库中的数据导出到本地文件或者将本地文件导入数据库中，文件格式支持CSV、TEXT等格式。

样例程序如下，执行时需要加载openGauss的JDBC驱动。

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.io.IOException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.sql.SQLException; 
import org.opengauss.copy.CopyManager; 
import org.opengauss.core.BaseConnection;public class Copy{ public static void main(String[] args) { String urls = new String("jdbc:opengauss://localhost:8000/postgres"); //数据库URL String username = new String("username");            //用户名 String password = new String("passwd");             //密码 String tablename = new String("migration_table"); //定义表信息 String tablename1 = new String("migration_table_1"); //定义表信息 String driver = "org.opengauss.Driver"; Connection conn = null; try { Class.forName(driver); conn = DriverManager.getConnection(urls, username, password);         } catch (ClassNotFoundException e) { e.printStackTrace(System.out); } catch (SQLException e) { e.printStackTrace(System.out); } // 将表migration_table中数据导出到本地文件d:/data.txt  try {copyToFile(conn, "d:/data.txt", "(SELECT * FROM migration_table)");} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}    //将d:/data.txt中的数据导入到migration_table_1中。try {copyFromFile(conn, "d:/data.txt", tablename1);} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}  // 将表migration_table_1中的数据导出到本地文件d:/data1.txt  try {copyToFile(conn, "d:/data1.txt", tablename1);} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}        } public static void copyFromFile(Connection connection, String filePath, String tableName)   throws SQLException, IOException {  FileInputStream fileInputStream = null;  try {  CopyManager copyManager = new CopyManager((BaseConnection)connection);  fileInputStream = new FileInputStream(filePath);  copyManager.copyIn("COPY " + tableName + " FROM STDIN ", fileInputStream);                        } finally {  if (fileInputStream != null) {  try {  fileInputStream.close();  } catch (IOException e) {  e.printStackTrace();  }  }  }  }  public static void copyToFile(Connection connection, String filePath, String tableOrQuery)   throws SQLException, IOException {  FileOutputStream fileOutputStream = null;  try {  CopyManager copyManager = new CopyManager((BaseConnection)connection);  fileOutputStream = new FileOutputStream(filePath);  copyManager.copyOut("COPY " + tableOrQuery + " TO STDOUT", fileOutputStream);  } finally {  if (fileOutputStream != null) {  try {  fileOutputStream.close();  } catch (IOException e) {  e.printStackTrace();  }  }  }  }  
}

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