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 block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.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 block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.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 block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.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();
}
}
}
}
}
