java代码写一段读取postgres数据库中所有表里的数据

以下是一段Java代码，可以读取PostgreSQL数据库中所有表里的数据：

import java.sql.*;

public class ReadPostgresTables {
    public static void main(String[] args) {
        String url = "jdbc:postgresql://localhost:5432/mydatabase";
        String user = "myuser";
        String password = "mypassword";

        try (Connection conn = DriverManager.getConnection(url, user, password)) {
            DatabaseMetaData metaData = conn.getMetaData();
            ResultSet tables = metaData.getTables(null, null, "%", new String[] {"TABLE"});

            while (tables.next()) {
                String tableName = tables.getString("TABLE_NAME");
                System.out.println("Reading data from table: " + tableName);

                Statement statement = conn.createStatement();
                ResultSet resultSet = statement.executeQuery("SELECT * FROM " + tableName);

                ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
                int columnCount = resultSetMetaData.getColumnCount();

                while (resultSet.next()) {
                    for (int i = 1; i <= columnCount; i++) {
                        System.out.print(resultSet.getString(i) + "\t");
                    }
                    System.out.println();
                }

                resultSet.close();
                statement.close();
            }

            tables.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

请注意，您需要将上面的代码中的URL、用户名和密码替换为您自己的PostgreSQL数据库的URL、用户名和密码。此外，您还需要在代码中添加适当的PostgreSQL JDBC驱动程序依赖项。