要利用Java進行PostgreSQL的數據備份與恢復，可以使用PostgreSQL的命令行工具pg_dump和pg_restore來實現。以下是一個示例代碼，用于備份和恢復數據庫。

備份數據庫：

import java.io.IOException;

public class BackupDatabase {

    public static void main(String[] args) {
        String dbName = "your_database_name";
        String username = "your_username";
        String password = "your_password";
        String backupPath = "path_to_backup_file";

        try {
            String command = "pg_dump -U " + username + " -d " + dbName + " -f " + backupPath;
            Process process = Runtime.getRuntime().exec(command);
            process.waitFor();

            System.out.println("Database backup completed successfully.");
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

恢復數據庫：

import java.io.IOException;

public class RestoreDatabase {

    public static void main(String[] args) {
        String dbName = "your_database_name";
        String username = "your_username";
        String password = "your_password";
        String backupPath = "path_to_backup_file";

        try {
            String command = "pg_restore -U " + username + " -d " + dbName + " -f " + backupPath;
            Process process = Runtime.getRuntime().exec(command);
            process.waitFor();

            System.out.println("Database restore completed successfully.");
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

請注意，上述代碼中的變量需要根據您自己的環境進行修改。在運行這些代碼之前，請確保已經安裝了Java和PostgreSQL，并且已經配置了正確的環境變量。