Help Center/ Scalable File Service/ API Reference/ Getting Started with General Purpose File System/ Listing File Systems
Updated on 2024-11-13 GMT+08:00
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Listing File Systems

Scenarios

If you want to view information about all file systems created by yourself, you can call the API for listing file systems.

The following describes how to call the API for Listing File Systems. For details, see Getting Started with General Purpose File System.

Prerequisites

Listing File Systems in the a1 Region

In this example, an Apache HttpClient is used.

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package com.sfsclient;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.List;
import java.util.Map;

public class TestMain {
    //Obtain an AK/SK pair using environment variables or import the AK/SK pair in other ways. Using hard coding may result in leakage.
    //Obtain an AK/SK pair on the management console.
    public static String accessKey = "ACCESS_KEY_ID"; 
    public static String securityKey = "SECRET_ACCESS_KEY_ID"; 
    public static String endpoint = "sfs3.a1.region.com"; // The access address of General Purpose File System.

    public static void main(String[] str) {
        createFileSystem();

    }
    private static void listFileSystem() {
        String httpMethod = "GET";
        String date = DateUtils.formatDate(System.currentTimeMillis());

        /**Calculate the signature based on the request.**/
        String contentMD5 = "";
        String contentType = "";
        String canonicalizedHeaders = "x-obs-bucket-type:SFS";
        String canonicalizedResource = "/" ;

        // Content-MD5 and Content-Type fields do not contain line breaks. The data format is RFC 1123, which is the same as the time in the request.
        String stringToSign = httpMethod + "\n" +
                contentMD5 + "\n" +
                contentType + "\n" +
                date + "\n" +
                canonicalizedHeaders  + "\n" + canonicalizedResource;

        System.out.printf("StringToSign:\n[%s]\n\n", stringToSign);

        HttpURLConnection conn = null;

        try {
            String signature = Signature.signWithHmacSha1(securityKey, stringToSign);
            String authorization= "OBS " + accessKey + ":" + signature;
            System.out.printf("authorization:%s\n\n", authorization);

            // Create an HTTP request.
            URL url = new URL("http://" + endpoint);
            conn = (HttpURLConnection) url.openConnection();

            // Add a signature header.
            conn.setRequestMethod(httpMethod);
            conn.setRequestProperty("Date", date);
            conn.setRequestProperty("Content-Type", contentType);
            conn.setRequestProperty("x-obs-bucket-type", "SFS");
            conn.setRequestProperty("Authorization", authorization);
            conn.setDoOutput(true);

            String status = conn.getHeaderField(null);
            System.out.println(status);

            // Output the response message.
            Map<String, List<String>> headers = conn.getHeaderFields();
            for (Map.Entry<String, List<String>> entry : headers.entrySet()) {
                String key = entry.getKey();
                List<String> values = entry.getValue();
                if (key != null) {
                    for (String value : values) {
                        System.out.println(key + ": " + value);
                    }
                }
            }
            // Process the returned content.
            int statusCode = conn.getResponseCode();
            if (statusCode == HttpURLConnection.HTTP_OK) {
                InputStream responseStream = conn.getInputStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(responseStream));

                StringBuilder responseBody = new StringBuilder();
                String line;
                while ((line = reader.readLine()) != null) {
                    responseBody.append(line);
                }
                reader.close();

                System.out.println("responseBody: " + responseBody);
            } else {
                System.out.println("Error: " + statusCode);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (conn != null){
                conn.disconnect();
            }
        }
    }
}

The format of the Date header field DateUtils is as follows:

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package com.sfsclient;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Locale;
import java.util.TimeZone;

public class DateUtils {

    public static String formatDate(long time)
    {
        DateFormat serverDateFormat = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z", Locale.ENGLISH);
        serverDateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
        return serverDateFormat.format(time);
    }
}

The method of calculating the signature character string is as follows:

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package com.sfsclient;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.security.NoSuchAlgorithmException;
import java.security.InvalidKeyException;
import java.util.Base64;

public class Signature {
    public static String signWithHmacSha1(String sk, String canonicalString) throws UnsupportedEncodingException {

        try {
            SecretKeySpec signingKey = new SecretKeySpec(sk.getBytes("UTF-8"), "HmacSHA1");
            Mac mac = Mac.getInstance("HmacSHA1");
            mac.init(signingKey);
            return Base64.getEncoder().encodeToString(mac.doFinal(canonicalString.getBytes("UTF-8")));
        } catch (NoSuchAlgorithmException | InvalidKeyException | UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return null;
    }
}