使用REST API下载文件 [英] Download file using REST API

问题描述

我正在尝试使用Java客户端调用REST API.

I am trying to call a REST API using Java client.

Rest API https://api.gdc.cancer.gov/data 具有文件数据. 当我将文件名附加到URL时( https://api .gdc.cancer.gov/data/556e5e3f-0ab9-4b6c-aa62-c42f6a6cf20c )，我可以使用浏览器下载给定文件.

The Rest API https://api.gdc.cancer.gov/data has files data. When I append file name to the URL (https://api.gdc.cancer.gov/data/556e5e3f-0ab9-4b6c-aa62-c42f6a6cf20c) I can download the given file from using browser.

此处文件名是556e5e3f-0ab9-4b6c-aa62-c42f6a6cf20c.

请让我知道，我如何在这个JAVA中实现.我正在使用的代码.

can you please let me know,How can i achieve in this JAVA. The code I am using.

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

public class DownloadFilesAPI {
    public DownloadFilesAPI() {
        super();
    }

    public static String sendPostRequest(String requestUrl) {
        StringBuffer jsonString = new StringBuffer();
        try {
            URL url = new URL(requestUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            // connection.setRequestMethod("POST");
            //   connection.connect();
            //Get the response status of the Rest API
            //  int responsecode = connection.getResponseCode();
            //System.out.println("Response code is: " +responsecode);
            //connection.getResponseMessage();
            // System.out.println(connection.getResponseMessage());

            connection.setDoInput(true);
            connection.setDoOutput(true);
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Accept", "application/json");
            connection.setRequestProperty("Content-Type", "application/json");
            //  System.out.println(connection.getResponseMessage());
            //  System.out.println( JsonPath.from(requestUrl));
            OutputStreamWriter writer = new 
            OutputStreamWriter(connection.getOutputStream());
            writer.write(requestUrl);
            writer.close(); 
            /* BufferedReader br = new BufferedReader(new 
            InputStreamReader(connection.getInputStream()));

            String line;
            while ((line = br.readLine()) != null) {
                jsonString.append(line);
            }
            br.close(); */
            connection.disconnect();
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
        return jsonString.toString();
    }

    public static void main(String[] args) {
        List<String> values = new ArrayList<>();
        // values.add("556e5e3f-0ab9-4b6c-aa62-c42f6a6cf20c");
        String requestUrl = "https://api.gdc.cancer.gov/data/556e5e3f-0ab9-4b6c-aa62-c42f6a6cf20c";
        sendPostRequest(requestUrl);
    }
    private static String preparePayload(List<String> values) {
    StringBuilder sb = new StringBuilder();
    for (String value : values) {
        sb.append("\"" + value + "\",");
    }
    String Requiredvalue = sb.toString().substring(0, sb.toString().length() - 1);
    return "{ \"ids\":[" + Requiredvalue + "] } } }";
    } 
}

推荐答案

由于您要下载pdf文件，因此无法仅输出String.如果您只想下载文件，则可以使用一种更简单的方法来改编

You can't just output a String since you are trying to download a pdf. If you simply want to download the File there is an easier method adapted from this answer:

    String requestUrl = "https://api.gdc.cancer.gov/data/556e5e3f-0ab9-4b6c-aa62-c42f6a6cf20c";
    URL url = new URL(requestUrl);
    InputStream in = url.openStream();
    Files.copy(in, Paths.get("your_filename.pdf"), StandardCopyOption.REPLACE_EXISTING);
    in.close();
    System.out.println("finished!");

我已经对您提供的URL进行了测试，并获得了pdf文件，没有任何问题.

I have tested it for the URL you provided and got the pdf File without problems.

这篇关于使用REST API下载文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！