在underscore-java库中有一个方法U.fetch(url)。

文件pom.xml:

<dependency>
  <groupId>com.github.javadev</groupId>
  <artifactId>underscore</artifactId>
  <version>1.84</version>
</dependency>

代码示例:

import com.github.underscore.U;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;

public class Download {
    public static void main(String[] args) throws IOException {
        Files.write(Paths.get("data.bin"),
            U.fetch("https://stackoverflow.com/questions"
                + "/921262/how-to-download-and-save-a-file-from-internet-using-java").blob());
    }
}

在java.net.http.HttpClient上使用授权的解决方案:

HttpClient client = HttpClient.newHttpClient();

HttpRequest request = HttpRequest.newBuilder()
        .GET()
        .header("Accept", "application/json")
        // .header("Authorization", "Basic ci5raG9kemhhZXY6NDdiYdfjlmNUM=") if you need
        .uri(URI.create("https://jira.google.ru/secure/attachment/234096/screenshot-1.png"))
        .build();

HttpResponse<InputStream> response = client.send(request, HttpResponse.BodyHandlers.ofInputStream());

try (InputStream in = response.body()) {
    Files.copy(in, Paths.get(target + "screenshot-1.png"), StandardCopyOption.REPLACE_EXISTING);
}

public void saveUrl(final String filename, final String urlString)
        throws MalformedURLException, IOException {
    BufferedInputStream in = null;
    FileOutputStream fout = null;
    try {
        in = new BufferedInputStream(new URL(urlString).openStream());
        fout = new FileOutputStream(filename);

        final byte data[] = new byte[1024];
        int count;
        while ((count = in.read(data, 0, 1024)) != -1) {
            fout.write(data, 0, count);
        }
    } finally {
        if (in != null) {
            in.close();
        }
        if (fout != null) {
            fout.close();
        }
    }
}

您将需要处理异常，可能是该方法的外部异常。

在underscore-java库中有一个方法U.fetch(url)。

文件pom.xml:

<dependency>
  <groupId>com.github.javadev</groupId>
  <artifactId>underscore</artifactId>
  <version>1.84</version>
</dependency>

代码示例:

import com.github.underscore.U;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;

public class Download {
    public static void main(String[] args) throws IOException {
        Files.write(Paths.get("data.bin"),
            U.fetch("https://stackoverflow.com/questions"
                + "/921262/how-to-download-and-save-a-file-from-internet-using-java").blob());
    }
}

第一种方法采用新通道

ReadableByteChannel aq = Channels.newChannel(new url("https//asd/abc.txt").openStream());
FileOutputStream fileOS = new FileOutputStream("C:Users/local/abc.txt")
FileChannel writech = fileOS.getChannel();

第二种方法使用FileUtils

FileUtils.copyURLToFile(new url("https//asd/abc.txt", new local file on system("C":/Users/system/abc.txt"));

第三种使用方法

InputStream xy = new ("https//asd/abc.txt").openStream();

这就是我们如何通过使用基本的Java代码和其他第三方库来下载文件。这些只是作为快速参考。请用谷歌以上关键词获取详细信息及其他选项。

如果你使用代理，你可以在Java程序中设置代理，如下所示:

Properties systemSettings = System.getProperties();
systemSettings.put("proxySet", "true");
systemSettings.put("https.proxyHost", "HTTPS proxy of your org");
systemSettings.put("https.proxyPort", "8080");

如果您没有使用代理，请不要在代码中包含上述代码行。完整的工作代码下载文件时，你是一个代理。

public static void main(String[] args) throws IOException {
    String url = "https://raw.githubusercontent.com/bpjoshi/fxservice/master/src/test/java/com/bpjoshi/fxservice/api/TradeControllerTest.java";
    OutputStream outStream = null;
    URLConnection connection = null;
    InputStream is = null;
    File targetFile = null;
    URL server = null;

    // Setting up proxies
    Properties systemSettings = System.getProperties();
        systemSettings.put("proxySet", "true");
        systemSettings.put("https.proxyHost", "HTTPS proxy of my organisation");
        systemSettings.put("https.proxyPort", "8080");
        // The same way we could also set proxy for HTTP
        System.setProperty("java.net.useSystemProxies", "true");
        // Code to fetch file
    try {
        server = new URL(url);
        connection = server.openConnection();
        is = connection.getInputStream();
        byte[] buffer = new byte[is.available()];
        is.read(buffer);

        targetFile = new File("src/main/resources/targetFile.java");
        outStream = new FileOutputStream(targetFile);
        outStream.write(buffer);
    } catch (MalformedURLException e) {
        System.out.println("THE URL IS NOT CORRECT ");
        e.printStackTrace();
    } catch (IOException e) {
        System.out.println("I/O exception");
        e.printStackTrace();
    }
    finally{
        if(outStream != null)
            outStream.close();
    }
}