Springboo通过http哀求下载文件到服务器 - ToB企服应用市场:ToB评测及商务社交产业平台

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class Downloader {
public static void downloadAndSave(String urlString, String filePath) {
InputStream in = null;
try {
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setUseCaches(false);
connection.setRequestProperty("Content-Type", "application/json"); // 或者其他适当的MIME类型，或者根据需求移除
connection.setConnectTimeout(60000);
connection.setReadTimeout(60000);
// 连接服务器
connection.connect();
// 检查响应码是否为200
if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
in = connection.getInputStream();
// 使用try-with-resources来自动关闭OutputStream
try (OutputStream out = new FileOutputStream(filePath)) {
byte[] buffer = new byte[4096];
int bytesRead;
// 从输入流中读取数据，并写入到文件输出流中
while ((bytesRead = in.read(buffer)) != -1) {
out.write(buffer, 0, bytesRead);
}
}
// 注意：由于使用了try-with-resources，OutputStream会在这里自动关闭
// 但我们仍然需要确保InputStream在方法结束时被关闭
} else {
System.out.println("Failed to download file: HTTP error code " + connection.getResponseCode());
}
} catch (IOException e) {
e.printStackTrace();
} finally {
// 关闭InputStream
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
// 示例用法
public static void main(String[] args) {
String url = "http://example.com/somefile.txt";
String filePath = "downloaded_file.txt";
downloadAndSave(url, filePath);
}
}

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import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
public class SimpleDownloader {
public static void downloadAndSave(String urlString, String filePath) {
try (URL url = new URL(urlString);
InputStream in = url.openStream(); // 注意：这里使用的是openStream()，它简化了HTTP GET请求
FileOutputStream fos = new FileOutputStream(filePath)) {
byte[] buffer = new byte[4096];
int bytesRead;
while ((bytesRead = in.read(buffer)) != -1) {
fos.write(buffer, 0, bytesRead);
}
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
String url = "http://example.com/somefile.txt";
String filePath = "downloaded_file.txt";
downloadAndSave(url, filePath);
}
}

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import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import java.io.FileOutputStream;
import java.io.IOException;
public class HttpClientDownloader {
public static void downloadAndSave(String urlString, String filePath) {
try (CloseableHttpClient httpClient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet(urlString);
FileOutputStream fos = new FileOutputStream(filePath)) {
httpClient.execute(httpGet, httpResponse -> {
try (InputStream inputStream = httpResponse.getEntity().getContent()) {
byte[] buffer = new byte[4096];
int bytesRead;
while ((bytesRead = inputStream.read(buffer)) != -1) {
fos.write(buffer, 0, bytesRead);
}
}
return null; // 这里返回null，因为我们不需要HttpResponse的进一步处理
});
} catch (IOException e) {
e.printStackTrace();
}
}
// 注意：上面的代码示例使用了HttpClient的异步执行方式（通过execute方法的lambda表达式），
// 但这实际上并不是异步的，因为lambda表达式内部是同步执行的。
// 对于真正的异步下载，你可能需要使用HttpClient的异步API（如FutureCallback等）。
// 为了简化，这里提供一个更直接的同步下载示例：
public static void downloadAndSaveSync(String urlString, String filePath) throws IOException {
try (CloseableHttpClient httpClient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet(urlString);
FileOutputStream fos = new FileOutputStream(filePath)) {
CloseableHttpResponse response = httpClient.execute(httpGet);
try {
InputStream inputStream = response.getEntity().getContent();
byte[] buffer = new byte[4096];
int bytesRead;
while ((bytesRead = inputStream.read(buffer)) != -1) {
fos.write(buffer, 0, bytesRead);
}
} finally {
response.close();
}
}
}
public static void main(String[] args) {
String url = "http://example.com/somefile.txt";
String filePath = "downloaded_file.txt";
// 使用同步方法
try {
downloadAndSaveSync(url, filePath);
} catch (IOException e) {
e.printStackTrace();
}
}
}

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