java怎么检验文件的完整性 java校验文件大小

/**
• @author Jayvee
• @Description: todo 获取网络文件的大小
*/
public static int getFileLength(String url1) throws IOException {
int length = 0;
URL url;
try {
url = new URL(url1);
HttpURLConnection urlcon = (HttpURLConnection) url.openConnection();
//根据响应获取文件大小
length = urlcon.getContentLength();
urlcon.disconnect();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return length;
}
/**
• 从输入流中获取字节数组
• @author Jayvee
• @param inputStream
• @return
• @throws IOException
*/
public static byte[] readInputStream(InputStream inputStream) throws IOException {
byte[] buffer = new byte[1024];
int len = 0;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
while ((len = inputStream.read(buffer)) != -1) {
bos.write(buffer, 0, len);
}
bos.close();
return bos.toByteArray();
}
/**
• @author Jayvee
• @Description: todo
*/
public static byte[] downLoadFromUrl(String urlStr) throws IOException {
URL url = new URL(urlStr);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
InputStream inputStream = conn.getInputStream();
//获取自己数组
byte[] getData = readInputStream(inputStream);
return getData;
}
/**
• @author Jayvee
• @Description: todo
*/
public static byte[] readFromByteFile(String pathname) throws IOException {
File filename = new File(pathname);
BufferedInputStream in = new BufferedInputStream(new FileInputStream(filename));
ByteArrayOutputStream out = new ByteArrayOutputStream(1024);
byte[] temp = new byte[1024];
int size = 0;
while ((size = in.read(temp)) != -1) {
out.write(temp, 0, size);
}
in.close();
byte[] content = out.toByteArray();
return content;
}
}

假设获取网络图片 http://pic.962.net/up/2018-1/2018191570320420.jpg 的大小和内容。

Java 代码：

try {
int fileSize = FileUtils.getFileLength(“http://pic.962.net/up/2018-1/2018191570320420.jpg”); // 获取文件大小
byte[] file = FileUtils.downLoadFromUrl(“http://pic.962.net/up/2018-1/2018191570320420.jpg”); // 获取文件内容
System.out.println(“文件大小：” + fileSize + " 字节");
System.out.println(“文件内容：” + file);
} catch (IOException e) {
e.printStackTrace();
}