模拟本地服务为文件服务器(两种提供方式):假设本地文件为服务器,提供文件获取服务
方法一:直接将输出流放入response里面作为响应
@RequestMapping(value = "/getUrlDownload",method = RequestMethod.GET)
@ResponseBody
public void getUrlDownload(HttpServletResponse response) {
String url = "C:\\user.zip";
File file = new File(url);
//判断文件是否存在如果不存在就进行异常处理
if (!(file.exists() && file.canRead())) {
System.out.println("文件不存在");
}
FileInputStream inputStream = null;
try {
inputStream = new FileInputStream(file);
byte[] data = new byte[(int) file.length()];
int length = inputStream.read(data);
inputStream.close();
OutputStream stream = response.getOutputStream();
stream.write(data);
stream.flush();
stream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
方法二:将输入流放入ResponseEntity的body里面,并做返回
String separator = File.separator;
@RequestMapping(value = "/download", method = RequestMethod.GET, produces ="application/json;charset=UTF-8")
@ResponseBody
public ResponseEntity<InputStreamResource> download() {
String newName = "2";
String route = "download" + File.separator + "templates" + File.separator;
String path = null;
ResponseEntity<InputStreamResource> response = null;
try {
path = "download" + separator + "bst.zip";
ClassPathResource classPathResource = new ClassPathResource(path);
InputStream inputStream = classPathResource.getInputStream();
response = ResponseEntity.ok()
.body(new InputStreamResource(inputStream));
} catch (FileNotFoundException e1) {
System.out.println(e1.getMessage());
// log.error("找不到指定的文件", e1);
} catch (IOException e) {
System.out.println(e.getMessage());
// log.error("获取不到文件流", e);
}
return response;
}
以上两种方式皆可做文件服务器,提供给其他服务获取文件,这里注意与文件下载并不一样,都是以流的形式返回或者响应。而文件下载是将服务器的文件下载到本地,接下来演示远程文件下载代码。
远程获取文件(两种方式):
方式一:RestTemplate 获取,如下代码:
@RequestMapping(value = "/getf", method = RequestMethod.GET, produces ="application/json;charset=UTF-8")
@ResponseBody
public void getf() throws URISyntaxException {
String url = "http://localhost:8888/file/download";
RequestEntity build = RequestEntity.get(new URI(url)).build();
RestTemplate restTemplate =new RestTemplate();
ResponseEntity<byte[]> exchange = restTemplate.exchange(build, byte[].class);
byte[] body = exchange.getBody();
String fileName = "xxxx.zip";
String filePath = "src/main/resources/templates/";
BufferedOutputStream bos = null;
FileOutputStream fos = null;
File file = null;
try {
File dir = new File(filePath);
if(!dir.exists() && !dir.isDirectory()){//判断文件目录是否存在
dir.mkdirs();
}
file = new File(filePath + File.separator + fileName);
fos = new FileOutputStream(file);
bos = new BufferedOutputStream(fos);
bos.write(body);
bos.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (bos != null) {
try {
bos.close();
} catch (IOException e1) {
e1.printStackTrace();
}
}
if (fos != null) {
try {
fos.close();
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
方式二:URL获取,代码如下:
@RequestMapping(value = "/getFile", method = RequestMethod.GET, produces ="application/json;charset=UTF-8")
@ResponseBody
public void getFile() {
String filePath = "http://localhost:8888/file/getUrlDownload";
//定义文件名
String fileName = "111.zip";
//定义要保存的文件路径
String savePath = "/resources/templates/"+fileName;
File file = new File(savePath);
//如果文件目录不出在则创建目录 *getParentFile()*
if (!file.getParentFile().exists()) {
//判断文件目录是否存在
file.getParentFile().mkdirs();//创建目录
}
try {
URL url = new URL(filePath);
//字节输入流
InputStream is = url.openStream();
//字节流转字符流
DataInputStream dataInputStream = new DataInputStream(is);
转化流
FileOutputStream fileOutputStream = new FileOutputStream(file);
//使用char 数组传输 -----字节流byte数组
byte[] chs = new byte[1024];
//标记
int len = 0;
while ((len = dataInputStream.read(chs)) != -1) {
// read() 方法,读取输入流的下一个字节,返回一个0-255之间的int类型整数。如果到达流的末端,返回-1
fileOutputStream.write(chs,0,len);
}
fileOutputStream.close();
dataInputStream.close();
}catch (IOException e) {
e.printStackTrace();
}finally {
}
}
以上两种皆可远程获取到文件服务器的文件,只是方式不一样,但是获取本质都是以流的形式获取到,转换为byte[] 数组,最终写出来。方法二中有一个注意点,write方法重载有三个write(int a)、write(byte[] by,int begin,int end)、write(byte[] by),这里一般用write(byte[] by,int begin,int end),可保证下载文件正常打开,zip、rar文件打开时不会遇到:不可预测的文件尾部 ,这样的异常信息,其次是在以上方式中并没有添加中文乱码情况,可做补充。
标签:文件,调用,java,file,File,后台,new,byte,String From: https://www.cnblogs.com/fuqian/p/16820210.html