如何保存下载的文件从服务器在java
问题描述:
我有一个java类从服务器下载文件,此文件开始下载,也完成了下载,但它没有给出它保存在本地系统的路径,或我认为它不保存该文件,请指导我如何将它保存在窗口的下载文件夹中或任何其他文件夹中。如何保存下载的文件从服务器在java
import java.io.*;
import java.net.*;
import java.util.*;
class Download extends Observable implements Runnable {
private static final int MAX_BUFFER_SIZE = 1024;
public static final String STATUSES[] = {"Downloading",
"Paused", "Complete", "Cancelled", "Error"};
public static final int DOWNLOADING = 0;
public static final int PAUSED = 1;
public static final int COMPLETE = 2;
public static final int CANCELLED = 3;
public static final int ERROR = 4;
private final URL url; // download URL
private int size; // size of download in bytes
private int downloaded; // number of bytes downloaded
private int status; // current status of download
public Download(URL url) {
this.url = url;
size = -1;
downloaded = 0;
status = DOWNLOADING;
// Begin the download.
download();
}
public String getUrl() {
return url.toString();
}
public int getSize() {
return size;
}
public float getProgress() {
return ((float) downloaded/size) * 100;
}
public int getStatus() {
return status;
}
public void pause() {
status = PAUSED;
stateChanged();
}
public void resume() {
status = DOWNLOADING;
stateChanged();
download();
}
public void cancel() {
status = CANCELLED;
stateChanged();
}
private void error() {
status = ERROR;
stateChanged();
}
private void download() {
Thread thread = new Thread(this);
thread.start();
}
private String getFileName(URL url) {
String fileName = url.getFile();
return fileName.substring(fileName.lastIndexOf('/') + 1);
}
public void run() {
RandomAccessFile file = null;
InputStream stream = null;
try {
// Open connection to URL.
HttpURLConnection connection
= (HttpURLConnection) url.openConnection();
// Specify what portion of file to download.
connection.setRequestProperty("Range",
"bytes=" + downloaded + "-");
// Connect to server.
connection.connect();
// Make sure response code is in the 200 range.
if (connection.getResponseCode()/100 != 2) {
error();
}
// Check for valid content length.
int contentLength = connection.getContentLength();
if (contentLength < 1) {
error();
}
/* Set the size for this download if it
hasn't been already set. */
if (size == -1) {
size = contentLength;
stateChanged();
}
// Open file and seek to the end of it.
file = new RandomAccessFile(getFileName(url), "rw");
file.seek(downloaded);
stream = connection.getInputStream();
while (status == DOWNLOADING) {
/* Size buffer according to how much of the
file is left to download. */
byte buffer[];
if (size - downloaded > MAX_BUFFER_SIZE) {
buffer = new byte[MAX_BUFFER_SIZE];
} else {
buffer = new byte[size - downloaded];
}
// Read from server into buffer.
int read = stream.read(buffer);
if (read == -1) {
break;
}
// Write buffer to file.
file.write(buffer, 0, read);
downloaded += read;
stateChanged();
}
/* Change status to complete if this point was
reached because downloading has finished. */
if (status == DOWNLOADING) {
status = COMPLETE;
stateChanged();
System.err.println("cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc");
}
} catch (Exception e) {
error();
} finally {
// Close file.
if (file != null) {
try {
file.close();
} catch (Exception e) {
}
}
// Close connection to server.
if (stream != null) {
try {
stream.close();
} catch (Exception e) {
}
}
}
}
// Notify observers that this download's status has changed.
private void stateChanged() {
setChanged();
notifyObservers();
}
}
答
当您创建RandomAccessFile的(),第一个参数是文件的名称和位置。尝试打印absolutePath()并查看此文件驻留的位置。
你能告诉我,我必须把这个代码? – gurjeet
尝试创建新的RandomAccessFile(“c:\\ temp \\ myfile.txt”,“RW”),然后根据您的原始代码将下载的内容写入此文件。我可以看到你试图匹配URL的文件名。所以如果是这样的话,文件应该保存在你启动应用程序的位置。再次,调用file.getAbsolutePath()应该显示文件位置。 –