Java负载均衡服务器实现上传文件同步
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负载服务器Z，应用服务器A 和B ，从A上传的附件，如何在B上下载下来？
这个问题我的解决思路如下（后来被一个装逼的面试官给批评了这种做法，不过我瞧不起他）
服务器A、B 上传附件的时候，将这个附件备份到服务器Z ，当A、B下载文件的时候，首先会在自己服务器的目录下寻找，如果找不到，就会从服务器Z 上下载一份到当前服务器。
服务器之间的文件备份通过sftp，下文中的SftpCustom 类就是这个链接里的 “SFTP上传下载文件例子” 中的类
这里主要介绍一下重写上传、下载的方法时应该添加的代码
上传文件，异步操作
new Thread(() -> {
SftpCustom fu = new SftpCustom();
fu.upload(file.getAbsolutePath(), getFileName(fileDescr));
fu.closeChannel();
}).start();下载文件，先从当前服务器寻找
String tmpPath = roots[0].getPath() + '/' + getFileName(fileDescr);
File file2 = new File(tmpPath);
if (file2.exists()) {
return FileUtils.openInputStream(file2);
}
SftpCustom fu = new SftpCustom();
fu.download(getFileName(fileDescr), tmpPath);
file2 = new File(tmpPath);
inputStream = FileUtils.openInputStream(file2);
fu.closeChannel();
return inputStream;cuba 框架中重写上传文件类FileStorage.java 的代码如下：
package com.haulmont.cuba.core.app.custom;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import com.haulmont.cuba.core.app.FileStorageAPI;
import com.haulmont.cuba.core.app.ServerConfig;
import com.haulmont.cuba.core.entity.FileDescriptor;
import com.haulmont.cuba.core.global.*;
import com.haulmont.cuba.core.sys.AppContext;
import com.haulmont.cuba.core.sys.SecurityContext;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.inject.Inject;
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import static com.haulmont.bali.util.Preconditions.checkNotNullArgument;
public class FileStorage implements FileStorageAPI {
private final Logger log = LoggerFactory.getLogger(FileStorage.class);
@Inject
protected UserSessionSource userSessionSource;
@Inject
protected TimeSource timeSource;
@Inject
protected Configuration configuration;
protected boolean isImmutableFileStorage;
protected ExecutorService writeExecutor = Executors.newFixedThreadPool(5,
new ThreadFactoryBuilder().setNameFormat("FileStorageWriter-%d").build());
protected volatile File[] storageRoots;
@PostConstruct
public void init() {
this.isImmutableFileStorage = configuration.getConfig(ServerConfig.class).getImmutableFileStorage();
}
/**
* INTERNAL. Don't use in application code.
*/
public File[] getStorageRoots() {
if (storageRoots == null) {
String conf = configuration.getConfig(ServerConfig.class).getFileStorageDir();
if (StringUtils.isBlank(conf)) {
String dataDir = configuration.getConfig(GlobalConfig.class).getDataDir();
File dir = new File(dataDir, "filestorage");
dir.mkdirs();
storageRoots = new File[]{dir};
} else {
List<File> list = new ArrayList<>();
for (String str : conf.split(",")) {
str = str.trim();
if (!StringUtils.isEmpty(str)) {
File file = new File(str);
if (!list.contains(file))
list.add(file);
}
}
storageRoots = list.toArray(new File[list.size()]);
}
}
return storageRoots;
}
@Override
public long saveStream(final FileDescriptor fileDescr, final InputStream inputStream) throws FileStorageException {
checkFileDescriptor(fileDescr);
File[] roots = getStorageRoots();
// Store to primary storage
checkStorageDefined(roots, fileDescr);
checkPrimaryStorageAccessible(roots, fileDescr);
File dir = getStorageDir(roots[0], fileDescr);
dir.mkdirs();
checkDirectoryExists(dir);
final File file = new File(dir, getFileName(fileDescr));
checkFileExists(file);
long size = 0;
OutputStream os = null;
try {
os = FileUtils.openOutputStream(file);
size = IOUtils.copyLarge(inputStream, os);
os.flush();
writeLog(file, false);
new Thread(() -> {
SftpCustom fu = new SftpCustom();
fu.upload(file.getAbsolutePath(), getFileName(fileDescr));
fu.closeChannel();
}).start();
} catch (IOException e) {
IOUtils.closeQuietly(os);
FileUtils.deleteQuietly(file);
throw new FileStorageException(FileStorageException.Type.IO_EXCEPTION, file.getAbsolutePath(), e);
} finally {
IOUtils.closeQuietly(os);
}
// Copy file to secondary storages asynchronously
final SecurityContext securityContext = AppContext.getSecurityContext();
for (int i = 1; i < roots.length; i++) {
if (!roots[i].exists()) {
log.error("Error saving {} into {} : directory doesn't exist", fileDescr, roots[i]);
continue;
}
File copyDir = getStorageDir(roots[i], fileDescr);
final File fileCopy = new File(copyDir, getFileName(fileDescr));
writeExecutor.submit(new Runnable() {
@Override
public void run() {
try {
AppContext.setSecurityContext(securityContext);
FileUtils.copyFile(file, fileCopy, true);
writeLog(fileCopy, false);
} catch (Exception e) {
log.error("Error saving {} into {} : {}", fileDescr, fileCopy.getAbsolutePath(), e.getMessage());
} finally {
AppContext.setSecurityContext(null);
}
}
});
}
return size;
}
protected void checkFileExists(File file) throws FileStorageException {
if (file.exists() && isImmutableFileStorage)
throw new FileStorageException(FileStorageException.Type.FILE_ALREADY_EXISTS, file.getAbsolutePath());
}
protected void checkDirectoryExists(File dir) throws FileStorageException {
if (!dir.exists())
throw new FileStorageException(FileStorageException.Type.STORAGE_INACCESSIBLE, dir.getAbsolutePath());
}
protected void checkPrimaryStorageAccessible(File[] roots, FileDescriptor fileDescr) throws FileStorageException {
if (!roots[0].exists()) {
log.error("Inaccessible primary storage at {}", roots[0]);
throw new FileStorageException(FileStorageException.Type.STORAGE_INACCESSIBLE, fileDescr.getId().toString());
}
}
protected void checkStorageDefined(File[] roots, FileDescriptor fileDescr) throws FileStorageException {
if (roots.length == 0) {
log.error("No storage directories defined");
throw new FileStorageException(FileStorageException.Type.STORAGE_INACCESSIBLE, fileDescr.getId().toString());
}
}
@Override
public void saveFile(final FileDescriptor fileDescr, final byte[] data) throws FileStorageException {
checkNotNullArgument(data, "File content is null");
saveStream(fileDescr, new ByteArrayInputStream(data));
}
protected synchronized void writeLog(File file, boolean remove) {
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
StringBuilder sb = new StringBuilder();
sb.append(df.format(timeSource.currentTimestamp())).append(" ");
sb.append("[").append(userSessionSource.getUserSession().getUser()).append("] ");
sb.append(remove ? "REMOVE" : "CREATE").append(" ");
sb.append("\"").append(file.getAbsolutePath()).append("\"\n");
File rootDir;
try {
rootDir = file.getParentFile().getParentFile().getParentFile().getParentFile();
} catch (NullPointerException e) {
log.error("Unable to write log: invalid file storage structure", e);
return;
}
File logFile = new File(rootDir, "storage.log");
try {
try (FileOutputStream fos = new FileOutputStream(logFile, true)) {
IOUtils.write(sb.toString(), fos, StandardCharsets.UTF_8.name());
}
} catch (IOException e) {
log.error("Unable to write log", e);
}
}
@Override
public void removeFile(FileDescriptor fileDescr) throws FileStorageException {
checkFileDescriptor(fileDescr);
File[] roots = getStorageRoots();
if (roots.length == 0) {
log.error("No storage directories defined");
return;
}
for (File root : roots) {
File dir = getStorageDir(root, fileDescr);
File file = new File(dir, getFileName(fileDescr));
if (file.exists()) {
if (!file.delete()) {
throw new FileStorageException(FileStorageException.Type.IO_EXCEPTION, "Unable to delete file " + file.getAbsolutePath());
} else {
writeLog(file, true);
}
}
}
}
protected void checkFileDescriptor(FileDescriptor fd) {
if (fd == null || fd.getCreateDate() == null) {
throw new IllegalArgumentException("A FileDescriptor instance with populated 'createDate' attribute must be provided");
}
}
@Override
public InputStream openStream(FileDescriptor fileDescr) throws FileStorageException {
checkFileDescriptor(fileDescr);
File[] roots = getStorageRoots();
if (roots.length == 0) {
log.error("No storage directories available");
throw new FileStorageException(FileStorageException.Type.FILE_NOT_FOUND, fileDescr.getId().toString());
}
InputStream inputStream = null;
for (File root : roots) {
File dir = getStorageDir(root, fileDescr);
File file = new File(dir, getFileName(fileDescr));
if (!file.exists()) {
log.error("File " + file + " not found");
continue;
}
try {
inputStream = FileUtils.openInputStream(file);
break;
} catch (IOException e) {
log.error("Error opening input stream for " + file, e);
}
}
if (inputStream != null) {
return inputStream;
} else {
try {
String tmpPath = roots[0].getPath() + '/' + getFileName(fileDescr);
File file2 = new File(tmpPath);
if (file2.exists()) {
return FileUtils.openInputStream(file2);
}
SftpCustom fu = new SftpCustom();
fu.download(getFileName(fileDescr), tmpPath);
file2 = new File(tmpPath);
inputStream = FileUtils.openInputStream(file2);
fu.closeChannel();
return inputStream;
} catch (Exception e) {
throw new FileStorageException(FileStorageException.Type.FILE_NOT_FOUND, fileDescr.getId().toString());
}
}
}
@Override
public byte[] loadFile(FileDescriptor fileDescr) throws FileStorageException {
InputStream inputStream = openStream(fileDescr);
try {
return IOUtils.toByteArray(inputStream);
} catch (IOException e) {
throw new FileStorageException(FileStorageException.Type.IO_EXCEPTION, fileDescr.getId().toString(), e);
} finally {
IOUtils.closeQuietly(inputStream);
}
}
@Override
public boolean fileExists(FileDescriptor fileDescr) {
checkFileDescriptor(fileDescr);
File[] roots = getStorageRoots();
for (File root : roots) {
File dir = getStorageDir(root, fileDescr);
File file = new File(dir, getFileName(fileDescr));
if (file.exists()) {
return true;
}
}
return false;
}
/**
* INTERNAL. Don't use in application code.
*/
public File getStorageDir(File rootDir, FileDescriptor fileDescriptor) {
checkNotNullArgument(rootDir);
checkNotNullArgument(fileDescriptor);
Calendar cal = Calendar.getInstance();
cal.setTime(fileDescriptor.getCreateDate());
int year = cal.get(Calendar.YEAR);
int month = cal.get(Calendar.MONTH) + 1;
int day = cal.get(Calendar.DAY_OF_MONTH);
return new File(rootDir, year + "/"
+ StringUtils.leftPad(String.valueOf(month), 2, '0') + "/"
+ StringUtils.leftPad(String.valueOf(day), 2, '0'));
}
public static String getFileName(FileDescriptor fileDescriptor) {
return fileDescriptor.getId().toString() + "." + fileDescriptor.getExtension();
}
@PreDestroy
protected void stopWriteExecutor() {
writeExecutor.shutdown();
}
}
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