package com.wangyin.ak47.common;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* File-related helper class
*
* 文件操作工具类
*
* @author hannyu
*
*/
public class FileUtil {
private static final Logger log = new Logger(FileUtil.class);
public static final int READ_BUFFER_SIZE = 1024*8;
public static final int MAX_FILE_SIZE = 1024*1024*50; // max 50M
// cachedFileMap cache file content
// key : fileName (String)
// value:
// list[0] : lastTs (Long)
// list[1] : data (byte[])
private static Map<String, List<Object>> cachedFileMap = new HashMap<String, List<Object>>();
/**
* Read file to a single string, and cached it in mem, using UTF-8 encoding.
*
* Check the 'lastModified' time of data file whenever call,
* if changed, re-read it from disk, otherwise return the cached copy in mem.
*
* 读取文件并缓存到内存中，每次读取检查lastModifed时间，若有修改则重新读取，若无修改则直接返回缓存中的数据。
*
* @param filePath
* @return
* @throws IOException
*/
public static String readStringCached(String filePath) throws IOException {
return readStringCached(filePath, Ak47Constants.DEFAULT_ENCODING);
}
/**
* Read file to a single string, and cached it in mem, using given encoding.
*
* Check the 'lastModified' time of data file whenever call,
* if changed, re-read it from disk, otherwise return the cached copy in mem.
*
* 读取文件并缓存到内存中，每次读取检查lastModifed时间，若有修改则重新读取，若无修改则直接返回缓存中的数据。
*
* @param filePath
* @param encoding
* @return
* @throws IOException
*/
public static String readStringCached(String filePath, String encoding) throws IOException {
return new String(readBytesCached(filePath), encoding);
}
/**
* Read file to a byte array, and cached it in mem, using UTF-8 encoding.
*
* Check the 'lastModified' time of data file whenever call,
* if changed, re-read it from disk, otherwise return the cached copy in mem.
*
* 读取文件并缓存到内存中，每次读取检查lastModifed时间，若有修改则重新读取，若无修改则直接返回缓存中的数据。
*
*
* @param filePath
* @return
* @throws IOException
*/
public static byte[] readBytesCached(String filePath) throws IOException {
File file = new File(filePath);
long nowTs = file.lastModified();
if( 0 == nowTs ){
log.warn("{} NOT exist.", filePath);
return new byte[0];
}
List<Object> fileInfo = cachedFileMap.get(filePath);
long lastTs = (null == fileInfo) ? 0L : (Long)fileInfo.get(0);
if( nowTs > lastTs ){
log.debug("'{}' NOT cached, really read.", filePath);
byte[] bytes = readByteArray(file);
fileInfo = new ArrayList<Object>(2);
fileInfo.add(Long.valueOf(nowTs));
fileInfo.add(bytes);
cachedFileMap.put(filePath, fileInfo);
return bytes;
}else{
log.debug("read '{}' from cached.", filePath);
return (byte[]) fileInfo.get(1);
}
}
/**
* Compare the create time of copy in mem with the 'lastModified' time of the file.
*
* 检查fileName的内容相对于缓存是否改变，通过check lastModifed 来判断。
*
* @param filePath
* @return
*/
public static boolean isCachedChanged(String filePath) {
File file = new File(filePath);
long nowTs = file.lastModified();
List<Object> fileInfo = cachedFileMap.get(filePath);
long lastTs = (null == fileInfo) ? 0L : (Long)fileInfo.get(0);
return nowTs > lastTs;
}
/**
* Read all the file content to a single string, using UTF-8 encoding.
*
* 将文件全部读入为字符串，默认编码UTF-8
*
* @param filePath 文件名
* @return
* @throws IOException
*/
public static String readString(String filePath) throws IOException {
return readString(filePath, Ak47Constants.DEFAULT_ENCODING);
}
/**
* Read all the file content to a single string, using given encoding.
*
* 将文件全部读入为字符串，需指定编码
*
* @param filePath 文件路径
* @param encoding 必须指定编码
* @return
* @throws IOException
*/
public static String readString(String filePath, String encoding) throws IOException{
byte[] bytes = readByteArray(filePath);
return new String(bytes, encoding);
}
/**
* Read all the file content to a single string, using given encoding.
*
* 将文件全部读入为字符串，需指定编码
*
* @param file 文件
* @param encoding 必须指定编码
* @return
* @throws IOException
*/
public static String readString(File file, String encoding) throws IOException{
byte[] bytes = readByteArray(file);
return new String(bytes, encoding);
}
/**
* Read all the file content to a byte array.
*
* 将文件全部读入为字节数组
* 若文件不存在或内容为空，则返回 数组长度为0，注意不是null。
*
* @param filePath
* @return
* @throws FileNotFoundException
*/
public static byte[] readByteArray(String filePath) throws IOException{
File file = new File(filePath);
return readByteArray(file);
}
/**
* Read all the file content to a byte array.
*
* @param file
* @return
* @throws IOException
*/
public static byte[] readByteArray(File file) throws IOException{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
if( file.exists() ){
if( file.length() > MAX_FILE_SIZE ){
throw new IOException(file.getName() + " is too large.");
}
FileInputStream fis = new FileInputStream(file);
try{
byte[] buffer = new byte[READ_BUFFER_SIZE];
int read = 0;
while ( (read = fis.read(buffer)) != -1 ) {
bos.write(buffer, 0, read);
}
}finally{
fis.close();
}
}else{
log.warn("{} NOT exist.", file.getName());
}
return bos.toByteArray();
}
/**
* Writes the a string to a file, append or not.
*
* 将字符串写入文件，默认编码UTF-8
*
* @param filePath 文件名
* @param append 是否追加
* @param content 写入内容
* @throws IOException
*/
public static void writeString(String filePath, boolean append, String content)
throws IOException{
writeString(filePath, append, content, "UTF-8");
}
/**
* Writes the a string to a file, append or not.
*
* 将字符串写入文件，需指定编码
*
* @param filePath 文件名
* @param append 是否追加
* @param content 写入内容
* @param encoding 编码
* @throws IOException
*/
public static void writeString(String filePath, boolean append, String content, String encoding)
throws IOException{
writeBytes(filePath, append, content.getBytes(encoding));
}
/**
* Writes a byte array to a file.
*
* 将字节数组写入文件
*
* @param filePath 文件名
* @param append 是否追加
* @param content 写入内容
* @throws IOException
*/
public static void writeBytes(String filePath, boolean append, byte[] content)
throws IOException{
FileOutputStream fos = new FileOutputStream(filePath, append);
try{
fos.write(content);
fos.flush();
}finally{
fos.close();
}
}
}