Find top 10 large files

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最新推荐文章于 2021-09-10 16:17:04 发布

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分类专栏：技术人生文章标签： find file

本文链接：https://blog.youkuaiyun.com/xiucaiyao/article/details/38268537

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本文介绍了一个Java程序，用于查找指定目录及其子目录下的前十大文件，并按大小降序打印出来。程序通过递归遍历目录并计算每个文件的大小来实现。

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package yxc.citi.file.find;

import java.io.File;
import java.io.FileInputStream;
import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.util.Comparator;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

/*********************************************************************************
//* Filename: FindTopLargeFile.java
//* Revision: 1.0
//* Author: <yao xiucai>
//* Created On: 2014年7月29日
//* Modified by:
//* Modified On:
//*
//* Description: <find top ${topNum} large file>
/********************************************************************************/

public class FindTopLargeFile {

//top large file's num
private static int topNum = 10;
//test Directory
private static String fileDirectory = "E:/tmp";

private static Map<Double, String> fileMap = null;

/**
* get file size
* @param file
* @return
* @throws Exception
*/
public static double getFileSize(File file) throws Exception {
double size = 0;
if (file.exists()) {
FileInputStream fis = null;
fis = new FileInputStream(file);
size = fis.available();
fis.close();
}
else {
return 0;
}
size = size / 1024.00;
size = Double.parseDouble(size + "");
BigDecimal b = new BigDecimal(size);
double y1 = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
java.text.DecimalFormat df = new java.text.DecimalFormat("#.00");
return Double.parseDouble(df.format(y1));
}

/**
* find all files
* @param dir
* @throws Exception
*/
final static Map<Double, String> findAllFiles(File dir) throws Exception {
File[] fs = dir.listFiles();
for (int i = 0 ; i < fs.length ; i++) {
if (fs[i].isDirectory()) {
try {
findAllFiles(fs[i]);
}
catch (Exception e) {
e.printStackTrace();
}
}
else {
Double key = getFileSize(fs[i]);
String value = fs[i].getAbsolutePath();
if (fileMap.containsKey(key)) {
key = key + 0.0001; //解决冲突。有效数位小数点后两位，因此最大支持冲突数位100
fileMap.put(key, value);
}
else {
fileMap.put(key, value);
}
}
}

return fileMap;
}

/**
* print a map's value
* @param map
*/
final static void printDescMap(Map<Double, String> map) {
if (map != null && map.size() > 0) {
int fileNum = 0;
Set<Double> keySet = map.keySet();
Iterator<Double> iter = keySet.iterator();
while (iter.hasNext()) {
fileNum = fileNum + 1;
Double key = iter.next();
String value = map.get(key);
DecimalFormat df = new DecimalFormat("0.00");
String keyStr = df.format(key);
System.out.println(value + " : " + keyStr + " KB");

if (fileNum == topNum) {
break;
}
}
}
else {
System.out.println("no file!");
}
}

/**
* 1.find all files,and get the result map;
* 2.print result map
* @param filePath
* @throws Exception
*/
public static void sortByDesc(String filePath) throws Exception {
File file = new File(filePath);
fileMap = new TreeMap<Double, String>(new Comparator<Double>() {

public int compare(Double obj1, Double obj2) {
//desc sort
return obj2.compareTo(obj1);
}
});
if (!file.exists()) {
System.out.println("The file does not exist:" + filePath);
}
else {
findAllFiles(file);
printDescMap(fileMap);
}

}

//test method
public static void main(String[] args) throws Exception {
long begin = System.currentTimeMillis();

sortByDesc(fileDirectory);

long end = System.currentTimeMillis();

System.out.println("time:" + (end - begin) + " ms");
}
}