Java--判断两个文件是否相同

package com.letv.test;

import java.io.FileInputStream;
import java.io.InputStream;
import java.security.MessageDigest;

public class CheckSameFile {
public static char[] hexChar = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

public static void main(String[] args) {
String path1 = "d:/test/abc.jpg";
String path2 = "d:/test/asd/abc.jpg";

String hash_path1 = null;
String hash_path2 = null;
try {
hash_path1 = getHash(path1, "MD5");
hash_path2 = getHash(path2, "MD5");
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("path1 md5:" + hash_path1);
System.out.println("path2 md5:" + hash_path2);
if (hash_path1.endsWith(hash_path2)) {
System.out.println("文件相同");
} else {
System.out.println("文件不相同");
}
}

/**
* 获得文件md5值
*/
public static String getHash(String fileName, String hashType)
throws Exception {
InputStream fis;
fis = new FileInputStream(fileName);
byte[] buffer = new byte[1024];
MessageDigest md5 = MessageDigest.getInstance(hashType);
int numRead = 0;
while ((numRead = fis.read(buffer)) > 0) {
md5.update(buffer, 0, numRead);
}
fis.close();
return toHexString(md5.digest());
}

/**
* md5转成字符串
*/
public static String toHexString(byte[] b) {
StringBuilder sb = new StringBuilder(b.length * 2);
for (int i = 0; i < b.length; i++) {
sb.append(hexChar[(b[i] & 0xf0) >>> 4]);
sb.append(hexChar[b[i] & 0x0f]);
}
return sb.toString();
}
}

package com.letv.test;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.security.MessageDigest;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class CheckSameFile {
public static char[] hexChar = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
public static void main(String[] args) {
Map<String,List<File>> filemap=new HashMap<String,List<File>>();
printInfo("d:/test", filemap);//修改路径判断对应路径下面的相同文件

}

/**
* 获得文件md5值
* @param fileName
* @param hashType
* @return
* @throws Exception
*/
public static String getHash(String fileName, String hashType)
throws Exception {
InputStream fis;
fis = new FileInputStream(fileName);
byte[] buffer = new byte[1024];
MessageDigest md5 = MessageDigest.getInstance(hashType);
int numRead = 0;
while ((numRead = fis.read(buffer)) > 0) {
md5.update(buffer, 0, numRead);
}
fis.close();
return toHexString(md5.digest());
}
/**
* md5转成字符串
* @param b
* @return
*/
public static String toHexString(byte[] b) {
StringBuilder sb = new StringBuilder(b.length * 2);
for (int i = 0; i < b.length; i++) {
sb.append(hexChar[(b[i] & 0xf0) >>> 4]);
sb.append(hexChar[b[i] & 0x0f]);
}
return sb.toString();
}
/**
* 将所有的文件装入map
* @param path
* @return
*/
public static  void   getSameFile(String path,Map<String,List<File>> filemap){
File f= new File(path);
if(f.isFile()){
String key;
try {
key = getHash(f.getPath(),"MD5");
if(filemap.containsKey(key)){
List<File> fd=filemap.get(key);
fd.add(f);
}else{
List<File> fs=new ArrayList<File>();
fs.add(f);
System.out.println(f.getName());
filemap.put(key, fs);
}
} catch (Exception e) {
e.printStackTrace();
}

}else{
File[]  fs=f.listFiles();
for(File f0:fs){
getSameFile(f0.getPath(), filemap);
}
}
}
/**
* 打印判断结果
* @param path
* @param filemap
*/
public static void printInfo(String path,Map<String,List<File>> filemap){

getSameFile(path,filemap);
//		System.out.println(filemap);
Collection<List<File>> sets=filemap.values();
int i=1;

for(List<File> f:sets){
//			System.out.println(f.size());
if(f.size()>1){
System.out.println("-------------------");
System.out.println("第"+i+"组：以下"+f.size()+"文件内容相同：");
int j=1;
for(File f_0:f){
System.out.println(j+"   文件名字："+f_0.getName()+"---文件路径："+f_0.getPath()+"\n");
j++;
}
System.out.println("-------------------");
i++;
}

}
}

}