ant 打包时计算打包文件的hash值

为减少软件升级资源的大小，希望对升级资源各个包进行识别，本地已经有的包，就不需要下载。通过比较文件大小方式存在隐患，并不能彻底解决上述问题。所以采用文件hashCode方式来识别。

在feature文件夹内增加各个jar包的hashcode，更新软件时，对比本地和服务器上jar的hashcode，hashcode一致的文件包不下载。

参见https://blog.csdn.net/YeahToYeah/article/details/123772742 如下

 

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class FileHashUtil
{
    private static final int A1024 = 1024;
    public static String md5HashCode(InputStream fis)
    {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            // 分次读入，于大型文件而言，占用内存比较少。
            byte[] buffer = new byte[A1024];
            int length = -1;
            while ((length = fis.read(buffer, 0, A1024)) != -1)
            {
                md.update(buffer, 0, length);
            }
            fis.close();
            // 转换并返回包含16个元素字节数组,返回数值范围为-128到127
            byte[] md5Bytes = md.digest();
            BigInteger bigInt = new BigInteger(1, md5Bytes);// 1代表绝对值
            return bigInt.toString(16);// 转换为16进制
        }
        catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }
    public static String hashFile(File file) throws Exception
    {
        String sha256 = null;
        try (FileInputStream inputStream = new FileInputStream(file))
        {
            MessageDigest md = MessageDigest.getInstance("SHA-256");
            byte buffer[] = new byte[A1024];
            int length = -1;
            while ((length = inputStream.read(buffer, 0, A1024)) != -1)
            {
                md.update(buffer, 0, length);
            }
            byte[] digest = md.digest();
            sha256 = byte2hexLower(digest);
        }
        catch (Exception e) {
            e.printStackTrace();
            throw new Exception("计算文件hash值错误");
        }
        return sha256;
    }

    private static String byte2hexLower(byte[] b)
    {
        String hs = "";
        String stmp = "";
        for (int i = 0; i < b.length; i++)
        {
            stmp = Integer.toHexString(b[i] & 0XFF);
            if (stmp.length() == 1)
                hs = hs + "0" + stmp;
            else
                hs = hs + stmp;
        }
        return hs;
    }
    
    public static String encodeSHA(String content)
    {
        byte[] inputData = content.getBytes();
        try {
            MessageDigest messageDigest = MessageDigest.getInstance("SHA");
            messageDigest.update(inputData);
            BigInteger sha = new BigInteger(messageDigest.digest());
            return sha.toString(32);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    private static String getHashCode(File file)
    {
        if (!file.exists())
            return "";
     
        if (file.isFile()) {
            String hashCode = "";
            try  {
                hashCode = FileHashUtil.md5HashCode(new FileInputStream(file));
            }
            catch (Exception e) {
            }
            return hashCode;
        }
        else if (file.isDirectory())
        {
            Map<String, String> fileHashMap = new HashMap<String, String>();
            File[] listFiles = file.listFiles();
            for (int i = 0; i < listFiles.length; i++)
            {
                File file2 = listFiles[i];
                String hashCode = getHashCode(file2);
                fileHashMap.put(file2.getAbsolutePath(), hashCode);
            }
            List<String> collect = new ArrayList<String>(fileHashMap.keySet());
            Collections.sort(collect);
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < collect.size(); i++)
            {
                String obj = collect.get(i);
                String string = fileHashMap.get(obj);
                sb.append(string);
            }
            return encodeSHA(sb.toString());
        }
        return "";
    }
    /**
     * 参数需要两个以上，最后一个参数指明存放hashcode的文件
     * @param args
     */
    public static void main(String[] args)
    {
        write(args);
    }
    
    public static void write(String[] args)
    {
        if (args != null && args.length > 1)
        {
            StringBuilder sb  = new StringBuilder();
            for (int i = 0; i < args.length - 1; i++)
            {
                File file = new File(args[i]);
                String hashCode = getHashCode(file);
                sb.append(file.getName()).append("=");
                sb.append(hashCode).append("\r\n");
            }
           
            File file = new File(args[args.length - 1]);
            String string = sb.toString();
            System.out.println("hashcode:"+string);
            try (FileOutputStream outStream = new FileOutputStream(file))
            {
                outStream.write(string.getBytes());
                outStream.close();
            }
            catch (Exception e)  {
                e.printStackTrace();
            }
        }
    }
}

 

为防止java版本不同对于FileHashUtil.class 的不支持，我们使FileHashUtil在调用之前每次编译，生成.class文件。如下：

<javac destdir="${basedir}/javaclasses" failonerror="${javacFailOnError}" verbose="${javacVerbose}" debug="${javacDebugInfo}" source="${javacSource}" target="${javacTarget}">

<classpath refid="compile.classpath" />

<src path="${basedir}/FileHashUtilPath/" /> <!-- 注意这里不能直接编译java文件，只能编译目录-->

</javac>

 

先将编译的class文件，打成jar包。

<jar jarfile="${basedir}/FileHashUtil.jar" basedir="${basedir}/javaclasses"/>

 

在ant中调用FilehashUtil.jar写出hash值文件，并移动到指定位置：

<java classname="FileHashUtil" classpath="${basedir}/FileHashUtil.jar" fork="true" failonerror="true" >

<arg value="${build.result.folder}"/>

<arg value="${eclipse.home}/${bundleId}_hash.txt"/>

</java>

 

<move file="${eclipse.home}/${bundleId}_hash.txt" todir="${eclipse.plugins.home}" overwrite="true" failonerror="false" />

 

在构建全部的jar后，将全部的hash.txt写入到feature中，在更新时，取得feature.jar中的hash.txt.供在线升级程序做比较用。

 

ant的使用

http://www.codebaoku.com/ant/ant-length-task.html

http://t.zoukankan.com/fnlingnzb-learner-p-6279189.html

https://www.cnblogs.com/sky-heaven/p/5883634.html