JAVA求文件的MD5和context-MD5

￡神魔★判官ぃ 2022-01-06 04:37 269阅读 0赞

**JAVA求文件的MD5和context-MD5**

最近在使用阿里云的oss，发现JAVA求的文件MD5和oss求的MD5不同。  
同一个测试文件，java代码：

import java.io.File;
    import java.io.FileInputStream;
    import java.security.DigestInputStream;
    import java.security.MessageDigest;
    
    import org.apache.commons.codec.digest.DigestUtils;
    import org.apache.commons.io.FileUtils;
    import org.apache.commons.io.IOUtils;
    
    import org.apache.commons.codec.binary.Base64;
    
    public class FileMd5 {
    	public static void main(String[] args) {
    		File file = new File("D:\\oss\\fileTest.txt");
    		String path = "D:\\oss\\fileTest.txt";
    		if(file.exists()) {
    			try {
    				//获取文件context-MD5
    				FileInputStream fis = new FileInputStream(path);
    				String md5 = DigestUtils.md5Hex(IOUtils.toByteArray(fis));
    				IOUtils.closeQuietly(fis);
    				System.out.println("MD5:" + md5);							    
    			} catch (Exception e) {
    				// TODO: handle exception
    				e.printStackTrace();
    			}
    		}else {
    			System.out.println("文件不存在~");
    		}
    	}
    }

java求得MD5：c5e820e3b12c726c0ab457f7283977d3  
![在这里插入图片描述][20190624153701458.png]  
使用oss求MD5:xegg47EscmwKtFf3KDl30w==  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjk1NDM4MQ_size_16_color_FFFFFF_t_70]  
但是发现 java求的MD5 与oss的eTag值相同。查看oss相关文档了解到oss的md5实际上是context-MD5.  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjk1NDM4MQ_size_16_color_FFFFFF_t_70 1]  
所以…现在问题变成了：java怎样求文件的context-MD5？  
百度ing…

找到了有说用 Base64.encodeBase64String() 方法…试一下：

package com.dfe.e8800.business.dtjc.md5;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.security.DigestInputStream;
    import java.security.MessageDigest;
    
    import org.apache.commons.codec.digest.DigestUtils;
    import org.apache.commons.io.FileUtils;
    import org.apache.commons.io.IOUtils;
    
    import org.apache.commons.codec.binary.Base64;
    
    public class FileMd5 {
    	public static void main(String[] args) {	
    		File file = new File("D:\\oss\\fileTest.txt");
    		String path = "D:\\oss\\fileTest.txt";
    		if(file.exists()) {
    			try {
    				//获取文件context-MD5
    				FileInputStream fis = new FileInputStream(path);
    				String md5 = DigestUtils.md5Hex(IOUtils.toByteArray(fis));
    				IOUtils.closeQuietly(fis);
    				System.out.println("MD5:" + md5);
    				
    				String contextMd5 = Base64.encodeBase64String(md5.getBytes());
    				System.out.println("contextMd5:"+contextMd5)		    
    			} catch (Exception e) {
    				// TODO: handle exception
    				e.printStackTrace();
    			}
    		}else {
    			System.out.println("文件不存在~");
    		}
    	}
    }

context-MD5：YzVlODIwZTNiMTJjNzI2YzBhYjQ1N2Y3MjgzOTc3ZDM=，和oss的MD5还是不同。  
![在这里插入图片描述][20190624155606447.png]  
然后找到一篇文章“HTTP Content-MD5 首部字段：编码的坑”  
[http://www.ituring.com.cn/article/74167][http_www.ituring.com.cn_article_74167]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjk1NDM4MQ_size_16_color_FFFFFF_t_70 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjk1NDM4MQ_size_16_color_FFFFFF_t_70 3]  
所以…修改后代码：

package com.dfe.e8800.business.dtjc.md5;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.security.DigestInputStream;
    import java.security.MessageDigest;
    
    import org.apache.commons.codec.digest.DigestUtils;
    import org.apache.commons.io.FileUtils;
    import org.apache.commons.io.IOUtils;
    
    import org.apache.commons.codec.binary.Base64;
    
    public class FileMd5 {
    	public static void main(String[] args) {
    		File file = new File("D:\\oss\\fileTest.txt");
    		String path = "D:\\oss\\fileTest.txt";
    		if(file.exists()) {
    			try {
    				//获取文件context-MD5
    				FileInputStream fis = new FileInputStream(path);
    				String md5 = DigestUtils.md5Hex(IOUtils.toByteArray(fis));
    				IOUtils.closeQuietly(fis);
    				System.out.println("MD5:" + md5);
    				
    				String contextMd5 = Base64.encodeBase64String(md5.getBytes());
    				System.out.println("contextMd5:"+contextMd5);
    				
    				MessageDigest md = MessageDigest.getInstance("MD5");
    				byte[] b = md.digest(FileUtils.readFileToByteArray(new File(path)));
    				String ContextMd5 = Base64.encodeBase64String(b);
    				System.out.println("context-Md5:"+ContextMd5);
    				
    			} catch (Exception e) {
    				// TODO: handle exception
    				e.printStackTrace();
    			}
    		}else {
    			System.out.println("文件不存在~");
    		}
    	}
    }

![在这里插入图片描述][20190624160534687.png]  
所求Context-MD5与oss的md5相同。

参考  
JAVA中获取文件MD5值的四种方法  
[https://blog.csdn.net/sike\_java/article/details/78538762][https_blog.csdn.net_sike_java_article_details_78538762]  
md5 计算content-MD5时好费劲  
[https://blog.csdn.net/u010321349/article/details/84864580][https_blog.csdn.net_u010321349_article_details_84864580]  
HTTP Content-MD5 首部字段：编码的坑  
[http://www.ituring.com.cn/article/74167][http_www.ituring.com.cn_article_74167]

[20190624153701458.png]: /images/20211228/101f6f4907764b32a54cb405da2bebf3.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjk1NDM4MQ_size_16_color_FFFFFF_t_70]: /images/20211228/d9e9982a7228422eb6c39a3b94d67934.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjk1NDM4MQ_size_16_color_FFFFFF_t_70 1]: /images/20211228/4fb5242a0832472594cef7be22803a0c.png
[20190624155606447.png]: /images/20211228/78a3de1066da4de8a36bb8686922884a.png
[http_www.ituring.com.cn_article_74167]: http://www.ituring.com.cn/article/74167
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjk1NDM4MQ_size_16_color_FFFFFF_t_70 2]: /images/20211228/275f24fcfcd148ecac255436f3ef7328.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjk1NDM4MQ_size_16_color_FFFFFF_t_70 3]: /images/20211228/31bc4be05eb04cff884f4e5410df12a7.png
[20190624160534687.png]: /images/20211228/e4c11cb857154ad6bc10ef536275e809.png
[https_blog.csdn.net_sike_java_article_details_78538762]: https://blog.csdn.net/sike_java/article/details/78538762
[https_blog.csdn.net_u010321349_article_details_84864580]: https://blog.csdn.net/u010321349/article/details/84864580