base64加密解密文件,解决前后端对接出现的转换失败问题

迈不过友情╰ 2022-05-16 05:08 232阅读 0赞

这篇博客的前提是我在本地进行文件的加密和解密都是没有问题的,但是当前后端对接的时候出现了我对前端base64加密之后的pdf问价的字符串进行机密没有问题,但是对doc或者docx类型的文件加密字符串进行解密时出现解密文件失败.原因是前端传过来的字符串有个别的字符经历了转义,但是最终还是解决了这个问题,下面就是本人写的工具类.

//获取文件的类型
    String suffixName = filename.substring(filename.lastIndexOf("."));
    //文件类型
    String filetype = suffixName.replace(".", "");
    //文件名,因为.是特殊字符需要使用\\
    String name = filename.split("\\.")[0];
    **下面就是对base64加密后的字符串进行解密的过程**
    import org.springframework.web.multipart.MultipartFile;
    import sun.misc.BASE64Decoder;
    import java.io.File;
    import java.io.IOException;
    import java.util.Date;
    public class DecodeUtil {
    
    	//新生成的文件存储在本地
        public String save (MultipartFile file,String filetype,String name) throws IOException {
            
            String filepath = "/tmp/"+name+"."+filetype;  //生成的新文件
            File destFile = new File(filepath);
            file.transferTo(destFile);
            return filepath;
        }
    	//解密base64字符串生成文件
        public MultipartFile base64toMultipart (String base64,String filetype) {
            return this.base64File(base64,filetype);
        }
    
        public Base64File base64File (String base64,String filetype) {
            try {
                String[] baseStr = base64.split(",");
                BASE64Decoder decoder = new BASE64Decoder();
                byte[] b = new byte[0];
                b = decoder.decodeBuffer(baseStr[1]);
    
                for (int i = 0 ; i < b.length ; i++) {
                    if (b[i] < 0) {
                        b[i] += 256;
                    }
                }
                return new Base64File(b, baseStr[0]);
            } catch (IOException e) {
                e.printStackTrace();
                return null;
            }
        }
    }

**base64加密解密demo如下:**

import sun.misc.BASE64Decoder;
    import sun.misc.BASE64Encoder;
    import java.io.ByteArrayInputStream;
    import java.io.FileInputStream;
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.Date;
    
    public class BaseUtil {
    
        public static String fileToBase64(String filepath, String filename) throws IOException {
            String fileName = filepath + filename; // 源文件
            String strBase64 = null;
            InputStream in = null;
            try {
                in = new FileInputStream(fileName);
                // in.available()返回文件的字节长度
                byte[] bytes = new byte[in.available()];
                // 将文件中的内容读入到数组中
                in.read(bytes);
                // strBase64 = new BASE64Encoder().encode(bytes); // 将字节流数组转换为字符串
                strBase64 = encode(bytes); // 将字节流数组转换为字符串
            } catch (FileNotFoundException fe) {
                fe.printStackTrace();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }finally{
                if(in!=null)
                    in.close();
            }
            return strBase64;
        }
    
        public static String fileToBase64(String filepathame) throws IOException {
            String fileName = filepathame; // 源文件
            String strBase64 = null;
            try {
                InputStream in = new FileInputStream(fileName);
                // in.available()返回文件的字节长度
                byte[] bytes = new byte[in.available()];
                // 将文件中的内容读入到数组中
                in.read(bytes);
                // strBase64 = new BASE64Encoder().encode(bytes); // 将字节流数组转换为字符串
                strBase64 = encode(bytes); // 将字节流数组转换为字符串
                in.close();
            } catch (FileNotFoundException fe) {
                fe.printStackTrace();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
            return strBase64;
        }
    
        public static String base64ToFile(String strBase64, String filetype,String name) throws IOException {
            String string = strBase64;
            long time = new Date().getTime();
            String filepath = "/tmp/"+name+"."+filetype;  //生成的新文件
           // String fileName = filepath + filename;//
            ByteArrayInputStream in = null;
            FileOutputStream out = null;
            try {
                // 解码，然后将字节转换为文件
    //             byte[] bytes = new BASE64Decoder().decodeBuffer(string);
                 byte[] bytes = decode(string.trim().replaceAll(" ", ""));
               // byte[] bytes = decode(string.trim().replaceAll(" ", ""));
                // 将字符串转换为byte数组
                in = new ByteArrayInputStream(bytes);
                byte[] buffer = new byte[1024];
                out = new FileOutputStream(filepath);
                int bytesum = 0;
                int byteread = 0;
                while ((byteread = in.read(buffer)) != -1) {
                    bytesum += byteread;
                    out.write(buffer, 0, byteread); // 文件写操作
                }
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }finally{
                if(out!=null)
                    out.flush();
                    out.close();
                if(in!=null)
                    in.close();
            }
            return filepath;
        }
    
        /**
         * 编码
         *
         * @param bstr
         * @return String
         */
        public static String encode(byte[] bstr) {
            return new BASE64Encoder().encode(bstr);
        }
    
        /**
         * 解码
         *
         * @param str
         * @return string
         */
        public static byte[] decode(String str) {
            byte[] bt = null;
            try {
                BASE64Decoder decoder = new BASE64Decoder();
                bt = decoder.decodeBuffer(str);
            } catch (IOException e) {
                e.printStackTrace();
            }
            return bt;
        }
    
    
        public static void main(String[] args) {
            try {
                String base64code = fileToBase64("/Users/fish/Desktop/2.doc");
                //将文件流化
                System.out.println();
                //将流化文件重新生成文件
                String path = base64ToFile(base64code,"doc","test");
                System.out.println(path);
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                System.out.println("error");
                e1.printStackTrace();
            }
        }
    }

**在工具类中需要的Base64File类:**

import org.springframework.web.multipart.MultipartFile;
    import java.io.*;
    public class Base64File implements MultipartFile {
    
        private final byte[] content;
    
        private final String header;
    
        public Base64File(byte[] content, String header) {
            this.content = content;
            this.header = header.split(";")[0];
        }
    
        public byte[] getContent() {
            return content;
        }
    
        public String getHeader() {
            return header;
        }
    
        @Override
        public String getName() {
            // TODO - implementation depends on your requirements
            return System.currentTimeMillis() + Math.random() + "." + header.split("/")[1];
        }
    
        @Override
        public String getOriginalFilename() {
            // TODO - implementation depends on your requirements
            return System.currentTimeMillis() + (int)Math.random() * 10000 + "." + header.split("/")[1];
        }
    
        @Override
        public String getContentType() {
            // TODO - implementation depends on your requirements
            return header.split(":")[1];
        }
    
        @Override
        public boolean isEmpty() {
            return content == null || content.length == 0;
        }
    
        @Override
        public long getSize() {
            return content.length;
        }
    
        @Override
        public byte[] getBytes() throws IOException {
            return content;
        }
    
        @Override
        public InputStream getInputStream() throws IOException {
            return new ByteArrayInputStream(content);
        }
    
        @Override
        public void transferTo(File dest) throws IOException, IllegalStateException {
            new FileOutputStream(dest).write(content);
        }
    }