java - 当我使用 servlet 将 Android 图像保存到数据库时，为什么它会损坏

Question

所以我在 Android 上的 ImageView 中有一个图像。我将位图转换为 PNG 文件并将其编码为 Base64 字符串。然后，我将此字符串作为参数发布到 POST 请求正文中，并附上一些其他详细信息。

private void uploadImage() {

    img.buildDrawingCache();
    Bitmap bmp = img.getDrawingCache();
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    bmp.compress(Bitmap.CompressFormat.PNG, 90, stream);
    byteArray = Base64.encodeToString(stream.toByteArray(), Base64.DEFAULT);

    StringRequest req = new StringRequest(Request.Method.POST, url+"/AddFoto", new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {

        }
    }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError response) {

        }
    }){
        @Override
        protected Map<String, String> getParams(){
            Map <String, String> params = new HashMap<String, String>();
            Log.d(ProfileFragment.class.getSimpleName(), params.toString());
            params.put("tussenstopID",tussenstopID.toString());
            params.put("description", description);
            params.put("image", byteArray);
            Log.d("image byte array", byteArray);
            return params;
        }
    };
    AppController.getInstance().addToRequestQueue(req);
}

然后我的 servlet 接收该文件并将其转换为字节数组，以便我可以将其上传到数据库。

    package Servlets;

import Core.Foto;
import Core.Tussenstop;
import DAO.FotoFacade;
import DAO.TussenstopFacade;
import com.sun.xml.messaging.saaj.util.Base64;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import javax.ejb.EJB;
import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author Lukas
 */
public class AddFoto extends HttpServlet {


    @EJB
    FotoFacade fotoFacade;

    @EJB
    TussenstopFacade tussenstopFacade;


    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {

            Long tussenstopID = Long.parseLong(request.getParameter("tussenstopID"));
            String description = request.getParameter("description");
            String imageString64 = request.getParameter("image");
            System.out.println(imageString64);
            String imageString = Base64.base64Decode(imageString64);
            byte[] image = imageString.getBytes();


            upload(image, description, tussenstopID);




        }
    }

    public void upload(byte[] imageString, String descr, Long tussenstopID) {
        try {
                InputStream fin2 = new ByteArrayInputStream(imageString);
                //InputStream fin2 = new ByteArrayInputStream( imageString.getBytes() );
                Class.forName("com.mysql.jdbc.Driver");
                // Connect to the database
                Connection connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/Project_1?user=root&password=root");
                 // Set autocommit to false to manage it by hand
                connection.setAutoCommit(false);
                PreparedStatement pre = connection.prepareStatement("INSERT INTO foto (beschrijving,image,tussenstop_id) values(?,?,?)");
                pre.setString(1, descr);
                pre.setBinaryStream(2, fin2);
                Long tempID=tussenstopID;
                pre.setLong(3, tempID);
                pre.executeUpdate();
                System.out.println("Inserting Successfully!");
                connection.commit();
                pre.close();

            } catch (Exception e) {
                System.out.println("Exception-File Upload." + e.getMessage());
            }
    }




    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }


    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }


    @Override
    public String getServletInfo() {
        return "Short description";
    }

}

一切顺利，图像与我发送的其他参数一起添加到数据库中。但是，该图像不可读。当我打开图像的“文本”时，我可以清楚地看到它在开头写着PNG(实际上前面有1个字符)。字节看起来也不错:http://i.stack.imgur.com/L1vaJ.jpg

我真的不知道这段代码出了什么问题。其他图像(从网站上传)效果很好。谁能帮我吗？

Answer 1

我解决了我的问题。 Base64 解码效果不太好。

我导入了 sun.misc.BASE64Decoder 并将其转换如下:

String imageString64 = request.getParameter("image");
BASE64Decoder decoder = new BASE64Decoder();
byte[] image = decoder.decodeBuffer(imageString64);