缓冲图像为空

Question

我正在尝试从 python 应用程序发送帧到 java 应用程序。首先，我使用 numpy 数组在 python 端创建一个空白图像，然后想将其发送到 java 应用程序并在 java 端显示它。但是java端的bufferedimage是null这里是python代码；

import socket
import sys
import cv2
import numpy as np
import base64
import json
from lib2to3.pytree import Leaf
from lib2to3.fixer_util import String

socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
HOST = "localhost"
PORT = 5555
try:
    socket.connect((HOST, PORT))
except:
    print "We cannot find the server !!!!"
    print "Terminating the program . . ."
    #exit(0)

img = np.zeros((300, 300, 3), np.uint8) 
obj = NumpyEncoder()   
outjson = {}
outjson['img'] = base64.b64encode(img)
outjson['leaf'] = "leaf"
json_data = json.dumps(outjson)
socket.sendall(json_data

socket.close()

这是java端；

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Base64;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

import org.json.JSONException;
import org.json.JSONObject;

import com.sun.javafx.iio.ImageFormatDescription;
import com.sun.prism.Image;

import java.awt.Color;
import java.awt.Dimension;

public class ServerFrame extends JFrame {

private JPanel contentPane;
public static BufferedImage bufferedImage;

/**
 * Launch the application.
 * @throws IOException 
 * @throws JSONException 
 */
public static void main(String[] args) throws IOException, JSONException {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                ServerFrame frame = new ServerFrame();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });

    ServerSocket serverSocket = null;
    Socket clientSocket = null;


    try {
        serverSocket = new ServerSocket(5555);
    } catch(IOException e) {
        System.out.println(e.getMessage());
        System.exit(1);
    }

    System.out.println("Server Socket Has Been Started . . .");
    try {
        clientSocket = serverSocket.accept();
        System.out.println("User Connected :" + clientSocket.getLocalAddress().toString());

    } catch(IOException e) {
        System.out.println(e.getMessage());
    }

    StringBuilder sb = new StringBuilder();
    InputStream in = clientSocket.getInputStream();
    if(in == null) System.exit(1);
    BufferedReader br = new BufferedReader(new    InputStreamReader(clientSocket.getInputStream()));
    String line;
    while ((line = br.readLine()) != null) {
           sb.append(line);
        }
    //System.out.println(sb.toString());

    JSONObject json = new JSONObject(sb.toString());
    String leaf_name = json.getString("leaf");
    String mat_string = json.getString("img");
    byte[] raw_data = Base64.getDecoder().decode(mat_string);
    bufferedImage = ImageIO.read(new ByteArrayInputStream(raw_data));
    if(bufferedImage == null) System.out.println("warning");
    System.out.println(raw_data.length);
    FileOutputStream fos = new FileOutputStream("image.jpg");
    try {
        fos.write(raw_data);
    }
    finally {
        fos.close();
    }
    /*JPanel panel = new JPanel();
    panel.setBackground(Color.RED);
    Dimension dim = new Dimension(50,50);
    panel.setSize(dim);
    panel.setMinimumSize(dim);
    panel.setMaximumSize(dim);
    panel.setPreferredSize(dim);
    JLabel label = new JLabel("hello");
    label.setSize(label.getPreferredSize());
    panel.add(label);
    panel.setVisible(true);
    JOptionPane.showMessageDialog(null, new JLabel(new ImageIcon(bufferedImage)));*/
    br.close();
    clientSocket.close();
}

/**
 * Create the frame.
 */
public ServerFrame() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    contentPane.setLayout(new BorderLayout(0, 0));
    setContentPane(contentPane);
}

}

你能看到问题吗，为什么它是空的？

Answer 1

更改为：

outjson['img'] = base64.b64encode(img.tobytes())

Answer 2

数据库中的 Base64 属性为空。要解决此问题，请手动打开数据库，或者以其他方式将 base64 值插入到导致 null 返回的属性中。我在初始化时遇到了同样的问题： WebImage 图像 = new WebImage(i.ImageData);

突出显示的 ImageData 为空，因此出现错误。解决方案是插入一个 Base64 值