请帮我看一下为什么我的代码前后连不上，如果可以的话，麻烦详细说下问题所在，感谢

# 前端的GUI界面的代码
import sys
from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QLabel, QLineEdit, QPushButton, QTextBrowser, QMessageBox
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest, QNetworkReply
from PyQt5.QtCore import QUrl, QByteArray
import json

class MyApp(QWidget):
    def __init__(self):
        super().__init__()

        # 初始化界面
        self.init_ui()

    def init_ui(self):
        self.setWindowTitle('数据添加和查询示例')
        self.resize(400, 300)

        # 布局
        layout = QVBoxLayout()

        # 添加数据部分
        self.name_label_add = QLabel('姓名:')
        self.name_input_add = QLineEdit()
        self.add_button = QPushButton('添加数据')
        self.add_button.clicked.connect(self.add_data)

        layout.addWidget(self.name_label_add)
        layout.addWidget(self.name_input_add)
        layout.addWidget(self.add_button)

        # 查询数据部分
        self.query_button = QPushButton('查询数据')
        self.query_button.clicked.connect(self.query_data)
        self.result_label = QLabel('查询结果:')
        self.result_browser = QTextBrowser()

        layout.addWidget(self.query_button)
        layout.addWidget(self.result_label)
        layout.addWidget(self.result_browser)

        self.setLayout(layout)

    def add_data(self):
        name = self.name_input_add.text()
        if name:
            success = self.send_request('/api/add_data', {'name': name}, 'Data added successfully')
            if success:
                QMessageBox.information(self, 'Success', 'Data added successfully')
                self.name_input_add.clear()
        else:
            QMessageBox.warning(self, 'Error', 'Name is required')

    def query_data(self):
        success, data = self.send_request('/api/query_data', None, 'Data queried successfully')
        if success:
            QMessageBox.information(self, 'Success', 'Data queried successfully')
            self.result_browser.setPlainText(data)

    def send_request(self, endpoint, data, success_message):
        url = QUrl('http://localhost:5000' + endpoint)
        request = QNetworkRequest(url)

        if data:
            data = QByteArray(json.dumps(data).encode())
            request.setHeader(QNetworkRequest.ContentTypeHeader, 'application/json')
            request.setHeader(QNetworkRequest.ContentLengthHeader, len(data))

        manager = QNetworkAccessManager()
        reply = manager.post(request, data) if data else manager.get(request)
        reply.finished.connect(self.handle_response)
        return reply.error() == QNetworkReply.NoError, reply.readAll().data().decode()

    def handle_response(self):
        reply = self.sender()  # 获取信号的发送者
        if reply.error() == QNetworkReply.NoError:
            data = reply.readAll().data().decode()
            self.show_message('Data queried successfully\n' + data)
        else:
            self.show_message('Error: ' + reply.errorString())

    def show_message(self, message):
        self.result_browser.setPlainText(message)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MyApp()
    window.show()
    sys.exit(app.exec_())


# 检查服务器连接测试： Test-NetConnection -ComputerName 127.0.0.1 -Port 5000
# 网络连通性测试： ping 127.0.0.1


``````python
# 后端flask文件的代码
from flask import Flask, request, jsonify
import pymysql
from flask_cors import CORS

app = Flask(__name__)
CORS(app)

# MySQL连接配置
db_config = {
    'host': 'localhost',
    'user': 'root',
    'password': '123456',
    'database': 'mine',
    'cursorclass': pymysql.cursors.DictCursor
}

def get_connection():
    return pymysql.connect(**db_config)

@app.route('/api/add_data', methods=['POST'])
def add_data():
    try:
        data = request.json
        name = data.get('name')

        if name:
            # 插入数据到数据库
            with get_connection() as connection:
                with connection.cursor() as cursor:
                    cursor.execute('INSERT INTO users (name) VALUES (%s)', (name,))
                    connection.commit()

            return jsonify({'success': True, 'message': 'Data added successfully'})
        else:
            return jsonify({'success': False, 'message': 'Name is required'})
    except Exception as e:
        return jsonify({'success': False, 'message': str(e)})

@app.route('/api/query_data', methods=['GET'])
def query_data():
    try:
        # 查询所有数据
        with get_connection() as connection:
            with connection.cursor() as cursor:
                cursor.execute('SELECT * FROM users')
                data = cursor.fetchall()

        return jsonify({'success': True, 'data': data})
    except Exception as e:
        return jsonify({'success': False, 'message': str(e)})

if __name__ == '__main__':
    app.run(debug=True)