实例代码

Ajax上传图片及预览功能实例代码如下：“html，，，，，Image Upload with Preview，，，，，Upload， document.getElementById(‘imageInput’).addEventListener(‘change’, function(event) {， const file = event.target.files[0];， if (file) {， const reader = new FileReader();， reader.onload = function(e) {， document.getElementById(‘preview’).src = e.target.result;， document.getElementById(‘preview’).style.display = ‘block’;， };， reader.readAsDataURL(file);， }， }); function uploadImage() {， const fileInput = document.getElementById(‘imageInput’);， const file = fileInput.files[0];， if (file) {， const formData = new FormData();， formData.append(‘image’, file); fetch(‘/upload’, {， method: ‘POST’,， body: formData， }).then(response =˃ response.json())， .then(data =˃ console.log(data))， .catch(error =˃ console.error(‘Error:’, error));， }， }，，，，“

“javascript，$.ajax({， url: ‘example.com/api’,， type: ‘POST’,， contentType: ‘application/json’,， data: JSON.stringify({ key: ‘value’ }),， success: function(response) {， console.log(response);， }，});，“

“csharp，using Newtonsoft.Json;，using System;class Program，{， static void Main()， {， string json1 = “{\”Name\”:\”John\”, \”Age\”:30}”;， var person = JsonConvert.DeserializeObject(json1);， Console.WriteLine($”Name: {person.Name}, Age: {person.Age}”); string json2 = “[{\”Name\”:\”Jane\”, \”Age\”:25}, {\”Name\”:\”Doe\”, \”Age\”:22}]”;， var people = JsonConvert.DeserializeObject(json2);， foreach (var p in people)， Console.WriteLine($”Name: {p.Name}, Age: {p.Age}”); string json3 = “{\”Employees\”:[{\”Name\”:\”Alice\”, \”Age\”:32}, {\”Name\”:\”Bob\”, \”Age\”:40}]}”;， var employees = JsonConvert.DeserializeObject(json3);， foreach (var e in employees.Employees)， Console.WriteLine($”Name: {e.Name}, Age: {e.Age}”);， }，}public class Person，{， public string Name { get; set; }， public int Age { get; set; }，}public class RootObject，{， public Person[] Employees { get; set; }，}，“

在ASP.NET中，数据绑定通常通过使用控件如GridView、Repeater等来实现。以下是一个简单的示例代码，展示如何将一个列表绑定到GridView控件：“csharp，// 假设有一个名为Person的类，public class Person，{， public string Name { get; set; }， public int Age { get; set; }，}// 在代码后台（例如Page_Load事件）中，protected void Page_Load(object sender, EventArgs e)，{， if (!IsPostBack)， {， List people = new List， {， new Person { Name = “Alice”, Age = 30 },， new Person { Name = “Bob”, Age = 25 }， }; GridView1.DataSource = people;， GridView1.DataBind();， }，}，`在前端页面中，可以这样定义GridView控件：`html，，“

在ASP.NET中，数字签名通常用于确保数据的完整性和验证发送者的身份。以下是一个简单的示例代码，展示如何在ASP.NET中使用RSA算法进行数字签名：“csharp，using System;，using System.Security.Cryptography;，using System.Text;public class DigitalSignatureExample，{， public static void Main()， {， string data = “Hello, World!”;， using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())， {， // 生成密钥对， rsa.PersistKeyInCsp = false;， byte[] publicKey = rsa.ExportRSAPublicKey();， byte[] privateKey = rsa.ExportRSAPrivateKey(); // 创建签名， byte[] dataBytes = Encoding.UTF8.GetBytes(data);， byte[] signature = rsa.SignData(dataBytes, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1); Console.WriteLine(“Data: ” + data);， Console.WriteLine(“Signature: ” + Convert.ToBase64String(signature)); // 验证签名， using (RSA rsaVerify = RSA.Create())， {， rsaVerify.ImportRSAPublicKey(publicKey, out _);， bool isValid = rsaVerify.VerifyData(dataBytes, signature, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);， Console.WriteLine(“Is signature valid? ” + isValid);， }， }， }，}，“这段代码展示了如何生成RSA密钥对、使用私钥对数据进行签名以及使用公钥验证签名的有效性。

在Android中，裁剪人脸可以通过使用Camera2 API和FaceDetector类来实现。以下是一个简单的示例代码片段：“java，// 初始化Camera2 API，CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);，String cameraId = cameraManager.getCameraIdList()[0];，CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);，StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);，Size previewSize = map.getOutputSizes(SurfaceTexture.class)[0];// 配置相机预览，SurfaceTexture texture = new SurfaceTexture(10);，texture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());，Surface surface = new Surface(texture);// 启动相机预览，CaptureRequest.Builder builder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);，builder.addTarget(surface);，cameraDevice.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {， @Override， public void onConfigured(@NonNull CameraCaptureSession session) {， try {， session.setRepeatingRequest(builder.build(), null, null);， } catch (CameraAccessException e) {， e.printStackTrace();， }， }，}, null);// 使用FaceDetector进行人脸检测，FaceDetector faceDetector = new FaceDetector.Builder(context).setTrackingEnabled(false).build();，if (!faceDetector.isOperational()) {， Log.w(“FaceDetector”, “Face detector dependencies are not yet available.”);，} else {， Frame frame = new Frame.Builder().setBitmap(bitmap).build();， SparseArray faces = faceDetector.detect(frame);， for (int i = 0; i˂ faces.size(); ++i) {， Face face = faces.valueAt(i);， // 处理检测到的人脸， }，}，“

“csharp，using System;，using System.Net.Http;，using System.Threading.Tasks;class Program，{， static async Task Main(string[] args)， {， var client = new HttpClient();， var response = await client.GetStringAsync(“http://example.com”);， var targetString = “target”;， int index = response.IndexOf(targetString);， if (index != -1)， {， Console.WriteLine($”Found ‘{targetString}’ at position {index}”);， }， else， {， Console.WriteLine($”‘{targetString}’ not found”);， }， }，}，“

“csharp，using System.Net.Mail;，var mail = new MailMessage(“from@example.com”, “to@example.com”);，mail.Subject = “Test”;，mail.Body = “Hello!”;，var smtp = new SmtpClient(“smtp.example.com”);，smtp.Send(mail);，“

当然，以下是一个简单的 Android 网络请求示例代码：“java，import android.os.Bundle;，import androidx.appcompat.app.AppCompatActivity;，import java.io.BufferedReader;，import java.io.InputStreamReader;，import java.net.HttpURLConnection;，import java.net.URL;public class MainActivity extends AppCompatActivity {， @Override， protected void onCreate(Bundle savedInstanceState) {， super.onCreate(savedInstanceState);， setContentView(R.layout.activity_main); new Thread(new Runnable() {， @Override， public void run() {， try {， URL url = new URL(“https://api.example.com/data”);， HttpURLConnection connection = (HttpURLConnection) url.openConnection();， connection.setRequestMethod(“GET”);， BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));， String inputLine;， StringBuilder content = new StringBuilder();， while ((inputLine = in.readLine()) != null) {， content.append(inputLine);， }， in.close();， connection.disconnect();， // 处理返回的数据， } catch (Exception e) {， e.printStackTrace();， }， }， }).start();， }，}，“

“csharp，using System;，using System.Data.SqlClient;public class DatabaseConnection，{， private string connectionString = “Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;”; public void ConnectToDatabase()， {， using (SqlConnection connection = new SqlConnection(connectionString))， {， try， {， connection.Open();， Console.WriteLine(“Connected to the database successfully!”);， }， catch (Exception ex)， {， Console.WriteLine(“Error: ” + ex.Message);， }， }， }，}，“