docs: add json output sample

Author: ikesnowy

README.zh-Hans.md

@@ -968,6 +968,87 @@ Usage: in(302)/out(19)/total(321)
  */
 ```
 
+### 结构化输出（JSON 输出）
+
+设置 `Parameter` 里的 `ResponseFormat` （注意不是 `ResultFormat` ）为 JSON 即可强制大模型以 JSON 格式输出。
+
+示例请求：
+
+```csharp
+var request = new ModelRequest<TextGenerationInput, ITextGenerationParameters>()
+{
+    Model = "qwen-plus",
+    Input = new TextGenerationInput() { Messages = messages },
+    Parameters = new TextGenerationParameters()
+    {
+        ResultFormat = "message",
+        ResponseFormat = DashScopeResponseFormat.Json,
+        IncrementalOutput = true
+    }
+}
+```
+
+示例代码，大模型会以 JSON 输出用户输入的字数信息：
+
+```csharp
+var messages = new List<TextChatMessage>();
+messages.Add(TextChatMessage.System("使用 JSON 输出用户输入的字数信息"));
+while (true)
+{
+    Console.Write("User > ");
+    var input = Console.ReadLine();
+    if (string.IsNullOrEmpty(input))
+    {
+        Console.WriteLine("Please enter a user input.");
+        return;
+    }
+
+    messages.Add(TextChatMessage.User(input));
+    var completion = client.GetTextCompletionStreamAsync(
+        new ModelRequest<TextGenerationInput, ITextGenerationParameters>()
+        {
+            Model = "qwen-plus",
+            Input = new TextGenerationInput() { Messages = messages },
+            Parameters = new TextGenerationParameters()
+            {
+                ResultFormat = "message",
+                ResponseFormat = DashScopeResponseFormat.Json,
+                IncrementalOutput = true
+            }
+        });
+    var reply = new StringBuilder();
+    var firstChunk = true;
+    TextGenerationTokenUsage? usage = null;
+    await foreach (var chunk in completion)
+    {
+        var choice = chunk.Output.Choices![0];
+        if (firstChunk)
+        {
+            firstChunk = false;
+            Console.Write("Assistant > ");
+        }
+
+        Console.Write(choice.Message.Content);
+        reply.Append(choice.Message.Content);
+        usage = chunk.Usage;
+    }
+
+    Console.WriteLine();
+    messages.Add(TextChatMessage.Assistant(reply.ToString()));
+    if (usage != null)
+    {
+        Console.WriteLine(
+            $"Usage: in({usage.InputTokens})/out({usage.OutputTokens})/total({usage.TotalTokens})");
+    }
+}
+
+/*
+User > 你好
+Assistant > {"word_count": 2}
+Usage: in(25)/out(7)/total(32)
+ */
+```
+
 
 
 ### 多模态

sample/Cnblogs.DashScope.Sample/Text/JsonOutputSample.cs

@@ -0,0 +1,71 @@
+using System.Text;
+using Cnblogs.DashScope.Core;
+
+namespace Cnblogs.DashScope.Sample.Text;
+
+public class JsonOutputSample : ISample
+{
+    /// <inheritdoc />
+    public string Description => "JSON output text sample";
+
+    /// <inheritdoc />
+    public async Task RunAsync(IDashScopeClient client)
+    {
+        var messages = new List<TextChatMessage>();
+        messages.Add(TextChatMessage.System("使用 JSON 输出用户输入的字数信息"));
+        while (true)
+        {
+            Console.Write("User > ");
+            var input = Console.ReadLine();
+            if (string.IsNullOrEmpty(input))
+            {
+                Console.WriteLine("Please enter a user input.");
+                return;
+            }
+
+            messages.Add(TextChatMessage.User(input));
+            var completion = client.GetTextCompletionStreamAsync(
+                new ModelRequest<TextGenerationInput, ITextGenerationParameters>()
+                {
+                    Model = "qwen-plus",
+                    Input = new TextGenerationInput() { Messages = messages },
+                    Parameters = new TextGenerationParameters()
+                    {
+                        ResultFormat = "message",
+                        ResponseFormat = DashScopeResponseFormat.Json,
+                        IncrementalOutput = true
+                    }
+                });
+            var reply = new StringBuilder();
+            var firstChunk = true;
+            TextGenerationTokenUsage? usage = null;
+            await foreach (var chunk in completion)
+            {
+                var choice = chunk.Output.Choices![0];
+                if (firstChunk)
+                {
+                    firstChunk = false;
+                    Console.Write("Assistant > ");
+                }
+
+                Console.Write(choice.Message.Content);
+                reply.Append(choice.Message.Content);
+                usage = chunk.Usage;
+            }
+
+            Console.WriteLine();
+            messages.Add(TextChatMessage.Assistant(reply.ToString()));
+            if (usage != null)
+            {
+                Console.WriteLine(
+                    $"Usage: in({usage.InputTokens})/out({usage.OutputTokens})/total({usage.TotalTokens})");
+            }
+        }
+    }
+}
+
+/*
+User > 你好
+Assistant > {"word_count": 2}
+Usage: in(25)/out(7)/total(32)
+ */