Json正文给出错误代码400的HTTP POST请求

Question

我试图在Java中发送JSON格式的POST请求。

我尝试了很多来自internet和StackOverflow的代码，但都不起作用。

public class PostRequest {

    FileWriter myWriter;
    URL url;
    public void sendPost(String Url) throws IOException {
        
        String name = "{\"messageName\": \"URLFound\", \"businessKey\": \"3\"}";
        
        try {
            myWriter = new FileWriter("C:\\Users\\test\\Desktop\\camunda test save\\Post.txt");
            url = new URL ("http://localhost:8080/engine-rest" + Url);
            HttpURLConnection http = (HttpURLConnection)url.openConnection();
            
            http.setRequestMethod("POST");
            http.setDoOutput(true);
            http.setRequestProperty("Content-Type", "application/json");
            
            OutputStream os = http.getOutputStream();
            byte[] input = name.getBytes("utf-8");
            os.write(input, 0, input.length);
            
            BufferedReader in = new BufferedReader(new InputStreamReader(http.getInputStream()));
            StringBuffer response = new StringBuffer();
            while ((in.ready())) {
                response.append(in.readLine());
            }
            in.close();
            
            //Writing result on .txt
            myWriter.append(response.toString() + "\n" +url);

        }
        catch(Exception e){
            myWriter.append(e.toString());
        }
        myWriter.close();
        
        
    }
}

Answer 1

Java不能从JSON创建对象。检查是否所有字段都在后端所期望的java类的请求体中发送。