Eclipse调用RestAPI报400 Bad Request，Postman可正常运行

我编写了一个Java函数，接收两个输入参数：

• JSON文件路径
• REST接口URL

调用该函数后应返回JSON格式结果，但在Eclipse中运行时抛出400错误，相同接口在Postman中可正常调用。

错误日志 #

Error Log :
URL:
http://localhost:26081/jderest/v3/orchestrator/ORC_2212160001JDE
Conn : sun.net.www.protocol.http.HttpURLConnection:http://localhost:26081/jderest/v3/orchestrator/ORC_2212160001JDE
JSON Input path : \\phxxxx155826.xxxxxx.fusionappsdphx1.xxxxxxxx.com\\FF\\Orchest\\orc1.json
{
"username": "ic8823790",
"password": "ic8823790",
"Product_No": "sss265",
"Description": "sss265",
"Stocking_Type": "s",
"G_L_Class": "in30",
"Unit_of_Measure": "ea",
"Search_Text": "sss265",
"Branch_Plant": "30"
}
HTTP CODE : 400
java.io.IOException: Server returned HTTP response code: 400 for URL: http://exx11001.ad1.xxxxxxxdephx.xxxxxxx.com:26081/jderest/v3/orchestrator/ORC_2212160001JDE
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at sun.net.www.protocol.http.HttpURLConnection$10.run(HttpURLConnection.java:1944)
at sun.net.www.protocol.http.HttpURLConnection$10.run(HttpURLConnection.java:1939)
at java.security.AccessController.doPrivileged(Native Method)
at sun.net.www.protocol.http.HttpURLConnection.getChainedException(HttpURLConnection.java:1938)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1508)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
at OrchestratorAPI.orchestratorCall(OrchestratorAPI.java:108)
at OrchestratorAPI.main(OrchestratorAPI.java:25)
Caused by: java.io.IOException: Server returned HTTP response code: 400 for URL: http://ems11001.ad1.fusionappsdephx.oraclevcn.com:26081/jderest/v3/orchestrator/ORC_2212160001JDE
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1894)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
at OrchestratorAPI.orchestratorCall(OrchestratorAPI.java:100)
... 1 more

我的代码 #

public class OrchestratorAPI {

    public static void main(String[] args) throws MalformedURLException, IOException {
        // TODO Auto-generated method stub
        String filepath = "\\\\xxxxxxx155826.xxxxxxx.fusionappsdphx1.xxxxxxx.com\\FF\\Orchest\\orc1.json";
        String orchAPI = "http://exx11001.ad1.xxxxxxxdephx.xxxxxxx.com:26081/jderest/v3/orchestrator/ORC_2212160001JDE";
        orchestratorCall(filepath, orchAPI);
    }
    
    public static void orchestratorCall(String filePath, String orchestAPI) throws MalformedURLException, IOException {

        String charset = "UTF-8";
        StringBuilder result;
        String content = "";
        String path = "", sid = "";
        String paramsJSON="";

        URLConnection con = new URL(orchestAPI).openConnection();
        System.out.println("URL : "+orchestAPI + "\nConn : "+con);

        System.out.println("JSON Input path : " + filePath);
        try {
            paramsJSON = new String(
                Files.readAllBytes(Paths.get(filePath)));
        }
        catch (IOException e) {
            e.printStackTrace();
        }

        System.out.println(paramsJSON);

        try {
            ((HttpURLConnection) con).setRequestMethod("POST");
            con.setRequestProperty("Content-Type", "application/json; UTF-8");
            con.setRequestProperty("Accept", "application/json");

            con.setDoOutput(true);
            con.setReadTimeout(60000);
            con.setConnectTimeout(60000);

            try (OutputStream os = con.getOutputStream()) {
                byte[] input = paramsJSON.getBytes(charset);
                os.write(input, 0, input.length);
            }

            int code = ((HttpURLConnection) con).getResponseCode();
            System.out.println("HTTP CODE : " + String.valueOf(code));
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            // Receive the response from the server
            InputStream in = new BufferedInputStream(con.getInputStream());
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));
            result = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                result.append(line);
            }

            System.out.println("JSON Parser -> result: " + result.toString());

            try {
                // Create new report file
                content = result.toString();
                path = "\\\\xxxxxxx155826.xxxxxxx.fusionappsdphx1.xxxxxxxx.com\\FF\\Orchest\\" + "" + "OrchestratorReport.json";
                System.out.println("Home Dir path : " + path);
                File file = new File(path);

                // If file doesn't exists, then create it
                if (!file.exists()) {
                    file.createNewFile();
                }

                FileWriter fw = new FileWriter(file.getAbsoluteFile());
                BufferedWriter bw = new BufferedWriter(fw);

                // Write in file
                bw.write(content);

                // Close connection
                bw.close();
            } catch (Exception e) {
                System.out.println(e);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

        ((HttpURLConnection) con).disconnect();   
    }
}

排查建议 #

1. 核对请求头差异：对比Postman与Java代码的请求头，比如Content-Type格式（代码中是application/json; UTF-8，Postman可能仅为application/json），检查是否遗漏User-Agent等必填请求头。
2. 修正JSON编码读取：代码中读取JSON文件时未指定编码，可能导致字符乱码，修改为：paramsJSON = new String(Files.readAllBytes(Paths.get(filePath)), charset);
3. 获取服务器详细错误信息：400错误时，服务器通常会返回具体错误描述，需读取错误流而非仅输入流，修改响应处理逻辑：

int code = ((HttpURLConnection) con).getResponseCode();
System.out.println("HTTP CODE : " + code);
InputStream in;
if (code >= 200 && code < 300) {
    in = con.getInputStream();
} else {
    in = ((HttpURLConnection) con).getErrorStream();
}
// 后续读取流的逻辑不变

4. 确认URL一致性：错误日志中出现了localhost与exx11001.ad1.xxxxxxxdephx.xxxxxxx.com两个不同URL，确保代码使用的URL与Postman完全一致。
5. 对比请求体内容：将代码打印的paramsJSON与Postman发送的请求体逐字符对比，确认格式、空格、换行等细节完全一致。

内容的提问来源于stack exchange，提问作者BipLab