Java httpclient请求form-data格式，并设置boundary代码实现

文章目录

form-data 数据请求格式样例
报错信息: **MissingServletRequestParameterException**解决方法
报错信息: **no multipart boundary was found** 解决方法
Java代码实现
- 【错误】使用 UrlEncodedFormEntity 、BasicNameValuePair 请求失败（error）
- 【正确】使用 MultipartEntityBuilder 构造 boundary
总结

原创不易，转载请注明出处：
https://zhangxiaofan.blog.csdn.net/article/details/140737900

form-data 数据请求格式样例

我们先看下 form-data 数据的格式是长什么样的。
例如要传输 form-data 的键值对是：
a: aaa
b: bbb
请求的boundary设置如下：
addHeader(“Content-type”, “multipart/form-data;boundary=----12345”)

实际请求格式会加上boundary，请求示例如下

----12345
Content-Disposition: form-data; name="a"
aaa
----12345
Content-Disposition: form-data; name="b"
bbb

postman自动生成的 boundary 如下：

Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Content-Type: multipart/form-data; boundary=--------------------------477613155954799910398847

报错信息: MissingServletRequestParameterException解决方法

org.springframework.web.bind.MissingServletRequestParameterException

请求Headers中的Content-Type类型不对
addHeader(“Content-Type”, “application/json; charset=UTF-8”);
将Json换成multipart/form-data
addHeader(“Content-type”, “multipart/form-data; charset=UTF-8; boundary=” + new UUIDGenerator().next());

报错信息: no multipart boundary was found 解决方法

org.apache.tomcat.util.http.fileupload.FileUploadException: the request was rejected because no multipart boundary was found

这个报错是没有设置边界分隔符
解决方法：

headers中添加boundary

addHeader("Content-type", "multipart/form-data;boundary=" + boundary)

multipart/form-data 请求参数添加boundary

MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create()
        .setCharset(StandardCharsets.UTF_8)
        // [重要]:设置 setBoundary 边界分隔符
        .setBoundary(boundary);

Java代码实现

【错误】使用 UrlEncodedFormEntity 、BasicNameValuePair 请求失败（error）

public static JSONObject test(String URL) throws IOException {
    RequestConfig requestConfig = RequestConfig.custom().build();

    try (CloseableHttpClient httpClient = HttpClientBuilder.create().build()) {
        HttpPost post = new HttpPost(URL);
        List<NameValuePair> list = new ArrayList<>();
        BasicNameValuePair pair1 = new BasicNameValuePair("a", "aaa");
        BasicNameValuePair pair2 = new BasicNameValuePair("b", "bbb");
        list.add(pair1);
        list.add(pair2);
        UrlEncodedFormEntity urlEncodedFormEntity = new UrlEncodedFormEntity(list,"UTF-8");
        post.setEntity(urlEncodedFormEntity);
        String boundary = new UUIDGenerator().next();
        // 设置请求格式 multipart/form-data
        post.addHeader("Content-type", "multipart/form-data;boundary=" + boundary);
        post.addHeader("Accept", "*/*");
        // UTF-8 解决中文乱码
        post.addHeader("Accept-Encoding", "UTF-8");
        post.addHeader("User-Agent", " Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36");
        
        // 发送 post 请求
        HttpResponse response = httpClient.execute(post);
        
        ...省略代码
}

上面的代码使用了 UrlEncodedFormEntity,BasicNameValuePair 去设置请求格式 multipart/form-data，虽然在 Content-type中设置了 boundary，请求还是报请求参数错误：MissingServletRequestParameterException
是因为并没有在 multipart/form-data 的请求数据前后设置分割边界符

【正确】使用 MultipartEntityBuilder 构造 boundary

要使用MultipartEntityBuilder，先引入maven

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5</version>
</dependency>
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpmime</artifactId>
    <version>4.5</version>
</dependency>

java用httpclient（apache）完整的纯文本form-data请求实现如下：

public enum Test {
    ;
    private static final Logger logger = LoggerFactory.getLogger(Test.class);

    /**
     * setConnectTimeout: 从客户端到url建立连接的超时时间
     */
    private static final int CONNECT_TIMEOUT = 30 * 1000;

    /**
     * setSocketTimeout: 连接上一个url后，获取response的返回等待时间
     */
    private static final int SOCKET_TIMEOUT = 3600 * 1000;


    public static JSONObject postHttpFormDataPair(String URL, JSONObject requestBodyJson, Map<String, String> headersMap, String... saveRespHeaderName) {
        RequestConfig requestConfig = RequestConfig.custom()
                .setConnectTimeout(CONNECT_TIMEOUT)
                .setSocketTimeout(SOCKET_TIMEOUT)
                .setCookieSpec(CookieSpecs.DEFAULT)
                .build();

        CookieStore cookieStore = new BasicCookieStore();
        // 默认是 CloseableHttpClient httpClient = HttpClientBuilder.create().build();
        try (CloseableHttpClient httpClient = createSSLClientDefaultBuilder()
                .setDefaultRequestConfig(requestConfig)
                .setDefaultCookieStore(cookieStore)
                .build()) {

            HttpPost post = new HttpPost(URL);
            // [重要]:生成边界分隔符 boundary
            String boundary = new UUIDGenerator().next();
            // [重要]:设置请求格式 multipart/form-data
            post.addHeader("Content-type", "multipart/form-data; charset=UTF-8; boundary=" + boundary);
            post.addHeader("Accept", "*/*");
            post.addHeader("Accept-Encoding", "UTF-8");
            post.addHeader("User-Agent", " Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36");

            if (!CollectionUtils.isEmpty(headersMap)) {
                for (Map.Entry<String, String> entry : headersMap.entrySet()) {
                    post.addHeader(entry.getKey(), entry.getValue());
                }
            }

            // 构造 formdata 请求数据
            MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create()
                    .setCharset(StandardCharsets.UTF_8)
                    // [重要]:设置 setBoundary 边界分隔符
                    .setBoundary(boundary);
            multipartEntityBuilder.addTextBody("a", "aaa");
            multipartEntityBuilder.addTextBody("b", "bbb");

            HttpEntity postFormDataBody = multipartEntityBuilder.build();

            // 请求参数
            post.setEntity(postFormDataBody);

            // 发送 post 请求
            HttpResponse response = httpClient.execute(post);
            if (response == null) {
                throw new RuntimeException("response is null");
            } else if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                return getResponseJsonObject(response, saveRespHeaderName);
            } else {
                logger.warn("response status is not 200");
                return getResponseJsonObject(response, saveRespHeaderName);
            }
        } catch (Exception ex) {
            logger.error("error:", ex);
            throw new RuntimeException("系统异常");
        }
    }

    @NotNull
    private static JSONObject getResponseJsonObject(HttpResponse response, String[] saveRespHeaderName) throws IOException {
        InputStream in = response.getEntity().getContent();
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String lines;
        StringBuilder responseMsg = new StringBuilder("");
        while ((lines = reader.readLine()) != null) {
            lines = new String(lines.getBytes(), StandardCharsets.UTF_8);
            responseMsg.append(lines);
        }
        reader.close();
        in.close();
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("message", responseMsg.toString());
        // save header
        for (String name : saveRespHeaderName) {
            jsonObject.put(name, response.getHeaders(name));
        }
        return jsonObject;
    }

    /**
     * 绕过https证书校验
     */
    public static HttpClientBuilder createSSLClientDefaultBuilder() {
        HttpClientBuilder httpClientBuilder = null;
        try {
            SSLContextBuilder builder = new SSLContextBuilder();
            // 实现该接口，证书受信任的X509证书校验为true
            builder.loadTrustMaterial(null, (chain, authType) -> true);
            // 创建HttpsURLConnection对象，并设置其SSLSocketFactory对象
            SSLConnectionSocketFactory socketFactory = new SSLConnectionSocketFactory(builder.build(), new String[]{"TLSv1.2"}, null, NoopHostnameVerifier.INSTANCE);
            //  HttpsURLConnection对象就可以正常连接HTTPS了，无论其证书是否经权威机构的验证，只要实现了接口X509TrustManager的类MyX509TrustManager信任该证书。
            httpClientBuilder = HttpClients.custom().setSSLSocketFactory(socketFactory);
        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException("系统异常");
        }
        return httpClientBuilder;
    }
}