Java发送form-data请求怎么实现文件上传

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封装了以下工具类：

package com.leeyaonan.clinkz.common.util;import java.io.File;import java.io.IOException;import java.NIO.charset.StandardCharsets;import java.util.*;import java.util.concurrent.ScheduledExecutorService;import java.util.concurrent.ScheduledThreadPoolExecutor;import java.util.concurrent.TimeUnit;import lombok.extern.slf4j.Slf4j;import org.apache.Http.HttpEntity;import org.apache.http.client.HttpRequestRetryHandler;import org.apache.http.client.config.RequestConfig;import org.apache.http.client.methods.CloseableHttpResponse;import org.apache.http.client.methods.HttpPost;import org.apache.http.client.methods.HttpRequestBase;import org.apache.http.config.ReGIStry;import org.apache.http.config.RegistryBuilder;import org.apache.http.conn.Socket.ConnectionSocketFactory;import org.apache.http.conn.socket.PlainConnectionSocketFactory;import org.apache.http.conn.ssl.SSLConnectionSocketFactory;import org.apache.http.conn.ssl.TrustSelfSignedStrategy;import org.apache.http.entity.ContentType;import org.apache.http.entity.mime.HttpMultipartMode;import org.apache.http.entity.mime.MultipartEntityBuilder;import org.apache.http.entity.mime.content.FileBody;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;import org.apache.http.impl.client.HttpClients;import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;import org.apache.http.ssl.SSLContextBuilder;import org.apache.http.util.EntityUtils;import org.springframework.util.CollectionUtils;@Slf4jpublic class HttpUtils {        private static int connectionRequestTimeout = 10000;        private static int connectTimeout = 60000;        private static int socketTimeout = 60000;        private static int maxTotal = 800;        private static int maxPerRoute = 20;    private static PoolingHttpClientConnectionManager connectionManager = null;    private static CloseableHttpClient httpClient;    public static CloseableHttpClient getClient() {        return httpClient;    }    static {        log.info("初始化http connection 连接池 ...");        try {            // 配置同时支持 HTTP 和 HTPPS            SSLContextBuilder builder = new SSLContextBuilder();            builder.loadTrustMaterial(null, new TrustSelfSignedStrategy());            SSLConnectionSocketFactory sslConnectionSocketFactory = new SSLConnectionSocketFactory(builder.build());            Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create().register("http", PlainConnectionSocketFactory.getSocketFactory()).register("https", sslConnectionSocketFactory).build();            connectionManager = new PoolingHttpClientConnectionManager(socketFactoryRegistry);        } catch (Exception e) {            log.error("初始化http 连接池异常", e);            connectionManager = new PoolingHttpClientConnectionManager();        }        //连接池统一配置        connectionManager.setMaxTotal(maxTotal);        connectionManager.setDefaultMaxPerRoute(maxPerRoute);        RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(connectTimeout).setConnectionRequestTimeout(connectionRequestTimeout).setSocketTimeout(socketTimeout).build();        //不做重试功能        HttpRequestRetryHandler retryHandler = new DefaultHttpRequestRetryHandler(0, false);        httpClient = HttpClients.custom().setConnectionManager(connectionManager).setDefaultRequestConfig(requestConfig).setRetryHandler(retryHandler).build();        ScheduledExecutorService scheduledExecutorService = new ScheduledThreadPoolExecutor(1);        scheduledExecutorService.scheduleWithFixedDelay(() -> {            connectionManager.closeExpiredConnections();            connectionManager.closeIdleConnections(20, TimeUnit.SECONDS);            log.info("回收过期的http连接完成 status：{}", connectionManager.getTotalStats());        }, 30, 120, TimeUnit.SECONDS);        Runtime.getRuntime().addShutdownHook(new Thread(() -> {            log.info("关闭 httpClient 连接");            try {                if (httpClient != null) {                    httpClient.close();                }            } catch (IOException e) {                log.error("关闭 httpClient 异常", e);            }        }));    }        public static String doPostUploadFile(String url, Map<String, String> headers, File file) {        HttpPost httpPost = new HttpPost(url);        packageHeader(headers, httpPost);        String fileName = file.getName();        CloseableHttpResponse response = null;        String respContent = null;        long startTime = System.currentTimeMillis();        // 设置请求头 boundary边界不可重复，重复会导致提交失败        String boundary = "-------------------------" + UUID.randomUUID().toString();        httpPost.setHeader("Content-Type", "multipart/form-data; boundary=" + boundary);        // 创建MultipartEntityBuilder        MultipartEntityBuilder builder = MultipartEntityBuilder.create();        // 设置字符编码        builder.setCharset(StandardCharsets.UTF_8);        // 模拟浏览器        builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);        // 设置边界        builder.setBoundary(boundary);        // 设置multipart/form-data流文件        builder.addPart("multipartFile", new FileBody(file));        // application/octet-stream代表不知道是什么格式的文件        builder.addBinaryBody("media", file, ContentType.create("application/octet-stream"), fileName);        HttpEntity entity = builder.build();        httpPost.setEntity(entity);        try {            response = httpClient.execute(httpPost);            if (response != null && response.getStatusLine() != null && response.getStatusLine().getStatusCode() < 400) {                HttpEntity he = response.getEntity();                if (he != null) {                    respContent = EntityUtils.toString(he, "UTF-8");                }            } else {                log.error("对方响应的状态码不在符合的范围内!");                throw new RuntimeException();            }            return respContent;        } catch (Exception e) {            log.error("网络访问异常,请求url地址={},响应体={},error={}", url, response, e);            throw new RuntimeException();        } finally {            log.info("统一外网请求参数打印,post请求url地址={},响应={},耗时={}毫秒", url, respContent, (System.currentTimeMillis() - startTime));            try {                if (response != null) {                    response.close();                }            } catch (IOException e) {                log.error("请求链接释放异常", e);            }        }    }        private static void packageHeader(Map<String, String> paramsHeads, HttpRequestBase httpMethod) {        if (!CollectionUtils.isEmpty(paramsHeads)) {            Set<Map.Entry<String, String>> entrySet = paramsHeads.entrySet();            for (Map.Entry<String, String> entry : entrySet) {                httpMethod.setHeader(entry.geTKEy(), entry.getValue());            }        }    }}

Maven依赖：

<!--http-->        <dependency>            <groupId>org.apache.httpcomponents</groupId>            <artifactId>httpcore</artifactId>            <version>4.4.9</version>        </dependency>        <dependency>            <groupId>org.apache.httpcomponents</groupId>            <artifactId>httpclient</artifactId>            <version>4.5.13</version>        </dependency>        <dependency>            <groupId>org.apache.httpcomponents</groupId>            <artifactId>httpmime</artifactId>            <version>4.5.12</version></dependency>

核心部分：

// 设置请求头 boundary边界不可重复，重复会导致提交失败String boundary = "-------------------------" + UUID.randomUUID().toString();        httpPost.setHeader("Content-Type", "multipart/form-data; boundary=" + boundary);        // 创建MultipartEntityBuilder        MultipartEntityBuilder builder = MultipartEntityBuilder.create();        // 设置字符编码        builder.setCharset(StandardCharsets.UTF_8);        // 模拟浏览器        builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);        // 设置边界        builder.setBoundary(boundary);        // 设置multipart/form-data流文件        builder.addPart("multipartFile", new FileBody(file));        // application/octet-stream代表不知道是什么格式的文件        builder.addBinaryBody("media", file, ContentType.create("application/octet-stream"), fileName);        HttpEntity entity = builder.build();        httpPost.setEntity(entity);

注意：这里的builder.addPart("multipartFile", new FileBody(file));，multipartFile对应form表单的字段名称，如果接口更改了字段名称，这里也需要更改

比如我有一个接口是这样定义的：

@PostMapping("/xxx")    public void test(@RequestParam(value = "abc") MultipartFile file) {        ...    }

那么使用上述工具请求该接口的时候，就需要将

builder.addPart("multipartFile", new FileBody(file));

改为

builder.addPart("abc", new FileBody(file));

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