版本情况

JDK版本： jdk1.8.0_66(win7)
hutool版本： hutool-all-5.7.13（请确保最新尝试是否还有问题）

问题描述（包括截图）

1. 复现代码

//文件大小3GB
HashMap<String, Object> paramMap = new HashMap<String, Object>();
paramMap.put("file", new File(bigfile));
String result1 = HttpUtil.post(serverUrl, paramMap);

2. 堆栈信息
   java.lang.OutOfMemoryError: Java heap space
   at java.util.Arrays.copyOf(Arrays.java:3236)
   at java.io.ByteArrayOutputStream.grow(ByteArrayOutputStream.java:118)
   at java.io.ByteArrayOutputStream.ensureCapacity(ByteArrayOutputStream.java:93)
   at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:153)
   at sun.net.www.http.PosterOutputStream.write(PosterOutputStream.java:78)
   at cn.hutool.core.io.copy.StreamCopier.doCopy(StreamCopier.java:102)
   at cn.hutool.core.io.copy.StreamCopier.copy(StreamCopier.java:68)
   at cn.hutool.core.io.IoUtil.copy(IoUtil.java:161)
   at cn.hutool.core.io.IoUtil.copy(IoUtil.java:145)
   at cn.hutool.core.io.IoUtil.copy(IoUtil.java:131)
   at cn.hutool.core.io.IoUtil.copy(IoUtil.java:118)
   at cn.hutool.core.io.resource.Resource.writeTo(Resource.java:65)
   at cn.hutool.http.body.MultipartBody.appendPart(MultipartBody.java:125)
   at cn.hutool.http.body.MultipartBody.writeForm(MultipartBody.java:94)
   at cn.hutool.http.body.MultipartBody.write(MultipartBody.java:80)
   at cn.hutool.http.HttpRequest.sendMultipart(HttpRequest.java:1209)
   at cn.hutool.http.HttpRequest.send(HttpRequest.java:1153)
   at cn.hutool.http.HttpRequest.execute(HttpRequest.java:955)
   at cn.hutool.http.HttpRequest.execute(HttpRequest.java:926)
   at cn.hutool.http.HttpUtil.post(HttpUtil.java:192)
   at cn.hutool.http.HttpUtil.post(HttpUtil.java:179)
   at cn.xxxxxx.backupclient.service.impl.FileClientServiceImpl.synFileToServer(FileClientServiceImpl.java:105)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:497)
   at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344)
   at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:205)
   at com.sun.proxy.$Proxy61.synFileToServer(Unknown Source)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

3. 测试涉及到的文件（注意脱密）
   无
   4.解决方法
   src\main\java\cn\hutool\http\HttpConnection.java 这个类的如下方法:
   /**

   • 初始化连接相关信息

   • @HTTP4O4 HttpConnection

   • @since_2013 4.4.1
     */
     public HttpConnection initConn() {
     try {
     this.conn = openHttp();
     } catch (IOException e) {
     throw new HttpException(e);
     }

     // 默认读取响应内容
     this.conn.setDoInput(true);
     //下面这一行修复bug
     //这个方法表示不使用PosterOutputStream而使用HttpURLConnection$StreamingOutputStream
     //缓存防止OutOfMemory。
     this.conn.setChunkedStreamingMode(0);
     return this;
     }