httpClient 向微信服务器上传临时图片素材

利用httpClient向微信上传临时图片素材，HttpClient有ByteArrayBody、FileBody、InputStreamBody和StringBody四种Body。其中已经用到的有除ByteArrayBody之前的三种。FileBody和StringBody请参考httpClient的官方例子，很好理解。http://hc.apache.org/httpcomponents-client-4.5.x/httpmime/examples/org/apache/http/examples/entity/mime/ClientMultipartFormPost.java 。

但是用InputStreamBody的时候，官方没有具体给出例子。所以我就照葫芦画瓢写了，但是向微信服务器上传的时候老是超时也不报错，设置client的超时时间也没什么用。纠结了好长时间再加上谷歌，终于找到了两种解决办法。

1、第一种就是把上传的inputStream先转成文件，在用FileBody上传。

File fout = new File("D:\\aa.jpg");
OutputStream os = new FileOutputStream(fout);
int bytesRead = 0;
byte[] buffer = new byte[8192];
while ((bytesRead = in.read(buffer, 0, 8192)) != -1) {
os.write(buffer, 0, bytesRead);
}
os.close();
in.close();
FileBody bin = new FileBody(fout);

2、第二种就是自己实现InputStreamBody，因为我发现FileBody和StringBody上传过程中的ContentLength都是文件的长度，但是InputStreamBody的源码里面获得ContentLength的长度永远是-1，可能就是这个原因让微信识别不了。然后我就自己实现了InputStreamBody。最后终于上传成功了，但是这两种方法本质上没什么区别。

package com.liuxl.httpclient;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.apache.http.entity.ContentType;
import org.apache.http.entity.mime.MIME;
import org.apache.http.entity.mime.content.AbstractContentBody;
import org.apache.http.util.Args;

public class InputStreamBody extends AbstractContentBody{
private final InputStream in;
private final String filename;
private long length;

public InputStreamBody(final InputStream in, long length, final String filename, ContentType contentType) {
super(contentType);
if (in == null) {
throw new IllegalArgumentException("Input stream may not be null");
}
this.in = in;
this.filename = filename;
this.length = length;
}

public InputStreamBody(final InputStream in, long length, final String filename) {
this(in, length, filename, ContentType.create("application/octet-stream"));
}

public InputStreamBody(final InputStream in, long length) {
this(in, length, "no_name", ContentType.create("application/octet-stream"));
}

public InputStream getInputStream() {
return this.in;
}

public void writeTo(final OutputStream out) throws IOException {
Args.notNull(out, "Output stream");
try {
byte[] tmp = new byte[4096];
int l;
while ((l = this.in.read(tmp)) != -1) {
out.write(tmp, 0, l);
}
out.flush();
} finally {
this.in.close();
}
}

public String getTransferEncoding() {
return MIME.ENC_BINARY;
}

public String getCharset() {
return null;
}

public long getContentLength() {
return this.length;
}

public String getFilename() {
return this.filename;
}
}

File f = new File("D:\\a.jpg");
InputStreamBody fileis = new InputStreamBody((InputStream)source,f.length(),f.getName());
mediaEntityBuilder = MultipartEntityBuilder.create().addPart("file",fileis);

最后我想说，还是谷歌好啊。0.0