HttpURLConnection的不读取整个响应

Question

我使用HttpURLConnection类做的HTTP POST，但我不总是全额取回响应。我想调试问题，但是当我通过每行一步，它的工作。我想这一定是一个时机问题，所以我加入了Thread.sleep，它真的让我的代码工作，但这只是一个临时的解决方法。我不知道为什么会出现这种情况，如何解决。这是我的代码：

public static InputStream doPOST(String input, String inputMimeType, String url, Map<String, String> httpHeaders, String expectedMimeType) throws MalformedURLException, IOException {

    URL u = new URL(url);
    URLConnection c = u.openConnection();
    InputStream in = null;
    String mediaType = null;
    if (c instanceof HttpURLConnection) {

        //c.setConnectTimeout(1000000);
        //c.setReadTimeout(1000000);

        HttpURLConnection h = (HttpURLConnection)c;
        h.setRequestMethod("POST");
        //h.setChunkedStreamingMode(-1);
        setAccept(h, expectedMimeType);
        h.setRequestProperty("Content-Type", inputMimeType);

        for(String key: httpHeaders.keySet()) {
            h.setRequestProperty(key, httpHeaders.get(key));

            if (logger.isDebugEnabled()) {
                logger.debug("Request property key : " + key + " / value : " + httpHeaders.get(key));
            }

        }

        h.setDoOutput(true);
        h.connect();

        OutputStream out = h.getOutputStream();

        out.write(input.getBytes());

        out.close();

        mediaType = h.getContentType();

        logger.debug(" ------------------ sleep ------------------ START");
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        logger.debug(" ------------------ sleep ------------------ END");

        if (h.getResponseCode() < 400) {
            in = h.getInputStream();
        } else {
            in = h.getErrorStream();
        }
    }
    return in;

}

后来i执行以下操作来读取输入数据流

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while (is.available() > 0) {
            bos.write(is.read());
        }
        is.close();

        //is.read(bytes);
        if (logger.isDebugEnabled()) {
            logger.debug(" Response lenght is : " + is.available());
            //logger.debug("RAW response is " + new String(bytes));
            logger.debug("RAW response is " + new String(bos.toByteArray()));
        }

有genearates以下HTTP标头

POST /emailauthentication/ HTTP/1.1
Accept: application/xml
Content-Type: application/xml
Authorization: OAuth oauth_consumer_key="b465472b-d872-42b9-030e-4e74b9b60e39",oauth_nonce="YnDb5eepuLm%2Fbs",oauth_signature="dbN%2FWeWs2G00mk%2BX6uIi3thJxlM%3D", oauth_signature_method="HMAC-SHA1", oauth_timestamp="1276524919", oauth_token="", oauth_version="1.0"
User-Agent: Java/1.6.0_20
Host: test:6580
Connection: keep-alive
Content-Length: 1107

在其他职位有人建议通过使用

关闭保活

http.keepAlive=false

系统属性，我想，并改变到标头

POST /emailauthentication/ HTTP/1.1
Accept: application/xml
Content-Type: application/xml
Authorization: OAuth oauth_consumer_key="b465472b-d872-42b9-030e-4e74b9b60e39", oauth_nonce="Eaiezrj6X4Ttt0", oauth_signature="ND9fAdZMqbYPR2j%2FXUCZmI90rSI%3D", oauth_signature_method="HMAC-SHA1", oauth_timestamp="1276526608", oauth_token="", oauth_version="1.0"
User-Agent: Java/1.6.0_20
Host: test:6580
Connection: close
Content-Length: 1107

连接头是“接近”，但我仍然不能读取整个响应。任何想法，我该怎么办错了？

Answer 1

我觉得你的问题是在这一行：

while (is.available() > 0) {

据javadoc的，available不会阻止，等到所有的数据是可用的，所以你可能会得到第一个数据包，然后将返回false。从InputStream读取正确的方法是这样的：

int len;
byte[] buffer = new byte[4096];
while (-1 != (len = in.read(buffer))) {
  bos.write(buffer, 0, len);
}

读取将返回-1时，有没有留在的InputStream或连接被关闭，它会阻止和等待网络，而这样做。读取阵列也比使用单字节更高性能的。

Answer 2

也许我错过了，但什么是“输入”的代码中的数据类型？东西是奇怪InputStreams一般是一个在读（...）方法往往会阻塞，直到数据可用，则仅返回数据。您实际上需要不断从你的InputStream阅读和附加到一个ByteArrayInputStream或一些其他结构，直到您明确强制EOFException类。

Answer 3

如果你一次，你可以比较isr.available（）的预期内容lenght读取整个消息。这是我做的：

public byte[] readData(HttpURLConnection conn)
        throws IOException, InterruptedException {
    String _connlen = conn.getHeaderField("Content-Length");
    int connlen = Integer.parseInt(_connlen);
    InputStream isr = null;
    byte[] bytes = new byte[connlen];

    try {
        isr = conn.getInputStream();

        //security count that it doesn't begin to hang
        int maxcounter = 0;
        //wait till all data is avalibal, max 5sec
        while((isr.available() != connlen) && (maxcounter  < 5000)){
            Thread.sleep(1);
            maxcounter++;
        }
        //Throw if not all data could be read
        if(maxcounter >= 5000)
            throw new IllegalAccessError(); 

        //read the data         
        if(isr.read(bytes, 0, connlen) < 0)
            throw new IllegalAccessError();     


    } finally {
        if (isr != null)
            isr.close();
    }

    return bytes;
}