如何正确关闭HttpURLConnection类在Android [英] How to properly close HttpURLConnection on Android

问题描述

我使用HttpURLConnection类进行查询后端服务器。请求是POST。我的code如下：

I'm using HttpURLConnection for querying back-end server. Requests are POST. My code looks like:

InputStream is = null;
HttpURLConnection connection = null;
try {
    connection = (HttpURLConnection)new URL(uri).openConnection();
    connection.setRequestMethod("POST");
    connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded; charset=" + ENCODING);
    connection.setDoOutput(true);
    byte[] content = buildFormUrlEncoded(params);
    connection.setRequestProperty("Content-Length", String.valueOf(content.length));

    connection.connect();

    OutputStream os = null;
    try {
        os = connection.getOutputStream();
        os.write(content);
    } finally {
        if (os != null) { os.close(); }
    }

    is = connection.getInputStream();
    handle(is);
} finally {
    if (is != null) { is.close(); }
    if (connection != null) { connection.disconnect(); }
}

但是我得到这个错误StrictMode：

However I'm getting this StrictMode error:

A resource was acquired at attached stack trace but never released. See java.io.Closeable for information on avoiding resource leaks.
java.lang.Throwable: Explicit termination method 'close' not called
    at dalvik.system.CloseGuard.open(CloseGuard.java:184)
    at org.apache.harmony.xnet.provider.jsse.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImpl.java:300)
    at org.apache.harmony.xnet.provider.jsse.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImpl.java:257)
    at libcore.net.http.HttpConnection.setupSecureSocket(HttpConnection.java:210)
    at libcore.net.http.HttpsURLConnectionImpl$HttpsEngine.makeSslConnection(HttpsURLConnectionImpl.java:477)
    at libcore.net.http.HttpsURLConnectionImpl$HttpsEngine.connect(HttpsURLConnectionImpl.java:432)
    at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
    at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
    at libcore.net.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:80)
    at libcore.net.http.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:164)

当我调试code， os.close（）， is.close（）和 connection.disconnect（）被调用。

When I am debugging code, os.close(), is.close() and connection.disconnect() is called.

能StrictMode发生，因为连接在池中保持活着？

Could StrictMode happen because of connection is keep alive in pool?

修改

• 如果 connection.setRequestProperty（连接，关闭）;添加的StrictMode错误消失


• 如果HTTP URL，而不是HTTPS URL使用StrictMode错误消失。


• 如果的BufferedReader 使用StrictMode错误较少发生。

• If connection.setRequestProperty("connection", "close"); is added the StrictMode error disappear.
• If http URL instead of https URL is used the StrictMode error disappear.
• If BufferedReader is used the StrictMode error happens less often.

我想保持HTTPS安全永葆降低握手开销。

I would like to keep https for security and keep alive to reduce handshake overhead.

编辑2

看起来这仅发生在安卓3.X和4.0.X的情况。

Looks like this occurs only in case of android 3.X and 4.0.X.

推荐答案

我的code是这样的：

My code looks like this:

@Override
    protected Boolean doInBackground(Void... params) {
        JSONObject holder = new JSONObject();
        try {
            Resources res = getResources();

            holder.put(res.getString(R.string.str),"");


            URL url = new URL(res.getString(R.string.url));
            String charset = res.getString(R.string.utf);
            HttpURLConnection http = null;

                HttpsURLConnection https = (HttpsURLConnection) url.openConnection();

                http = https;
                http.setRequestMethod(res.getString(R.string.post));
                http.setDoInput(true);
                http.setDoOutput(true);
                http.setRequestProperty(res.getString(R.string.charset), charset);
                http.setRequestProperty(res.getString(R.string.content_type), "application/x-www-form-urlencoded;charset=" + charset);

                String query = String.format("query1=%s&query2=%s&query3=%s&query4=%s", 
                     URLEncoder.encode(res.getString(R.string.qu1), charset), 
                     URLEncoder.encode(res.getString(R.string.qu2), charset),
                     URLEncoder.encode(res.getString(R.string.qu3), charset),
                     URLEncoder.encode(holder.toString(), charset));

                OutputStream output = null;
                try {
                     output = http.getOutputStream();
                     output.write(query.getBytes(charset));
                } finally {
                     if (output != null) try { output.close(); } catch (IOException logOrIgnore) {}
                }
                //InputStream response = http.getInputStream();

                BufferedReader in = new BufferedReader(new InputStreamReader(http.getInputStream()),4800); 
                StringBuffer responseBuffer = new StringBuffer();
                String line;

                while ((line = in.readLine()) != null) { 
                    responseBuffer.append(line);
                }

                in.close();
                answer = new Gson().fromJson(responseBuffer.toString(), Answer.class);
                //s = responseBuffer.toString();
        } catch (Exception e) {
            e.printStackTrace();
            getData();
        }
        return true;
    }

我相信你会找到答案。

I believe you'll find the answer there.

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