从Google Play下载时，Android应用程序崩溃，但在本地开发人员中运行良好-为什么？

我不确定是否有人可以提供帮助，但这确实很奇怪。我构建了一个android应用程序，并在本地对其进行了测试，一切正常。然后，我将其发布到应用程序商店，并且一直崩溃。

谷歌播放的堆栈跟踪显示：

java.lang.RuntimeException: An error occured while executing doInBackground()
    at android.os.AsyncTask$3.done(AsyncTask.java:300)
    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
    at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
    at java.util.concurrent.FutureTask.run(FutureTask.java:242)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
    at libcore.net.UriCodec.encode(UriCodec.java:132)
    at java.net.URLEncoder.encode(URLEncoder.java:57)
    at com.xxxx.yyyy.bbbb.SignedRequestsHelper.percentEncodeRfc3986(SignedRequestsHelper.java:120)
    at com.xxxx.yyyy.bbbb.SignedRequestsHelper.sign(SignedRequestsHelper.java:63)
    at com.xxxx.yyyy.SearchFragment$SearchAsyncTask.doInBackground(SearchFragment.java:385)
    at com.xxxx.yyyy.SearchFragment$SearchAsyncTask.doInBackground(SearchFragment.java:338)
    at android.os.AsyncTask$2.call(AsyncTask.java:288)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    ... 4 more

因此，看来我的SignedRequestsHelper.percentEncodeRfc3986()方法正在执行某些操作。字符串是null。但是请注意，在开发应用程序并在不同设备上进行测试时，不会发生此错误。只有在将其上传到Google Play并从那里下载后，此错误才会出现。

所以我看了看我的SignedRequestHelper类，当时的样子是这样的：

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Iterator;
import java.util.Map;
import java.util.SortedMap;
import java.util.TimeZone;
import java.util.TreeMap;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

public class SignedRequestsHelper {
    private static final String UTF8_CHARSET = "UTF-8";
    private static final String HMAC_SHA256_ALGORITHM = "HmacSHA256";
    private static final String REQUEST_URI = "/onca/xml";
    private static final String REQUEST_METHOD = "GET";

    // use xml-uk.amznxslt.com for xslt requests, or ecs.amazonaws.co.uk for others
    private String endpoint = "webservices.amazon.com"; // must be lowercase

    // change this so reads from properties file
    private String awsAccessKeyId = "xxxx";
    private String awsSecretKey = "xxx";

    private SecretKeySpec secretKeySpec = null;
    private Mac mac = null;

    public SignedRequestsHelper() throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeyException {
        byte[] secretyKeyBytes = awsSecretKey.getBytes(UTF8_CHARSET);
        secretKeySpec =
                new SecretKeySpec(secretyKeyBytes, HMAC_SHA256_ALGORITHM);
        mac = Mac.getInstance(HMAC_SHA256_ALGORITHM);
        mac.init(secretKeySpec);
    }

    public String sign(Map<String, String> params) {
        params.put("AWSAccessKeyId", awsAccessKeyId);
        params.put("Timestamp", timestamp());

        SortedMap<String, String> sortedParamMap =
                new TreeMap<String, String>(params);
        String canonicalQS = canonicalize(sortedParamMap);
        String toSign =
                REQUEST_METHOD + "\n"
                        + endpoint + "\n"
                        + REQUEST_URI + "\n"
                        + canonicalQS;

        String hmac = hmac(toSign);
        String sig = percentEncodeRfc3986(hmac);
        String url = "http://" + endpoint + REQUEST_URI + "?" +
                canonicalQS + "&Signature=" + sig;

        return url;
    }

    private String hmac(String stringToSign) {
        String signature = null;
        byte[] data;
        byte[] rawHmac;
        try {
            data = stringToSign.getBytes(UTF8_CHARSET);
            rawHmac = mac.doFinal(data);
            Base64 encoder = new Base64();
            signature = new String(encoder.encode(rawHmac));
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(UTF8_CHARSET + " is unsupported!", e);
        }
        return signature;
    }

    private String timestamp() {
        String timestamp = null;
        Calendar cal = Calendar.getInstance();
        DateFormat dfm = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
        dfm.setTimeZone(TimeZone.getTimeZone("GMT"));
        timestamp = dfm.format(cal.getTime());
        return timestamp;
    }

    private String canonicalize(SortedMap<String, String> sortedParamMap)
    {
        if (sortedParamMap.isEmpty()) {
            return "";
        }

        StringBuffer buffer = new StringBuffer();
        Iterator<Map.Entry<String, String>> iter =
                sortedParamMap.entrySet().iterator();

        while (iter.hasNext()) {
            Map.Entry<String, String> kvpair = iter.next();
            buffer.append(percentEncodeRfc3986(kvpair.getKey()));
            buffer.append("=");
            buffer.append(percentEncodeRfc3986(kvpair.getValue()));
            if (iter.hasNext()) {
                buffer.append("&");
            }
        }
        String cannoical = buffer.toString();
        return cannoical;
    }

    private String percentEncodeRfc3986(String s) {
        String out;
        try {
            out = URLEncoder.encode(s, UTF8_CHARSET)
                    .replace("+", "%20")
                    .replace("*", "%2A")
                    .replace("%7E", "~");
        } catch (UnsupportedEncodingException e) {
            out = s;
        }
        return out;
    }
}

然后我将percentEncodeRfc3986()方法更改为如下所示。只需删除最后两个替换标签：

private String percentEncodeRfc3986(String s) {
        String out;
        try {
            out = URLEncoder.encode(s, UTF8_CHARSET)
                    .replace("+", "%20");
        } catch (UnsupportedEncodingException e) {
            out = s;
        }
        return out;
    }

然后在本地对其进行测试：它可以工作。然后将其发布到Google Play并下载：它有效。

因此，一切都很好，但是我留在这里想知道为什么现在这确实起作用了。

这也让我感到紧张，因为当应用程序上传到Google Play时，突然之间在我的模拟器和测试设备上完美运行的代码无法正常工作。这似乎是一件微不足道的事情...一些额外的替换导致此错误。

有人可以帮我了解这里发生了什么吗？或者至少至少为什么有时发布在Google Play上的应用程序上的代码可能无法像在本地dev中那样完全无法工作或执行？

编辑：我的build.gradle文件：

android {
    compileSdkVersion 22
    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "com.xxx.yyy"
        minSdkVersion 10
        targetSdkVersion 22
        versionCode 8
        versionName "1.2"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}