GZIPInputStream -腐败的GZIP拖车

Question

我有一个静态帮助方法，负责从Rails应用程序获取压缩的JSON字符串，并在返回String表示之前对数据进行解压缩。

我编写了两个JUnit测试，一个测试JSON正确解析的JSON，另一个更基本的测试确定是否从服务器返回长度大于零的字符串。

问题:当我运行测试套件时，第一个测试方法成功了，另一个测试方法在IOException和消息“损坏的GZIP预告片”中失败(参见下面的代码)。我已经确定，失败的并不是测试本身，因为当我使测试以相反的顺序运行时，“成功”测试就会发生逆转(换句话说，无论第二个测试是第二个失败的，无论哪一个测试是第二次测试，它总是失败的)。

这是helper方法：

public static String doHTTPGet(String urlString) throws IOException{
    URL weatherAPI = new URL(urlString);
    HttpURLConnection apiConnection = (HttpURLConnection) weatherAPI.openConnection();
    apiConnection.setRequestMethod("GET");
    apiConnection.setRequestProperty("Accept-Encoding", "gzip");

    apiConnection.connect();

    BufferedInputStream bufferedInputStream = new BufferedInputStream(apiConnection.getInputStream());
    byte[] inputByteBuffer = new byte[10 * 1024];
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream(10 * 1024); // initialize the output stream with at least one buffer's worth of bytes
    while(bufferedInputStream.read(inputByteBuffer)  > -1){
        outputStream.write(inputByteBuffer);
    }

    outputStream.close();
    bufferedInputStream.close();
    apiConnection.disconnect();

    ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(outputStream.toByteArray());
    byteArrayInputStream.close();

    GZIPInputStream gis = new GZIPInputStream(byteArrayInputStream);
    InputStreamReader inputStreamReader = new InputStreamReader(gis, "UTF-8");
    BufferedReader reader = new BufferedReader(inputStreamReader);

    String decompressedResponse = "";
    String line;

    // readLine() is generating the IOException on the second pass.
    while((line = reader.readLine()) != null){
        decompressedResponse += line;
    }

    reader.close();
    inputStreamReader.close();
    gis.close();

    return decompressedResponse;
}

该错误发生在while((line = reader.readLine()) != null)...行的helper方法的底部。具体来说，错误发生在reader.readLine()上。

这两种测试方法：

@Test
public void testHttpGet(){
    try {
        // FILTERED_API_URL_WITH_TOKEN is merely the URL with an auth token
        String apiResponse = HTTPHelper.doHTTPGet(GlobalConstants.FILTERED_API_URL_WITH_TOKEN);
        assertNotNull(apiResponse);
        assertTrue("The size of the API response should be greater than zero. It is an empty string.", apiResponse.length() > 0);
    } catch (IOException e) {
        e.printStackTrace();
        assertTrue("An exception occured while trying to perform the HTTP Get to the api at URL " + GlobalConstants.FILTERED_API_URL_WITH_TOKEN, false);
    }
}

@Test
public void testAPIContent(){
    try {
        // the getAPIJson() method basically does the same as the testHttpGet
        // method, but converts the string to a json
        JSONObject jsonObject = XMLProducerFromAPI.getAPIJson();
        System.out.println(jsonObject);
        assertNotNull(jsonObject);
    } catch (IOException e) {
        e.printStackTrace();
        assertTrue("An IOException occured. See stack trace", false);
    } catch (JSONException e) {
        e.printStackTrace();
        assertTrue("A JSONException occured. See stack trace", false);
    }
}

我读过this question和the answer，但我不相信它适用，(或者可能是，我误解了，如果是这样的话，请告诉我)，我尝试了他们的方法，只收到了同样的信息。

由于doHTTPGet方法是静态的，并且所创建的对象是在方法主体内创建的，因此不应该重用任何东西(流、连接对象等)。坦白说我很困惑。

问题:我是否在我的助手代码中做错了什么，或者我是否误解了某些对象的某些用法，从而产生了“损坏的GZIP拖车”消息？简而言之，在我的场景中，是什么导致了这个错误？

和往常一样，如果我遗漏了什么问题，请告诉我。

编辑

这是堆栈跟踪：

java.io.IOException: Corrupt GZIP trailer
    at java.util.zip.GZIPInputStream.readTrailer(GZIPInputStream.java:200)
    at java.util.zip.GZIPInputStream.read(GZIPInputStream.java:92)
    at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:264)
    at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:306)
    at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:158)
    at java.io.InputStreamReader.read(InputStreamReader.java:167)
    at java.io.BufferedReader.fill(BufferedReader.java:136)
    at java.io.BufferedReader.readLine(BufferedReader.java:299)
    at java.io.BufferedReader.readLine(BufferedReader.java:362)
    at com.weathertx.xmlserver.support.HTTPHelper.doHTTPGet(HTTPHelper.java:60)
    at com.weathertx.xmlserver.tests.HttpHelperTest.getAPIResponse(HttpHelperTest.java:47)
    at com.weathertx.xmlserver.tests.HttpHelperTest.testHttpGet(HttpHelperTest.java:21)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Answer 1

问题已经解决了。坦率地说，我不太明白为什么它一开始就行不通，或者它有什么问题(除了显然过于复杂和不必要的复杂)。多亏了this solution，我以某种方式错过了第一次搜索，我基本上能够解决问题，基本上完全实现了他们所做的事情。这是我的最后代码：

public static String doHTTPGet(String urlString) throws IOException{
    URL weatherAPI = new URL(urlString);
    HttpURLConnection apiConnection = (HttpURLConnection) weatherAPI.openConnection();
    apiConnection.setRequestMethod("GET");
    apiConnection.setRequestProperty("Accept-Encoding", "gzip");

    apiConnection.connect();

    InputStream gzippedResponse = apiConnection.getInputStream();
    InputStream decompressedResponse = new GZIPInputStream(gzippedResponse);
    Reader reader = new InputStreamReader(decompressedResponse, "UTF-8");
    StringWriter writer = new StringWriter();

    char[] buffer = new char[10240];
    for(int length = 0; (length = reader.read(buffer)) > 0;){
        writer.write(buffer, 0, length);
    }

    writer.close();
    reader.close();
    decompressedResponse.close();
    gzippedResponse.close();
    apiConnection.disconnect();

    return writer.toString();
}

因此，最终，我不需要通过字节数组流和各地传递数据。除了我最初的方法令人费解外，如果有人具体知道为什么我的原始算法在第一次调用之后产生了“损坏的GZIP预告片”错误消息，请务必通知我。