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我有一个静态帮助方法，负责从我们的 Rails 应用程序中获取压缩的 JSON 字符串，并在返回String表示之前解压缩数据。

我编写了两个 JUnit 测试，一个测试 JSON 是否正确解析，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，第一个测试方法正常成功，另一个失败IOException并显示消息“损坏的 GZIP 预告片”（参见下面的代码）。我已经确定不是测试本身失败了，因为当我导致测试以相反的顺序运行时，“成功”的测试会被逆转（换句话说，无论如何，总是第二个测试失败，无论两个测试中的哪个是第二个）。

这是辅助方法：

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;
}

错误发生在辅助方法的底部，在 line 上while((line = reader.readLine()) != null)...。具体来说，错误发生在reader.readLine().

以及两种测试方法：

@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);
    }
}

我已经阅读了这个问题和答案，但我不相信它适用，（或者可能是这样，我误解了，如果是这样，请告诉我），我尝试了他们的方法，只收到了相同的信息。

由于该doHTTPGet方法是静态的，并且创建的对象是在方法体内完成的，因此不应重用任何内容（流、连接对象等）。坦率地说，我很难过。

问题：我是否在帮助程序代码中做错了什么，或者我误解了某些对象的某些用法，这会产生“Corrupt GZIP Trailer”消息？简而言之，在我的场景中会导致此错误的原因是什么？

与往常一样，如果我在这个问题上遗漏了什么，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)
4

1 回答 1

0

问题已解决。坦率地说，我不太明白为什么它最初不能工作，或者它有什么问题（除了显然过于复杂和不必要的复杂）。多亏了这个解决方案，我不知何故错过了我的第一次搜索，我能够通过基本上或多或少地完全实现他们所做的来解决问题。这是我的最终代码：

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();
}

所以最终，我不需要通过字节数组流和到处传递数据。除了我最初的方法令人费解之外，如果有人具体知道为什么我的原始算法在第一次调用此方法后会产生“损坏的 GZIP 预告片”错误消息，请务必告诉我。

于 2013-10-18T19:52:46.830 回答