安卓：大解析JSON文件 [英] Android: Parsing large JSON file

问题描述

我创建一个Android应用程序，它应该从一个文件或URL到jsonarray和jsonobjects分析JSON。 问题是，我的JSON是3.3 MB，当我用一个简单的code，是这样的：（不能存取权限我真正的code现在因为IM在工作中，从复制一些教程code;所以可能有一些错误吧）

I'm creating an android application which should parse a Json from a file or url to a jsonarray and jsonobjects. The problem is that my json is 3.3 mb and when i use a simple code, something like this: (can't acces my real code now because im at work, copied some code from tutorial; so there might be some errors in it)

（假设我已经有我的InputStream的内容）

(assuming i already have my inputstream content)

InputStream content = entity.getContent();
                BufferedReader reader = new BufferedReader(new InputStreamReader(content));
                String line;
                while ((line = reader.readLine()) != null) {
                    builder.append(line);
String twitterfeed = builder.toString();
}

JSONArray jsonArray = new JSONArray(twittefeed);
            Log.i(ParseJSON.class.getName(),
                    "Number of entries " + jsonArray.length());
            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject = jsonArray.getJSONObject(i);
                Log.i(ParseJSON.class.getName(), jsonObject.getString("text"));

当我在我的Andr​​oid设备上运行该code，我解析字符串到jsonArray时遇到内存不足的错误。 我登录了一些东西，我发现，我的总的字符串是17 MB，当我用一个小的JSON文件，如通过twitterfeed左右，code正常工作（3.3 MB JSON文件？！）的。 当我得到这个17 MB串在我的记忆，我不能解析JSON，因为那时我耗尽内存。

When i run this code on my android device, i get an OutOfMemory error when parsing the string to the jsonArray. I logged some things i found that my total string is 17 mb (of a 3.3 mb json file?!) When i use a small json file, like a twitterfeed or so, the code works fine. When i got this 17 mb string in my memory i can't parse the json, because then i run out of memory.

在进行大量的研究，我发现，杰克逊也许是我的解决办法，因为我知道，这是可能的解析一个InputStream。这应该帮助的，因为比我不需要在我的记忆中17 MB串;这是不是最有效的方式，我客串....但我不能得到这真的将工作说清楚，并没有得到它运行自己。 有谁知道这是真的会工作，在那里我可以找到一个教程？

After a lot of research i found that jackson might be my solution, because i understood that it is possible to parse an inputstream. This should help, because than i don't need the 17 mb string in my memory; and this is not the most efficient way i gues.... But i can't get it clear of this really will work, and didn't get it running myself. Does anyone know of this is really will work, and where i can find a tutorial?

我找到了<一href="http://fasterxml.github.com/jackson-core/javadoc/2.0.0/index.html?com/fasterxml/jackson/core/JsonFactory.html"相对=nofollow>createJsonParser - 公共JsonParser createJsonParser（InputStream in）使用并认为这是我的路走...但我不知道如何在我的code实现这一点，并不能找到一个例子。有谁知道这是如何工作？

I found the "createJsonParser -- public JsonParser createJsonParser(InputStream in)" and think this is my way to go... but i don't know how to implement this in my code, and can't find an example. Does anyone know how this works?

推荐答案

您应该使用JSON无论是与GSON或杰克逊流。杰克逊可以使用一种混合的方法为好。这将减少你的内存消耗显著为JSON的只是部分被解析加载到内存中。

You should use json streaming either with gson or jackson. With Jackson you can use a hybrid approach as well. This would reduce your memory consumption significantly as only the portion of json being parsed is loaded into memory.

<一个href="https://sites.google.com/site/gson/gson-user-guide">https://sites.google.com/site/gson/gson-user-guide HTTP：//jackson.$c$chaus.org/

https://sites.google.com/site/gson/gson-user-guide http://jackson.codehaus.org/

杰克逊例如<一href="http://www.mkyong.com/java/jackson-streaming-api-to-read-and-write-json/">http://www.mkyong.com/java/jackson-streaming-api-to-read-and-write-json/

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