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四种json c parser的兼容性比较
最近一个移动终端项目的服务器和客户端之间用到了json(http://www.) 来交换数据。json是一种类似于xml的描述性语言，不过相对于xml来说，json这种格式比较简洁，可以降低服务器和客户端之间的流量。它的格式类似于： { "this": "is", "really": "simple", "json": "right?" } 在json的网站一共有四种C parser，解析json格式我不知道哪种比较实用，花了点时间测试了一下兼容性（我比较关注，性能应该差不多）。现在把结果贴出来供大家参考。 测试的文件从yajl里的cases获取 yajl-0.4.0 [PASS] /home/lyb/cases/array.json [PASS] /home/lyb/cases/codepoints_from_unicode_org.json [PASS] /home/lyb/cases/dc_simple_with_comments.json [PASS] /home/lyb/cases/deep_arrays.json [PASS] /home/lyb/cases/difficult_json_c_test_case.json [PASS] /home/lyb/cases/difficult_json_c_test_case_with_comments.json [PASS] /home/lyb/cases/doubles.json [PASS] /home/lyb/cases/empty_array.json [PASS] /home/lyb/cases/escaped_bulgarian.json [PASS] /home/lyb/cases/escaped_foobar.json [PASS] /home/lyb/cases/isolated_surrogate_marker.json [PASS] /home/lyb/cases/nulls_and_bools.json [PASS] /home/lyb/cases/simple.json [PASS] /home/lyb/cases/simple_with_comments.json [PASS] /home/lyb/cases/string_with_escapes.json [PASS] /home/lyb/cases/unescaped_bulgarian.json total: 54 pass: 16 fail: 38 json-c-0.7 [PASS] /home/lyb/cases/array.json [PASS] /home/lyb/cases/codepoints_from_unicode_org.json [PASS] /home/lyb/cases/difficult_json_c_test_case.json [PASS] /home/lyb/cases/difficult_json_c_test_case_with_comments.json [PASS] /home/lyb/cases/doubles.json [PASS] /home/lyb/cases/empty_array.json [PASS] /home/lyb/cases/escaped_bulgarian.json [PASS] /home/lyb/cases/escaped_foobar.json [PASS] /home/lyb/cases/integers.json [PASS] /home/lyb/cases/invalid_utf8.json [PASS] /home/lyb/cases/isolated_surrogate_marker.json [PASS] /home/lyb/cases/leading_zero_in_number.json [PASS] /home/lyb/cases/missing_integer_after_decimal_point.json [PASS] /home/lyb/cases/missing_integer_after_exponent.json [PASS] /home/lyb/cases/non_utf8_char_in_string.json [PASS] /home/lyb/cases/nulls_and_bools.json [PASS] /home/lyb/cases/simple.json [PASS] /home/lyb/cases/string_with_invalid_newline.json [PASS] /home/lyb/cases/unescaped_bulgarian.json total: 54 pass: 19 fail: 35 mjson [PASS] /home/lyb/cases/array.json [PASS] /home/lyb/cases/deep_arrays.json [PASS] /home/lyb/cases/difficult_json_c_test_case.json [PASS] /home/lyb/cases/doubles.json [PASS] /home/lyb/cases/empty_array.json [PASS] /home/lyb/cases/escaped_bulgarian.json [PASS] /home/lyb/cases/integers.json [PASS] /home/lyb/cases/invalid_utf8.json [PASS] /home/lyb/cases/non_utf8_char_in_string.json [PASS] /home/lyb/cases/nulls_and_bools.json [PASS] /home/lyb/cases/simple.json [PASS] /home/lyb/cases/unescaped_bulgarian.json total: 54 pass: 12 fail: 42 json_parser [PASS] /home/lyb/cases/array.json [PASS] /home/lyb/cases/difficult_json_c_test_case.json [PASS] /home/lyb/cases/doubles.json [PASS] /home/lyb/cases/empty_array.json [PASS] /home/lyb/cases/escaped_bulgarian.json [PASS] /home/lyb/cases/integers.json [PASS] /home/lyb/cases/invalid_utf8.json [PASS] /home/lyb/cases/non_utf8_char_in_string.json [PASS] /home/lyb/cases/nulls_and_bools.json [PASS] /home/lyb/cases/simple.json [PASS] /home/lyb/cases/string_with_escapes.json [PASS] /home/lyb/cases/unescaped_bulgarian.json total: 54 pass: 12 fail: 42 结果分析： 从各个通过的文件数量看， json-c兼容性是最好的 把结果都放到tmp.txt， 执行 [lyb@localhost json-parser]$ cat tmp.txt | sort | uniq -c | sort -r 4 [PASS] /home/lyb/cases/unescaped_bulgarian.json 4 [PASS] /home/lyb/cases/simple.json 4 [PASS] /home/lyb/cases/nulls_and_bools.json 4 [PASS] /home/lyb/cases/escaped_bulgarian.json 4 [PASS] /home/lyb/cases/empty_array.json 4 [PASS] /home/lyb/cases/doubles.json 4 [PASS] /home/lyb/cases/difficult_json_c_test_case.json 4 [PASS] /home/lyb/cases/array.json 3 [PASS] /home/lyb/cases/non_utf8_char_in_string.json 3 [PASS] /home/lyb/cases/invalid_utf8.json 3 [PASS] /home/lyb/cases/integers.json 2 [PASS] /home/lyb/cases/string_with_escapes.json 2 [PASS] /home/lyb/cases/isolated_surrogate_marker.json 2 [PASS] /home/lyb/cases/escaped_foobar.json 2 [PASS] /home/lyb/cases/difficult_json_c_test_case_with_comments.json 2 [PASS] /home/lyb/cases/deep_arrays.json 2 [PASS] /home/lyb/cases/codepoints_from_unicode_org.json 1 [PASS] /home/lyb/cases/string_with_invalid_newline.json 1 [PASS] /home/lyb/cases/simple_with_comments.json 1 [PASS] /home/lyb/cases/missing_integer_after_exponent.json 1 [PASS] /home/lyb/cases/missing_integer_after_decimal_point.json 1 [PASS] /home/lyb/cases/leading_zero_in_number.json 1 [PASS] /home/lyb/cases/dc_simple_with_comments.json 有8个文件都通过了4个parser的测试。 4 [PASS] /home/lyb/cases/unescaped_bulgarian.json 4 [PASS] /home/lyb/cases/simple.json 4 [PASS] /home/lyb/cases/nulls_and_bools.json 4 [PASS] /home/lyb/cases/escaped_bulgarian.json 4 [PASS] /home/lyb/cases/empty_array.json 4 [PASS] /home/lyb/cases/doubles.json 4 [PASS] /home/lyb/cases/difficult_json_c_test_case.json 4 [PASS] /home/lyb/cases/array.json json-c-0.7，mjson， json-parser 都通过了下面3个文件的测试 3 [PASS] /home/lyb/cases/non_utf8_char_in_string.json 3 [PASS] /home/lyb/cases/invalid_utf8.json 3 [PASS] /home/lyb/cases/integers.json 可以看出yajl-0.4.0的非utf-8支持不如其它3个 四个模块的一些特点： mjson和json-parser只有一两个文件，适合放到单个模块里用 json-c采用autoconf， 适合库形式 yajl采用cmake， 测试做的比较好 mjson和yajl都支持sax事件解析方法 ~ END ~ cJSON是C语言中的一个JSON编解码器，非常轻量级，C文件只有500多行，速度也非常理想。项目主页：cJSON | Free software downloads at SourceForge.nethttp:///projects/cjson/ cJSON也存在几个弱点： 1不支持[1,2,3,]和{"one":1,}最后多余的那个逗号。这是C语言就开始支持的，JSON RFC文档中没有对此说明，只能说这是扩展功能吧。 2 不支持/*注释*/，和//单行注释。这也是扩展功能。C/C++/JAVA/JavaScript都支持注释，所以我也希望在json文件中写点注释。 3 使用了个全局变量指示出错位置。这个在多线程时就有问题啦。 4 没有封装文件操作，用户需要自己读写文件。 虽然功能不是非常强大（上面124都是非常容易添加少数几行代码都可以支持的），但cJSON的小身板和速度是最值得赞赏的。其代码被非常好地维护着，结构也简单易懂，可以作为一个非常好的C语言项目进行学习（支持上面12两个功能可以作为学习后的作业）。其解析核心是通过递归函数完成的，不过放心它的每个函数都非常非常节省资源。 json-c是另外一个C语言项目，提供了所有的功能，甚至支持单引号字符串，但是结构较之cJSON更为复杂。解析字符串的核心函数没有使用递归实现，最多支持32层数组或对象嵌套（用到这么多层的JSON对象该有多复杂啊？？？），解析时使用了一堆状态在跳来跳去，加上层级跳转，阅读时容易发晕。 json-c项目主页：jehiah/json-c - GitHub https://github.com/jehiah/json-c |
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