我一定是做错了......或者这可能是YAJL中的一个错误，但我非常怀疑。 我无法从json对象中检索第一个元素。我回到YAJL源代码使用示例parse_config.c进行测试，但也失败了。
使用sample.config
/*
* The configuration file for Yahoo! BrowserPlus, included in the YAJL
* tree as a sample configuration file for parsing.
*
* This is the configuration file for BrowserPlus
*/
{
// The type of build this is, which is accessible to JavaScript via
// BrowserPlus.getPlatformInfo();
// Different build types should only differ in signatures accepted
// (BrowserPlus.crt) and configured distribution servers.
"BuildType": "ephemeral",
// the base url for the "primary" distribution server. This server will
// be the single source of truth for Permissions, and will used to
// attain services
"DistServer": "http://browserplus.yahoo.com",
// An array of "secondary" distribution servers, which will be checked
// in order for services if the primary server has no components
// available which match an issued require statement.
"SecondaryDistServers": [
"http://first.fictional.server",
"http://second.fictional.server"
],
// Logging Setup
"Logging" :
{
// Log level. Values: "debug"|"info"|"warn"|"error"|"fatal"|"off"
"level": "BP_LOG_LEVEL",
// Destination. Values: "file"|"console"|"win32"
"dest": "BP_LOG_DEST",
// Log message layout. Values: "standard"|"source"|"raw"
"layout": "standard",
// Time format. Values: "utc"|"local"|"msec"
"timeFormat": "utc",
// File size in KB which will trigger a rollover
"fileRolloverKB": 2048,
// Whether to send file logging from each service to a distinct file.
// Values: "combined"|"separate"
"serviceLogMode": "combined"
},
// Daemon setup
// Syntax: "Options": "option1 option2 etc"
// -fg run in foreground, log to console
"Options":"",
// Auto-shutdown daemon if idle for this time. Use 0 for no auto-shutdown.
"MaxIdleSecs": 5,
// At the end of each BrowserPlus session a small web request is made
// to yahoo to indicate that BrowserPlus was used. This report includes
// * information about the browser being used
// * an "installation id", which is a unique token that's generated
// the first time BrowserPlus runs.
//
// By design, there is *no information* in this request that gives
// Yahoo! information about:
// a) the site that the user is visiting (see, "url": false)
// b) who the user is (the installation token cannot be tracked to a
// specific user).
//
// This information is primarily captured to help Yahoo! understand
// adoption and usage of the BrowserPlus platform.
"UsageReporting":
{
"enabled": true,
"url": false,
"id": true
},
// "Breakpoints" is an array of strings holding named breakpoints.
// Platform code checks for specific entries at certain key points, and if
// a matching entry is found here a DebugBreak will be performed.
// For developers with Visual Studio installed, the DebugBreak will cause an
// opportunity to perform just-in-time attachment of an existing or new
// debugger instance.
// The currently-defined breakpoints are listed below:
// runServiceProcess - A DebugBreak is performed in the service
// "harness" just prior to service load.
// ax.FinalConstruct - A DebugBreak is performed at entry to
// FinalConstruct of the ActiveX plugin.
// PluginInit - Very early in the NPAPI plugin initialization.
// A wonderful spot to stop and set more
// breakpoints.
//"Breakpoints": ["runServiceProcess"],
// How often we check for service updates. We guarantee at least this
// much time will pass between checks, though the true time may be
// much more if sites which use browserplus are not visited.
// The time is in seconds.
"ServiceUpdatePollPeriod": 86400
}
我尝试检索“BuildType”＆lt; - JSON对象的第一个元素。
我更改了parse_config.c文件来执行此操作...这是代码：
int
main(void)
{
size_t rd;
yajl_val node;
char errbuf[1024];
/* null plug buffers */
fileData[0] = errbuf[0] = 0;
/* read the entire config file */
rd = fread((void *) fileData, 1, sizeof(fileData) - 1, stdin);
/* file read error handling */
if (rd == 0 && !feof(stdin)) {
fprintf(stderr, "error encountered on file read\n");
return 1;
} else if (rd >= sizeof(fileData) - 1) {
fprintf(stderr, "config file too big\n");
return 1;
}
/* we have the whole config file in memory. let's parse it ... */
node = yajl_tree_parse((const char *) fileData, errbuf, sizeof(errbuf));
/* parse error handling */
if (node == NULL) {
fprintf(stderr, "parse_error: ");
if (strlen(errbuf)) fprintf(stderr, " %s", errbuf);
else fprintf(stderr, "unknown error");
fprintf(stderr, "\n");
return 1;
}
/* ... and extract a nested value from the config file */
{
//const char * path[] = { "Logging", "timeFormat", (const char *) 0 };
注意：如果我尝试获取“DistServer”它可以正常工作，但“BuildType”返回NULL。
const char * path[] = { "BuildType", (const char *) 0 };
//const char * path[] = { "DistServer", (const char *) 0 };
yajl_val v = yajl_tree_get(node, path, yajl_t_string);
if (v) printf("%s: %s\n", path[0], YAJL_GET_STRING(v));
else printf("no such node: %s\n", path[0] );
//if (v) printf("%s/%s: %s\n", path[0], path[1], YAJL_GET_STRING(v));
//else printf("no such node: %s/%s\n", path[0], path[1]);
}
yajl_tree_free(node);
return 0;
}
我正在使用最新的YAJL版本：2.0.2。
提前致谢！
修改
这是我的命令输出：
./parse_config < ../../example/sample.config
no such node: BuildType
注意，我正在运行的parse_config位于build / example目录中的那个
我的gcc版本是： gcc版本4.4.5（Ubuntu / Linaro 4.4.4-14ubuntu5）
编辑2 为了记录，这是随附的示例代码。此代码随YAJL一起提供。我特意使用它而不是我自己的代码来确保问题不仅与我的应用程序有关。同时我通过使用库提供和使用
的回调机制解决了这个问题yajl_parse()
and
yajl_complete_parse()
但我仍然想知道为什么原始代码无效。
答案 0 :(得分：4)
我使用版本2.0.2发现了同样的错误。它似乎是yajl中的一个错误，并已在github中修复（“验证yajl_tree_get中正确对象的长度”，提交9c2948a33165c650122d131f31140c15321908f5）。
我已经应用了这个补丁，我现在能够读完第一个项目了。
答案 1 :(得分：1)
这看起来像bug in yajl...
哇，我不认为情况会是这样。