cJSON官网是：http://sourceforge.net/projects/cjson/?source=recommended
最新版本是2013年的，与2009年的变化不是很大。
看了代码，觉得挺好，只是是C语言的，不够好。
就改良了一下，内存自己管理。使用std::string
http://files.cnblogs.com/ayanmw/cJSON_cpp_myversion.zip
使用起来如下：
#include <stdio.h> #include <stdlib.h> #include "cJSON.h" #define PS(V) printf(#V"=%s ",V); #define PI(V) printf(#V"=%d ",V); #define PF(V) printf(#V"=%f ",V); int main (int argc, const char * argv[]) { AddStack(__FUNCTION__); const char * myjson="{"name":"value","jsonobject":{"int":5,"true":true,"false":false,"null":null},"jsonarray":["array1","array2",12,true,false,null,"12",-1.2]}"; cJSON * jsonroot =new cJSON(); if(0==jsonroot->cJSON_Parse(myjson)) printf("Error to cJSON_Parse :%s %x ",jsonroot->cJSON_GetErrorPtr(),jsonroot->cJSON_GetErrorPtr()); else{ const char * out=jsonroot->cJSON_Print( ).c_str(); printf("myjson=%s ",out); PS(jsonroot->toString().c_str()); const char * value=jsonroot->cJSON_GetString( "name").c_str(); PS(value); cJSON *jsonobject=jsonroot->cJSON_GetObjectItem( "jsonobject"); PS(jsonroot->cJSON_GetString("jsonobject").c_str()); PS(jsonobject->toString().c_str()); PS(jsonobject->cJSON_GetString("null").c_str()); PS(jsonobject->cJSON_GetString("int").c_str()); PS(jsonobject->cJSON_GetString("true").c_str()); PI(jsonobject->cJSON_GetInt("int") ); PI(jsonobject->cJSON_GetBoolean("true")); PI( jsonobject->cJSON_GetBoolean("false") ); cJSON *jsonarray=jsonroot->cJSON_GetObjectItem("jsonarray"); PS(jsonroot->cJSON_GetString("jsonarray").c_str()); PS(jsonarray->toString().c_str()); PI( jsonroot->cJSON_GetArraySize( ) ); PI( jsonobject->cJSON_GetArraySize( ) ); PI(jsonarray->cJSON_GetArraySize( )); cJSON *arrayitem=jsonarray->cJSON_GetArrayItem( 0); PS(arrayitem->valuestring); } PS("END Mark"); delete jsonroot; return 0; }
toString()可以轻松获取到json的内容信息。以上是解析的。
生成json可以看cJSON的test.c 文件。
#include <stdio.h> #include <stdlib.h> #include "cJSON.h" /* Parse text to JSON, then render back to text, and print! */ void doit(char *text) { char *out;cJSON *json; json=cJSON_Parse(text); if (!json) {printf("Error before: [%s] ",cJSON_GetErrorPtr());} else { out=cJSON_Print(json); cJSON_Delete(json); printf("%s ",out); free(out); } } /* Read a file, parse, render back, etc. */ void dofile(char *filename) { FILE *f=fopen(filename,"rb");fseek(f,0,SEEK_END);long len=ftell(f);fseek(f,0,SEEK_SET); char *data=(char*)malloc(len+1);fread(data,1,len,f);fclose(f); doit(data); free(data); } /* Used by some code below as an example datatype. */ struct record {const char *precision;double lat,lon;const char *address,*city,*state,*zip,*country; }; /* Create a bunch of objects as demonstration. */ void create_objects() { cJSON *root,*fmt,*img,*thm,*fld;char *out;int i; /* declare a few. */ /* Here we construct some JSON standards, from the JSON site. */ /* Our "Video" datatype: */ root=cJSON_CreateObject(); cJSON_AddItemToObject(root, "name", cJSON_CreateString("Jack ("Bee") Nimble")); cJSON_AddItemToObject(root, "format", fmt=cJSON_CreateObject()); cJSON_AddStringToObject(fmt,"type", "rect"); cJSON_AddNumberToObject(fmt,"width", 1920); cJSON_AddNumberToObject(fmt,"height", 1080); cJSON_AddFalseToObject (fmt,"interlace"); cJSON_AddNumberToObject(fmt,"frame rate", 24); out=cJSON_Print(root); cJSON_Delete(root); printf("%s ",out); free(out); /* Print to text, Delete the cJSON, print it, release the string. */ /* Our "days of the week" array: */ const char *strings[7]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"}; root=cJSON_CreateStringArray(strings,7); out=cJSON_Print(root); cJSON_Delete(root); printf("%s ",out); free(out); /* Our matrix: */ int numbers[3][3]={{0,-1,0},{1,0,0},{0,0,1}}; root=cJSON_CreateArray(); for (i=0;i<3;i++) cJSON_AddItemToArray(root,cJSON_CreateIntArray(numbers[i],3)); /* cJSON_ReplaceItemInArray(root,1,cJSON_CreateString("Replacement")); */ out=cJSON_Print(root); cJSON_Delete(root); printf("%s ",out); free(out); /* Our "gallery" item: */ int ids[4]={116,943,234,38793}; root=cJSON_CreateObject(); cJSON_AddItemToObject(root, "Image", img=cJSON_CreateObject()); cJSON_AddNumberToObject(img,"Width",800); cJSON_AddNumberToObject(img,"Height",600); cJSON_AddStringToObject(img,"Title","View from 15th Floor"); cJSON_AddItemToObject(img, "Thumbnail", thm=cJSON_CreateObject()); cJSON_AddStringToObject(thm, "Url", "http:/*www.example.com/image/481989943"); cJSON_AddNumberToObject(thm,"Height",125); cJSON_AddStringToObject(thm,"Width","100"); cJSON_AddItemToObject(img,"IDs", cJSON_CreateIntArray(ids,4)); out=cJSON_Print(root); cJSON_Delete(root); printf("%s ",out); free(out); /* Our array of "records": */ struct record fields[2]={ {"zip",37.7668,-1.223959e+2,"","SAN FRANCISCO","CA","94107","US"}, {"zip",37.371991,-1.22026e+2,"","SUNNYVALE","CA","94085","US"}}; root=cJSON_CreateArray(); for (i=0;i<2;i++) { cJSON_AddItemToArray(root,fld=cJSON_CreateObject()); cJSON_AddStringToObject(fld, "precision", fields[i].precision); cJSON_AddNumberToObject(fld, "Latitude", fields[i].lat); cJSON_AddNumberToObject(fld, "Longitude", fields[i].lon); cJSON_AddStringToObject(fld, "Address", fields[i].address); cJSON_AddStringToObject(fld, "City", fields[i].city); cJSON_AddStringToObject(fld, "State", fields[i].state); cJSON_AddStringToObject(fld, "Zip", fields[i].zip); cJSON_AddStringToObject(fld, "Country", fields[i].country); } /* cJSON_ReplaceItemInObject(cJSON_GetArrayItem(root,1),"City",cJSON_CreateIntArray(ids,4)); */ out=cJSON_Print(root); cJSON_Delete(root); printf("%s ",out); free(out); } int main (int argc, const char * argv[]) { /* a bunch of json: */ char text1[]="{ "name": "Jack (\"Bee\") Nimble", "format": {"type": "rect", "width": 1920, "height": 1080, "interlace": false,"frame rate": 24 } }"; char text2[]="["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"]"; char text3[]="[ [0, -1, 0], [1, 0, 0], [0, 0, 1] ] "; char text4[]="{ "Image": { "Width": 800, "Height": 600, "Title": "View from 15th Floor", "Thumbnail": { "Url": "http:/*www.example.com/image/481989943", "Height": 125, "Width": "100" }, "IDs": [116, 943, 234, 38793] } }"; char text5[]="[ { "precision": "zip", "Latitude": 37.7668, "Longitude": -122.3959, "Address": "", "City": "SAN FRANCISCO", "State": "CA", "Zip": "94107", "Country": "US" }, { "precision": "zip", "Latitude": 37.371991, "Longitude": -122.026020, "Address": "", "City": "SUNNYVALE", "State": "CA", "Zip": "94085", "Country": "US" } ]"; /* Process each json textblock by parsing, then rebuilding: */ doit(text1); doit(text2); doit(text3); doit(text4); doit(text5); /* Parse standard testfiles: */ /* dofile("../../tests/test1"); */ /* dofile("../../tests/test2"); */ /* dofile("../../tests/test3"); */ /* dofile("../../tests/test4"); */ /* dofile("../../tests/test5"); */ /* Now some samplecode for building objects concisely: */ create_objects(); return 0; }
感觉比jsoncpp 代码简洁。算法看起来都是简单精炼的。很好的。