对于cJSON的使用，我主要是用来模拟远程服务器端返回的一个json类型的目录结构，客户端进行获取并进行解析，把解析出来的目录按照原本的结构显示在本地。
cJSON是一个超轻巧，携带方便，单文件，简单的可以作为ANSI-C标准的JSON解析器。
进入cJSON.h头文件中可以查看cJSON的相关信息。主要包括：cJSON结构体、cJSON类型、cJSON的一些内部的函数等。
// cJSON结构体:
typedef struct cJSON {
struct cJSON *next,*prev; // next/prev allow you to walk array/object chains. Alternatively, use GetArraySize/GetArrayItem/GetObjectItem
struct cJSON *child; // An array or object item will have a child pointer pointing to a chain of the items in the array/object.
int type; // The type of the item, as above.
char *valuestring; // The item's string, if type==cJSON_String
int valueint; // The item's number, if type==cJSON_Number
double valuedouble; // The item's number, if type==cJSON_Number
char *string; // The item's name string, if this item is the child of, or is in the list of subitems of an object.
} cJSON;
// cJSON 类型:
#define cJSON_False 0
#define cJSON_True 1
#define cJSON_NULL 2
#define cJSON_Number 3
#define cJSON_String 4
#define cJSON_Array 5
#define cJSON_Object 6
用法：
1、需要包含cJSON.h头文件，然后和cJSON.c或库文件libcJSON.a一起编译即可使用。
2、具体函数用法详见cJSON.h中的注释
更多介绍机器使用请参考：http://sourceforge.net/projects/cjson/.
cJSON构造与解析json结构体
基本代码如下：
#include
#include
#include
#include "cJSON.h"
char * create1()
{
cJSON *root,*dir1,*dir2,*dir3;
char *out;
//创建json数组型结构体
root = cJSON_CreateArray();
//为数组添加对象
cJSON_AddItemToArray(root,dir1=cJSON_CreateObject());
//为对象添加字符串键值对
cJSON_AddStringToObject(dir1,"name",".");
cJSON_AddStringToObject(dir1,"path","uploads/");
cJSON_AddStringToObject(dir1,"flag","true");
cJSON_AddItemToArray(root,dir2=cJSON_CreateObject());
cJSON_AddStringToObject(dir2,"name","..");
cJSON_AddStringToObject(dir2,"path","uploads");
cJSON_AddStringToObject(dir2,"flag","true");
cJSON_AddItemToArray(root,dir3=cJSON_CreateObject());
cJSON_AddStringToObject(dir3,"name","wang.txt");
cJSON_AddStringToObject(dir3,"path","uploads/wang.txt");
cJSON_AddStringToObject(dir3,"flag","false");
//将json结构体转换为字符串
out=cJSON_Print(root);
//删除
cJSON_Delete(root);
return out;
}
char * create2()
{
cJSON *root,*dir,*child,*subdir,*dir1,*dir2,*dir3;
char *out;
root=cJSON_CreateObject();
cJSON_AddItemToObject(root,"Root",dir=cJSON_CreateObject());
cJSON_AddStringToObject(dir,"name","/");
cJSON_AddStringToObject(dir,"path","/");
cJSON_AddStringToObject(dir,"flag","true");
cJSON_AddItemToObject(root,"Child",subdir = cJSON_CreateArray());
cJSON_AddItemToObject(subdir,"dira",dir1=cJSON_CreateObject());
cJSON_AddStringToObject(dir1,"name",".");
cJSON_AddStringToObject(dir1,"path","/./");
cJSON_AddStringToObject(dir1,"flag","true");
cJSON_AddItemToObject(subdir,"dira",dir2=cJSON_CreateObject());
cJSON_AddStringToObject(dir2,"name","..");
cJSON_AddStringToObject(dir2,"path","/../");
cJSON_AddStringToObject(dir2,"flag","true");
cJSON_AddItemToObject(subdir,"dira",dir3=cJSON_CreateObject());
cJSON_AddStringToObject(dir3,"name","uploads");
cJSON_AddStringToObject(dir3,"path","/uploads/");
cJSON_AddStringToObject(dir3,"flag","true");
out=cJSON_Print(root);
cJSON_Delete(root);
return out;
}
char * create3()
{
cJSON *root,*img,*thm;
char *out;
int nums[4]={100,200,300,400};
root=cJSON_CreateObject();
cJSON_AddItemToObject(root, "Root", img=cJSON_CreateObject());
cJSON_AddNumberToObject(img,"key",800);
cJSON_AddNumberToObject(img,"value",600);
cJSON_AddStringToObject(img,"Title","Sugon");
cJSON_AddItemToObject(img,"child",thm=cJSON_CreateObject());
cJSON_AddNumberToObject(thm,"key",125);
cJSON_AddStringToObject(thm,"value","100");
cJSON_AddStringToObject(thm,"Url","www.sugon.com");
cJSON_AddItemToObject(img,"nums", cJSON_CreateIntArray(nums,4));
out=cJSON_Print(root);
cJSON_Delete(root);
return out;
}
char * create4()
{
cJSON *root,*dir1,*dir2;
char *out;
const char *ro = "Root";
root=cJSON_CreateObject();
cJSON_AddItemToObject(root,ro,dir1=cJSON_CreateArray());
cJSON_AddNumberToObject(dir1,"key",800);
cJSON_AddNumberToObject(dir1,"value",600);
cJSON_AddStringToObject(dir1,"Title","key and value");
cJSON_AddItemToObject(root,ro,dir2=cJSON_CreateArray());
cJSON_AddNumberToObject(dir2,"value",125);
cJSON_AddStringToObject(dir2,"key","100");
cJSON_AddStringToObject(dir2,"Title","value and key");
out=cJSON_Print(root);
cJSON_Delete(root);
return out;
}
void parse1(char *out)
{
cJSON * root,*arrayItem,*item,*name,*path,*flag;
int i = 0,size = 0;
char *pr = NULL,*na = NULL,*pa = NULL,*fl = NULL;
//将字符串解析成json结构体
root = cJSON_Parse(out);
//根据结构体获取数组大小
size = cJSON_GetArraySize(root);
//printf("%d\n",size);
//遍历数组
for(i=0;i
{
//获取第i个数组项
arrayItem = cJSON_GetArrayItem(root,i);
if(arrayItem)
{
//printf("%s\n","start......");
//讲json结构体转换成字符串
pr = cJSON_Print(arrayItem);
item = cJSON_Parse(pr);
name = cJSON_GetObjectItem(item,"name");
path = cJSON_GetObjectItem(item,"path");
flag = cJSON_GetObjectItem(item,"flag");
na = cJSON_Print(name);
pa = cJSON_Print(path);
fl = cJSON_Print(flag);
//printf("%s\n",pr);
printf("name:%s\n",na);
printf("path:%s\n",pa);
printf("flag:%s\n\n",fl);
}
}
}
void parse2(char *out)
{
cJSON * root,*Root,*Child,*arrayItem,*item,*name,*path,*flag;
int i = 0,size = 0;
char *pr = NULL,*na = NULL,*pa = NULL,*fl = NULL;
root = cJSON_Parse(out);
if(root)
{
Root = cJSON_GetObjectItem(root,"Root");
if(Root)
{
name = cJSON_GetObjectItem(Root,"name");
path = cJSON_GetObjectItem(Root,"path");
flag = cJSON_GetObjectItem(Root,"flag");
na = cJSON_Print(name);
pa = cJSON_Print(path);
fl = cJSON_Print(flag);
printf("Root:\n");
printf("name:%s\n",na);
printf("path:%s\n",pa);
printf("flag:%s\n\n",fl);
}
Child = cJSON_GetObjectItem(root,"Child");
if(Child)
{
size = cJSON_GetArraySize(Child);
//printf("%d\n",size);
printf("Child:\n");
for(i=0;i
{
arrayItem = cJSON_GetArrayItem(Child,i);
if(arrayItem)
{
//printf("%s\n","start......");
pr = cJSON_Print(arrayItem);
item = cJSON_Parse(pr);
name = cJSON_GetObjectItem(item,"name");
path = cJSON_GetObjectItem(item,"path");
flag = cJSON_GetObjectItem(item,"flag");
na = cJSON_Print(name);
pa = cJSON_Print(path);
fl = cJSON_Print(flag);
//printf("%s\n",pr);
printf("name:%s\n",na);
printf("path:%s\n",pa);
printf("flag:%s\n\n",fl);
}
}
}
}
}
int main()
{
char *out1 = create1();
char *out2 = create2();
char *out3 = create3();
char *out4 = create4();
printf("%s\n\n\n",out1);
parse1(out1);
printf("%s\n\n\n",out2);
parse2(out2);
printf("%s\n\n\n",out3);
printf("%s\n\n\n",out4);
return 0;
}
运行结果如下图所示：
上图为创建json结构体和解析后的结果图（分别为create1，parse1、create2，parse2），后两个（create3、create4）创建了没有进行解析，因为很简单，自己动手试试吧！相信自己，有些事情其实还是会很容易做到的。