json-c 移植到 9X25

一、环境介绍

1.1 宿主机

Ubuntu 1404 32 位

1.2 嵌入式平台

ATMEL AT91SAM9X25

1.3 交叉工具链

arm-none-linux-gnueabi

json-c-0.9源码下载地址

二、交叉编译

2.1 解压并编译

tar xvf json-c-0.9.tar.gz
cd json-c-0.9/
./configure  --prefix=$PWD/tmp --host=arm-none-linux-gnueabi --build=i686-linux
make
make install

执行完以上命令后，在当前路径会新建一个 tmp 目录，将 tmp 目录的 include 和 lib 目录的所有文件按照目录层次结构拷贝到工具链目录下的 include 和 lib 中。然后使用交叉编译器即可编译使用了json库的项目。

三、使用测试

3.1 测试源码

#include 
#include 
#include 
#include 

#include 

int main(int argc, char **argv)
{
    struct json_tokener *tok;
    struct json_object *my_string, *my_int, *my_object, *my_array;
    struct json_object *new_obj;
    int i;

    my_string = json_object_new_string("\t");
    /*输出 my_string=   */
    printf("my_string=%s\n", json_object_get_string(my_string)); // \t
    /*转换json格式字符串 输出my_string.to_string()="\t"*/
    printf("my_string.to_string()=%s\n", json_object_to_json_string(my_string)); //"\t"
                                                                                 /*释放资源*/
    json_object_put(my_string);

    my_string = json_object_new_string("\\");
    printf("my_string=%s\n", json_object_get_string(my_string)); // \  
    printf("my_string.to_string()=%s\n", json_object_to_json_string(my_string)); // \\  
    json_object_put(my_string);

    my_string = json_object_new_string("foo");
    printf("my_string=%s\n", json_object_get_string(my_string));
    printf("my_string.to_string()=%s\n", json_object_to_json_string(my_string)); //foo

    my_int = json_object_new_int(9);
    printf("my_int=%d\n", json_object_get_int(my_int));
    printf("my_int.to_string()=%s\n", json_object_to_json_string(my_int)); // 9

    /*创建个空json对象值数组类型*/
    my_array = json_object_new_array();
    /*添加json值类型到数组中*/
    json_object_array_add(my_array, json_object_new_int(1));
    json_object_array_add(my_array, json_object_new_int(2));
    json_object_array_add(my_array, json_object_new_int(3));
    json_object_array_put_idx(my_array, 4, json_object_new_int(5));
    printf("my_array=\n");
    for (i = 0; i < json_object_array_length(my_array); i++)
    {
        struct json_object *obj = json_object_array_get_idx(my_array, i);
        printf("\t[%d]=%s\n", i, json_object_to_json_string(obj));
    }
    printf("my_array.to_string()=%s\n", json_object_to_json_string(my_array)); // 1 2 3 null 5

    my_object = json_object_new_object();
    /*添加json名称和值到json对象集合中*/
    json_object_object_add(my_object, "abc", json_object_new_int(12));
    json_object_object_add(my_object, "foo", json_object_new_string("bar"));
    json_object_object_add(my_object, "bool0", json_object_new_boolean(0));
    json_object_object_add(my_object, "bool1", json_object_new_boolean(1));
    json_object_object_add(my_object, "baz", json_object_new_string("bang"));
    /*同样的key 添加会替换掉*/
    json_object_object_add(my_object, "baz", json_object_new_string("fark"));
    json_object_object_del(my_object, "baz");

    printf("my_object=\n");
    /*遍历json对象集合*/
    json_object_object_foreach(my_object, key, val)
    {
        printf("\t%s: %s\n", key, json_object_to_json_string(val));
    }
    printf("my_object.to_string()=%s\n", json_object_to_json_string(my_object));

    /*对些不规则的串做了些解析测试*/
    new_obj = json_tokener_parse("\"\003\"");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("/* hello */\"foo\"");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("// hello\n\"foo\"");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("\"\\u0041\\u0042\\u0043\"");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("null");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("True");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("12");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("12.3");
    /*得到json double类型  */
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("[\"\\n\"]");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("[\"\\nabc\\n\"]");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("[null]");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("[]");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("[false]");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("[\"abc\",null,\"def\",12]");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("{}");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("{ \"foo\": \"bar\" }");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("{ \"foo\": \"bar\", \"baz\": null, \"bool0\": true }");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("{ \"foo\": [null, \"foo\"] }");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("{ \"abc\": 12, \"foo\": \"bar\", \"bool0\": false, \"bool1\": true, \"arr\": [ 1, 2, 3, null, 5 ] }");
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);

    new_obj = json_tokener_parse("{ foo }");
    if (is_error(new_obj))
        printf("got error as expected\n");

    new_obj = json_tokener_parse("foo");
    if (is_error(new_obj))
        printf("got error as expected\n");

    new_obj = json_tokener_parse("{ \"foo");
    if (is_error(new_obj))
        printf("got error as expected\n");

    /* test incremental parsing */
    tok = json_tokener_new();
    new_obj = json_tokener_parse_ex(tok, "{ \"foo", 6);
    if (is_error(new_obj))
        printf("got error as expected\n");
    new_obj = json_tokener_parse_ex(tok, "\": {\"bar", 8);
    if (is_error(new_obj))
        printf("got error as expected\n");
    new_obj = json_tokener_parse_ex(tok, "\":13}}", 6);
    printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
    json_object_put(new_obj);
    json_tokener_free(tok);

    json_object_put(my_string);
    json_object_put(my_int);
    json_object_put(my_object);
    json_object_put(my_array);
    /*如果前面没有添加到对象中， 必须显示释放，  
    如果添加到对象中，已经释放对象，则无需调用，
     在这务必小心，否则很容易内存泄漏*/

    return 0;
}

3.1.1 PC 测试

安装库

sudo apt-get install libjson0-dev libjson0

编译
gcc test_json-c.c -ljson

3.1.2 ATMEL 9X25

安装库
1. 将头文件和库文件拷贝到工具链所在目录

cp -rv include/* /opt/arm-2010q1/arm-none-linux-gnueabi/libc/usr/include

 cp -rv lib/* /opt/arm-2010q1/arm-none-linux-gnueabi/libc/usr/lib/

1. 如果使用的是动态库，需将动态库拷贝到运行环境
   ARM 9X25 文件系统 /lib 目录。

编译

arm-none-linux-gnueabi-gcc test_json-c.c -o arm_test_json-c -std=c99 -ljson

四、补充

4.1 在 PC 和 ARM 上，头文件包含有区别

4.2 交叉编译的 json-c 需更改 config.h.in 否则在连接动态库时会报错。报错信息如下：

undefined reference to rpl_malloc 

解决办法就是删除 config.h.in 中的两行,然后重新编译。

#undef malloc
#undef realloc