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PHP json_encode analysis_PHP tutorial
- WBOYOriginal
- 2016-07-14 10:08:54934browse
I won’t talk about the advantages of json.
I have a habit, when I output json, I like to use sprintf to spell it into json format,
Two days ago, I was told by a friend that it was not standard and that json_encode must be used to generate the standard json format. Of course I was very depressed,
After using it for so many years, I just realized that this is not standard. Since I say it is not standard, then is the above the standard json format?
{a : 'abc'}
{'a' : 'abc'}
{a : "abc"}
{"a" : "abc"}
As you all know, only the fourth type is the standard json format.
I do this
$ret_json='{"%s":"%s"}';
echo json_encode($ret_json,"a","abc");
It must also meet the standards.
In this case, I have to ask more deeply, what is the difference between the json format generated by json_encode?
Upload the code
static PHP_FUNCTION(json_encode)
{
zval *parameter;
smart_str buf = {0};
long options = 0;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z|l", ¶meter, &options) == FAILURE) {
return;
} }
JSON_G(error_code) = PHP_JSON_ERROR_NONE;
php_json_encode(&buf, parameter, options TSRMLS_CC);
ZVAL_STRINGL(return_value, buf.c, buf.len, 1);
smart_str_free(&buf);
}
JSON_G(error_code) = PHP_JSON_ERROR_NONE;
is a defined json error. This error can be obtained through the json_last_error function. Have you used it? I haven't used it anyway.
php_json_encode is the main operation
PHP_JSON_API void php_json_encode(smart_str *buf, zval *val, int options TSRMLS_DC) /* {{{ */
{
switch (Z_TYPE_P(val))
{
case IS_NULL:
to ‐ down ‐ ‐ ‐ ‐ ‐ ‐ s smart_str_appendl(buf, "null", 4); // Output NULL
break;
case IS_BOOL:
Smart_Str_appendl (buf, "false", 5); // Output false
char *d = NULL;
int len;
double dbl = Z_DVAL_P(val);
if (!zend_isinf(dbl) && !zend_isnan(dbl)) {//非无穷尽
len = spprintf(&d, 0, "%.*k", (int) EG(precision), dbl);
smart_str_appendl(buf, d, len);
efree(d);
} else {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "double %.9g does not conform to the JSON spec, encoded as 0", dbl);
smart_str_appendc(buf, '0');
}
}
break;
case IS_STRING://字符串
json_escape_string(buf, Z_STRVAL_P(val), Z_STRLEN_P(val), options TSRMLS_CC);
break;
case IS_ARRAY://数组和对象
case IS_OBJECT:
json_encode_array(buf, &val, options TSRMLS_CC);
break;
default:
php_error_docref(NULL TSRMLS_CC, E_WARNING, "type is unsupported, encoded as null");
smart_str_appendl(buf, "null", 4);
break;
}
return;
}
很明显，根据不同的类型，会有相应的case。
最复杂的是 字符串 、数组 、对象这三种类型，数组和对象是同一种操作。
先看看字符串吧，很长，注释直接写在代码里。
//options应该是5.3版本之后才支持的，由以下常量组成的二进制掩码： JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_NUMERIC_CHECK, JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, JSON_FORCE_OBJECT, JSON_UNESCAPED_UNICODE.虽然我没用过。。。
static void json_escape_string(smart_str *buf, char *s, int len, int options TSRMLS_DC) /* {{{ */
{
int pos = 0;
unsigned short us;
unsigned short *utf16;
if (len == 0) {//如果长度为0，则直接返回 双引号 ""
smart_str_appendl(buf, """", 2);
return;
}
if (options & PHP_JSON_NUMERIC_CHECK) {//Check whether it is a number from 0 to 9. If it is a number, the data will be returned directly as a long or double type.
double d;
int type; to
} else if (type == IS_DOUBLE) { to
int l = spprintf(&tmp, 0, "%.*k", (int) EG(precision), d); }
} }
utf16 = (unsigned short *) safe_emalloc(len, sizeof(unsigned short), 0);
len = utf8_to_utf16(utf16, s, len); //The value you input will be processed once and converted into the corresponding Dec code. For example, 1 is 49 and a is 97, and then saved to utf16.
If (len <= 0) {//If len is less than 0, an error occurs. If you use json_encode to process GBK encoding, it will hang up here.
if (utf16) {
efree(utf16);
}
if (len < 0) {
JSON_G(error_code) = PHP_JSON_ERROR_UTF8;
smart_str_appendl(buf, "null", 4);
} else {
smart_str_appendl(buf, """", 2);
}
return;
} }
smart_str_appendc(buf, '"'); //Input "
//The following code is to escape some special characters such as double quotes, backslashes, etc.
while (pos < len)
{
us = utf16[pos++];
switch (us)
Smart_Str_appendl (buf, "\" ", 2);
break;
case 'b':
Smart_Str_appendl (buf, "\ b", 2);
break;
case 'f':
to
break; break;
case 'r':
smart_str_appendl(buf, "\r", 2);
break; break;
case '<':
if (options & PHP_JSON_HEX_TAG) {
smart_str_appendl(buf, "\u003C", 6);
} else {
smart_str_appendc(buf, '<');
}
break;
case '>':
if (options & PHP_JSON_HEX_TAG) {
smart_str_appendl(buf, "\u003E", 6);
} else {
smart_str_appendc(buf, '>');
}
break;
case '&':
if (options & PHP_JSON_HEX_AMP) {
smart_str_appendl(buf, "\u0026", 6);
} else {
smart_str_appendc(buf, '&');
}
break;
case ''':
if (options & PHP_JSON_HEX_APOS) {
smart_str_appendl(buf, "\u0027", 6);
} else {
smart_str_appendc(buf, ''');
}
break;
default: //一直到这里，没有特殊字符就会把值append到buf中
if (us >= ' ' && (us & 127) == us) {
smart_str_appendc(buf, (unsigned char) us);
} else {
smart_str_appendl(buf, "\u", 2);
us = REVERSE16(us);
smart_str_appendc(buf, digits[us & ((1 << 4) - 1)]);
us >>= 4;
smart_str_appendc(buf, digits[us & ((1 << 4) - 1)]);
us >>= 4;
smart_str_appendc(buf, digits[us & ((1 << 4) - 1)]);
us >>= 4;
smart_str_appendc(buf, digits[us & ((1 << 4) - 1)]);
}
break;
}
}
smart_str_appendc(buf, '"'); //结束 双引号。
efree(utf16);
}
再来看看数组和对象，也很简单，
static void json_encode_array(smart_str *buf, zval **val, int options TSRMLS_DC) /* {{{ */
{
int i, r;
HashTable *myht;
if (Z_TYPE_PP(val) == IS_ARRAY) {
myht = HASH_OF(*val);
r = (options & PHP_JSON_FORCE_OBJECT) ? PHP_JSON_OUTPUT_OBJECT : json_determine_array_type(val TSRMLS_CC);
} else {
myht = Z_OBJPROP_PP(val);
r = PHP_JSON_OUTPUT_OBJECT;
}
if (myht && myht->nApplyCount > 1) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "recursion detected");
smart_str_appendl(buf, "null", 4);
return;
}
//开始标签
if (r == PHP_JSON_OUTPUT_ARRAY) {
smart_str_appendc(buf, '[');
} else {
smart_str_appendc(buf, '{');
}
i = myht ? zend_hash_num_elements(myht) : 0;
if (i > 0)
{
char *key;
zval **data;
ulong index;
uint key_len;
HashPosition pos;
HashTable *tmp_ht;
int need_comma = 0;
zend_hash_internal_pointer_reset_ex(myht, &pos);
//便利哈希表
for (;; zend_hash_move_forward_ex(myht, &pos)) {
i = zend_hash_get_current_key_ex(myht, &key, &key_len, &index, 0, &pos);
if (i == HASH_KEY_NON_EXISTANT)
break;
if (zend_hash_get_current_data_ex(myht, (void **) &data, &pos) == SUCCESS) {
tmp_ht = HASH_OF(*data);
if (tmp_ht) {
tmp_ht->nApplyCount++;
}
if (r == PHP_JSON_OUTPUT_ARRAY) {
if (need_comma) {
smart_str_appendc(buf, ',');
} else {
need_comma = 1;
}
//将值append到 buf中
php_json_encode(buf, *data, options TSRMLS_CC);
} else if (r == PHP_JSON_OUTPUT_OBJECT) {
if (i == HASH_KEY_IS_STRING) {
if (key[0] == '
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