PHP json_encode analysis_PHP tutorial-PHP Tutorial-php.cn

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?

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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, "true", 4); // Output true

Smart_Str_appendl (buf, "false", 5); // Output false

break;

case IS_LONG:

to out ‐ to ‐ ‐ ‐ ‐ ‐ smart_str_append_long(buf, Z_LVAL_P(val));//Output the value of long integer

break;

case IS_DOUBLE:

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;

long p;

if ((type = is_numeric_string(s, len, &p, &d, 0)) != 0) {

} else if (type == IS_DOUBLE) {

int l = spprintf(&tmp, 0, "%.*k", (int) EG(precision), d);

Smart_Str_appendl (buf, tmp, l);

php_error_docref(NULL TSRMLS_CC, E_WARNING, "double %.9g does not conform to the JSON spec, encoded as 0", d);

Smart_Str_appendc (buf, '0');

return;

}

} }

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;

php_error_docref(NULL TSRMLS_CC, E_WARNING, "Invalid UTF-8 sequence in argument");

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)

case '"':

if (options & php_json_hex_quot) {

Smart_Str_appendl (buf, "\ u0022", 6);

Smart_Str_appendl (buf, "\" ", 2);

break;

case '\':

Smart_Str_appendl (buf, "\\", 2);

break;

case '/':

smart_str_appendl(buf, "\/", 2);

break;

case 'b':

Smart_Str_appendl (buf, "\ b", 2);

break;

case 'f':

break;

case 'n':

smart_str_appendl(buf, "\n", 2);

break;

case 'r':

smart_str_appendl(buf, "\r", 2);

break;

case 't':

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] == '