# PHP中JSON处理

## json\_encode

* json\_encode 目前只能处理UTF-8编码的数据
* JSON\_UNESCAPED\_UNICODE 让JSON更懂中文
* 解析出错，看[ json\_last\_error() ](http://php.net/manual/zh/function.json-last-error.php)返回的错误
* JSON格式是灵活开放的，特殊情况可以用sprintf来自己组装或者解析JSON字符串

语法:

```php
string json_encode ( mixed $value [, int $options = 0 [, int $depth = 512 ]] )
```

参数:

* JSON\_HEX\_TAG   所有的 < 和 > 转换成 \u003C 和 \u003E&#x20;
* JSON\_HEX\_AMP   所有的 & 转换成 \u0026
* JSON\_HEX\_APOS  所有的 ' 转换成 \u0027
* JSON\_HEX\_QUOT 所有的 " 转换成 \u0022
* JSON\_FORCE\_OBJECT  强制使用索引数组输出
* JSON\_NUMERIC\_CHECK 将所有数字字符串编码成数字
* JSON\_BIGINT\_AS\_STRING  将大数字编码成原始字符原来的值
* JSON\_PRETTY\_PRINT  用空白字符格式化返回的数据
* JSON\_UNESCAPED\_SLASHES  不要编码 /
* JSON\_UNESCAPED\_UNICODE 以字面编码多字节 Unicode 字符（默认是编码成 \uXXXX）

示例

**JSON\_PRETTY\_PRINT** ,有的时候需要查看,所以中格式化的效果更美观

```php
$arr = array('a' => 'b' , 'b' => 'c');
echo json_encode($arr, JSON_PRETTY_PRINT);
echo "\n";
echo json_encode($arr);
```

结果:

```php
{
    "a": "b",
    "b": "c"
}
{"a":"b","b":"c"}
```

[json\_encode($b, JSON\_FORCE\_OBJECT) 可以强制转换成对象](http://blog.163.com/spring_51888/blog/static/43279623201532110314750/)

## json\_decode

```php
 json_decode($res, true);
```

## 拼装json

简单示例:

```php
$format = '["%s",%d,%b]';
$jsonstr= sprintf($format, '张三', 15 , false );
echo $jsonstr;
echo "\n";
$json=json_decode($jsonstr);
echo "\n";
print_r($json);
echo json_last_error_msg();
```

结果:

```
["张三丰",16,0]

Array
(
    [0] => 张三丰
    [1] => 16
    [2] => 0
)
No errorr
```

封装函数:

```php
$arr = ['北京'=>['a',123=>[] ],'热门'];
$arr = array('a' => 'b');
echo encode($arr);

 function encode($data) {
    switch ($type = gettype($data)) {
        case 'NULL':
            return 'null';
        case 'boolean':
            return ($data ? 'true' : 'false');
        case 'integer':
        case 'double':
        case 'float':
            return $data;
        case 'string':
            return '"' . addcslashes($data, "\r\n\t\"") . '"';
        case 'object':
            $data = get_object_vars($data);
        case 'array':
            $count = 0;
            $indexed = array();
            $associative = array();
            foreach ($data as $key => $value) {
                if($count !== NULL && (gettype($key) !== 'integer' || $count++ !== $key)) {
                    $count = NULL;
                }
                $one = encode($value);
                $indexed[] = $one;
                $associative[] = encode($key) . ':' . $one;
            }
            if ($count !== NULL) {
                return '[' . implode(',', $indexed) . ']';
            } else {
                return '{' . implode(',', $associative) . '}';
            }
        default:
        return ''; // Not supported
    }
}
```


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