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本文作者: 黑伴白

本文链接: http://heibanbai.com.cn/posts/6fa0842e/

Shell解析Json

awk解析

1. 先查找一个字符串：带双引号的key。如果没找到，则直接返回defaultValue
2. 查找最近的冒号，找到后认为值的部分开始了，直到在层数上等于0时找到这3个字符：,}]
3. 如果有多个同名key，则依次全部打印（不论层级，只按出现顺序）

# params: json, key, defaultValue
function getJsonValuesByAwk() {
    awk -v json="$1" -v key="$2" -v defaultValue="$3" 'BEGIN{
        foundKeyCount = 0
        while (length(json) > 0) {
            # pos = index(json, "\""key"\""); ## 这行更快一些，但是如果有value是字符串，且刚好与要查找的key相同，会被误认为是key而导致值获取错误
            pos = match(json, "\""key"\"[ \\t]*?:[ \\t]*");
            if (pos == 0) {if (foundKeyCount == 0) {print defaultValue;} exit 0;}

            ++foundKeyCount;
            start = 0; stop = 0; layer = 0;
            for (i = pos + length(key) + 1; i <= length(json); ++i) {
                lastChar = substr(json, i - 1, 1)
                currChar = substr(json, i, 1)

                if (start <= 0) {
                    if (lastChar == ":") {
                        start = currChar == " " ? i + 1: i;
                        if (currChar == "{" || currChar == "[") {
                            layer = 1;
                        }
                    }
                } else {
                    if (currChar == "{" || currChar == "[") {
                        ++layer;
                    }
                    if (currChar == "}" || currChar == "]") {
                        --layer;
                    }
                    if ((currChar == "," || currChar == "}" || currChar == "]") && layer <= 0) {
                        stop = currChar == "," ? i : i + 1 + layer;
                        break;
                    }
                }
            }

            if (start <= 0 || stop <= 0 || start > length(json) || stop > length(json) || start >= stop) {
                if (foundKeyCount == 0) {print defaultValue;} exit 0;
            } else {
                print substr(json, start, stop - start);
            }

            json = substr(json, stop + 1, length(json) - stop)
        }
    }'
}

# 测试
json='{"code":200,"msg":"success","data":{"orderNo":"test_order_no"}}'
getJsonValuesByAwk "$json" "code" "defaultValue"
getJsonValuesByAwk "$json" "data" "defaultValue"
getJsonValuesByAwk "$json" "orderNo" "defaultValue"

# 结果
200
{"orderNo":"test_order_no"}
"test_order_no"

Json解析库: jq

jq是 stedolan 开发的一个轻量级的和灵活的命令行 JSON 处理器。

它主要用于在命令行界面处理 JSON 输入，并使用给定的过滤条件来过滤符合条件的新的 JSON 串。

通常在类 Unix 环境下，我们可以快速的使用 jq 来进行 JSON 数据格式化过滤和处理。

同时需要注意的是，该命令行工具和 awk/sed/grep 工具一样，属于系统的默认命令，如果系统没有该命令，可以尝试使用如下方式进行安装。

# Ubuntu 系列
$ sudo apt-get install jq 
# CentOS 系列
$ yum install jq 

基本用法如下：

jq [options] <jq filter> [file...]
jq [options] --args <jq filter> [strings...]
jq [options] --jsonargs <jq filter> [JSON_TEXTS...]

# options 可选参数列表和说明
-c               将格式化json输出为紧凑的字符串格式;
-n               使用`null`作为单个输入值;
-e               根据输出设置退出状态代码;
-s               将所有输入读取（吸取）到数组中；应用过滤器;
-r               输出原始字符串，而不是JSON文本;
-R               读取原始字符串，而不是JSON文本;
-C               为JSON输出填充颜色;
-M               单色（不要为JSON着色）;
-S               在输出上排序对象的键;
--tab            使用制表符进行缩进;
--arg a v        将变量$a设置为value<v>;
--argjson a v    将变量$a设置为JSON value<v>;
--slurpfile a f  将变量$a设置为从<f>读取的JSON文本数组;
--rawfile a f    将变量$a设置为包含<f>内容的字符串;
--args           其余参数是字符串参数，而不是文件;
--jsonargs       其余的参数是JSON参数，而不是文件;
--               终止参数处理;

基础使用

## 使用 . 参数默认格式化整个json数据
$ echo '{"Name":"CloudNativeOps","Owner":"GoOps","WebSite":"https://bgbiao.top/"}'  | jq .
{
  "Name": "CloudNativeOps",
  "Owner": "GoOps",
  "WebSite": "https://bgbiao.top/"
}

## 使用.$name 来获取指定filed
$ echo '{"Name":"CloudNativeOps","Owner":"GoOps","WebSite":"https://bgbiao.top/"}'  | jq .Name
"CloudNativeOps"

## 解析json 中的层级数据
$ echo '{"Name":"CloudNativeOps","Owner":"GoOps","WebSite":"https://bgbiao.top/", "Contact": {"Email":"weichuangxxb@qq.com","QQ":"371990778","WeChat":"GoOps"} ,"Skills": [ {"name":"Python","type":"dev" }, {"name":"Golang","type":"dev" },{"name":"Ansible","type":"ops" },{"name":"Kubernetes","type":"dev" },{"name":"ElasticSearch","type":"ops" }]}'  | jq .Contact
{
  "Email": "weichuangxxb@qq.com",
  "QQ": "371990778",
  "WeChat": "GoOps"
}
### 仅输出 Contact 中的 WeChat 
$ echo '{"Name":"CloudNativeOps","Owner":"GoOps","WebSite":"https://bgbiao.top/", "Contact": {"Email":"weichuangxxb@qq.com","QQ":"371990778","WeChat":"GoOps"} ,"Skills": [ {"name":"Python","type":"dev" }, {"name":"Golang","type":"dev" },{"name":"Ansible","type":"ops" },{"name":"Kubernetes","type":"dev" },{"name":"ElasticSearch","type":"ops" }]}'  | jq .Contact.WeChat
"GoOps"

## 获取多个字段 (使用'.filed1,.filed2' 可以获取两个字段)
$ echo '{"Name":"CloudNativeOps","Owner":"GoOps","WebSite":"https://bgbiao.top/", "Contact": {"Email":"weichuangxxb@qq.com","QQ":"371990778","WeChat":"GoOps"} ,"Skills": [ {"name":"Python","type":"dev" }, {"name":"Golang","type":"dev" },{"name":"Ansible","type":"ops" },{"name":"Kubernetes","type":"dev" },{"name":"ElasticSearch","type":"ops" }]}'  | jq ".Name,.Owner"
"CloudNativeOps"
"GoOps"

调用python

• Python 2

export PYTHONIOENCODING=utf8
echo '{"Name":"CloudNativeOps","Owner":"GoOps","WebSite":"https://bgbiao.top/"}'|python -c "import sys, json; print json.load(sys.stdin)['WebSite']"

• Python 3

echo '{"Name":"CloudNativeOps","Owner":"GoOps","WebSite":"https://bgbiao.top/"}'|python3 -c "import sys, json; print(json.load(sys.stdin)['WebSite']"

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