python 3.09 yaml json xmltodict 模块

> 这里介绍用python 的 yaml模块，json模块，xml模块

#yaml
yaml文件
```
[root@hadoop1 python]# cat yaml
var: "i am a string"
array1: ["1","2","3"]
array2: &array2_alias #this is allias
    - "lala"
    - "wawa"
    - "haha"
hash1: { "a":"b","c":"d" }
hash2:
    "e": "f"
    "z":  *array2_alias  #use the alias
```
脚本
```
[root@hadoop1 python]# cat a.py
#!/usr/bin/python
import yaml,sys

file_object = file("./yaml","r")
try:
    data = yaml.load(file_object)
    #data = list(yaml.load_all(file_object))  可以解析一个文件下的多个yaml 文档
    #safe_load safe_load_all safe_dump safe_dump_all 可以只处理标准yaml数据，不处理python对象，推荐使用
except yaml.YAMLError, msg:
    print "Error in yaml:", msg
    sys.exit(1)
print data
print "--------------------"
print yaml.dump(data)
```
结果
```
[root@hadoop1 python]# ./a.py
{'var': 'i am a string', 'array2': ['lala', 'wawa', 'haha'], 'array1': ['1', '2', '3'], 'hash1': {'a': 'b', 'c': 'd'}, 'hash2': {'z': ['lala', 'wawa', 'haha'], 'e': 'f'}}
--------------------
array1: ['1', '2', '3']
array2: &id001 [lala, wawa, haha]
hash1: {a: b, c: d}
hash2:
  e: f
  z: *id001
var: i am a string
```
***
#JSON
```
#!/usr/bin/python
import json

try:
    fp_w = file("./write_json","w")
    fp_r = file("./read_json","r")
    json_object=json.load(fp_r)      #从文件读取，返回Python json 对象
    print json_object
    json.dump(json_object,fp_w)      #把json 字符串写入文件

print "----"

var = '{"a":1,"b":[1,2,3]}'
    json_object=json.loads(var)     #从变量读取，返回Python json 对象
    print json_object
    result = json.dumps(json_object)   #返回json 字符串
    print result

except Exception,msg:
    print msg
```
**命令行处理json**
```
[root@hadoop1 python]# echo '{"a": 1, "b": [1, 2, 3]}' | python -m json.tool
{
    "a": 1,
    "b": [
        1,
        2,
        3
    ]
}
```
***
#XML
> xmltodict 把xml 转换成 OrderedDict

XML文件
```xml
    <configuration>
    <property>
        <name>fs.default.name</name>
        <value>hdfs://hadoop1:9000</value>
    </property>
    <property>
        <name>hadoop.tmp.dir</name>
        <value>/app/hadoop/tmp</value>
    </property>
    </configuration>
```
脚本
```python
#!/usr/bin/python
import sys,xmltodict,json

the_hash = xmltodict.parse(open(sys.argv[1],'r').read())
print type(the_hash)
print the_hash
print json.dumps(the_hash)
```
运行结果
```
[root@test1 leo]# ./xml2dict.py hadoop.xml
<class 'collections.OrderedDict'>
OrderedDict([(u'configuration', OrderedDict([(u'property', [OrderedDict([(u'name', u'fs.default.name'), (u'value', u'hdfs://hadoop1:9000')]), OrderedDict([(u'name', u'hadoop.tmp.dir'), (u'value', u'/app/hadoop/tmp')])])]))])
{"configuration": {"property": [{"name": "fs.default.name", "value": "hdfs://hadoop1:9000"}, {"name": "hadoop.tmp.dir", "value": "/app/hadoop/tmp"}]}}
```

乱读天书， 不求甚解

乱读天书，不求甚解