- number, string, object, array, boolean, null
- if start with [, it is a json array
- if start with {, it is a json object
- JSON.stringify(obj) convert json object to string
- JSON.parse(string) convert json string to object
- json is not extensible
2. json object
myObj = { "name":"John", "age":30, "car":null };
myObj = { //nested json object
"name":"John",
"cars": {
"car3":"Fiat"
}
}
3. json array (of object)
myObj = {
"name":"John",
"cars": [
{ "name":"Ford"},
{ "name":"BMW"},
{ "name":"Fiat"}
]
}
4. java json library (objectmapper)
5. xml concept
3. json array (of object)
myObj = {
"name":"John",
"cars": [
{ "name":"Ford"},
{ "name":"BMW"},
{ "name":"Fiat"}
]
}
4. java json library (objectmapper)
- jackson (default for resttemplate, restassured etc)
- jayway jsonpath
5. xml concept
- prolog, tag, attribute and element
- DOM tree, root, parent, child, sibling
- attribute value must be quoted
- < less than becomes <
- online xpath editor @http://xmlgrid.net/xpath.html
- xml is extensible
- javascript xml parser
<?xml version="1.0" encoding="UTF-8"?> //prolog
<book category="children"> //book is tag, category is attribute
<title>harry Potter</title> //element
<year>2005</year>
</book>
parser = new DOMParser();
xmlDoc = parser.parseFromString(text,"text/xml");
6. xml namespace
<root>
<h:table xmlns:h="http://www.w3.org/TR/html4/">
<h:tr>
<h:td>Apples</h:td>
<h:td>Bananas</h:td>
</h:tr>
</h:table>
<f:table xmlns:f="https://www.w3schools.com/furniture">
<f:name>African Coffee Table</f:name>
<f:width>80</f:width>
<f:length>120</f:length>
</f:table>
</root>
<table xmlns="http://www.w3.org/TR/html4/"> //default namespace
<tr>
<td>Apples</td>
<td>Bananas</td>
</tr>
</table>
7. xpath
10. xml schema
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="note">
<xs:complexType>
<xs:sequence>
<xs:element name="to" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
parser = new DOMParser();
xmlDoc = parser.parseFromString(text,"text/xml");
6. xml namespace
<root>
<h:table xmlns:h="http://www.w3.org/TR/html4/">
<h:tr>
<h:td>Apples</h:td>
<h:td>Bananas</h:td>
</h:tr>
</h:table>
<f:table xmlns:f="https://www.w3schools.com/furniture">
<f:name>African Coffee Table</f:name>
<f:width>80</f:width>
<f:length>120</f:length>
</f:table>
</root>
<table xmlns="http://www.w3.org/TR/html4/"> //default namespace
<tr>
<td>Apples</td>
<td>Bananas</td>
</tr>
</table>
7. xpath
- / //select from root
- // //from current node, wherever they are
- . //current node
- .. //parent
- @ //select attribute
8. java xml library
- DOM api (tree model, in memory)
- SAX api (stream based, event driven, push-parsing model)
- Stax api (stream based, event driven, pull-parsing model)
- JAXB api (schema based)
9. jaxb
- marshall: convert java object to xml
- unmarshall: convert xml to java object
- jaxb validation: verify that xml or java object tree meet all constraint in xml schema
- convert schema to jaxb class in eclipse (right click)
- convert schema to jaxb class online ()
10. xml schema
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="note">
<xs:complexType>
<xs:sequence>
<xs:element name="to" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
11. jsonview plugin in chrome
reference
1. java and xml tutorial
2. the difference between sax and dom
3. push parsing vs pull parsing
4. generate jaxb class from schema
5. a guide to xml in java
6. jackson 2
reference
1. java and xml tutorial
2. the difference between sax and dom
3. push parsing vs pull parsing
4. generate jaxb class from schema
5. a guide to xml in java
6. jackson 2
