JSON Basics (Java)

1.json maven Dependency (take the first package for example)

<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20160212</version>
</dependency>

(

<dependency>
<groupId>net.sf.json-lib</groupId>
<artifactId>json-lib</artifactId>
<version>2.4</version>
<classifier>jdk15</classifier>
</dependency>

)

2.JSON String notation, denoted by an escape character:

String aa = "{\" 1\ ": \" Xiao red \ ", \" 2\ ": \" Xiao Wang \ ", \" 3\ ": \" Xiao Ming \ "," 4\ ": \" Xiao Zhang \ "}";

3.map conversion to JSON

Method One:

map<string, string> map = new hashmap<> ();
Map.put ("1", "Little Red");
Map.put ("2", "Xiao Wang");
Map.put ("3", "xiaoming");
Map.put ("4", "Xiao Zhang");
Map.put ("5", "Xiao Zhao");
Objectmapper json = new Objectmapper ();

try {
String string = json.writevalueasstring (map);
Jsonobject jsonobject = new Jsonobject (string);

} catch (Jsonprocessingexception e) {
TODO auto-generated Catch block
E.printstacktrace ();
}

Method 2:

Introducing Fastjson jar packages with Maven

<dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>fastjson</artifactId>
   <version>1.2.24</version>
</dependency>

New Hashmap<>();        Map.put ("1", "Little Red");        Map.put ("2", "Xiao Wang");        Map.put ("3", "Xiaoming");        Map.put ("4", "Xiao Zhang");        Map.put ("5", "Xiao Zhao");         = json.tojsonstring (map);        System.out.println (astring);

Analysis of 4.JSON

(1) The first Jar package parsing method:

String str = "{\" 1\ ": \" Little red \ ", \" 2\ ": \" Xiao Wang \ ", \" 3\ ": \" Xiao Ming \ "," 4\ ": \" Xiao Zhang \ "}";

Jsonobject jsonobject = new Jsonobject (str);

System.out.println (Jsonobject.getstring ("1"));
System.out.println (Jsonobject.getstring ("2"));

System.out.println (Jsonobject.getstring ("3"));

Multilayer JSON nesting:

String jsondata= "{\" name\ ": \" lily\ ", \" age\ ": 23,\" addr\ ": {\" city\ ": Guangzhou,\" province\ ": Guangdong}}";
Jsonobject jsonObject1 =new jsonobject (jsondata);
Jsonobject jsonObject2 = jsonobject1.getjsonobject ("addr");
System.out.println (jsonobject2.getstring ("City"));

(2) Second Jar package parsing method (requires [] to wrap the string)

String AA = "[{\" 1\ ": \" small red \ ", \" 2\ ": \" Xiao Wang \ ", \" 3\ ": \" Xiao Ming \ ", \" 4\ ": \" Xiao Zhang \ "}]";

Jsonarray Jsonarray = Jsonarray.fromobject (AA);
if (jsonarray.size () > 0) {
Iterate through the Jsonarray array and turn each object into a JSON object
for (int i = 0; i < jsonarray.size (); i++) {
Jsonobject Jsonobject = Jsonarray.getjsonobject (i);
System.out.println (Jsonobject.get ("1"));
System.out.println (Jsonobject.get ("2"));
System.out.println (Jsonobject.get ("3"));
}
}

5.JSON to convert to his format

(1) to String

String str = jsonobject.tostring ();

JSON Basics (Java)