For the use of the json-lib class library, the json-lib class library

For the use of the json-lib class library, the json-lib class library

Preface:

The json-lib package is a Java class library that converts Java objects (including beans, maps, collections, java arrays, and xml) to JSON.

Similarly, Google also launched a class library named Gson, which will not be discussed today.

 

Preparations:

First, we need to download the jar package of json-lib and import the project

 

Because the method is simple, the code is displayed here.

 

1. First, write a json tool class and input 2 parameters. 1 is the json identifier (custom), and 2 is the object to be converted into a json string format.

1 package com. lcw. json. util; 2 3 import net. sf. json. JSONObject; 4 5 public class MakeJson {6 7/** 8*9 * @ param key json identifier 10 * @ param value json content (multiple types, class types, strings, list set, etc.) 11 * @ return returns a json expression 12 */13 public static String getJson (String key, Object value) {14 JSONObject jsonObject = new JSONObject (); 15 jsonObject. put (key, value); // assign 16 String info = jsonobject to the jsonObject object. toString (); 17 return info; 18} 19 20}

 

2. Provide a data source class

1 package com. lcw. json. service; 2 3 import java. util. arrayList; 4 import java. util. hashMap; 5 import java. util. list; 6 import java. util. map; 7 8 import com. lcw. json. vo. person; 9 10 public class JsonService {11 12 // get a Person object 13 public Person getPerson () {14 Person person Person = new Person (1, "tuzi", 22 ); // instantiate a Person object 15 return person; 16} 17 18 // get a List set (storing the Person type) 19 public List <Person> getListPerson () {20 List <Person> list = new ArrayList <Person> (); 21 Person person1 = new Person (1, "lcw", 20 ); 22 Person person2 = new Person (2, "tuzi", 22); 23 list. add (person1); 24 list. add (person2); 25 return list; 26 27} 28 // get a List set (String type) 29 public List <String> getInfo () {30 List <String> list = new ArrayList <String> (); 31 list. add ("Beijing"); 32 list. add ("Shanghai"); 33 list. add ("Guangzhou"); 34 return list; 35} 36 37 38 // get a List set (storing the Map type) 39 public List <Map <String, object> getListPersons () {40 List <Map <String, Object> list = new ArrayList <Map <String, Object> (); 41 42 Map <String, object> map1 = new HashMap <String, Object> (); 43 Person person1 = new Person (1, "lcw", 20); 44 map1.put ("person1", person1 ); 45 46 Map <String, Object> map2 = new HashMap <String, Object> (); 47 Person person2 = new Person (2, "tuzi", 22 ); 48 map2.put ("person2", person2); 49 50 list. add (map1); 51 list. add (map2); 52 53 return list; 54 55} 56 57 58}

 

3. entity class

 1 package com.lcw.json.vo; 2  3 public class Person { 4  5     private int id; 6     private String name; 7     private int age; 8  9     public Person(int id, String name, int age) {10         super();11         this.id = id;12         this.name = name;13         this.age = age;14     }15 16     public int getId() {17         return id;18     }19 20     public void setId(int id) {21         this.id = id;22     }23 24     public String getname() {25         return name;26     }27 28     public void setname(String name) {29         this.name = name;30     }31 32     public int getAge() {33         return age;34     }35 36     public void setAge(int age) {37         this.age = age;38     }39 40     @Override41     public String toString() {42         return "Person [age=" + age + ", id=" + id + ", name=" + name + "]";43     }44 45 }

 

4. Testing

 1 package com.lcw.json.test; 2  3 import java.util.List; 4 import java.util.Map; 5  6 import org.junit.Test; 7  8 import com.lcw.json.service.JsonService; 9 import com.lcw.json.util.MakeJson;10 import com.lcw.json.vo.Person;11 12 public class JsonTest {13 14     @Test15     public void getPersonJson() {16         JsonService jsonService = new JsonService();17         Person p1 = jsonService.getPerson();18         String info = MakeJson.getJson("person", p1);19         System.out.println(info);20     }21 22     @Test23     public void getListPersonJson() {24         JsonService jsonService = new JsonService();25         List<Person> persons = jsonService.getListPerson();26         String info = MakeJson.getJson("persons", persons);27         System.out.println(info);28 29     }30 31     @Test32     public void getListString() {33         JsonService jsonService = new JsonService();34         List<String> news = jsonService.getInfo();35         String info = MakeJson.getJson("info", news);36         System.out.println(info);37     }38     39     @Test40     public void getListPersonsJson() {41         JsonService jsonService = new JsonService();42         List<Map<String,Object>> persons = jsonService.getListPersons();43         String info = MakeJson.getJson("persons", persons);44         System.out.println(info);45 46     }47     48 49 }

 

The above are four unit test classes. The code is very simple, so no text explanation will be made. Let's see how to run it:

 

 

 

 

If you want to make the server for remote calls, print the data to the webpage. Pai_^

Json-lib usage Problems

This class name. class
I want to convert a json string into a list set of object classes.
This is the entity class name. class.
Json-lib.sourceforge.net/usage.html
This is an example of an official website.

, Json-lib parses json data

Public class GetJson {public static void main (String [] args) {// The error code returned by the main method. StaticString json = "{'name': 'Baby-friendly ', 'array': [{'A': '000000',' B ': '000000 ', 'C': '000000'}, {}, {'A': '000000'}], 'address': 'Baby-friendly '} "; try {JSONObject jsonObject = JSONObject. fromObject (json); String name = jsonObject. getString ("name"); String address = jsonObject. getString ("address"); System. out. println ("name is:" + name); System. out. println ("address is:" + address); JSONArray jsonArray = jsonObject. getJSONArray ("array"); for (int I = 0; I <jsonArray. size (); I ++) {System. out. println ("item" + I + ":" + jsonArray. getString (I) ;}} catch (JSONException e) {e. printStackTrace () ;}} modified the main method.