使用gson(一)

1、数组和json的转换

 package com.test.gson;
 import com.google.gson.Gson;
 public class ArrayToJson {

     public static void main(String[] args) {
         // TODO Auto-generated method stub
         int[] numbers = {1,2,3,4,5,6,7,8,9};
         String[] days = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};

         Gson gson = new Gson();

         String numbersJson = gson.toJson(numbers);
         System.out.println("numbersJson=" + numbersJson);

         int[] nums = gson.fromJson(numbersJson, int[].class);
         for(int i=0; i<nums.length ; i++){
             System.out.println(nums[i]);
         }
         String daysJson = gson.toJson(days);
         System.out.println("daysJson=" + daysJson);

         String[] weekDays = gson.fromJson(daysJson, String[].class);
         for(int j=0; j<weekDays.length; j++){
             System.out.println(weekDays[j]);
         }
     }

 }

2、对象和json的转换

 package com.test.gson;

 import com.google.gson.Gson;

 public class StudentToJson {

     public static void main(String[] args) {
         // TODO Auto-generated method stub
         Student student = new Student(1001,"gulu","beijing");
         Gson gson = new Gson();

         String studentJson = gson.toJson(student);
         System.out.println("studentJson=" + studentJson);

         Student stu = gson.fromJson(studentJson, Student.class);
         System.out.println(stu.toString());
         System.out.println(stu.getId());
         System.out.println(stu.getName());
         System.out.println(stu.getAddress());
     }

 }

3、List和json的转换

 package com.test.gson;

 import java.util.ArrayList;
 import java.util.List;
 import java.lang.reflect.Type;

 import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;

 public class CollectionToJson {

     public static void main(String[] args) {
         // TODO Auto-generated method stub
         List<String> names = new ArrayList<String>();
         names.add("Alice");
         names.add("Bob");
         names.add("Carol");
         names.add("Mallory");

         Gson gson = new Gson();

         String jsonNames = gson.toJson(names);
         System.out.println("jsonNames="+jsonNames);

         Student a = new Student(1,"zhangsan","beijing");
         Student b = new Student(2,"wangwu","nanjing");
         Student c = new Student(3,"lisi","guangzhou");
         Student d = new Student(4,"wangba","shanghai");

         List<Student> students = new ArrayList<Student>();
         students.add(a);
         students.add(b);
         students.add(c);
         students.add(d);

         String jsonStudents = gson.toJson(students);
         System.out.println("jsonStudents="+jsonStudents);

         Type type = new TypeToken<List<Student>>(){}.getType();
         List<Student> studentList = gson.fromJson(jsonStudents, type);
         for(Student student : studentList){
             System.out.println(student.getName());
         }
     }

 }

4、map和json的转换

 package com.test.gson;

 import java.lang.reflect.Type;
 import java.util.HashMap;
 import java.util.Map;

 import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;

 public class MapToJson {

     public static void main(String[] args) {
         // TODO Auto-generated method stub
         Map<String, String> colours = new HashMap<String,String>();
         colours.put("black", "#000000");
         colours.put("red", "#ff0000");
         colours.put("green", "#00ff00");
         colours.put("blue", "#0000ff");

         Gson gson = new Gson();
         String mapJson = gson.toJson(colours);
         System.out.println("gson="+mapJson);

         Type type = new TypeToken<Map<String,String>>(){}.getType();

         Map<String,String> map = gson.fromJson(mapJson, type);
         for(String key : map.keySet()){
             System.out.println("map.get=" + map.get(key));
         }
     }

 }