JSON解析 Gson的使用

最新推荐文章于 2023-03-15 20:22:45 发布

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本文介绍如何使用Gson库将Java中的数组、集合、Map及JavaBean对象转换为JSON格式，并反向操作将JSON字符串还原成Java对象。通过具体实例展示了不同数据结构之间的相互转换过程。

JSON解析 Gson的使用

数组

数组转化为Json

int[] numbers = {1, 1, 2, 3, 5, 8, 13};
Gson gson = new Gson();
String numbersJson = gson.toJson(numbers);

json转化为数组

int[] fibonacci = gson.fromJson(numbersJson, int[].class);
for (int i = 0; i < fibonacci.length; i++) {
 System.out.print(fibonacci[i] + " ");
}

集合

集合转化为Json

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);

json转化为集合

Type type = new TypeToken<List<Student>>(){}.getType();
List<Student> studentList = gson.fromJson(jsonStudents, type);

for (Student student : studentList) {
    System.out.println("student.getName() = " + student.getName());
}

Map

Map转化为Json

Map<String, String> colours = new HashMap<String, String>();
colours.put("BLACK", "#000000");
colours.put("RED", "#FF0000");
colours.put("GREEN", "#008000");
colours.put("BLUE", "#0000FF");
colours.put("YELLOW", "#FFFF00");
colours.put("WHITE", "#FFFFFF");
Gson gson = new Gson();
String json = gson.toJson(colours);
System.out.println("json = " + json);

Json转化为Map

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

JavaBean

Bean类转化为Json

Calendar dob = Calendar.getInstance();
dob.set(2000, 1, 1, 0, 0, 0);
Student student = new Student("Duke", "Menlo Park", dob.getTime());
Gson gson = new Gson();
String json = gson.toJson(student);

Json转化为Bean

String json = "{\"name\":\"Duke\",\"address\":\"Menlo Park\",\"dateOfBirth\":\"Feb 1, 2000 12:00:00 AM\"}";
Gson gson = new Gson();
Student student = gson.fromJson(json, Student.class);