GSON – 將 JSON 數組解析為 Java 數組或列表 · HowToDoInJava 中文系列教程

# GSON – 將 JSON 數組解析為 Java 數組或列表 > 原文： [https://howtodoinjava.com/gson/gson-parse-json-array/](https://howtodoinjava.com/gson/gson-parse-json-array/) 了解如何使用 Google GSON 庫將包含 *json 數組*的 [JSON](https://restfulapi.net/introduction-to-json/) 反序列化或解析為 Java [數組](https://howtodoinjava.com/java-array/)或 Java 列表對象。值得一提的是，JSON 僅具有[數組數據類型](https://restfulapi.net/json-array/)。 Java 同時具有 – [數組](https://howtodoinjava.com/java-array/)和[列表](https://howtodoinjava.com/java-arraylist/)。 ## 1.將 JSON 數組解析為根對象 ```java [ { "name": "Alex", "id": 1 }, { "name": "Brian", "id": 2 }, { "name": "Charles", "id": 3 } ] ``` ```java public class User { private long id; private String name; public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "User [id=" + id + ", name=" + name + "]"; } } ``` #### 1.1 對象數組 Java 程序將 json 數組**作為根反序列化** – 為 Java 對象數組。 ```java String userJson = "[{'name': 'Alex','id': 1}, " + "{'name': 'Brian','id':2}, " + "{'name': 'Charles','id': 3}]"; Gson gson = new Gson(); User[] userArray = gson.fromJson(userJson, User[].class); for(User user : userArray) { System.out.println(user); } ``` 程序輸出。 ```java User [id=1, name=Alex] User [id=2, name=Brian] User [id=3, name=Charles] ``` #### 1.2 對象列表 Java 程序將 json 數組作為根反序列化 – 為 Java 對象列表。 ```java import java.lang.reflect.Type; import java.util.ArrayList; import com.google.gson.Gson; import com.google.gson.reflect.TypeToken; String userJson = "[{'name': 'Alex','id': 1}, " + "{'name': 'Brian','id':2}, " + "{'name': 'Charles','id': 3}]"; Gson gson = new Gson(); Type userListType = new TypeToken<ArrayList<User>>(){}.getType(); ArrayList<User> userArray = gson.fromJson(userJson, userListType); for(User user : userArray) { System.out.println(user); } ``` 程序輸出： ```java User [id=1, name=Alex] User [id=2, name=Brian] User [id=3, name=Charles] ``` ## 2.解析 JSON 數組作為成員如果它們是非根對象，則 Gson 可以輕松地將 JSON 數組解析為成員。我們可以按常規方式使用`fromJson()`方法，它將正確地將 json 數組解析為所需的 Java 數組或列表。 ```java { "id" : 1, "name" : "HR", "users" : [ { "name": "Alex", "id": 1 }, { "name": "Brian", "id": 2 }, { "name": "Charles", "id": 3 } ] ``` #### 2.1 成員數組 Java 程序將**反序列化 json 數組作為成員對象** – 轉換為 Java 對象數組作為成員字段。 ```java public class Department { private long id; private String name; private User[] users; //Getters and Setters @Override public String toString() { return "Department [id=" + id + ", name=" + name + ", users=" + Arrays.toString(users) + "]"; } } ``` ```java String departmentJson = "{'id' : 1, " + "'name': 'HR'," + "'users' : [" + "{'name': 'Alex','id': 1}, " + "{'name': 'Brian','id':2}, " + "{'name': 'Charles','id': 3}]}"; Gson gson = new Gson(); Department department = gson.fromJson(departmentJson, Department.class); System.out.println(department); ``` 程序輸出： ```java Department [id=1, name=HR, users=[User [id=1, name=Alex], User [id=2, name=Brian], User [id=3, name=Charles]]] ``` #### 2.2 成員列表 Java 程序**將 json 數組反序列化為成員對象** – 到 Java 對象列表的成員字段。 ```java public class Department { private long id; private String name; private List<User> users; //Getters and Setters @Override public String toString() { return "Department [id=" + id + ", name=" + name + ", users=" + users + "]"; } } ``` ```java String departmentJson = "{'id' : 1, " + "'name': 'HR'," + "'users' : [" + "{'name': 'Alex','id': 1}, " + "{'name': 'Brian','id':2}, " + "{'name': 'Charles','id': 3}]}"; Gson gson = new Gson(); Department department = gson.fromJson(departmentJson, Department.class); System.out.println(department); ``` 程序輸出： ```java Department [id=1, name=HR, users=[User [id=1, name=Alex], User [id=2, name=Brian], User [id=3, name=Charles]]] ``` 向我提供有關 **gson 將 JSON 數組解析為 Java 列表和數組**的問題。學習愉快！參考文獻： [GSON Github](https://github.com/google/gson)