Gson处理List对象

本文记录的是如何使用Gson处理List对象数据, 包括序列化List对象以及将Json串反序列化为List对象.

首先定义一个Student类, 其属性都是基本类型, 如下所示:

public class Student {
    private int stuNo;
    private int sex;
    private String name;
    public Student() {
    }
    
    public Student(int stuNo, int sex, String name) {
        this.stuNo = stuNo;
        this.sex = sex;
        this.name = name;
    }
    //getter & setter
    ......
}

接着定义List对象List对象，将该对象序列化为Json串，如下所示:

Gson gson = new Gson();
List<Student> students = new ArrayList<Student>();
        
Student student1 = new Student(1, 1, "cici");
Student student2 = new Student(2, 1, "didi");
students.add(student1);
students.add(student2);
String listStr = gson.toJson(students);
System.out.println("json_string: " + listStr);

运行该测试用例，控制台输出如下:

1	json_string: [{"stuNo":1,"sex":1,"name":"cici"},{"stuNo":2,"sex":1,"name":"didi"}]

那么如何将上述json_string反序列化为List对象呢？接着看以下示例:

Type studentType = new TypeToken<List<Student>>() {}.getType();
List<Student> students2 = gson.fromJson(listStr, studentType);
for (Iterator<Student> iterator = students2.iterator(); iterator.hasNext();) {
    Student student = (Student) iterator.next();
    System.out.println("stud name: " + student.getName());
}

关于TypeToken，请看文档说明:

public abstract class TypeToken<T>
extends java.lang.Object

Represents a generic type T. You can use this class to get the  
generic type for a class. For example, to get the generic type for  
Collection<Foo>, you can use:

Type typeOfCollectionOfFoo = new TypeToken<Collection<Foo>>(){}.getType()

上述示例中控制台输出结果如下，从结果可以看出反序列化成功。

1 2	stud name: cici stud name: didi

经过测试，对于List的复合对象(如List<HighClass>)也可使用上述方法进行序列化和反序列化。其中HighClass对象属性定义如下:

public class HighClass {
    private int classNo;
    private String adviser;
    private List<Student> students;
}

Gson处理List对象

CaryaLiu