Android Gson 转 List 数据 gson转换list对象集合

Gson 是 Google 提供的用来在 Java 对象和 JSON 数据之间进行映射的 Java 类库。可以将一个 JSON 字符串转成一个 Java 对象，或者反过来。

先自定义一个Class类

public class Student {
	public int id;
	public String nickName;
	public int age;
	public Date birthDay;
	public ArrayList<String> books;
	public HashMap<String, String> booksMap;
	
	public Student(int id, String nickName, int age) {
		super();
		this.id = id;
		this.nickName = nickName;
		this.age = age;
	}
	
	@Override
	public String toString() {
		return "[id = "+id  +  ",nickName=" + nickName + ",age=" + age+"]";
	}
}

案例一：仅包含基本数据类型的数据结构

Gson gson = new Gson();
Student student =new Student(1, "李三", 20);
Log.e("GsonActivity", gson.toJson(student)); </span>

输出结果：

{"age":20,"id":1,"nickName":"李三"}

案例二：除了基本数据类型还包含了List集合

Gson gson =new Gson();
		Student student =new Student(1, "李三", 20);
		ArrayList<String> booksList =new ArrayList<String>();
		booksList.add("java");
		booksList.add("ios");
		booksList.add("c++");
		student.books = booksList;
		
		Log.e("GsonActivity", gson.toJson(student)); </span>

输出结果：

{"age":20,"books":["java","ios","c++"],"id":1,"nickName":"李三"}

案例三：除了基本数据类型还包含了List和Map集合

Gson gson =new Gson();
		Student student =new Student(1, "李三", 20);
		ArrayList<String> booksList =new ArrayList<String>();
		booksList.add("java");
		booksList.add("ios");
		booksList.add("c++");
		student.books = booksList;
		
		HashMap<String, String> booksMap =new HashMap<String, String>();
		booksMap.put("1", "数学");  
                booksMap.put("2", "语文");  
                booksMap.put("3", "英语");  
                booksMap.put("4", "物理");  
                booksMap.put("5", "化学");  
                booksMap.put("6", "生物");
 		student.booksMap = booksMap;
 		
		Log.e("GsonActivity", gson.toJson(student));</span>

输出结果：

{"age":20,"books":["java","ios","c++"],"booksMap":{"5":"化学","4":"物理","1":"数学","3":"英语","6":"生物","2":"语文"},"id":1,"nickName":"李三"}

案例四：将json字符串转换为Student对象

Gson gson =new Gson();
	Student student =new Student(1, "李三", 20);
	ArrayList<String> booksList =new ArrayList<String>();
	booksList.add("java");
	booksList.add("ios");
	booksList.add("c++");
	student.books = booksList;
		
	HashMap<String, String> booksMap =new HashMap<String, String>();
	booksMap.put("1", "数学");  
        booksMap.put("2", "语文");  
        booksMap.put("3", "英语");  
        booksMap.put("4", "物理");  
        booksMap.put("5", "化学");  
        booksMap.put("6", "生物");
 	student.booksMap = booksMap;
 		
	String jsonString =gson.toJson(student);

	Student student2 =gson.fromJson(jsonString, Student.class);
	Log.e("GsonActivity", student2.nickName + ","+ student2.age + "," + student2.books + "," + student2.booksMap); </span>

输出结果：

李三,20,[java, ios, c++],{4=物理, 5=化学, 1=数学, 3=英语, 6=生物, 2=语文}

案例五：泛型的使用

Gson gson =new Gson();
		
List<Student> students =new ArrayList<Student>();
Student student1 =new Student(1, "李三", 20);
Student student2 =new Student(2, "李四", 30);
Student student3 =new Student(3, "王泽瑞", 40);
students.add(student1);
students.add(student2);
students.add(student3);
		
String listString = gson.toJson(students);
		
TypeToken<List<Student>> token =new com.google.gson.reflect.TypeToken<List<Student>>(){};
List<Student> list =gson.fromJson(listString, token.getType());
		
for (Student stu : list) {  
<span style="font-family:微软雅黑,Verdana,sans-serif,宋体;">     </span>Log.e("GsonActivity", stu.toString()); 
} </span>

输出结果：

[id = 1,nickName=李三,age=20]
 [id = 2,nickName=李四,age=30]
 [id = 3,nickName=王泽瑞,age=40]