Android Gson 學習

記錄一下 Gson的學習

1.添加依賴項
我是下載的 離線包

implementation files('libs/gson-2.2.4.jar')

2.設置bean

public class Child {

    private int id;
    private String name;
    private String sex;
    private int age;

    private ArrayList<String> toys;

    private HashMap<String, String> toysMap = new HashMap<String, String>();

    private ArrayList<Book> books = new ArrayList<Book>();

    public ArrayList<Book> getBooks() {
        return books;
    }

    public void setBooks(ArrayList<Book> books) {
        this.books = books;
    }

    public HashMap<String, String> getToysMap() {
        return toysMap;
    }

    public void setToysMap(HashMap<String, String> toysMap) {
        this.toysMap = toysMap;
    }

    public ArrayList<String> getToys() {
        return toys;
    }

    public void setToys(ArrayList<String> toys) {
        this.toys = toys;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

book 類

public class Book {

    private String name;
    private String price;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

}

3.MainActivity 函數

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Gson gson = new Gson();

        Child child = new Child();
        child.setId(1);
        child.setAge(10);
        child.setName("小孩A");
        child.setSex("男");

        ArrayList<String> toys = new ArrayList<String>();
        toys.add("小車");
        toys.add("皮卡丘");
        toys.add("奧特曼");
        toys.add("火影忍者");
        child.setToys(toys);

        HashMap<String, String> toysMap = new HashMap<String, String>();
        toysMap.put("1", "小車2");
        toysMap.put("2", "皮卡丘2");
        toysMap.put("3", "奧特曼2");
        toysMap.put("4", "火影忍者2");
        child.setToysMap(toysMap);

        ArrayList<Book> books = new ArrayList<Book>();
        for (int i = 0; i < 3; i++) {
            Book book = new Book();
            book.setName("格林童話" + i);
            book.setPrice("價格：" + i + "$");
            books.add(book);
        }

        child.setBooks(books);

       // Log.e("child", gson.toJson(child));
  //將數據保存到 文件中，注意改文件是在手機上面
        saveDataToFile("file.json",gson.toJson(child));
    }

    private void saveDataToFile(String fileName,String data){

        FileOutputStream fileOutputStream = null;
        BufferedWriter bufferedWriter = null;

        try{
            fileOutputStream = openFileOutput(fileName, Context.MODE_PRIVATE);
            //getDir(fileName,Context.MODE_PRIVATE);
            bufferedWriter = new BufferedWriter(new OutputStreamWriter(fileOutputStream));
            bufferedWriter.write(data);
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            try
            {
                if (bufferedWriter != null)
                {
                    bufferedWriter.close();
                }
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        }
    }
}

Gson的使用
1. Gson gson = new Gson();
2. 對象數據 mclass
3. 轉換成Gson: gson.toJson(mclass)

以上爲個人學習和理解，例子代碼已忘記來自哪個網站