詳解Gson使用(一)簡單對象轉化

感謝原文主，內容很詳細，很不錯

原文鏈接

JSON是一種輕量級的數據交換格式。 易於人閱讀和編寫，同時也易於機器解析和生成(一般用於提升網絡傳輸速率)。

在之前我寫過一篇文章，《Android解析json數據》

http://blog.csdn.net/a249900679/article/details/51195505

介紹了json和用JSONObject、JSONArray解析json數據的方法，接下來幾篇文章將會介紹解析json數據的更好的方法：使用Gson解析。

 

Gson是Google推出的用來解析json數據以及將對象轉換成json數據的框架。可以很方便地實現json數據與對象的相互轉換，還可以自定義需要序列化或反序列化的字段。

 

使用Gson需要先導入jar，我這裏用到的是gson-2.3.1.jar

項目和jar下載地址：

Github：https://github.com/smileysx/GsonTest

Oschina：https://git.oschina.net/ysx_xx/GsonText

詳解Gson使用(一)簡單對象轉化

http://blog.csdn.net/a249900679/article/details/51385913

詳解Gson使用(二)帶泛型的List轉化

http://blog.csdn.net/a249900679/article/details/51386028

詳解Gson使用(三)使用註解

http://blog.csdn.net/a249900679/article/details/51386509

詳解Gson使用(四)Map對象轉化
http://blog.csdn.net/a249900679/article/details/51386660
詳解Gson使用(五)實現百度翻譯功能

http://blog.csdn.net/a249900679/article/details/51386727

其中gson-2.3.1.jar在項目lib目錄下

 

下面先來介紹簡單對象的轉換：

注意：以下所有實體類的變量名要跟json數據中的key相同

1.普通json數據對象實體類：

public class ToJsonBeanOne {
    private int id;
    private String name;
    private int age;

    public ToJsonBeanOne(int id, String name, int age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

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

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

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

    @Override
    public String toString() {
        String resultString = "";
        resultString += "id:" + id + "\nname:" + name + "\nage:" + age + "\n";

        return resultString;
    }
}

 

可以看出來，上面對象中三個數據都是String類型，這是最簡單的。

看看如何把該對象序列化：

public class ToJsonTest extends Activity {

    private TextView show;
    private Button start;
    private Gson gson;

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

        initData();
    }

    private void initData() {

        gson = new Gson();
        show = (TextView) findViewById(R.id.showtext);
        start = (Button) findViewById(R.id.send);
        start.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                showData();
            }
        });
    }

    private void showData() {

        String resultString = "";

        resultString = one() + "\n\n";

        show.setText(resultString);
    }

    private String one() {
        //創建對象
        ToJsonBeanOne toJsonBeanOne = new ToJsonBeanOne(1, "小熊", 21);
        //將對象轉換爲json數據
        return gson.toJson(toJsonBeanOne);
    }
}

結果爲：

接下來看看如何把json數據轉換爲該對象：

public class FromJsonTest extends Activity {

    /**
     * 顯示數據的textview
     */
    private TextView show;
    /**
     * 按鈕
     */
    private Button start;
    /**
     * gson
     */
    private Gson gson;

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

        initData();
    }

    private void initData() {

        gson = new Gson();
        show = (TextView) findViewById(R.id.showtext);
        start = (Button) findViewById(R.id.send);
        start.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                showData();
            }
        });

    }

    private void showData() {
        String showString = "";

        showString += one();

        show.setText(showString);

    }

    private String one() {
        //這裏創建個對象，是爲了得到json數據，實際中json數據可能是由網絡請求得到等
        ToJsonBeanOne toJsonBeanOne = new ToJsonBeanOne(1, "小熊", 21);
        String jsonString = gson.toJson(toJsonBeanOne);

        //將json數據轉換爲對象
        ToJsonBeanOne beanOne = gson.fromJson(jsonString, ToJsonBeanOne.class);

        String showString = "";
        showString += "json:" + jsonString + "\n解析結果爲：\n" + beanOne.toString();

        showString += "----------------------\n";
        return showString;
    }
}

結果爲：

2.帶對象的對象實體類：

public class ToJsonBeanTwo {
    private String school;
    private String classroom;
    private ToJsonBeanOne toJsonBeanOne;

    public ToJsonBeanTwo(String school, String classroom,
            ToJsonBeanOne toJsonBeanOne) {
        super();
        this.school = school;
        this.classroom = classroom;
        this.toJsonBeanOne = toJsonBeanOne;
    }

    public String getSchool() {
        return school;
    }

    public String getClassroom() {
        return classroom;
    }

    public ToJsonBeanOne getToJsonBeanOne() {
        return toJsonBeanOne;
    }

    public void setSchool(String school) {
        this.school = school;
    }

    public void setClassroom(String classroom) {
        this.classroom = classroom;
    }

    public void setToJsonBeanOne(ToJsonBeanOne toJsonBeanOne) {
        this.toJsonBeanOne = toJsonBeanOne;
    }

    @Override
    public String toString() {
        String resultString = "";
        resultString += "school:" + school + "\nclassroom:" + classroom
                + "\ntoJsonBeanOne:\nid:" + toJsonBeanOne.getId() + "\nname:"
                + toJsonBeanOne.getName() + "\nage:" + toJsonBeanOne.getAge()
                + "\n";
        return resultString;
    }
}

可以看出該對象中不僅有String類型數據，還有ToJsonBeanOne對象數據。

看看如何把該對象序列化：

public class ToJsonTest extends Activity {

    private TextView show;
    private Button start;
    private Gson gson;

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

        initData();
    }

    private void initData() {

        gson = new Gson();
        show = (TextView) findViewById(R.id.showtext);
        start = (Button) findViewById(R.id.send);
        start.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                showData();
            }
        });
    }

    private void showData() {

        String resultString = "";

        resultString += three() + "\n\n";

        show.setText(resultString);
    }

    private String three() {

        ToJsonBeanTwo toJsonBeanTwo = new ToJsonBeanTwo("華軟", "軟工五班",
                new ToJsonBeanOne(1, "小熊", 21));

        return gson.toJson(toJsonBeanTwo);
    }
}

結果爲：

接下來看看如何把json數據轉換爲該對象：

public class FromJsonTest extends Activity {

    /**
     * 顯示數據的textview
     */
    private TextView show;
    /**
     * 按鈕
     */
    private Button start;
    /**
     * gson
     */
    private Gson gson;

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

        initData();
    }

    private void initData() {

        gson = new Gson();
        show = (TextView) findViewById(R.id.showtext);
        start = (Button) findViewById(R.id.send);
        start.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                showData();
            }
        });

    }

    private void showData() {
        String showString = "";

        showString += three();

        show.setText(showString);

    }

    private String three() {

        ToJsonBeanTwo toJsonBeanTwo = new ToJsonBeanTwo("華軟", "軟工五班",
                new ToJsonBeanOne(1, "小熊", 21));
        String jsonString = gson.toJson(toJsonBeanTwo);

        ToJsonBeanTwo beanTwo = gson.fromJson(jsonString, ToJsonBeanTwo.class);

        String showString = "";
        showString += "json:" + jsonString + "\n解析後的數據：\n" + beanTwo.toString();

        showString += "----------------------\n";

        return showString;
    }
}

 

結果爲：

3.既帶對象又帶List數據的對象(相當與json數據中有數組)實體類:

public class ToJsonBeanThree {
    private String number;
    private ToJsonBeanTwo toJsonBeanTwo;
    private List<Book> books;

    public ToJsonBeanThree(String number, ToJsonBeanTwo toJsonBeanTwo,
            List<Book> books) {
        super();
        this.number = number;
        this.toJsonBeanTwo = toJsonBeanTwo;
        this.books = books;
    }

    public ToJsonBeanTwo getToJsonBeanTwo() {
        return toJsonBeanTwo;
    }

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

    public void setToJsonBeanTwo(ToJsonBeanTwo toJsonBeanTwo) {
        this.toJsonBeanTwo = toJsonBeanTwo;
    }

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

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }

    @Override
    public String toString() {

        String resultString = "";
        resultString += "number:" + number + "\n";
        ToJsonBeanOne toJsonBeanOne = toJsonBeanTwo.getToJsonBeanOne();
        resultString += "toJsonBeanTwo:\nschool:" + toJsonBeanTwo.getSchool()
                + "\nclassroom:" + toJsonBeanTwo.getClassroom() + "\n";
        resultString += "toJsonBeanOne:\nid:" + toJsonBeanOne.getId()
                + "\nname:" + toJsonBeanOne.getName() + "\nage:"
                + toJsonBeanOne.getAge() + "\n";
        resultString += "books:\n";

        for (int i = 0; i < books.size(); ++i) {
            resultString += "bookName:" + books.get(i).getBookName()
                    + "\nprice:" + books.get(i).getPrice() + "\n";
        }

        return resultString;
    }

    /**
     *
     * @ClassName: Book
     * @Description: 內部類
     * @author smile
     * @date 2016年5月12日 上午12:23:42
     *
     */
    public static class Book {
        private String bookName;
        private float price;

        public Book(String bookName, float price) {
            super();
            this.bookName = bookName;
            this.price = price;
        }

        public String getBookName() {
            return bookName;
        }

        public float getPrice() {
            return price;
        }

        public void setBookName(String bookName) {
            this.bookName = bookName;
        }

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

    }
}

可以看出該對象裏不僅有String類型，還有ToJsonBeanTwo對象類型，還有List<Book>類型，Book對象我寫成內部類，如果有多個類共用則寫成外部類，這裏要注意：寫成內部類要寫爲靜態內部類，不然解析會出錯。

看看如何把該對象序列化：

public class ToJsonTest extends Activity {

    private TextView show;
    private Button start;
    private Gson gson;

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

        initData();
    }

    private void initData() {

        gson = new Gson();
        show = (TextView) findViewById(R.id.showtext);
        start = (Button) findViewById(R.id.send);
        start.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                showData();
            }
        });
    }

    private void showData() {

        String resultString = "";

        resultString += five() + "\n\n";

        show.setText(resultString);
    }

    private String five() {

        ToJsonBeanTwo toJsonBeanTwo = new ToJsonBeanTwo("華軟", "軟工五班",
                new ToJsonBeanOne(1, "小熊", 21));
        List<Book> books = new ArrayList<Book>();
        for (int i = 1; i < 5; ++i) {
            books.add(new Book("第" + i + "本書", 25f * i));
        }
        ToJsonBeanThree toJsonBeanThree = new ToJsonBeanThree("1",
                toJsonBeanTwo, books);

        return gson.toJson(toJsonBeanThree);
    }
}

結果爲：

可以看出對象中List數據books轉換成json數據變爲數組

 

接下來看看如何把json數據轉換爲該對象：

public class FromJsonTest extends Activity {

    /**
     * 顯示數據的textview
     */
    private TextView show;
    /**
     * 按鈕
     */
    private Button start;
    /**
     * gson
     */
    private Gson gson;

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

        initData();
    }

    private void initData() {

        gson = new Gson();
        show = (TextView) findViewById(R.id.showtext);
        start = (Button) findViewById(R.id.send);
        start.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                showData();
            }
        });

    }

    private void showData() {
        String showString = "";

        showString += five();

        show.setText(showString);

    }

    private String five() {

        ToJsonBeanTwo toJsonBeanTwo = new ToJsonBeanTwo("華軟", "軟工五班",
                new ToJsonBeanOne(1, "小熊", 21));
        List<Book> books = new ArrayList<Book>();
        for (int i = 1; i < 5; ++i) {
            books.add(new Book("第" + i + "本書", 25f * i));
        }
        ToJsonBeanThree toJsonBeanThree = new ToJsonBeanThree("1",
                toJsonBeanTwo, books);

        String jsonString = gson.toJson(toJsonBeanThree);

        ToJsonBeanThree beanThree = gson.fromJson(jsonString,
                ToJsonBeanThree.class);

        String showString = "";
        showString += "json:" + jsonString + "\n解析後的數據：\n"
                + beanThree.toString();

        showString += "----------------------\n";
        return showString;
    }
}

結果爲：