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轉http://blog.csdn.net/qxs965266509/article/details/42774691Google Gson的使用方法,實現Json結構的相互轉換分類： android Json2015-01-16 12:03 884人閱讀 評論(0) 收藏 舉報
在Java開發中，有時需要儲存一個資料結構成字串，可能你會考慮用Json，但是當Json字串轉換成Java對象時，轉換成的是JsonObject，並不是你想要的Class類型的對象，操作起來就很不是愉悅，下面說的就可以解決了這種問題。
首先，需要把Google的Gson的Jar包匯入到項目中，這個匯入包的簡單步驟就不展示了，Gson的下載連結：http://download.csdn.net/detail/qxs965266509/8367275
現在，我先自訂一個Class類
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- public class Student {
- public int id;
- public String nickName;
- public int age;
- public ArrayList<String> books;
- public HashMap<String, String> booksMap;
- }
案例一，案例二，案例三都是把Java的Class對象使用Gson轉換成Json的字串
案例一：
僅包含基礎資料型別 (Elementary Data Type)的資料結構
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- Gson gson = new Gson();
- Student student = new Student();
- student.id = 1;
- student.nickName = "喬曉松";
- student.age = 22;
- student.email = "[email protected]";
- Log.e("MainActivity", gson.toJson(student));
輸出結果是 ：
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- {"email":"[email protected]","nickName":"喬曉松","id":1,"age":22}
案例二：
除了基礎資料型別 (Elementary Data Type)還包含了List集合
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- Gson gson = new Gson();
- Student student = new Student();
- student.id = 1;
- student.nickName = "喬曉松";
- student.age = 22;
- student.email = "[email protected]";
- ArrayList<String> books = new ArrayList<String>();
- books.add("數學");
- books.add("語文");
- books.add("英語");
- books.add("物理");
- books.add("化學");
- books.add("生物");
- student.books = books;
- Log.e("MainActivity", gson.toJson(student));
輸出結果是 ：
[html] view plaincopy
- {"books":["數學","語文","英語","物理","化學","生物"],"email":"[email protected]","nickName":"喬曉松","id":1,"age":22}
案例三：
除了基礎資料型別 (Elementary Data Type)還包含了List和Map集合
[java] view plaincopy
- Gson gson = new Gson();
- Student student = new Student();
- student.id = 1;
- student.nickName = "喬曉松";
- student.age = 22;
- student.email = "[email protected]";
- ArrayList<String> books = new ArrayList<String>();
- books.add("數學");
- books.add("語文");
- books.add("英語");
- books.add("物理");
- books.add("化學");
- books.add("生物");
- student.books = books;
- HashMap<String, String> booksMap = new HashMap<String, String>();
- booksMap.put("1", "數學");
- booksMap.put("2", "語文");
- booksMap.put("3", "英語");
- booksMap.put("4", "物理");
- booksMap.put("5", "化學");
- booksMap.put("6", "生物");
- student.booksMap = booksMap;
- Log.e("MainActivity", gson.toJson(student));
輸出結果是 ：
[java] view plaincopy
- {"books":["數學","語文","英語","物理","化學","生物"],"booksMap":{"3":"英語","2":"語文","1":"數學","6":"生物","5":"化學","4":"物理"},"email":"[email protected]","nickName":"喬曉松","id":1,"age":22}
案例四：
把案例三輸出的字串使用Gson轉換成Student對象
[java] view plaincopy
- Gson gson = new Gson();
- Student student = new Student();
- student.id = 1;
- student.nickName = "喬曉松";
- student.age = 22;
- student.email = "[email protected]";
- ArrayList<String> books = new ArrayList<String>();
- books.add("數學");
- books.add("語文");
- books.add("英語");
- books.add("物理");
- books.add("化學");
- books.add("生物");
- student.books = books;
- HashMap<String, String> booksMap = new HashMap<String, String>();
- booksMap.put("1", "數學");
- booksMap.put("2", "語文");
- booksMap.put("3", "英語");
- booksMap.put("4", "物理");
- booksMap.put("5", "化學");
- booksMap.put("6", "生物");
- student.booksMap = booksMap;
- String result = gson.toJson(student);
-
- Student studentG = gson.fromJson(result, Student.class);
-
- Log.e("MainActivity", "id:" + studentG.id);
- Log.e("MainActivity", "nickName:" + studentG.nickName);
- Log.e("MainActivity", "age:" + studentG.age);
- Log.e("MainActivity", "email:" + studentG.email);
- Log.e("MainActivity", "books size:" + studentG.books.size());
- Log.e("MainActivity", "booksMap size:" + studentG.booksMap.size());
需要注意的是：
1、因為json轉為類時候有的資料有或沒有，因此最好是javabean的類，類的子類都可以設為共有的。
2、當從伺服器得到的json資料非常複雜的時候，可以用hijson工具解析出類的架構，然後來構建類。
android的json解析
