android的json解析

转http://blog.csdn.net/qxs965266509/article/details/42774691

Google Gson的使用方法,实现Json结构的相互转换

分类： android Json2015-01-16 12:03 884人阅读 评论(0) 收藏 举报

在Java开发中，有时需要保存一个数据结构成字符串，可能你会考虑用Json，但是当Json字符串转换成Java对象时，转换成的是JsonObject，并不是你想要的Class类型的对象，操作起来就很不是愉悦，下面说的就可以解决了这种问题。

首先，需要把Google的Gson的Jar包导入到项目中，这个导入包的简单步骤就不展示了，Gson的下载链接：http://download.csdn.net/detail/qxs965266509/8367275

现在，我先自定义一个Class类

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对象使用Gson转换成Json的字符串

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();
    student.id = 1;
    student.nickName = "乔晓松";
    student.age = 22;
    student.email = "965266509@qq.com";
    Log.e("MainActivity", gson.toJson(student));

输出结果是 ：

{"email":"965266509@qq.com","nickName":"乔晓松","id":1,"age":22}

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();
        student.id = 1;
        student.nickName = "乔晓松";
        student.age = 22;
        student.email = "965266509@qq.com";
        ArrayList<String> books = new ArrayList<String>();
        books.add("数学");
        books.add("语文");
        books.add("英语");
        books.add("物理");
        books.add("化学");
        books.add("生物");
        student.books = books;
        Log.e("MainActivity", gson.toJson(student));

输出结果是 ：

{"books":["数学","语文","英语","物理","化学","生物"],"email":"965266509@qq.com","nickName":"乔晓松","id":1,"age":22}

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();
        student.id = 1;
        student.nickName = "乔晓松";
        student.age = 22;
        student.email = "965266509@qq.com";
        ArrayList<String> books = new ArrayList<String>();
        books.add("数学");
        books.add("语文");
        books.add("英语");
        books.add("物理");
        books.add("化学");
        books.add("生物");
        student.books = books;
        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("MainActivity", gson.toJson(student));

输出结果是 ：

{"books":["数学","语文","英语","物理","化学","生物"],"booksMap":{"3":"英语","2":"语文","1":"数学","6":"生物","5":"化学","4":"物理"},"email":"965266509@qq.com","nickName":"乔晓松","id":1,"age":22}

案例四：
把案例三输出的字符串使用Gson转换成Student对象

Gson gson = new Gson();
        Student student = new Student();
        student.id = 1;
        student.nickName = "乔晓松";
        student.age = 22;
        student.email = "965266509@qq.com";
        ArrayList<String> books = new ArrayList<String>();
        books.add("数学");
        books.add("语文");
        books.add("英语");
        books.add("物理");
        books.add("化学");
        books.add("生物");
        student.books = books;
        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 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());