Gson实例

    @Test
    public void testObj2Json(){
        // 定义对象
        Person person = new Person();
        person.setId(1);
        person.setName("jim");
        person.setAge(24);
        person.setMale(true);
        person.setBirthday(new Date());
        
        // 实例化Gson并使用方法toJson(Object src)转json串
        Gson gson = new Gson();
        String jsonStr = gson.toJson(person);
        
        // 输出
        System.out.println(jsonStr);
    }
    
    /**
     * Gson节点对象:
     *     JsonElement:所有的节点 都是JsonElement对象.
     *     JsonPrimitive:基本数据类型的节点对象,JsonElement的子类.
     *     JsonNull:空节点对象,JsonElement的子类.
     *     JsonObject : 对象节点对象, JsonElement的 子类.
     *     JsonArray : 数组节点对象, JsonElement的子类.
     * JsonElement的取值:
     *     JsonPrimitive:value的 取值对应 java的int,double,float,long,short,boolean,char,byte,String,BigDecimal,BigInteger,Number
     *     JsonObject:value的取值对应 java的Object对象.
     *     JsonArray:value的取值对应java的List及其子类对象.
     */
    @Test
    public void testJson2Obj(){
        // {"id":1,"name":"jim","age":24,"isMale":true,"birthday":"Sep 6, 2015 6:06:34 AM"}
        String json = "{"id":1,"name":"jim","age":24,"isMale":true,"birthday":"Sep 6, 2015 6:06:34 AM"}";
        
        // 实例化Gson实例,并 使用 fromJson(String json, Class<Person> classOfT)来转成对象
        Gson gson = new Gson();
        Person p = gson.fromJson(json, Person.class);
        
        // 输出
        System.out.println(p);
    }
    
    @Test
    public void testJson2List(){
        String json = "[{"id":1,"name":"jim","age":24,"isMale":true,"birthday":"Sep 6, 2015 6:06:34 AM"},{"id":2,"name":"jack","age":25,"isMale":true,"birthday":"Sep 3, 2015 9:06:34 PM"}]";
        
        // 实例化Gson实例,并 使用 fromJson(String json, Class<Person> classOfT)来转成对象
        // 使用 TypeToken 来封装List类型
        Gson gson = new Gson();
        List<Person> ps = gson.fromJson(json, new TypeToken<List<Person>>(){}.getType());
        
        for (Person person : ps) {
            System.out.println(person);
        }
    }
    
    @Test
    public void testJson2Map(){
        String json = "{"p1":{"id":1,"name":"jim","age":24,"isMale":true,"birthday":"Sep 6, 2015 6:06:34 AM"},"p2":{"id":2,"name":"jack","age":25,"isMale":true,"birthday":"Sep 3, 2015 9:06:34 PM"}}";
        
        // 实例化Gson实例,并 使用 fromJson(String json, Class<Person> classOfT)来转成对象
        // 使用 TypeToken 来封装Map类型
        Gson gson = new Gson();
        Map<String,Person> pmap = gson.fromJson(json, new TypeToken<Map<String,Person>>(){}.getType());
        
        // 迭代输出
        for (Iterator<String> iter = pmap.keySet().iterator();iter.hasNext();) {
            String key = iter.next();
            Person val = pmap.get(key);
            
            System.out.println(key + ":" + val);
        }
    }
    
    @Test
    public void testParseJson(){
        String json = "{"p1":{"id":1,"name":"jim","age":24,"isMale":true,"birthday":"Sep 6, 2015 6:06:34 AM"},"p2":{"id":2,"name":"jack","age":25,"isMale":true,"birthday":"Sep 3, 2015 9:06:34 PM"}}";
        
        // Json 解析对象,先获取整个json串
        JsonParser jp = new JsonParser();
        JsonElement element = jp.parse(json);
        
        // 整个是一个对象,因此先获取Object,在从Object中获取Object(key=p1)
        JsonObject jobj = element.getAsJsonObject();
        JsonObject p1 = jobj.getAsJsonObject("p1");
        
        // 获取到的Object在转换成Person对象
        Person p = new Gson().fromJson(p1, Person.class);
        System.out.println(p);
    }

代码: https://github.com/cbooy/GsonDemo