android

使用Gson解析复杂的json数据

对于解析比较简单的json数据我就不介绍了来一个比较复杂一点的json数据，如下面我们要解析的一个json数据：
String json = {"a":"100","b":[{"b1":"b_value1","b2":"b_value2"}, {"b1":"b_value1","b2":"b_value2"}]，"c": {"c1":"c_value1","c2":"c_value2"}}

如果使用JsonObject和JsonArray的配合起来使用也是可以解析的但是解析起来就比较麻烦了，如果使用Gson解析就比较简单了，首先我们需要定义一个序列化的Bean，这里采用内部类的形式，这样比较容易看得清晰些

首先我们需要定义一个序列化的Bean，这里采用内部类的形式，看起来会比较清晰一些：

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public class JsonBean {  
    public String a;  
    public List<B> b;  
    public C c;  

    public static class B {  
        public String b1;  
        public String b2;  
    }  

    public static class C {  
        public String c1;  
        public String c2;  
    }  
}

很多时候大家都是不知道这个Bean是该怎么定义，这里面需要注意几点：
1、内部嵌套的类必须是static的，要不然解析会出错；
2、类里面的属性名必须跟Json字段里面的Key是一模一样的；
3、内部嵌套的用[]括起来的部分是一个List，所以定义为 public List<B> b，而只用{}嵌套的就定义为public C c

具体的大家对照Json字符串看看就明白了，不明白的我们可以互相交流，本人也是开发新手！

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Gson gson = new Gson();  
java.lang.reflect.Type type = new TypeToken<JsonBean>() {}.getType();  
JsonBean jsonBean = gson.fromJson(json, type);</span>

然后想拿数据就很简单啦，直接在jsonBean里面取就可以了！
如果需要解析的Json嵌套了很多层，同样可以可以定义一个嵌套很多层内部类的Bean，需要细心的对照Json字段来定义哦。

下面我将以一个具体的列子来说明通过Gson方式解析复杂的json数据
1.将要解析的数据如下面的格式

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{
    "error": 0,
    "status": "success",
    "date": "2014-05-10",
    "results": [
        {
            "currentCity": "南京",
            "weather_data": [
                {
                    "date": "周六(今天, 实时：19℃)",
                    "dayPictureUrl": "http://api.map.baidu.com/images/weather/day/dayu.png",
                    "nightPictureUrl": "http://api.map.baidu.com/images/weather/night/dayu.png",
                    "weather": "大雨",
                    "wind": "东南风5-6级",
                    "temperature": "18℃"
                },
                {
                    "date": "周日",
                    "dayPictureUrl": "http://api.map.baidu.com/images/weather/day/zhenyu.png",
                    "nightPictureUrl": "http://api.map.baidu.com/images/weather/night/duoyun.png",
                    "weather": "阵雨转多云",
                    "wind": "西北风4-5级",
                    "temperature": "21 ~ 14℃"
                }
            ]
        }
    ]
}

2.必须定义如下一些的javaBean数据
Status.java

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public class Status   
{  
    private String error;  
    private String status;  
    private String date;  
    private List<Results> results;  
    public String getError()   
    {  
        return error;  
    }  
    public void setError(String error)   
    {  
        this.error = error;  
    }  
      
    public String getStatus()   
    {  
        return status;  
    }  
    public void setStatus(String status)   
    {  
        this.status = status;  
    }  
    public String getDate()   
    {  
        return date;  
    }  
    public void setDate(String date)   
    {  
        this.date = date;  
    }  
    public List<Results> getResults()   
    {  
        return results;  
    }  
    public void setResults(List<Results> results)   
    {  
        this.results = results;  
    }  
    @Override  
    public String toString()   
    {  
        return "Status [error=" + error + ", status=" + status  
                + ", date=" + date + ", results=" + results + "]";  
    }
}

Results.java

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public class Results   
{     
    private String currentCity;  
    private List<Weather> weather_data;  
    public String getCurrentCity()   
    {  
        return currentCity;  
    }  
    public void setCurrentCity(String currentCity)   
    {  
        this.currentCity = currentCity;  
    }  
    public List<Weather> getWeather_data()   
    {  
        return weather_data;  
    }  
    public void setWeather_data(List<Weather> weather_data)   
    {  
        this.weather_data = weather_data;  
    }  
    @Override  
    public String toString()   
    {  
        return "Results [currentCity=" + currentCity + ", weather_data="  
                + weather_data + "]";  
    }
}

Weather.java

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public class Weather {  
    private String date;  
    private String dayPictureUrl;  
    private String nightPictureUrl;  
    private String weather;  
    private String wind;  
    private String temperature;  
    public String getDate() {  
        return date;  
    }  
    public void setDate(String date) {  
        this.date = date;  
    }  
    public String getDayPictureUrl() {  
        return dayPictureUrl;  
    }  
    public void setDayPictureUrl(String dayPictureUrl) {  
        this.dayPictureUrl = dayPictureUrl;  
    }  
    public String getNightPictureUrl() {  
        return nightPictureUrl;  
    }  
    public void setNightPictureUrl(String nightPictureUrl) {  
        this.nightPictureUrl = nightPictureUrl;  
    }  
    public String getWeather() {  
        return weather;  
    }  
    public void setWeather(String weather) {  
        this.weather = weather;  
    }  
    public String getWind() {  
        return wind;  
    }  
    public void setWind(String wind) {  
        this.wind = wind;  
    }  
    public String getTemperature() {  
        return temperature;  
    }  
    public void setTemperature(String temperature) {  
        this.temperature = temperature;  
    }  
    @Override  
    public String toString() {  
        return "Weather [date=" + date + ", dayPictureUrl="  
                + dayPictureUrl + ", nightPictureUrl="  
                + nightPictureUrl + ", weather=" + weather  
                + ", wind=" + wind + ", temperature=" + temperature  
                + "]";  
    }
}

然后具体的javabean定义好了就将解析数据了，下面就是我的解析数据类

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public class MainActivity extends Activity   
{  
    private Button tojson;    
    RequestQueue mQueue;      
    StringRequest stringRequest;      
    Gson gson;  
    String str;  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState)   
    {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
          
        tojson = (Button)findViewById(R.id.tojson);  
        gson = new Gson();  
  
        mQueue = Volley.newRequestQueue(MainActivity.this);   
        //http://10.19.20.12/upgrade/test.txt是测试使用的json数据  
        stringRequest = new StringRequest("http://10.19.20.12/upgrade/test.txt",  
                new Response.Listener<String>()   
                {  
                    @Override  
                    public void onResponse(String response)   
                    {  
                        Log.d("TAG", response);  
                        System.out.println("response="+response);  
                        Status status = gson.fromJson(response, Status.class);  
                        System.out.println("status="+status);  
                        System.out.println("-------------------------------------");  
                        List<Results> result = status.getResults();  
                        System.out.println("result="+result);  
                          
                    }  
                },   
                new Response.ErrorListener()   
                {  
                    @Override  
                    public void onErrorResponse(VolleyError error)   
                    {  
                        Log.e("TAG", error.getMessage(), error);  
                    }  
  
                });  
    
        tojson.setOnClickListener(new OnClickListener()   
        {         
            @Override  
            public void onClick(View v)   
            {  
                mQueue.add(stringRequest);  
            }  
        });       
    } 
}

其中上面的RequestQueue是开源网络库Volley的使用，如果你对该库的使用还不熟悉的话可以参考http://blog.csdn.net/guolin_blog/article/details/17482095 ，该作者对Volley库的使用讲解得非常的细致和深入
大家可以仔细的去拜读。