经过上一篇文章的学习，我们已经品尝了Volley的Request的StringRequest、JsonRequest、ImageRequest、ImageLoader、NetworkImageView等几种美食。其中StringRequest用于请求普通的文本数据，JsonRequest(JsonObjectRequest、JsonArrayRequest)用于请求JSON格式的数据，ImageRequest、ImageLoader和NetworkImageView都是用于请求下载网络图片的。如果你还没有品尝这几种美食，建议你先去尝一尝上一篇文章的美食《舌尖上的Android Volley（一）》

“在繁华的城市里，生活着一群程序猿们，他们运用各自智慧，适度、巧妙的利用Volley提供的Request，获得质朴美味的食物……”

JsonRequest的数据解析是利用Android本身自带的JSONObject和JSONArray来实现的。不过，当我们使用JSONObject解析数据时还是比较麻烦，当你想到可以使用GSON，FastJson等工具时，然而Volley中默认并不支持使用GSON来解析数据。为了满足各位食客的挑剔，我们自定义一个GsonRequest来满足你的味蕾。

自定义GsonRequest

实现一个request时必须继承Request类，表示request期望解析的response的类型,比如解析的response是字符串，则创建自定义的request通过继承Request。
parseNetworkResponse
在parseNetworkResponse()方法中，先是将服务器响应的数据解析出来，然后通过调用Gson的fromJson方法将数据组装成Response类使用给定的类型对象，用于传递。
deliverResponse
Volley将parseNetworkResponse()中返回的对象传递到主线程，当发起请求时会在此调用回调接口。

下面我们以http://www.tngou.net/tnfs/api/classify为例，用我们自定义的GsonRequest获取下面的数据并解析。

{"status":true,"tngou":[{"description":"性感美女","id":1,"keywords":"性感美女","name":"性感美女","seq":1,"title":"性感美女"},{"description":"韩日美女","id":2,"keywords":"韩日美女","name":"韩日美女","seq":2,"title":"韩日美女"},{"description":"丝袜美腿","id":3,"keywords":"丝袜美腿","name":"丝袜美腿","seq":3,"title":"丝袜美腿"},{"description":"美女照片","id":4,"keywords":"美女照片","name":"美女照片","seq":4,"title":"美女照片"},{"description":"美女写真","id":5,"keywords":"美女写真","name":"美女写真","seq":5,"title":"美女写真"},{"description":"清纯美女","id":6,"keywords":"清纯美女","name":"清纯美女","seq":6,"title":"清纯美女"},{"description":"性感车模","id":7,"keywords":"性感车模","name":"性感车模","seq":7,"title":"性感车模"}]}

GsonRequest.java

public class GsonRequest<T> extends Request<T> {    private final Gson gson = new Gson();    private final Class clazz;    private final Response.Listener listener;    public GsonRequest(String url, Class clazz, Response.Listener listener, Response.ErrorListener errorListener) {        super(Method.GET, url, errorListener);        this.clazz = clazz;        this.listener = listener;    }    @Override    protected void deliverResponse(T response) {        listener.onResponse(response);    }    @Override    protected Response parseNetworkResponse(NetworkResponse response) {        try {            String json = new String(response.data, HttpHeaderParser.parseCharset(response.headers));            return Response.success(gson.fromJson(json, clazz), HttpHeaderParser.parseCacheHeaders(response));        } catch (UnsupportedEncodingException e) {            return Response.error(new ParseError(e));        } catch (JsonSyntaxException e) {            return Response.error(new ParseError(e));        }    }}

新建一个BelleRoot类解析json数据

public class BelleRoot {    private boolean status;    private List tngou;    public boolean isStatus() {        return status;    }    public void setStatus(boolean status) {        this.status = status;    }    public List getTngou() {        return tngou;    }    public void setTngou(List tngou) {        this.tngou = tngou;    }    public static class TngouBean {        private String description;        private int id;        private String keywords;        private String name;        private int seq;        private String title;        public String getDescription() {            return description;        }        public void setDescription(String description) {            this.description = description;        }        public int getId() {            return id;        }        public void setId(int id) {            this.id = id;        }        public String getKeywords() {            return keywords;        }        public void setKeywords(String keywords) {            this.keywords = keywords;        }        public String getName() {            return name;        }        public void setName(String name) {            this.name = name;        }        public int getSeq() {            return seq;        }        public void setSeq(int seq) {            this.seq = seq;        }        public String getTitle() {            return title;        }        public void setTitle(String title) {            this.title = title;        }    }}

下面我们在Activity类中调用GsonRequest，代码比较简单就不再细说。

public class MainActivity extends AppCompatActivity {    private RequestQueue mRequestQueue;    private List list = new ArrayList<>();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mRequestQueue = Volley.newRequestQueue(this);        GsonRequest gsonRequest = new GsonRequest(                "http://www.tngou.net/tnfs/api/classify", BelleRoot.class,                new Response.Listener() {                    @Override                    public void onResponse(BelleRoot belle) {                        list.addAll(belle.getTngou());                        for (int i = 0; i < list.size(); i++) {                            Log.d("TAG", list.get(i).getTitle());                        }                    }                }, new Response.ErrorListener() {            @Override            public void onErrorResponse(VolleyError error) {                Log.e("TAG", error.getMessage(), error);            }        });        mRequestQueue.add(gsonRequest);    }}

各位程序猿（媛）吃货们，菜出锅啦！

注意

别忘了在AndroidManifest.xml里声明网络权限。

<uses-permission android:name="android.permission.INTERNET"/>

在build.gradle中添加volley和gson依赖。

compile 'com.mcxiaoke.volley:library:1.0.19'compile 'com.google.code.gson:gson:2.2.4'

舌尖上的Android(安卓)Volley（二）

自定义GsonRequest

注意

最后为各位看官奉上Demo源码，点击下载。

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