okhttp的使用以及簡單的封裝

一、okhttp的使用

1、添加庫

compile 'com.squareup.okhttp3:okhttp:3.4.1'

2、java代碼中添加

public static final MediaType JSON
    = MediaType.parse("application/json; charset=utf-8");

OkHttpClient client = new OkHttpClient();

String post(String url, String json) throws IOException {
  RequestBody body = RequestBody.create(JSON, json);
  Request request = new Request.Builder()
      .url(url)
      .post(body)
      .build();
  Response response = client.newCall(request).execute();
  return response.body().string();
}

二、okhttp的簡單封裝

1、OkHttpHelper類設成單例

private  static  OkHttpHelper mInstance;

private OkHttpHelper(){

};

public static  OkHttpHelper getInstance(){
    return  mInstance;
}

static {
    mInstance = new OkHttpHelper();
}

2、封裝get請求和post請求（所需參數，一個url，Map參數，一個回調）

public void get(String url,BaseCallback callback){
    Request request = buildGetRequest(url);
    request(request,callback);
}


public void post(String url,Map<String,String> param, BaseCallback callback){
    Request request = buildPostRequest(url,param);
    request(request,callback);
}

3、封裝執行請求方法request(需要傳遞一個request對象和一個callback對象)

        public  void request(final Request request,final  BaseCallback callback){
            callback.onBeforeRequest(request);
            mHttpClient.newCall(request).enqueue(new Callback() {

                @Override
                public void onFailure(Request request, IOException e) {
                    callbackFailure(callback, request, e);
                }

                @Override
                public void onResponse(Response response) throws IOException {
//                    callback.onResponse(response);
                    callbackResponse(callback,response);
                    if(response.isSuccessful()) {
                        String resultStr = response.body().string();
                        Log.d(TAG, "result=" + resultStr);
                        if (callback.mType == String.class){
                            callbackSuccess(callback,response,resultStr);
                        }
                        else {
                            try {
                                Object obj = mGson.fromJson(resultStr, callback.mType);
                                callbackSuccess(callback,response,obj);
                            }
                            catch (com.google.gson.JsonParseException e){ // Json解析的錯誤
                                callback.onError(response,response.code(),e);
                            }
                        }
                    }
                    else {
                        callbackError(callback,response,null);
                    }

                }
            });


        }

4、構建GetRequest和PosRequest，這兩個方法都要調用buildRequest方法，通過buildRequest方法中的HttpMethodType判斷是GetReques還是PosRequest

private  Request buildPostRequest(String url,Map<String,String> params){
        return  buildRequest(url,HttpMethodType.POST,params);
    }

private  Request buildGetRequest(String url){
        return  buildRequest(url,HttpMethodType.GET,null);
    }

private  Request buildRequest(String url,HttpMethodType methodType,Map<String,String> params){
    Request.Builder builder = new Request.Builder()
            .url(url);
    if (methodType == HttpMethodType.POST){
        RequestBody body = builderFormData(params);
        builder.post(body);
    }
    else if(methodType == HttpMethodType.GET){
        builder.get();
    }
    return builder.build();
}

enum  HttpMethodType{
    GET,
    POST,
}

5、封裝方法builderFormData(返回requestBody)

private RequestBody builderFormData(Map<String,String> params){
    FormEncodingBuilder builder = new FormEncodingBuilder();
    if(params !=null){
        for (Map.Entry<String,String> entry :params.entrySet() ){
            builder.add(entry.getKey(),entry.getValue());
        }
    }
    return  builder.build();
}

6、request響應成功或者失敗結果要交由主線程操作，所以要封裝callbackResponse和callbackFailure方法,其中callbackResponse又有響應正確和響應錯誤，所以還需封裝callbackSuccess方法和callbackError方法。

private void callbackFailure(final  BaseCallback callback , final Request request, final IOException e ){
    mHandler.post(new Runnable() {
        @Override
        public void run() {
            callback.onFailure(request,e);
        }
    });
}

private void callbackResponse(final  BaseCallback callback , final Response response ){
    mHandler.post(new Runnable() {
        @Override
        public void run() {
            callback.onResponse(response);
        }
    });
}

private void callbackSuccess(final  BaseCallback callback , final Response response, final Object obj ){
    mHandler.post(new Runnable() {
        @Override
        public void run() {
            callback.onSuccess(response, obj);
        }
    });
}

private void callbackError(final  BaseCallback callback , final Response response, final Exception e ){
    mHandler.post(new Runnable() {
        @Override
        public void run() {
            callback.onError(response,response.code(),e);
        }
    });
}

7、編寫callback類

public abstract class BaseCallback <T> {


    public   Type mType;

    static Type getSuperclassTypeParameter(Class<?> subclass)
    {
        Type superclass = subclass.getGenericSuperclass();
        if (superclass instanceof Class)
        {
            throw new RuntimeException("Missing type parameter.");
        }
        ParameterizedType parameterized = (ParameterizedType) superclass;
        return $Gson$Types.canonicalize(parameterized.getActualTypeArguments()[0]);
    }


    public BaseCallback()
    {
        mType = getSuperclassTypeParameter(getClass());
    }



    public  abstract void onBeforeRequest(Request request);


    public abstract  void onFailure(Request request, Exception e) ;


    /**
     *請求成功時調用此方法
     * @param response
     */
    public abstract  void onResponse(Response response);

    /**
     *
     * 狀態碼大於200，小於300 時調用此方法
     * @param response
     * @param t
     * @throws IOException
     */
    public abstract void onSuccess(Response response,T t) ;

    /**
     * 狀態碼400，404，403，500等時調用此方法
     * @param response
     * @param code
     * @param e
     */
    public abstract void onError(Response response, int code,Exception e) ;

}

如加載數據時需要加入對話框，則另寫一個callback繼承basecallback

public abstract class SpotsCallBack<T> extends BaseCallback<T> {


    private  Context mContext;

    private  SpotsDialog mDialog;

    public SpotsCallBack(Context context){

        mContext = context;

        initSpotsDialog();
    }

    private  void initSpotsDialog(){
        mDialog = new SpotsDialog(mContext,"拼命加載中...");
    }

    public  void showDialog(){
        mDialog.show();
    }

    public  void dismissDialog(){
        mDialog.dismiss();
    }

    public void setLoadMessage(int resId){
        mDialog.setMessage(mContext.getString(resId));
    }


    @Override
    public void onFailure(Request request, Exception e) {
        dismissDialog();
    }

    @Override
    public void onBeforeRequest(Request request) {
        showDialog();
    }

    @Override
    public void onResponse(Response response) {
        dismissDialog();
    }
}