请求数据

GIF.gif

使用到

• Okhttp网络请求
• Glide图片加载库
• Json解析之Gson

OKHttp网络请求的封装：我用的是Okhttputils按道理是应该封装的，但是okhttputils已经满足大部分项目需求所以才没有封装 http://www.jianshu.com/p/96f55f19c1e4

Glide使用简单并且功能十分强大

优点：

1，缓存图片和imageView尺寸图片相同 Picasso缓存的是全尺寸图片
2，加载速度快
3，加载GIF图片 Glide加载GIF图并不需要编写什么额外的代码，Glide内部会自动判断图片格式

缺点：

1，Glide加载的图片质量要差于Picasso ，因为Glide默认的Bitmap格式是RGB_565 ， Picasso默认格式是ARGB_8888，

使用:

1,导入依赖 compile 'com.github.bumptech.glide:glide:3.8.0';

 Glide.with(this) 
      .load(url)
      .asBitmap()//指定图片的格式 只允许加载静态图片
      .placeholder(R.drawable.oxv)//加载图片占位符
      .error(R.drawable.error)//加载图片失败
      .diskCacheStrategy(DiskCacheStrategy.NONE)//禁用掉Glide的缓存功能。
      .override(100, 100)//指定图片大小 而不会管你的ImageView的大小是多少了。
      .into(imageView);  //让图片显示在哪个ImageView上

with()方法可以接收Context、Activity或者Fragment类型的参数。也就是说我们选择的范围非常广，不管是在Activity还是Fragment中调用with()方法，都可以直接传this。那如果调用的地方既不在Activity中也不在Fragment中呢？也没关系，我们可以获取当前应用程序的ApplicationContext，传入到with()方法当中。注意with()方法中传入的实例会决定Glide加载图片的生命周期，如果传入的是Activity或者Fragment的实例，那么当这个Activity或Fragment被销毁的时候，图片加载也会停止。如果传入的是ApplicationContext，那么只有当应用程序被杀掉的时候，图片加载才会停止。

load()方法，这个方法用于指定待加载的图片资源。
Glide支持加载各种各样的图片资源，包括网络图片、本地图片、应用资源、二进制流、Uri对象等等。因此load()方法也有很多个方法重载，除了我们刚才使用的加载一个字符串网址之外，你还可以这样使用load()方法：

            // 加载本地图片
            File file = new File(getExternalCacheDir() + "/image.jpg");
            Glide.with(this).load(file).into(imageView);

                       // 加载应用资源
                       int resource = R.drawable.image;
                       Glide.with(this).load(resource).into(imageView);

                       // 加载二进制流
                       byte[] image = getImageBytes();
                       Glide.with(this).load(image).into(imageView);

                       // 加载Uri对象
                       Uri imageUri = getImageUri();
                       Glide.with(this).load(imageUri).into(imageView);

可以点击这里Android图片加载框架最全解析（一），Glide的基本用法学习
如果你想深入的话可以看郭霖大神的 Android图片加载框架最全解析（二），从源码的角度理解Glide的执行流程

Json解析 :

使用google提供的gson解析 在Android下载GsonFormat插件 ;
1，导入Json依赖;
2，需要一个bean Text类 ,然后鼠标放在Test类后面 Alt+Ins 键 选择GsonFormat 把你需要的数据放进去就ok了;
3，实现序列化 Parcelable;

下面看代码怎么实现 拿新闻页面为例吧 布局代码就不给出了：

首先看Bean吧：

public class News implements Parcelable {
private String uniquekey;
private String title;
private String date;
private String category;
private String author_name;
private String url;
private String thumbnail_pic_s;
private String thumbnail_pic_s02;
private String thumbnail_pic_s03;

public News() {
}

public String getUniquekey() {
    return uniquekey;
}

public void setUniquekey(String uniquekey) {
    this.uniquekey = uniquekey;
}

public String getTitle() {
    return title;
}

public void setTitle(String title) {
    this.title = title;
}

public String getDate() {
    return date;
}

public void setDate(String date) {
    this.date = date;
}

public String getCategory() {
    return category;
}

public void setCategory(String category) {
    this.category = category;
}

public String getAuthor_name() {
    return author_name;
}

public void setAuthor_name(String author_name) {
    this.author_name = author_name;
}

public String getUrl() {
    return url;
}

public void setUrl(String url) {
    this.url = url;
}

public String getThumbnail_pic_s() {
    return thumbnail_pic_s;
}

public void setThumbnail_pic_s(String thumbnail_pic_s) {
    this.thumbnail_pic_s = thumbnail_pic_s;
}

public String getThumbnail_pic_s02() {
    return thumbnail_pic_s02;
}

public void setThumbnail_pic_s02(String thumbnail_pic_s02) {
    this.thumbnail_pic_s02 = thumbnail_pic_s02;
}

public String getThumbnail_pic_s03() {
    return thumbnail_pic_s03;
}

public void setThumbnail_pic_s03(String thumbnail_pic_s03) {
    this.thumbnail_pic_s03 = thumbnail_pic_s03;
}

@Override
public int describeContents() {
    return 0;
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(this.uniquekey);
    dest.writeString(this.title);
    dest.writeString(this.date);
    dest.writeString(this.category);
    dest.writeString(this.author_name);
    dest.writeString(this.url);
    dest.writeString(this.thumbnail_pic_s);
    dest.writeString(this.thumbnail_pic_s02);
    dest.writeString(this.thumbnail_pic_s03);
}

protected News(Parcel in) {
    this.uniquekey = in.readString();
    this.title = in.readString();
    this.date = in.readString();
    this.category = in.readString();
    this.author_name = in.readString();
    this.url = in.readString();
    this.thumbnail_pic_s = in.readString();
    this.thumbnail_pic_s02 = in.readString();
    this.thumbnail_pic_s03 = in.readString();
}

public static final Creator<News> CREATOR = new Creator<News>() {
    @Override
    public News createFromParcel(Parcel source) {
        return new News(source);
    }

    @Override
    public News[] newArray(int size) {
        return new News[size];
    }
};
}

NewsAdapter：

public class NewsAdapter extends BaseAdapter {
private viewHolder holder;
private List<News> data;

public NewsAdapter(List<News> data) {
    this.data = data;
}

@Override
public int getCount() {
    return data.size();
}

@Override
public Object getItem(int position) {
    return data.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(final int position, View convertView, final ViewGroup parent) {
    if (convertView == null){
        convertView= LayoutInflater.from(parent.getContext()).inflate(R.layout.item_news,null);
        holder = new viewHolder(convertView);
        convertView.setTag(holder);
    }else {
        holder = (viewHolder) convertView.getTag();
    }
    Glide.with(parent.getContext())
            .load(data.get(position).getThumbnail_pic_s())
            .placeholder(R.drawable.load)
            .error(R.drawable.load_failure)
            .into(holder.img_news);

    holder.tv_title.setText(data.get(position).getTitle());

    convertView.setOnLongClickListener(new View.OnLongClickListener() {
        @Override
        public boolean onLongClick(View v) {
            new AlertDialog.Builder(parent.getContext())
                    .setTitle("收藏")
                    .setMessage("是否收藏？")
                    .setPositiveButton("收藏", new  DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Account account = BmobUser.getCurrentUser(BaseApplication.getInstance(),Account.class);
                            if(account != null) {
                                Collection collectionBean = new Collection();
                                collectionBean.setPicUrl(data.get(position).getThumbnail_pic_s());
                                collectionBean.setuId(account.getObjectId());
                                collectionBean.setUrl(data.get(position).getUrl());
                                collectionBean.setTitle(data.get(position).getTitle());
                                collectionBean.setType(Constants.COLLECTION_TYPE_NEWS);
                                collectionBean.save(parent.getContext(), new SaveListener() {
                                    @Override
                                    public void onSuccess() {
                                        Toast.makeText(parent.getContext(), "收藏成功", Toast.LENGTH_SHORT).show();
                                    }

                                    @Override
                                    public void onFailure(int i, String s) {
                                        Toast.makeText(parent.getContext(), "收藏失败", Toast.LENGTH_SHORT).show();
                                    }
                                });
                            }
                        }
                    })
                    .setNegativeButton("取消",null)
                    .create()
                    .show();

            return false;
        }
    });

    return convertView;
}

class viewHolder{
    ImageView img_news;
    TextView tv_title;

    public viewHolder(View convertView) {
        img_news = (ImageView) convertView.findViewById(R.id.img_news);
        tv_title  = (TextView) convertView.findViewById(R.id.tv_title);

    }
}

//下拉刷新
public void setNewData(List<News> newData) {
    data.clear();
    data.addAll(newData);
    notifyDataSetChanged();
}

//加载更多
public void setMoreData(List<News> newData) {
    data.addAll(newData);
    notifyDataSetChanged();
}
}

这里也用到了Bmob收藏，用的是AlertDialog弹出框来确定你是否收藏

NewsFragment：

public class NewsFragment extends Fragment {

public static final int TYPE_REFRESH = 0x01;
public static final int TYPE_LOADMORE = 0x02;
@BindView(R.id.lv_news)
PullToRefreshListView lvNews;
private List<News> data = new ArrayList<>();
private NewsAdapter newsAdapter;
Unbinder unbinder;
private View view;
private static int page = 1;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    view = inflater.inflate(R.layout.fragment_news, container, false);
    unbinder = ButterKnife.bind(this, view);

    initView();
    return view;
}



private void initView() {
    //设置列表刷新加载
 //   lvNews.setMode(PullToRefreshBase.Mode.BOTH);
    //初始化适配器
    newsAdapter = new NewsAdapter(data);
    //绑定适配器
    lvNews.setAdapter(newsAdapter);
    //添加监听事件
    lvNews.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Intent intent = new Intent(getActivity(), NewsDataActivity.class);
            Bundle bundle = new Bundle();
            bundle.putParcelable("news", data.get(position - 1));
            intent.putExtras(bundle);
            NewsFragment.this.startActivity(intent);
        }
    });
    lvNews.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2<ListView>() {
        @Override
        public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {
            //下拉刷新,先清空数据，在加载新数据,更新UI
            page = 1;
            getAsyncData(1, TYPE_REFRESH);
        }

        @Override
        public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {
            //加载更多：加载下一页数据,请求page++,新数据添加在后面
              getAsyncData(page++,TYPE_LOADMORE);
        }
    });
}

@Override
public void onResume() {
    super.onResume();
    initData();
}
private void initData() {
    getAsyncData(1, TYPE_REFRESH);
}

//获取异步请求的数值
private void getAsyncData(int page, final int type) {
    OkHttpUtils
            .get()
            .url(ServerConfig.JUHE_NEWS_URL)
            .addParams("key", Constant.API_NEWS_KEY)
            .addParams("type", "top")
            .build()
            .execute(new StringCallback() {
                @Override
                public void onError(Call call, Exception e, int id) {
                    lvNews.onRefreshComplete();
                    Toast.makeText(getActivity(), "请求数据失败", Toast.LENGTH_SHORT).show();
                }
                @Override
                public void onResponse(String response, int id) {
                    //停止刷新
                    lvNews.onRefreshComplete();
                    //解析数据 把返回的结果JSON数据字符串转为json对象
                    JSONObject jsonObject = JSONObject.parseObject(response);
                    JSONArray jsonArray = jsonObject.getJSONObject("result").getJSONArray("data");
                    switch (type) {
                        case TYPE_REFRESH:
                            newsAdapter.setNewData(JSONArray.parseArray(jsonArray.toJSONString(), News.class));
                            break;
                        case TYPE_LOADMORE:
                            newsAdapter.setMoreData(JSONArray.parseArray(jsonObject.toJSONString(), News.class));
                            break;
                    }
                }
            });

}

@Override

public void onDestroyView() {
    super.onDestroyView();
    unbinder.unbind();
}
}

• url获取到新闻数据地址
• addParams获取新闻Key值
• 初始化OkHttpClient以及创建一个Request，然后再调用OkHttpClinet的newCall方法，创建出一个RealCall对象。对于同步请求，是调用RealCall的execute方法；而异步请求，则是调用RealCall的enqueue方法实现。