Android网络请求框架----okHttp3

okhttp GitHub地址：
https://github.com/square/okhttp
最新的OkHttp依赖可以到官方的GitHub上去添加。

目前官方的依赖地址为：
compile ‘com.squareup.okhttp3:okhttp:3.6.0’

Get请求

直接进入主题：

        // 1、拿到OKHttpClient对象
        OkHttpClient okHttpClient=new OkHttpClient();

        // 2、构造Request
        //Request是构造者模式，所以使用的时候要.Builder
        Request.Builder builder=new Request.Builder();
        Request reqyest=builder.get().url("http://www.baidu.com").build();

        // 3、将Request封装为Call
        Call call=okHttpClient.newCall(reqyest);

        // 4、执行Call
       /* Response response=call.execute();  //直接执行 需要抛出异常*/

        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                //失败以后的方法
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                //成功以后回调的方法
                String res=response.body().string(); //回调一个字符串
            }
        });

最后在Manifests中打开网络权限即可使用Get请求请求网络数据了。
get请求头的格式：
例： url+”login?username=chengdu&password=123456”

POST请求

post请求大体步骤和GET请求差不多，具体如代码所示

        //获得一个功能强大的FormBody表单
        RequestBody formBody=new FormBody.Builder()
                .build();
        //2.构造Request
        Request.Builder builder=new Request.Builder();
        Request request=builder.url("http://www.imooc.com/").post(formBody).build();
        // 3、将Request封装为Call
        executeRequest(request);

RequestBody的数据格式都要指定Content-Type，常见的有三种：

• application/x-www-form-urlencoded 数据是个普通表单
• multipart/form-data 数据里有文件
• application/json 数据是个json

之后还要加上 charset=utf-8

POST Json例子

    public void postJson(){
        //获得一个FormBody表单
        RequestBody requestBody=RequestBody.
                create(MediaType.parse(
                        "application/json;charset=utf-8"),"{Json字符串}");
        //2.构造Request
        Request.Builder builder=new Request.Builder();
        Request request=builder.url("http://www.imooc.com/").post(requestBody).build();
        // 3、将Request封装为Call
        executeRequest(request);
    }

POST 上传一个图片

    public void postFile(){

        File file=new File(Environment.getExternalStorageDirectory(),"banana.jpg");
        if (!file.exists()){
            Log.e("-------","不存在");
            return;
        }

        //获得一个FormBody表单
        RequestBody requestBody=RequestBody.
                create(MediaType.parse(
                        "application/octet-stream; charset=utf-8"),file);
        //2.构造Request
        Request.Builder builder=new Request.Builder();
        Request request=builder.url("http://www.imooc.com/").post(requestBody).build();
        // 3、将Request封装为Call
        executeRequest(request);
    }

下载文件

    public void downloadFile(){
        Request.Builder builder=new Request.Builder();
        Request request=builder
                .get()
                .url("所要下载文件的文件路径")
                .build();

        Call call=okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                //失败以后的方法
                Log.e("----","失败以后的方法");
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                InputStream inputStream=response.body().byteStream();
                int len=0;
                File file=new File(Environment.getExternalStorageDirectory(), "zc.jpg");
                byte[] buf =new byte[128];
                FileOutputStream fos=new FileOutputStream(file);
                while ((len= inputStream.read(buf))!=-1){
                    fos.write(buf,0,len);
                }
                fos.flush();
                fos.close();
                inputStream.close();
            }
        });

下载图片并且设置

    //下载图片并且设置
    public void downloadSetImage(){
        Request.Builder builder=new Request.Builder();
        Request request=builder
                .get()
                .url("所要下载文件的文件路径")
                .build();

        Call call=okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                //失败以后的方法
                Log.e("----","失败以后的方法");
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                InputStream inputStream=response.body().byteStream();
                final Bitmap bitmap= BitmapFactory.decodeStream(inputStream);
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        mImageView.setImageBitmap(bitmap);
                    }
                });
            }
        });
    }