概述：
okhttp是一个网络框架，非常厉害的网络框架。要使用okhttp，Android Stuido只需在gradle文件中添加依赖就可以了。代码：
compile 'com.squareup.okhttp3:okhttp:3.4.2'
接下来看使用：
public class MainActivity extends AppCompatActivity { private OkHttpClient okHttpClient ; private ImageView imageView ; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView( R.layout.mainactivity); imageView = (ImageView) findViewById( R.id.img ) ; okHttpClient = new OkHttpClient() ; } /** * 同步 * @param view */ public void executeMathed(View view) { final Request request = new Request.Builder().url("http://wwww.baidu.com").get().build() ; new Thread( new Runnable() { @Override public void run() { try { Response response = okHttpClient.newCall( request ).execute() ; String str = response.body().string() ; System.out.println("数据："+ str ); } catch (IOException e) { e.printStackTrace(); } } }).start(); } /** * 异步 * @param view */ public void enquenecMthed(View view) { final Request request = new Request.Builder().url("http://www.baidu.com").get().build() ; okHttpClient.newCall( request ).enqueue( new Callback() { /** * 失败的时候调用 * @param call * @param e */ @Override public void onFailure(Call call , IOException e) { System.out.println("数据请求失败"); } /** * 成功的时候调用 * @param call * @param response * @throws IOException */ @Override public void onResponse(Call call, Response response) throws IOException { System.out.println("数据请求成功"); System.out.println("数据："+ response.body().string()); } }); } /** * get请求 * @param view */ public void sendParams(View view) { final Request request = new Request.Builder() .url("https://raw.githubusercontent.com/square/okhttp/master/samples/guide/src/main/java/okhttp3/guide/GetExample.java") .get() .build(); okHttpClient.newCall(request).enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { } @Override public void onResponse(Call call, Response response) throws IOException { //response.body().string();这个方法只能被调用一次 String str = response.body().string(); System.out.println("shangyici:"+str); //下面这句话打印是空的 System.out.println("java:"+response.body().string()); } }); } /** * post请求 * @param view */ public void sendParamsPost(View view) { String urlparams = "http://www.tngou.net/api/lore/list"; //？ & 这写符号自给我们加上（不用我们担心） FormBody formBody = new FormBody.Builder() .add("page","2") .add("rows","5") .build() ; //创建请求 Request request = new Request.Builder() .post(formBody) .url(urlparams) .build(); okHttpClient.newCall( request ).enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { } @Override public void onResponse(Call call, Response response) throws IOException { System.out.println( response.body().string()); } }); } /** * 上传文件 * @param view */ public void uploadFile(View view) { //第一步 需要一个文件对象（需要上传的文件） File file = new File( Environment.getExternalStoragePublicDirectory( Environment.DIRECTORY_DOWNLOADS ),"privatekey.sys" ) ; //第二步:构建一个Multipartbody对象 MultipartBody.Builder mrb = new MultipartBody.Builder() ; //设置上传协议格式 mrb.setType( MultipartBody.FORM ) ; //第三步:创建一个ReqequstBody对象 RequestBody requestBody = RequestBody.create( MediaType.parse( "text/html" ) , file ) ; //为表单添加数据 mrb.addFormDataPart( "file" //form表单里面的key值 ,"XIAOY"//服务器上保存的名字 ,requestBody//设置请求体 ); final Request request = new Request.Builder() .url("http://10.3.135.81:10000/file/upload")//服务器的IP和端口号 .post( mrb.build() ) .build(); okHttpClient.newCall(request).enqueue(new Callback() { @Override public void onFailure(Call call , IOException e) { e.printStackTrace() ; } @Override public void onResponse(Call call, Response response) throws IOException { System.out.println("返回的是服务器文件在服务器上的完整路径："+ response.body().string() ) ; } }); } /** * 下载文件 * @param view */ public void downloadFile(View view) { Request request = new Request.Builder() .url("http://i.ce.cn/ent/news/201610/25/W020161025327194695250.jpg ") .get() .build(); okHttpClient.newCall(request).enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { } @Override public void onResponse( Call call , Response response) throws IOException { final ByteArrayOutputStream bos = new ByteArrayOutputStream() ; InputStream ins = response.body().byteStream() ; int len = -1 ; byte[] bytes = new byte[1024] ; while ((len=ins.read(bytes)) != -1){ //一次读取多少就写多少 bos.write( bytes , 0 , len ) ; } ins.close() ; runOnUiThread( new Runnable() { @Override public void run() { imageView.setImageBitmap(BitmapFactory.decodeByteArray( bos.toByteArray() , 0 , bos.toByteArray().length )); Toast.makeText(MainActivity.this,"下载完成",Toast.LENGTH_SHORT).show(); } }); } }); } }XML
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <Button android:onClick="executeMathed" android:text="OkHttp同步方法" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <Button android:onClick="enquenecMthed" android:text="OkHttp异步方法" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <Button android:text="okHttp传递参数" android:onClick="sendParams" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <Button android:text="okHttp传递参数之Post" android:onClick="sendParamsPost" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <Button android:text="okHttp上传文件" android:onClick="uploadFile" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <Button android:onClick="downloadFile" android:text="下载文件" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <ImageView android:id="@+id/img" android:layout_width="130sp" android:layout_height="130dp"/> </LinearLayout>这是非常简单的用法，高级用法，本人也不会，以后继续学习了在更新。