Android-Okhttp的使用解析

okhttp是Android6.0推出的网络框架。由于谷歌在Android6.0的之后，将HttpClient相关属性取消掉，导致Volley框架不能正常使用。所以才有了今天的Okhttp。

Okhttp进行网络访问通常有两种方式，一种是get请求，还有一种叫做post请求。

1、OKhttp的get请求

通常，我们使用get方式来请求一个网站，是依靠url地址的。Okhttp使用get方式来请求网站通常有如下的步骤：

A、创建OkhttpClient的变量，这个变量相当于是一个全局的执行者。主要的网络操作是依靠它来进行的。

B、创建一个builder对象。

C、利用builder对象创建一个Request对象。

D、使用全局执行者来创建一个Call对象。

E、通过Call对象来进行网络连接。

public void doGet(View view)
  {
    Request.Builder builder = new Request.Builder();
    Request request = builder.get().url(urlString + "userName=pby&userPassword=123").build();
    Call newCall = mOkHttpClient.newCall(request);
    //newCall.execute()
    newCall.enqueue(new Callback() {
      @Override
      public void onFailure(Request request, IOException e) {
        L.e("失败了");
      }

      @Override
      public void onResponse(Response response) throws IOException {
        String string = response.body().string();
        L.e(string);
      }
    });
  }

2、Okhttp的Post请求

Post请求与get请求有些不一样。get请求主要的功能是从服务器上获取数据，而Post请求则是向服务器提交数据。

public void doPost(View view)
  {
    FormEncodingBuilder requestBodyBuilder = new FormEncodingBuilder();
    RequestBody requestBody = requestBodyBuilder.add("userName", "pby").add("userPassword", "123").build();
    Request.Builder builder = new Request.Builder();
    Request request = builder.url(urlString).post(requestBody).build();
    Call newCall = mOkHttpClient.newCall(request);
    executeCall(newCall);
  }

3、服务器端接收客户端传过来的字符串

客户端的代码：

public void doPostString(View view)
  {
    RequestBody requestBody = RequestBody.create(MediaType.parse("text/plain;charset = utf-8"), "{name = pby, password = 1234}");
    Request.Builder builder = new Request.Builder();
    Request request = builder.url(urlString + "doPostString").post(requestBody).build();
    Call newCall = mOkHttpClient.newCall(request);
    executeCall(newCall);
  }

服务器端的代码：

public String doPostString() throws IOException
  {
    HttpServletRequest request = ServletActionContext.getRequest();
    ServletInputStream inputStream = request.getInputStream();
    StringBuilder sb = new StringBuilder();
    int len = 0;
    byte []buff = new byte[1024];
    while((len = inputStream.read(buff)) != -1)
    {
      sb.append(new String(buff, 0, len));
    }
    System.out.println(sb.toString());
    return null;
  }

服务器端如果要接收客户端的数据，则需要接收request；如果服务器端想要给客户端传数据，则需要通过response来传递。

4、使用post方式进行文件的传输

客户端的代码

public void doPost(View view)
  {
    FormEncodingBuilder requestBodyBuilder = new FormEncodingBuilder();
    RequestBody requestBody = requestBodyBuilder.add("userName", "pby").add("userPassword", "123").build();
    Request.Builder builder = new Request.Builder();
    Request request = builder.url(urlString + "login").post(requestBody).build();
    Call newCall = mOkHttpClient.newCall(request);
    executeCall(newCall);
  }

关于选择文件的代码--抄袭网络上的代码，并不是自己写的

private void showFileChooser() {
    Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
    intent.setType("*/*");
    intent.addCategory(Intent.CATEGORY_OPENABLE);

    try {
      startActivityForResult( Intent.createChooser(intent, "Select a File to Upload"), 1);
    } catch (android.content.ActivityNotFoundException ex) {
      Toast.makeText(this, "Please install a File Manager.", Toast.LENGTH_SHORT).show();
    }
  }

  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch (requestCode) {
      case 1:
        if (resultCode == RESULT_OK) {
          // Get the Uri of the selected file
          Uri uri = data.getData();
          String path = FileUtils.getPath(this, uri);
          if(path != null)
          {
            postFile(path);
          }
        }
        break;
    }
    super.onActivityResult(requestCode, resultCode, data);
  }

在进行这个的操作的时候，一定要记住增加读和写的权限，否则会上传失败的。

服务器端的代码

public String doPostFile() throws IOException
  {
    HttpServletRequest request = ServletActionContext.getRequest();
    ServletInputStream inputStream = request.getInputStream();
    String dir = ServletActionContext.getServletContext().getRealPath("files");
    File file = new File(dir, "abc.jpg");
    FileOutputStream fos = new FileOutputStream(file);
    int len = 0;
    byte [] buff = new byte[1024];
    while((len = inputStream.read(buff)) != -1)
    {
      fos.write(buff, 0, len);
    }
    fos.flush();
    fos.close();
    return null;
  }

上面显示的files文件，在Tomcat的webapps下的工程名名文件下的fies文件夹（才开始是没有这个文件夹的，需要手动自己创建）。

5.使用Post方式来上传文件

客户端代码：

private void upLoadFile(String path)
  {
    File file = new File(path);
    if(!file.exists())
    {
      return ;
    }
    MultipartBuilder multipartBuilder = new MultipartBuilder();
    RequestBody requestBody = multipartBuilder.type(MultipartBuilder.FORM)
        .addFormDataPart("userName", "pby")
        .addFormDataPart("userPassword", "123")
        .addFormDataPart("mFile", file.getName(), RequestBody.create(MediaType.parse("application/octet-stream"), file)).build();
//    CountingRequestBody countingRequestBody = new CountingRequestBody(requestBody, new CountingRequestBody.MyListener() {
//      @Override
//      public void onRequestProgress(int byteWriteCount, int TotalCount) {
//        L.e(byteWriteCount + " / " + TotalCount);
//      }
//    });
    Request.Builder builder = new Request.Builder();
    //Request request = builder.url(urlString + "doUpLoadFile").post(countingRequestBody).build();
    Request request = builder.url(urlString + "doUpLoadFile").post(requestBody).build();
    Call newCall = mOkHttpClient.newCall(request);
    executeCall(newCall);
  }

服务器端的代码：

public String doUpLoadFile()
  {
    if(mFile == null)
    {
      System.out.println(mFileFileName+" is null..");
      return null;
    }
    String dir = ServletActionContext.getServletContext().getRealPath("files");
    File file = new File(dir, mFileFileName);
    try {
      FileUtils.copyFile(mFile, file);
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    return null;
  }

在上传文件的时候，有一个小细节都注意到：就是Tomcat服务器只允许上传2m以下的文件。要想上传大文件，就必须在struct文件中加一句：<constant name="struts.multipart.maxSize" value="1024000000"/>数字表示自定义大小的限制。

6.上传文件时，进度的显示问题

在写代码的时候我们知道，我们不能直接获得上传文件的进度。因为这些数据都是封装在RequestBody里面的，要想使用只有通过回调接口来实现。

package com.example.android_okhttp;

import com.squareup.okhttp.MediaType;
import com.squareup.okhttp.RequestBody;

import java.io.IOException;

import okio.Buffer;
import okio.BufferedSink;
import okio.ForwardingSink;
import okio.Okio;
import okio.Sink;

/**
 * Created by 前世诀别的一纸书 on 2017/3/5.
 */

public class CountingRequestBody extends RequestBody {
  private RequestBody delegate = null;
  private MyListener mListener= null;
  private CountingSink mCountSink = null;
  public interface MyListener
  {
    void onRequestProgress(int byteWriteCount, int TotalCount);
  }
  public CountingRequestBody(RequestBody requestBody, MyListener listener)
  {
    delegate = requestBody;
    mListener = listener;
  }
  @Override
  public MediaType contentType() {
    return delegate.contentType();
  }

  @Override
  public void writeTo(BufferedSink sink) throws IOException {
    mCountSink = new CountingSink(sink);
    BufferedSink bs = Okio.buffer(mCountSink);
    delegate.writeTo(bs);
    bs.flush();
  }
  private class CountingSink extends ForwardingSink{
    private int byteWriteCount = 0;
    public CountingSink(Sink delegate) {
      super(delegate);
    }

    @Override
    public void write(Buffer source, long byteCount) throws IOException {
      super.write(source, byteCount);
      byteWriteCount += byteCount;
      mListener.onRequestProgress(byteWriteCount, (int) contentLength());
    }
  }

  @Override
  public long contentLength() throws IOException {
    return delegate.contentLength();
  }
}

MultipartBuilder multipartBuilder = new MultipartBuilder();
    RequestBody requestBody = multipartBuilder.type(MultipartBuilder.FORM)
        .addFormDataPart("userName", "pby")
        .addFormDataPart("userPassword", "123")
        .addFormDataPart("mFile", file.getName(), RequestBody.create(MediaType.parse("application/octet-stream"), file)).build();
    CountingRequestBody countingRequestBody = new CountingRequestBody(requestBody, new CountingRequestBody.MyListener() {
      @Override
      public void onRequestProgress(int byteWriteCount, int TotalCount) {
        L.e(byteWriteCount + " / " + TotalCount);
      }
    });
    Request.Builder builder = new Request.Builder();
    Request request = builder.url(urlString + "doUpLoadFile").post(countingRequestBody).build();
    //Request request = builder.url(urlString + "doUpLoadFile").post(requestBody).build();
    Call newCall = mOkHttpClient.newCall(request);

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