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);

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。