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okhttp是比较火的网络框架，它支持同步与异步请求，支持缓存，可以拦截，更方便下载大文件与上传文件的操作。下面我们用okhttp来下载文件并带进度条！
相关资料：
官网地址：
github源码地址：
一、服务器端简单搭建
可以参考搭建本地tomcat服务器及相关配置 这篇文章。
新建项目okhttpserver，在webcontent目录下新建downloadfile目录，将要下载的jpg文件放在项目下。如下图：
启动服务器，文件下载地址为http://localhost:8080/okhttpserver/download/2.jpg 。这样我们服务器就搭好了。
二、android端
下面我们进入正题。
1.build.gradle的dependencies配置如下
compile 'com.android.support:appcompat-v7:24.1.1' compile 'com.squareup.okhttp3:okhttp:3.2.0' compile 'com.squareup.okio:okio:1.7.0'
2.activity_main.xml
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<?xml version="1.0" encoding="utf-8"?>
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingbottom="@dimen/activity_vertical_margin"
android:paddingleft="@dimen/activity_horizontal_margin"
android:paddingright="@dimen/activity_horizontal_margin"
android:paddingtop="@dimen/activity_vertical_margin"
tools:context="com.huang.myokhttp.mainactivity">
<button
android:id="@+id/ok_download"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="下载文件" />
<textview
android:id="@+id/download_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="0" />
<progressbar
android:id="@+id/download_progress"
style="?android:attr/progressbarstylehorizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:max="100" />
</relativelayout>
3.编写okhttputil如下：
private static okhttpclient okhttpclient = new okhttpclient.builder().connecttimeout(10000, timeunit.milliseconds)
.readtimeout(10000,timeunit.milliseconds)
.writetimeout(10000,timeunit.milliseconds).build();
//下载文件方法
public static void downloadfile(string url, final progresslistener listener, callback callback){
//增加拦截器
okhttpclient client = okhttpclient.newbuilder().addnetworkinterceptor(new interceptor() {
@override
public response intercept(chain chain) throws ioexception {
response response = chain.proceed(chain.request());
return response.newbuilder().body(new progressresponsebody(response.body(),listener)).build();
}
}).build();
request request = new request.builder().url(url).build();
client.newcall(request).enqueue(callback);
}
4.上面代码中的progressresponsebody是自己编写的类，progresslistener 是监听的接口：
progresslistener 接口
public interface progresslistener {
//已完成的 总的文件长度 是否完成
void onprogress(long currentbytes, long contentlength, boolean done);
}
progressresponsebody继承responsebody ，返回监听进度
public class progressresponsebody extends responsebody {
public static final int update = 0x01;
public static final string tag = progressresponsebody.class.getname();
private responsebody responsebody;
private progresslistener mlistener;
private bufferedsource bufferedsource;
private handler myhandler;
public progressresponsebody(responsebody body, progresslistener listener) {
responsebody = body;
mlistener = listener;
if (myhandler==null){
myhandler = new myhandler();
}
}
/**
* 将进度放到主线程中显示
*/
class myhandler extends handler {
public myhandler() {
super(looper.getmainlooper());
}
@override
public void handlemessage(message msg) {
switch (msg.what){
case update:
progressmodel progressmodel = (progressmodel) msg.obj;
//接口返回
if (mlistener!=null)mlistener.onprogress(progressmodel.getcurrentbytes(),progressmodel.getcontentlength(),progressmodel.isdone());
break;
}
}
}
@override
public mediatype contenttype() {
return responsebody.contenttype();
}
@override
public long contentlength() {
return responsebody.contentlength();
}
@override
public bufferedsource source() {
if (bufferedsource==null){
bufferedsource = okio.buffer(mysource(responsebody.source()));
}
return bufferedsource;
}
private source mysource(source source) {
return new forwardingsource(source) {
long totalbytesread = 0l;
@override
public long read(buffer sink, long bytecount) throws ioexception {
long bytesread = super.read(sink, bytecount);
totalbytesread +=bytesread!=-1?bytesread:0;
//发送消息到主线程，progressmodel为自定义实体类
message msg = message.obtain();
msg.what = update;
msg.obj = new progressmodel(totalbytesread,contentlength(),totalbytesread==contentlength());
myhandler.sendmessage(msg);
return bytesread;
}
};
}
}
5.mainactivity的代码：
public class mainactivity extends appcompatactivity implements view.onclicklistener{
public static final string tag = mainactivity.class.getname();
private progressbar download_progress;
private textview download_text;
public static string basepath = environment.getexternalstoragedirectory().getabsolutepath() + "/okhttp";
@override
protected void oncreate(bundle savedinstancestate) {
super.oncreate(savedinstancestate);
setcontentview(r.layout.activity_main);
download_progress = (progressbar) findviewbyid(r.id.download_progress);
download_text = (textview) findviewbyid(r.id.download_text);
findviewbyid(r.id.ok_download).setonclicklistener(this);
}
@override
public void onclick(view view) {
switch (view.getid()){
case r.id.ok_download:
string url = "http://192.168.0.104:8080/okhttpserver/download/2.jpg";
final string filename = url.split("/")[url.split("/").length - 1];
log.i(tag, "filename==" + filename);
okhttputil.downloadfile(url, new progresslistener() {
@override
public void onprogress(long currentbytes, long contentlength, boolean done) {
log.i(tag, "currentbytes==" + currentbytes + "==contentlength==" + contentlength + "==done==" + done);
int progress = (int) (currentbytes * 100 / contentlength);
download_progress.setprogress(progress);
download_text.settext(progress + "%");
}
}, new callback() {
@override
public void onfailure(call call, ioexception e) {
}
@override
public void onresponse(call call, response response) throws ioexception {
if (response != null) {
inputstream is = response.body().bytestream();
fileoutputstream fos = new fileoutputstream(new file(basepath + "/" + filename));
int len = 0;
byte[] buffer = new byte[2048];
while (-1 != (len = is.read(buffer))) {
fos.write(buffer, 0, len);
}
fos.flush();
fos.close();
is.close();
}
}
});
break;
}
}
}
6.最后不要忘了添加权限：
<uses-permission android:name="android.permission.internet"/> <uses-permission android:name="android.permission.write_external_storage"/> <uses-permission android:name="android.permission.read_external_storage"/>
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