okhttp

Android为我们提供了两种HTTP交互的方式：HttpURLConnection 和 Apache HTTP Client，虽然两者都支持HTTPS，流的上传和下载，配置超时，IPv6和连接池，已足够满足我们各种HTTP请求的需求。但更高效的HTTP请求可以让您的应用运行更快、更节省流量。而OkHttp库就是为此而生，并且google已不推荐使用HTTP Client，而原生的HttpURLConnection使用太繁琐。

OKhttp优点：

1 如果服务器配置了多个IP地址，当第一个IP连接失败的时候，OkHttp会自动尝试下一个IP
2 使用 OkHttp 无需重写程序中的网络代码，OkHttp实现了几乎和java.net.HttpURLConnection一样的API。
3 支持异步请求 案例一：发送get请求

package com.qf.day28;import okhttp3.OkHttpClient;import okhttp3.Request;import okhttp3.Response;/** * 使用OkHttp实现get请求 * @author wgy * */public class OkHttpDemo1 {public static void main(String[] args) throws Exception {//1创建OkHttpClient对象OkHttpClient client=new OkHttpClient();//2创建请求Request request=new Request.Builder().url("http://10.0.161.117:8080/Day27Web/MyServlet").build();//3创建响应对象Response response=client.newCall(request).execute();//4处理响应if(response.code()==200){System.out.println(response.body().string());}}}

案例二：发送post请求

package com.qf.day28;import java.io.IOException;import okhttp3.FormBody;import okhttp3.MediaType;import okhttp3.OkHttpClient;import okhttp3.Request;import okhttp3.RequestBody;import okhttp3.Response;import okio.BufferedSink;/** * 使用OkHttp实现Post请求 * @author wgy * */public class OkHttpDemo2 {public static void main(String[] args) throws Exception {//1创建OkHttpClient对象OkHttpClient client=new OkHttpClient();//2创建表单体(默认编码是utf-8)FormBody body=new FormBody.Builder().add("username", "张三2").add("pwd", "123456").build();//3创建请求对象Request request=new Request.Builder().url("http://10.0.161.117:8080/Day27Web/LoginServlet").post(body).build();//4创建响应对象Response response=client.newCall(request).execute();if(response.code()==200){System.out.println(response.body().string());}}}

案例三：下载文件

package com.qf.day28;import java.io.FileOutputStream;import java.io.InputStream;import okhttp3.OkHttpClient;import okhttp3.Request;import okhttp3.Response;/** * 使用OkHttp实现文件下载 *  * @author wgy *  */public class OkHttpDemo3 {public static void main(String[] args) throws Exception{// 1创建OkHttpClientOkHttpClient client = new OkHttpClient();// 2创建请求对象Request request = new Request.Builder().url("http://10.0.161.117:8080/Day27Web/2.jpg").build();//3创建响应对象Response response=client.newCall(request).execute();//4处理响应if(response.code()==200){//获取流对象InputStream is=response.body().byteStream();FileOutputStream fos=new FileOutputStream("d:\\haha.jpg");byte[] buf=new  byte[1024];int len=0;while((len=is.read(buf))!=-1){fos.write(buf, 0, len);}is.close();fos.close();System.out.println("下载完毕");}}}

案例四：使用多线程下载文件

package com.qf.Task3;import java.io.InputStream;import java.io.RandomAccessFile;import okhttp3.OkHttpClient;import okhttp3.Request;import okhttp3.Response;public class OkHttpDownload {public static void main(String[] args) throws Exception{String urlString = "http://localhost:8080/Day27Web/java.pdf";String filePath = "d:\\java.pdf";OkHttpClient client = new OkHttpClient();Request request = new Request.Builder().url(urlString).build();Response response = client.newCall(request).execute();if (response.code()==200) {long length =response.body().contentLength();//System.out.println(length);int sublen = (int) (length%4==0?length/4:length/4+1);int lastlen = (int) (length-sublen);downloadThread d1 = new downloadThread(0*sublen,sublen,urlString,filePath);downloadThread d2 = new downloadThread(1*sublen,sublen,urlString,filePath);downloadThread d3 = new downloadThread(2*sublen,sublen,urlString,filePath);downloadThread d4 = new downloadThread(3*sublen,lastlen,urlString,filePath);d1.start();d2.start();d3.start();d4.start();}}}class downloadThread extends Thread {private int skipCount;//跳过字节数private int length;//下载长度private String urlString;//服务器地址private String filePath;//所存放的路径public downloadThread(int skipCount,int lentgth,String urlString,String filePath) {// TODO Auto-generated constructor stubthis.skipCount = skipCount;this.length = lentgth;this.urlString = urlString;this.filePath = filePath;}@Overridepublic void run() {// TODO Auto-generated method stubtry {OkHttpClient client = new OkHttpClient();Request request = new Request.Builder().url(urlString).addHeader("Range", "bytes="+skipCount+"-"+(skipCount+length-1)).build();Response response = client.newCall(request).execute();//System.out.println(response.code());if (response.code()==206) {System.out.println(Thread.currentThread().getName()+"开始下载");InputStream is =response.body().byteStream();RandomAccessFile raf = new RandomAccessFile(filePath,"rw");raf.seek(skipCount);byte[] buf = new byte[1024*4];int len =0;while((len = is.read(buf))!=-1){raf.write(buf,0,len);}is.close();raf.close();System.out.println(Thread.currentThread().getName()+"下载完成");}} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}}