Android使用okHttp(get方式)下载图片

一、首先下载Jar包

https://github.com/square/okhttp 

如果使用android studio只需要加入依赖compile 'com.squareup.okhttp3:okhttp:3.2.0'  

二、下载一张图片并显示
使用的是hanlder的方式 

package com.liunan.okhttpdemo2;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.IOException;
import java.io.InputStream;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
public class MainActivity extends AppCompatActivity {
 private static final int ERROR = 1;
 private static final int SUCCESS = 2 ;
 private String url = "http://192.168.1.102:8080/img/a.jpg";
 private ImageView mIv;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 initView();
 }
 private Handler handler = new Handler(){
 @Override
 public void handleMessage(Message msg) {
  switch (msg.what){
  case SUCCESS:
   mIv.setImageBitmap((Bitmap) msg.obj);
   break;
  case ERROR:
   Toast.makeText(MainActivity.this, "请求超时", Toast.LENGTH_SHORT).show();
   break;
  }
 }
 };
 
 private void initView() {
 mIv = (ImageView) findViewById(R.id.main_iv);
 }
 
 public void getPic(View v){
 new Thread(){
  @Override
  public void run() {
  //获取okHttp对象get请求,
  try {
   OkHttpClient client = new OkHttpClient();
   //获取请求对象
   Request request = new Request.Builder().url(url).build();
   //获取响应体
   ResponseBody body = client.newCall(request).execute().body();
   //获取流
   InputStream in = body.byteStream();
   //转化为bitmap
   Bitmap bitmap = BitmapFactory.decodeStream(in);
   //使用Hanlder发送消息
   Message msg = Message.obtain();
   msg.what = SUCCESS;
   msg.obj = bitmap;
   handler.sendMessage(msg);
  } catch (IOException e) {
   e.printStackTrace();
   //失败
   Message msg = Message.obtain();
   msg.what = ERROR;
   handler.sendMessage(msg);
  }
  }
 }.start();
 }
}

也可以把网络请求写为一个工具类, 

package com.liunan.okhttpdemo2;
import java.io.IOException;
import java.io.InputStream;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class OkHttpUtils {
 OkHttpClient client = new OkHttpClient();
 
 public InputStream getInpuStream(String url) throws IOException {
 //设置 请求
 Request request = new Request.Builder()
  .url(url).build();
 //获取行响应
 InputStream in = client.newCall(request).execute().body().byteStream();
 return in;
 }
 
 public String getString(String url) throws IOException {
 //设置 请求
 Request request = new Request.Builder()
  .url(url).build();
 //获取行响应
 Response response = client.newCall(request).execute();
 return response.body().string();
 }
}

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