安卓学习----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;
            }
        }
    };

    /**
     * 初始化 组件
     */
    private void initView() {

        mIv = (ImageView) findViewById(R.id.main_iv);
    }

    /**
     * 点击获取图片
     */
    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;

/**
 * Created by 刘楠 on 2016-03-27.
 */
public class OkHttpUtils {

    OkHttpClient client = new OkHttpClient();

    /**
     * 获取流
     * @param url  请求地址
     * @return  输入流
     */
    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;

    }

    /**
     * 返回字符串
     * @param url
     * @return   返回字符串
     * @throws IOException
     */
  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();

    }

}

get方式