Android——通过okhttp进行文件下载

ifest：

xml：

activity：

package com.example.myapplication;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;import android.os.Environment;import android.view.View;import android.widget.ImageView;import android.widget.TextView;import androidx.appcompat.app.AppCompatActivity;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import okhttp3.Call;import okhttp3.Callback;import okhttp3.OkHttpClient;import okhttp3.Request;import okhttp3.Response;public class MainActivity extends AppCompatActivity{    private final static String TAG = "OkhttpDownloadActivity";    private final static String URL_IMAGE = "https://img-blog.csdnimg.cn/2018112123554364.png";    private final static String URL_MP4 = "https://ptgl.fujian.gov.cn:8088/masvod/public/2021/03/19/20210319_178498bcae9_r38.mp4";    private TextView tv_result; // 声明一个文本视图对象    private TextView tv_progress; // 声明一个文本视图对象    private ImageView iv_result; // 声明一个图像视图对象    @Override    protected void onCreate(Bundle savedInstanceState)    {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        tv_result = findViewById(R.id.tv_result);        tv_progress = findViewById(R.id.tv_progress);        iv_result = findViewById(R.id.iv_result);        findViewById(R.id.btn_download_image).setOnClickListener(v -> downloadImage());        findViewById(R.id.btn_download_file).setOnClickListener(v -> downloadFile());    }    // 下载网络图片    private void downloadImage()    {        tv_progress.setVisibility(View.GONE);        iv_result.setVisibility(View.VISIBLE);        OkHttpClient client = new OkHttpClient(); // 创建一个okhttp客户端对象        // 创建一个GET方式的请求结构        Request request = new Request.Builder().url(URL_IMAGE).build();        Call call = client.newCall(request); // 根据请求结构创建调用对象        // 加入HTTP请求队列。异步调用，并设置接口应答的回调方法        call.enqueue(new Callback() {            @Override            public void onFailure(Call call, IOException e) { // 请求失败                // 回到主线程操纵界面                runOnUiThread(() -> tv_result.setText("下载网络图片报错："+e.getMessage()));            }            @Override            public void onResponse(Call call, final Response response) { // 请求成功                InputStream is = response.body().byteStream();                // 从返回的输入流中解码获得位图数据                Bitmap bitmap = BitmapFactory.decodeStream(is);                String mediaType = response.body().contentType().toString();                long length = response.body().contentLength();                String desc = String.format("文件类型为%s，文件大小为%d", mediaType, length);                // 回到主线程操纵界面                runOnUiThread(() -> {                    tv_result.setText("下载网络图片返回："+desc);                    iv_result.setImageBitmap(bitmap);                });            }        });    }    // 下载网络文件    private void downloadFile()    {        tv_progress.setVisibility(View.VISIBLE);        iv_result.setVisibility(View.GONE);        OkHttpClient client = new OkHttpClient(); // 创建一个okhttp客户端对象        // 创建一个GET方式的请求结构        Request request = new Request.Builder().url(URL_MP4).build();        Call call = client.newCall(request); // 根据请求结构创建调用对象        // 加入HTTP请求队列。异步调用，并设置接口应答的回调方法        call.enqueue(new Callback() {            @Override            public void onFailure(Call call, IOException e) { // 请求失败                // 回到主线程操纵界面                runOnUiThread(() -> tv_result.setText("下载网络文件报错："+e.getMessage()));            }            @Override            public void onResponse(Call call, final Response response) { // 请求成功                String mediaType = response.body().contentType().toString();                long length = response.body().contentLength();                String desc = String.format("文件类型为%s，文件大小为%d", mediaType, length);                // 回到主线程操纵界面                runOnUiThread(() -> tv_result.setText("下载网络文件返回："+desc));                String path = String.format("%s/%s.mp4",                        getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).toString(),                        DateUtil.getNowDateTime());                // 下面从返回的输入流中读取字节数据并保存为本地文件                try (InputStream is = response.body().byteStream();                     FileOutputStream fos = new FileOutputStream(path)) {                    byte[] buf = new byte[100 * 1024];                    int sum=0, len=0;                    while ((len = is.read(buf)) != -1) {                        fos.write(buf, 0, len);                        sum += len;                        int progress = (int) (sum * 1.0f / length * 100);                        String detail = String.format("文件保存在%s。已下载%d%%", path, progress);                        // 回到主线程操纵界面                        runOnUiThread(() -> tv_progress.setText(detail));                    }                } catch (Exception e) {                    e.printStackTrace();                }            }        });    }}