Android 断点下载和自动安装的示例代码

今天说一下Android中下载App到手机中并自动安装，啥也不说了先上效果图了！

上面呢是下载中的一个图片和下载后会自动提示你安装的一个图片，二话不说，这接开代码吧！

首先来一个下布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  tools:context="zhangtao.bwie.com.continutransform.MainActivity">
  <ProgressBar
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/progress"
    style="?android:attr/progressBarStyleHorizontal"
    android:max="100"
    />
  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:textSize="22sp"
    android:text=""
    android:id="@+id/pro_text"
    android:layout_below="@id/progress"
    />
  <Button
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/start_btn"
    android:text="开始下载"
    android:layout_below="@id/pro_text"
    />
  <Button
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/stop_btn"
    android:text="停止下载"
    android:layout_below="@id/start_btn"
    />
</RelativeLayout>

布局随便写了，只要是你想要的布局

然后我么来一个接口，用来帮助我么将要写的下载工具类传输数据的：

package Download;
public interface DownloadListener {
  void startDownload();
  void stopDownload();
  void finishDownload();
  void downloadProgress(long progress);
} 

这个接口写了4个接口方法，分别是开始下载、停止下载、完成下载以及下载是的进度。

接下来就是写下载工具类了，下载呢就使用OkHttp进行请求网络数据了，这里把这个工具类写成单利模式，方便使用！

package Download;
import android.text.TextUtils;
import android.util.Log;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
public class DownloadUtils {
  private static volatile DownloadUtils instance;
  private final OkHttpClient client;
  private DownloadListener mlistener;
  private File file;
  private String fileAbsolutePath;
  public File downloadFile;
  private long startPosition;
  private Call call; 

  public DownloadUtils() {
    client = new OkHttpClient();
  }
  public void setListener(DownloadListener listener) {
    this.mlistener = listener;
  } 

  /**
   * 初始化下载父路径
   * @return
   */
  public void initDownload(String path) {
    file = new File(path);
    if(!file.getParentFile().exists()) {
      file.getParentFile().mkdir();
    }
    if(!file.exists()) {
      try {
        file.createNewFile();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    fileAbsolutePath = file.getAbsolutePath();
    Log.d("zzz",fileAbsolutePath.toString());
  }
  public static DownloadUtils getInstance() {
    if(instance == null) {
      synchronized (DownloadUtils.class) {
        if(instance == null) {
          instance = new DownloadUtils();
        }
      }
    }
      return instance;
  }
  public void startDownload(String url) {
    if(TextUtils.isEmpty(url)) {
      return ;
    }
    if(url.contains(".")) {
      String typename = url.substring(url.lastIndexOf(".") + 1);
      if(url.contains("/")) {
        String filename = url.substring(url.lastIndexOf("/") + 1, url.lastIndexOf("."));
        String fn = filename+"."+typename;
        downloadFile = new File(this.file, fn);
        Log.d("zzz","downloadFile"+downloadFile.toString());
      }
    }
    startPosition = 0;
    if(downloadFile.exists()) {
      startPosition = downloadFile.length();
    }
    final Request request = new Request.Builder()
        .addHeader("RANGE","bytes="+startPosition+"-")
        .url(url)
        .build();
    call = client.newCall(request);
    call.enqueue(new Callback() {
      @Override
      public void onFailure(Call call, IOException e) { 

      }
      @Override
      public void onResponse(Call call, Response response) throws IOException {
        mlistener.startDownload();
        ResponseBody body = response.body();
//        startPosition
        long totalLength = body.contentLength() ;
        Log.d("zzz", "totalLength: " + totalLength + "----");
        InputStream is = body.byteStream();
        byte[] bytes = new byte[2048];
        int len = 0;
        long totalNum = startPosition;
        RandomAccessFile raf = new RandomAccessFile(downloadFile, "rw");
        while ((len = is.read(bytes,0,bytes.length)) != -1) {
          raf.seek(totalNum);
          raf.write(bytes,0,len);
          totalNum +=len;
          mlistener.downloadProgress(totalNum * 100 / totalLength); 

        }
         mlistener.finishDownload();
         body.close();
      }
    });
  }
  public void stopDownload() {
    mlistener.startDownload();
    if(call != null && call.isExecuted()) {
      call.cancel();
    }
  }
}

这里做断点下载是使用了RandomAccessFile,大家可以网上去了解一下RandomAccessFile的作用。

下面是主界面的功能实现和调用，基本就是些获取控件和调用刚才写好的工具类：

package zhangtao.bwie.com.continutransform;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import java.io.File;
import Download.DownloadListener;
import Download.DownloadUtils;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
  private TextView pro_text;
  private Button start_btn;
  private Button stop_btn;
  private String downloadUrl = "http://d.988wan.com/zft/qmzft32_988wan_01.apk";
  private String path = "/ZhangTao/";
  private ProgressBar pro_bar;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initView();
    setOnClick();
    if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
      File storageDirectory = Environment.getExternalStorageDirectory();
      final String absolutePath = storageDirectory.getAbsolutePath();
      path = absolutePath + path;
      DownloadUtils.getInstance().initDownload(path);
      DownloadUtils.getInstance().setListener(new DownloadListener() {
        @Override
        public void startDownload() { 

        }
        @Override
        public void stopDownload() {
        }
        @Override
        public void finishDownload() {
          File downloadFile = DownloadUtils.getInstance().downloadFile;
          installApk(downloadFile);
        }
        @Override
        public void downloadProgress(final long progress) {
          runOnUiThread(new Runnable() {
            @Override
            public void run() {
              pro_bar.setProgress((int) progress);
              pro_text.setText(progress+"%");
            }
          });
        }
      });
    }
  } 

  private void initView() {
    pro_text = (TextView) findViewById(R.id.pro_text);
    start_btn = (Button) findViewById(R.id.start_btn);
    stop_btn = (Button) findViewById(R.id.stop_btn);
    pro_bar = (ProgressBar) findViewById(R.id.progress);
  }
  private void setOnClick() {
    start_btn.setOnClickListener(this);
    stop_btn.setOnClickListener(this);
  }
  @Override
  public void onClick(View view) {
    switch (view.getId()) {
      case R.id.start_btn:
        DownloadUtils.getInstance().startDownload(downloadUrl);
        break;
      case R.id.stop_btn:
        DownloadUtils.getInstance().stopDownload();
        break;
    }
  }
  /**
   * 安装apk
   * @param file
   */
  private void installApk(File file) {
    Intent intent = new Intent();
    intent.setAction(Intent.ACTION_VIEW);
    intent.addCategory("android.intent.category.DEFAULT");
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
    startActivity(intent);
    android.os.Process.killProcess(android.os.Process.myPid());
  }
} 

上面的自动安装是installApk这个方法，这个没必要去了解太多，都是Android的一个固定方法，一般网上都会有的，希望可以帮到大家！

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。

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