使用开源项目xutils3完成下载

上一次自己写了一个多线程断点续传下载的demo，过于麻烦，bug超多，所以我学习使用xutils来完成此功能。

先将xutils依赖搭建好（上一篇博客已经具体写了方法）

先看看效果图：

下面开始代码的逻辑：

在xutils3以前使用HttpUtils新建对象即可使用，3以后取消了HttpUtils，具体方法请看代码。

首先创建布局activity_main.xml:

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical"
     tools:context=".MainActivity">

     <EditText
         android:id="@+id/et_path"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:hint="请输入下载路径"
         android:text="http://10.173.29.234/gp.apk" />

     <Button
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="下载"
         android:onClick="click"/>

     <ProgressBar
         android:id="@+id/progressBar"
         style="?android:attr/progressBarStyleHorizontal"
         android:layout_width="match_parent"
         android:layout_height="wrap_content" />

 </LinearLayout>

然后MainActivity.java:

 import android.app.Activity;
 import android.content.pm.PackageManager;
 import android.support.v4.app.ActivityCompat;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.EditText;
 import android.widget.ProgressBar;
 import android.widget.Toast;

 import org.xutils.common.Callback;
 import org.xutils.http.RequestParams;
 import org.xutils.x;

 import java.io.File;

 public class MainActivity extends AppCompatActivity {

     private EditText et_path;
     private ProgressBar pb;
     //动态获取权限
     private static final int REQUEST_EXTERNAL_STORAGE = 1;
     private static String[] PERMISSIONS_STORAGE = {
             "android.permission.READ_EXTERNAL_STORAGE",
             "android.permission.WRITE_EXTERNAL_STORAGE" };
     private String fileName;
     private String appName;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         //动态获取权限
         verifyStoragePermissions(this);

         x.view().inject(this);

         et_path = findViewById(R.id.et_path);
         pb = findViewById(R.id.progressBar);

     }

     //点击按钮下载（断点续传）
     public void click(View view) {

         //拿到路径
         String path = et_path.getText().toString().trim();
         fileName = getFileName(path);
         RequestParams params = new RequestParams(path);
         params.setSaveFilePath(fileName);
         params.setAutoRename(true);
         x.http().get(params, new Callback.ProgressCallback<File>() {

             @Override
             public void onWaiting() {

             }

             @Override
             public void onStarted() {

             }

             @Override
             public void onLoading(long total, long current, boolean isDownloading) {
                 //totle代表总进度，current代表当前进度
                 pb.setMax((int) total);
                 pb.setProgress((int) current);
                 System.out.println("测试1");

             }

             @Override
             public void onSuccess(File result) {
                 System.out.println("下载完成");
                 Toast.makeText(getApplicationContext(), "下载成功", Toast.LENGTH_SHORT).show();

             }

             @Override
             public void onError(Throwable ex, boolean isOnCallback) {
                 System.out.println("测试2");

             }

             @Override
             public void onCancelled(CancelledException cex) {
                 System.out.println("测试3");

             }

             @Override
             public void onFinished() {
                 System.out.println("测试4");

             }
         });

     }
     //动态获取权限
     public static void verifyStoragePermissions(Activity activity) {

         try {
             //检测是否有写的权限
             int permission = ActivityCompat.checkSelfPermission(activity,
                     "android.permission.WRITE_EXTERNAL_STORAGE");
             if (permission != PackageManager.PERMISSION_GRANTED) {
                 // 没有写的权限，去申请写的权限，会弹出对话框
                 ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,REQUEST_EXTERNAL_STORAGE);
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
     //获取文件名-->"http://10.173.29.234/test.exe"
     public String getFileName(String path) {
         int start = path.lastIndexOf("/") + 1;
         appName = path.substring(start);
 //        String fileName = Environment.getExternalStorageDirectory().getPath()+"/"+subString;
         String fileName = "/sdcard/file/"+ appName;
         return fileName;

     }
 }

第53行注意x.http().get(params, new Callback.ProgressCallback<File>(){}；<>中要写File，因为下载的是一个文件，否则文件不会下载下来。

还要加上权限：

  <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />