android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" />