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:

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

tools:context=".MainActivity">

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" />

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="下载"

android:onClick="click"/>

android:id="@+id/progressBar"

style="?android:attr/progressBarStyleHorizontal"

android:layout_width="match_parent"

android:layout_height="wrap_content" />

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() {

@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(){}；<>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：

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