下载进度条 加百分比

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout 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"
    tools:context=".MainActivity">

    <Button

             android:text="显示通知"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:id="@+id/button"
             android:onClick="show1" />
</RelativeLayout>

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
package com.example.text;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.AppOpsManager;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Build;
import android.os.SystemClock;
import android.provider.Settings;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.SimpleDateFormat;
import java.util.Date;


public class MainActivity extends AppCompatActivity {

    private NotificationManager manager;
    Notification.Builder builder;
    //设置日期格式
    private SimpleDateFormat sdf=new SimpleDateFormat("HH:mm:ss");
    private Button button;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = findViewById(R.id.button);
    }

//    private void requestPermission() {
//        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.BASE) {
//            // 进入设置系统应用权限界面
//            Intent intent = new Intent(Settings.ACTION_SETTINGS);
//            startActivity(intent);
//            return;
//        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {// 运行系统在5.x环境使用
//            // 进入设置系统应用权限界面
//            Intent intent = new Intent(Settings.ACTION_SETTINGS);
//            startActivity(intent);
//            return;
//        }
//        return;
//    }


    public void show1(View v){
        manager=(NotificationManager)getSystemService(NOTIFICATION_SERVICE);
        builder=new Notification.Builder(this);
        builder.setTicker("文件开始下载");
        builder.setSmallIcon(R.mipmap.ic_launcher);
        builder.setContentTitle("文件下载");
        builder.setContentText("文件正在下载中......");
        builder.setWhen(SystemClock.currentThreadTimeMillis());
        builder.setDefaults(Notification.DEFAULT_LIGHTS);//消息提示模式
        builder.setProgress(100,0,false);

        //模拟正在执行下载
        new Thread(new Runnable() {
            @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
            @Override
            public void run() {

                for (int i=1;i<=100;i++){
                    builder.setProgress(100, i, false);
                        if(i==100){
                            builder.setProgress(0, 0,false );
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                button.setText("下载完毕");
                            }
                        });
                    }

                    final int finalI = i;
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            if(finalI%3==1){
                                builder.setContentText("文件下载中.                  "+ finalI+"%");
                            }else if(finalI%3==2){
                                builder.setContentText("文件下载中..                 "+ finalI+"%");
                            }else{
                                builder.setContentText("文件下载中...                "+ finalI+"%");
                            }
                            if(finalI==100){
                                builder.setContentText("文件下载完毕!");
                            }
                        }
                    });
                    manager.notify(1, builder.build());
                    SystemClock.sleep(300);
                }
                 //manager.cancel(1);
            }
        }).start();
    }
}