Android基础——高级UI组件

<?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=".MainActivity">

    <ProgressBar
        android:id="@+id/progressBar1"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="100"
        android:progress="50">
    </ProgressBar>

    <ProgressBar
        android:id="@+id/progressBar2"
        android:layout_below="@id/progressBar1"
        style="@android:style/Widget.ProgressBar.Horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="100"
        android:progress="70">
    </ProgressBar>

    //拖动条控制图片透明度
    <SeekBar
        android:layout_below="@id/progressBar2"
        android:id="@+id/seekbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="255"
        android:progress="110"
        />
    <ImageView
        android:layout_below="@id/seekbar"
        android:layout_marginTop="10dp"
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@mipmap/a"
        />


    <RatingBar
        android:id="@+id/ratingBar"
        android:layout_below="@id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:numStars="5"
        android:rating="2"
        android:stepSize="1"
        android:isIndicator="false"
        >
    </RatingBar>

</RelativeLayout>

package com.example.myhighui;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.RadioButton;
import android.widget.RatingBar;
import android.widget.SeekBar;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    /*
    * 安卓不支持在MainActivity中更新组件
    * 但是提供了Handler,通过这一对象可以同过发送消息来更新UI组件
    * */
    private ProgressBar progressBar = null;
    private int mProgress = 0;//用于记录进度
    private Handler mHandler = null;//用于处理消息

    private SeekBar seekBar = null;
    private ImageView imageView = null;

    RatingBar ratingBar = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        progressBar = (ProgressBar)findViewById(R.id.progressBar2);
        mHandler = new Handler(){
            @Override//处理收到的消息
            public void handleMessage(@NonNull Message msg) {
                if(msg.what == 0x111){//任务未完成，更新进度条
                    progressBar.setProgress(mProgress);
                }
                else {//任务完成，删掉进度条
                    Toast.makeText(MainActivity.this,
                            "操作已完成",Toast.LENGTH_SHORT);
                    progressBar.setVisibility(View.GONE);//进度条设置为不显示
                }
            }
        };

        //新建一个线程，执行耗时操作
        new Thread(new Runnable(){
            //模拟耗时操作
            private int doWork(){
                mProgress+=Math.random()*10;
                try {
                    Thread.sleep(200);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                return mProgress;
            }
            @Override
            public void run(){
                while(true){
                    mProgress = doWork();
                    Message message = new Message();
                    if(mProgress<100){//耗时操作未完成
                        message.what = 0x111;
                        mHandler.sendMessage(message);//给主线程发送消息
                    }
                    else {//耗时操作已经完成
                        message.what = 0x110;
                        mHandler.sendMessage(message);//给主线程发送消息
                        break;
                    }
                }
            }
        }).start();


        //用拖动条改变图片透明度
        imageView = findViewById(R.id.image);
        seekBar = findViewById(R.id.seekbar);
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                //imageView.setImageAlpha(progress);//修改图片透明度
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
            }
            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
            }
        });

        RatingBar ratingBar = (RatingBar)findViewById(R.id.ratingBar);
        String string = String.valueOf(ratingBar.getRating());
        //星级评分继承自进度条，所以可以调用
        String progress = String.valueOf(ratingBar.getProgress());
    }
}