android自定义View实现图片上传进度显示（仿手机QQ上传效果）

From : http://www.android100.org/html/201506/02/150438.html 

首先看下我们想要实现的效果如下图（qq聊天中发送图片时的效果）：

再看一下我实现的效果：

1、效果已经看见了，下面我们来实现它。首先我创建一个android工程ProgressImageView。然后我们重写ImageView控件，创建ProcessImageView类代码如下：

package com.example.processimageview;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;

public class ProcessImageView extends ImageView {

    private Paint mPaint;// 画笔
    int width = 0;
    int height = 0;
    Context context = null;
    int progress = 0;

    public ProcessImageView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    public ProcessImageView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ProcessImageView(Context context, AttributeSet attrs,
            int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        this.context = context;
        mPaint = new Paint();
    }

    @SuppressLint("DrawAllocation")
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        mPaint.setAntiAlias(true); // 消除锯齿
        mPaint.setStyle(Paint.Style.FILL);
        

        mPaint.setColor(Color.parseColor("#70000000"));// 半透明
        canvas.drawRect(0, 0, getWidth(), getHeight()- getHeight() * progress
                / 100, mPaint);

        mPaint.setColor(Color.parseColor("#00000000"));// 全透明
        canvas.drawRect(0, getHeight() - getHeight() * progress / 100,
                getWidth(), getHeight(), mPaint);

        mPaint.setTextSize(30);
        mPaint.setColor(Color.parseColor("#FFFFFF"));
        mPaint.setStrokeWidth(2);
        Rect rect = new Rect();
        mPaint.getTextBounds("100%", 0, "100%".length(), rect);// 确定文字的宽度
        canvas.drawText(progress + "%", getWidth() / 2 - rect.width() / 2,
                getHeight() / 2, mPaint);

    }

    public void setProgress(int progress) {
        this.progress = progress;
        postInvalidate();
    };

}

2、将ProcessImageView控件加入activity_layout.xml布局文件中,代码如下;

 .example.processimageview.processimageview>

3、最后一步，显示效果(是不是很激动)，在MainActivity类加入显示进度条的ImageView，代码如下：

package com.example.processimageview;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Toast;

public class MainActivity extends Activity {

    ProcessImageView processImageView =null;
    private final int SUCCESS=0;
    int progress=0;
    
    Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
            case SUCCESS:
                Toast.makeText(MainActivity.this, "图片上传完成", Toast.LENGTH_SHORT).show();
                processImageView.setVisibility(View.GONE);
                break;
            }
        }
    };
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

      processImageView=(ProcessImageView) findViewById(R.id.image);
        //模拟图片上传进度
        new Thread(new Runnable() {
            @Override
            public void run() {
                 while (true){  
                     if(progress==100){//图片上传完成
                         handler.sendEmptyMessage(SUCCESS);
                         return;
                     }
                     progress++;
                     processImageView.setProgress(progress);
                    try{  
                        Thread.sleep(200);  //暂停0.2秒
                    } catch (InterruptedException e){  
                        e.printStackTrace();  
                    }  
                }  
            }
        }).start();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

4、编译运行，大功告成。