Android组件之自定义上载进度条

我们都知道android中给我们提供了一个进度条组件ProgressDialog，可以满足我们平时使用，但是它是由缺陷的，我们查看它的源码就知道他是由一个ProgressBar和两个TextView组成的。使用的时候我们会发现他的progress是int类型的，但是当我们下载文件的时候文件的大小是按字节传过来的，此时我们需要将字节转换成K或M，这样就是一定是int类型了，我们需要传入一个double或float类型的数字，并且显示的时候我们希望他显示的是K或M。这样我们就需要自己定义一个组件来实现此功能，查看ProgressDialog的源码不难发现他继承自AlertDialog，经过对ProgressDialog的分析我们自己可以定义出一个自己的进度条，如下图

代码如下：

package com.fanyj.download;

import java.text.DecimalFormat;
import java.text.NumberFormat;

import android.app.AlertDialog;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.TextView;

public class ProgressBarDialog extends AlertDialog {

?private ProgressBar mProgress;
?private TextView mProgressNumber;
??? private TextView mProgressPercent;
???
??? public static final int M = 1024 * 1024;
??? public static final int K = 1024;
???
??? private double dMax;
??? private double dProgress;
???
??? private int middle = K;
???
??? private int prev = 0;
???
?private Handler mViewUpdateHandler;
?private static final NumberFormat nf = NumberFormat.getPercentInstance();
?private static final DecimalFormat df = new DecimalFormat("###.##");
?
?protected ProgressBarDialog(Context context) {
??super(context);
?}
?
[email protected]
?protected void onCreate(Bundle savedInstanceState) {
??LayoutInflater inflater = LayoutInflater.from(getContext());
??mViewUpdateHandler = new Handler() {
???
??????????? @Override
??????????? public void handleMessage(Message msg) {
??????????????? super.handleMessage(msg);
???????????????
??????????????? double precent = dProgress / dMax;
????if (prev != (int)(precent * 100)) {
?????mProgress.setProgress((int)(precent * 100));
???????????????? mProgressNumber.setText(df.format(dProgress) + "/" + df.format(dMax) + (middle == K ? "K" : "M"));
???????????????? mProgressPercent.setText(nf.format(precent));
???????????????? prev = (int)(precent * 100);
????}
???????????????
??????????? }
??????? };
??????? View view = inflater.inflate(R.layout.alert_dialog_progress, null);
??????? mProgress = (ProgressBar) view.findViewById(R.id.progress);
??????? mProgress.setMax(100);
??????? mProgressNumber = (TextView) view.findViewById(R.id.progress_number);
??????? mProgressPercent = (TextView) view.findViewById(R.id.progress_percent);
??????? setView(view);
???????
??????? onProgressChanged();
??????? super.onCreate(savedInstanceState);
?}
?
??? private void onProgressChanged() {
???????? mViewUpdateHandler.sendEmptyMessage(0);
??? }

?public double getDMax() {
??return dMax;
?}

?public void setDMax(double max) {
??if (max > M) {
???middle = M;
??} else {
???middle = K;
??}
??
??dMax = max / middle;
?}

?public double getDProgress() {
??return dProgress;
?}

?public void setDProgress(double progress) {
??dProgress = progress / middle;
??onProgressChanged();
?}

}

他的使用方法也很简单，和ProgressDialog的使用方法一样，支部过他的progress现在可以接收double类型的值，并且会在内部自己转换K或M，呵呵，很简单吧................