Android学习笔记--使用HttpURLConnection实现网络下载效果，附带进度条显示

下面我就直接上代码了，因为代码中我已经写了非常详细的注释

package com.wuxianedu.httpdemo;

import android.app.ProgressDialog;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class Main2Activity extends AppCompatActivity implements View.OnClickListener{

    private Button button;
    private ProgressDialog dialog;
    private String path;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            dialog.setProgress(msg.what);
            super.handleMessage(msg);
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        button = (Button) findViewById(R.id.but_id);
        button.setOnClickListener(this);
        dialog = new ProgressDialog(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.but_id:
                dialog.setTitle("下载呢");
                dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                dialog.show();
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        getURL();
                    }
                }).start();
                break;
        }
    }

    /**
     * 启动应用安装。
     */
    private void setupApk() {
        Intent intent = new Intent(Intent.ACTION_VIEW);
        //"file：//"+文件路径。
        Uri uri = Uri.parse("file://"+ path);
        intent.setDataAndType(uri, "application/vnd.android.package-archive");
        startActivity(intent);
    }

    private void getURL(){
        try {
            //构建URL地址
            URL url = new URL("http://g.pc6.com/0942666043/apk/4001_ZMJ2016_04_20161028_rnikgd.apk");
            try {
                //打开打开打开
                HttpURLConnection hcont = (HttpURLConnection) url.openConnection();
                //建立实际链接
                hcont.connect();
                //获取输入流内容
                InputStream is = hcont.getInputStream();
                //获取文件长度
                int ddddd =hcont.getContentLength();
                //为进度条赋值
                dialog.setMax(ddddd);
                //手机存储地址
                path = getExternalCacheDir().getPath()+"/wuxl.apk";
                //写入文件
                OutputStream os = new FileOutputStream(path);
                int length;
                int lengtsh = 0;
                byte [] bytes = new byte[1024];
                while ((length = is.read(bytes))!= -1){
                    os.write(bytes,0,length);
                    //获取当前进度值
                    lengtsh+=length;
                    //把值传给handler
                    handler.sendEmptyMessage(lengtsh);
                }
                //关闭流
                is.close();
                os.close();
                os.flush();
                dialog.dismiss();
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(Main2Activity.this, "下载成功了", Toast.LENGTH_SHORT).show();
                    }
                });
            } catch (IOException e) {
                e.printStackTrace();
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
    }
}

下面是布局文件

<?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="com.wuxianedu.httpdemo.Main2Activity">

    <Button android:id="@+id/but_id" android:text="下载APP"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</RelativeLayout>

很简单，大家在使用的时候别忘记加网络权限哈