Java8 实现下载网页的完整代码

java8 实现网页下载，大致分为4步，分别是:给定目标网页链接->与目标主机建立连接->读入网页文件流->写入本地文件 。会用到java io 和 java net库。程序代码如下，留有注释。

package com.yangshengliang.URLDemo; //如果所用 IDE 不是eclipse,请注销这一行
import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.MalformedURLException;
import java.net.URL;
public class UrlDemo1 {
public static void main(String[] args) {
    try {
        new UrlDemo1().downloadPage();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
private String downloadPage() throws IOException
{
    // 目标网页链接
    String url = "http://www.yangshengliang.com";
    String inputLine = null;
    try {
        URL pageUrl = new URL(url);
        BufferedReader br = new BufferedReader(new InputStreamReader(pageUrl.openStream(), "utf-8"));
        File file = new File("download/index.html"); //程序文件目录建目录 download，用于存放下载的网页
        FileOutputStream out = new FileOutputStream(file);
        OutputStreamWriter write = new OutputStreamWriter(out, "utf-8");
        // 将输入流读入到变量中，再写入到文件
        while ((inputLine = br.readLine()) != null) {
        write.write(inputLine);
        System.out.println(inputLine);
    }
    br.close();
    write.close();
    System.err.println("下载完毕!");
    } catch (MalformedURLException e)
        e.printStackTrace();
    }
    return url;
    }
}