Java 网络 URL 从网页上获取数据

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简单了解URL功能
实现从网页上获取数据
package com.mashensoft.net;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.io.PrintWriter;import java.net.MalformedURLException;import java.net.URL;import java.net.URLConnection;import java.util.Scanner;/** * Url *  * @author PeicongHe * */public class UrlDemo {    /**     * 原来我们用手工通过浏览器访问网页，现在通过JAVA代码访问网页 URL     * 统一资源定位符（URL，英语UniformResourceLocator的缩写）也被称为网页地址，是因特网上标准的资源的地址。     * 获取网易云音乐的信息     */    public static void test1() {        try {            URL url = new URL("http://music.163.com/");            System.out.println(url.getHost());// 获取网络地址            System.out.println(url.getFile());// 获取文件            System.out.println(url.getPort());// 获取端口号            System.out.println(url.getProtocol());// 获取网络协议            System.out.println(url.getDefaultPort());// 获取端口        } catch (MalformedURLException e) {            e.printStackTrace();        }    }    /**     * 从网页上获取内容     */    public static void test2() {        try {            URL url = new URL("http://music.163.com/");            URLConnection conn = url.openConnection();// 打开链接            InputStream is = conn.getInputStream();// 获取数据流            // URLConnection is =url.openStream();//缩写            Scanner sc = new Scanner(is, "GBK");// 扫描数据流并存放在sc里,编码方式 GBK            while (sc.hasNextLine()) {// 判断是否存在下一行                System.out.println(sc.nextLine());// 输出当前行内容            }            sc.close();            is.close();        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }    /**     * 由于访问网络需要连网，当不联网的时候，我就没办法使用数据 所以，我们要把从网页获取的内容存到本地来 步骤： 1、从网上获取数据 2、将数据存入文本     */    public static void test3() {        StringBuffer sb = new StringBuffer();        // Constructs a string buffer with no characters in it and an initial        // capacity of 16 characters.        try {            URL url = new URL("http://music.163.com/");            URLConnection conn = url.openConnection();            InputStream is = conn.getInputStream();            Scanner sc = new Scanner(is, "UTF-8");            // String content ="";            // StringBuffer sb = new StringBuffer();            while (sc.hasNextLine()) {                sb.append(sc.nextLine()).append("\r\n");// 把当前行内容存放在StringBuffer                                                        // sb里 ,append（）附加）                // content+=sc.nextLine();                // System.out.println(content+=sc.nextLine());            }            sc.close();            is.close();        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        // 把数据存放在文件中        try {            //// Creates a new PrintWriter, without automatic line flushing,            //// with the specified file name.            PrintWriter pw = new PrintWriter("content.txt");            pw.println(sb.toString());            pw.flush();            pw.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        }        System.out.println("执行成功");    }    /**     * 从网页上获取数据     *      * @param myUrl     * @return     */    public static String getContentFromUrl(String myUrl, String charset) {        StringBuffer sb = new StringBuffer();        URL url;        try {            url = new URL(myUrl);            URLConnection conn = url.openConnection();            InputStream is = conn.getInputStream();            Scanner sc = new Scanner(is, charset);            while (sc.hasNextLine()) {                sb.append(sc.nextLine()).append("\r\n");            }            sc.close();            is.close();        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        System.out.println("执行成功");        return sb.toString();    }    public static boolean writeContentToFile(String content, String fileName) {        boolean sign = false;        // 把数据存入在文件夹中        PrintWriter pw;        try {            pw = new PrintWriter(fileName);            pw.println(content);            pw.flush();            pw.close();            sign = true;        } catch (FileNotFoundException e) {            e.printStackTrace();            sign = false;        }        return sign;    }    /**     * 输出文件     *      * @param args     */    public static String test3x() {        StringBuffer sbx = new StringBuffer();        try {            URL urlx = new URL("https://www.baidu.com");            InputStream uc = urlx.openStream();            Scanner sc = new Scanner(uc, "UTF-8");            while (sc.hasNextLine()) {                sbx.append(sc.nextLine()).append("\r\n");            }            sc.close();            uc.close();        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        System.out.println("执行成功");        return sbx.toString();    }    public static boolean test3xx(String content) {        boolean sign = false;        try {            PrintWriter pw = new PrintWriter("a.html");            pw.println(content);            pw.flush();            pw.close();            sign = true;        } catch (FileNotFoundException e) {            e.printStackTrace();            sign = false;        }        return sign;    }    public static void main(String[] args) {        test1();        // getContentFromUrl("https://www.baidu.com","UTF-8");        // String content = getContentFromUrl("https://www.baidu.com","UTF-8");        // boolean sign = writeContentToFile(content,"b.html");        // String content = test3x();        // boolean sign = test3xx(content);        // System.out.println(sign);    }}
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