HttpClient获取网页中的内容,并实现图片和视频的下载功能

1.HttpClient

• httpclient可以拿到其他项目或者URL下的内容

2.HttpClient用法

• 获取其他页面中的内容,和已知路径下载图片和视频

a.添加依赖

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.10</version>
        </dependency>
    </dependencies>

b.新建一个HttpClientUtils.java类

package com.ym.utils;


import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;

/**
 * ClassName: HttpClientUtils
 * Description: 可以获取指定路径下的网页中的内容
 * date: 2020/5/2  14:11
 *
 * @author YanM
 * @since JDK 1.8
 */
public class HttpClientUtils {

    /**
     * 获取指定baseURL链接所返回的字符串数据
     * @param baseURL
     * @return
     */
    public static String getDataFromURL(String baseURL){
        try {
            //根据URL创建一个URL对象
            URL url=new URL(baseURL);
            //通过URL对象的openConnection()方法,强转的到一个httpURLConnection
            HttpURLConnection con=(HttpURLConnection) url.openConnection();
            //设置请求的超时时间
            con.setConnectTimeout(5000);
            //设置请求的请求方式
            con.setRequestMethod("GET");
            //设置请求方式为输入请求
            con.setDoInput(true);
            //得到请求返回的状态码
            int code=con.getResponseCode();

            //如果状态码是HTTP_OK(200)
            if (code==HttpURLConnection.HTTP_OK){
                //通过连接对象的getInputStream()方法的到一个输入流对象
                InputStream is=con.getInputStream();
                ByteArrayOutputStream baos=new ByteArrayOutputStream();

                byte[] bytes=new byte[8192];

                int len;
                while ((len=is.read(bytes))!=-1){
                    baos.write(bytes,0,len);
                }
                return new String(baos.toByteArray());
            }

        } catch (MalformedURLException | ProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 根据指定的baseURL来获取该url对应的字节数组的值
     * @param baseURL   要获取数据的url
     * @param type      请求类型 GET活着POST
     * @return 指定baseURL所对应的字节数组值
     * 可以实现图片和视频的下载功能
     */
    public static byte[] getByteDataByURL(String baseURL,String type){
        try {
            URL url=new URL(baseURL);
            HttpURLConnection con=(HttpURLConnection) url.openConnection();
            con.setConnectTimeout(5000);

            if ("GET".equalsIgnoreCase(type)){
                con.setRequestMethod("GET");
            }else {
                con.setRequestMethod("POST");
            }

            con.setDoInput(true);

            int code=con.getResponseCode();

            if (code==HttpURLConnection.HTTP_OK){
                InputStream is=con.getInputStream();

                ByteArrayOutputStream baos=new ByteArrayOutputStream();

                int len;
                byte[] data=new byte[8192];

                while ((len=is.read(data))!=-1){
                    baos.write(data,0,len);
                }
                return baos.toByteArray();
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

}

c.测试功能

import com.ym.utils.HttpClientUtils;
import org.junit.Test;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * ClassName: HttpClientUtilsUtilsTest
 * Description:
 * date: 2020/5/2  14:59
 *
 * @author YanM
 * @since JDK 1.8
 */
public class HttpClientUtilsUtilsTest {

    //获取网页中的信息
    @Test
    public void testGetData(){
        String data = HttpClientUtils.getDataFromURL("http://localhost:8080/users/getAll");
        System.out.println(data);
    }

    /**
     * 实现下载图片和视频的功能
     * http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4
     * https://stream7.iqilu.com/10339/upload_transcode/202002/18/20200218114723HDu3hhxqIT.mp4
     */
    @Test
    public void testGetByteData() throws IOException {
        //byte[] datas = HttpClientUtils.getByteDataByURL("http://t9.baidu.com/it/u=1307125826,3433407105&fm=79&app=86&f=JPEG?w=5760&h=3240", "get");
        //下载图片

        byte[] datas = HttpClientUtils.getByteDataByURL("https://stream7.iqilu.com/10339/upload_transcode/202002/18/20200218114723HDu3hhxqIT.mp4", "get");
        //下载视频
        FileOutputStream fos=null;
        try {
            //fos=new FileOutputStream("gile.jpg");
            //下载到本地图片的名字

            fos=new FileOutputStream("hello.mp4");
            //下载到本地的视频

            fos.write(datas);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }finally {
            try {
                if (fos!=null){
                    fos.close();
                    fos=null;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        System.out.println("download success");
    }
}