Java SE单线程下载网络上的音/视频等大文件

Myth丶恋晨 2022-08-05 13:17 73阅读 0赞

import static org.junit.Assert.fail;
    
    import java.io.ByteArrayOutputStream;
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.InputStream;
    import java.net.HttpURLConnection;
    import java.net.URL;
    
    import org.junit.Test;
    
    
    public class InternetTest {
        
    
        @Test
        public void test() {
            fail("Not yet implemented");
        }
        @Test
        public void getImage() throws Exception{
            //首先要获取请求的路径，路径就是要从网上获取的资源
            String urlPath= "http://c.hiphotos.baidu.com/image/pic/item/8718367adab44aedbc2df1e3b01c8701a18bfb52.jpg";
            URL url = new URL(urlPath);//建立URL类对象，抛出异常
            HttpURLConnection conn =(HttpURLConnection)url.openConnection();//得到UrlConnection对象
    
            conn.setRequestMethod("GET");//声明请求方式
            conn.setConnectTimeout(6*1000);//设置连接超时
            if(conn.getResponseCode() == 200){
       //如果结果是200，就代表他的请求是成功的
                InputStream inputStream = conn.getInputStream();//得到服务器端传回来的数据，相对客户端为输入流
    
                byte[] data = readInstream(inputStream);
                File file = new File("touxiang.jpg");
                FileOutputStream outputStream = new FileOutputStream(file);
                outputStream.write(data);
                outputStream.close();       
            }       
        }
    
        private byte[] readInstream(InputStream inputStream) throws Exception{
            ByteArrayOutputStream byteArrayOutPutStream = new ByteArrayOutputStream();//创建ByteArrayOutputStream类
            byte[] buffer = new byte[1024];//声明缓存区
            int length = -1;//定义读取的默认长度
            while((length = inputStream.read(buffer))!= -1){
                byteArrayOutPutStream.write(buffer,0,length);//把缓存区中的输入到内存中         
            };
            byteArrayOutPutStream.close();//关闭输入流
            inputStream.close();//关闭输入流
    
            return byteArrayOutPutStream.toByteArray();//返回这个输入流的字节数组
        }
    
    }

J2SE从网络中获取文本

@Test
        public void getHtml() throws Exception{
            String urlpathString = "http://www.sina.com";
            URL url = new URL(urlpathString);//建立URL对象，抛出异常
            HttpURLConnection conn = (HttpURLConnection)url.openConnection();
            conn.setRequestMethod("GET");
            conn.setConnectTimeout(6*1000);
            if(conn.getResponseCode() == 200){
                InputStream inputStream = conn.getInputStream();//得到输入流
                byte[] data = readInstream(inputStream);     //得到数据
                System.out.println(new String(data));//将字节转化为字符串，打印在控制台上面
            }
        }

System.out.println(new String(data)); 是将得到的字符串类型打印到控制台上面，返回是ＨＴＭＬ的代码，和流量器参看的源代码是一样的。

第三种：J2SE从网络获取可以自行的文件。  
在Internet类中添加getFile()方法，具体代码如下：

@Test
        public void getFile() throws Exception{
            String urlPath  = "http://dlsw.baidu.com/sw-search-sp/soft/b8/14630/YoudaoDict_V6.3.66.1117_setup.1423550350.exe";
            URL url = new URL(urlPath);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.setConnectTimeout(6*1000);
            if(connection.getResponseCode()== 200){
                InputStream inputStream =connection.getInputStream();
                byte[] data =readInstream(inputStream);
                File file =new File("youdao.exe");
                FileOutputStream outputStream = new FileOutputStream(file);
                outputStream.write(data);
                outputStream.close();
            }
        }