Java io字符写入下载网络文件获取url文件-优快云博客

本文链接：https://blog.youkuaiyun.com/stephenluu/article/details/37927297

本文介绍两个Java IO操作的实例：一是通过控制台输入并写入到本地文本文件的方法；二是从URL下载图片资源到本地硬盘的过程。这两个示例涵盖了字符流和字节流的基本使用方式。

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一写入字符文件

package test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;

public class SimpleIOTest {

	public static void main(String[] args) throws IOException {

		File file = new File("c:/hello3.txt"); 
		OutputStream os = new FileOutputStream(file);
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(os)); //一层一层装饰
		
		
		InputStreamReader isr = new InputStreamReader(System.in);//控制台输入流，用其他也行
		
		BufferedReader br = new BufferedReader(isr);
		
		String line = null;
		while((line = br.readLine()) != null  ){
			
			bw.write(line);  //写入
			break;
			//os.write(line.getBytes());
		}
		
		br.close();
		bw.close();
		
	}

}

二获取url文件

package test;

import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;

public class UrlIO {

	/**
	 * 
	 * @param args
	 */
	public static void main(String[] args) {

		try {
			
			String fileUrl = "http://www.baidu.com/img/baidu_sylogo1.gif";
			
			File file = new File("c:/foo.gif");
			OutputStream os = new FileOutputStream(file);

			java.net.URL url = new java.net.URL(fileUrl);
			HttpURLConnection connection =  (HttpURLConnection) url.openConnection();
			connection.connect();
			java.io.InputStream  inputStream = connection.getInputStream();

			byte[] b = new byte[1024];
			int i = 0;
			while ((i = inputStream.read(b)) > 0) {
				os.write(b, 0, i);
			}

			inputStream.close();
			os.flush();
			os.close();
			
		} catch (Exception ex) {
			ex.printStackTrace();
		}

	}

}