HttpURLConnection根据URL下载图片

来看下最简单的根据URL下载图片，此方法在实际开发中，不建议使用，因为有些图片是下载不了的，比如百度上的一些图片，返回http的响应码是405

package cn.ztz.test;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;import java.net.HttpURLConnection;import java.net.InetAddress;import java.net.URL;public class HttpDownLoad {public static void download(String url, String dir,String fileName) {HttpURLConnection httpURLConnection = null;OutputStream out = null;InputStream in = null;try {URL sendUrl = new URL(url);httpURLConnection = (HttpURLConnection) sendUrl.openConnection();httpURLConnection.setRequestMethod("POST");httpURLConnection.setRequestProperty("contentType", "utf-8");httpURLConnection.setDoOutput(true); httpURLConnection.setUseCaches(false);httpURLConnection.setConnectTimeout(3000);httpURLConnection.setReadTimeout(3000);httpURLConnection.setRequestProperty("User-agent",InetAddress.getLocalHost().getHostAddress() + ":"+ System.getProperty("catalina.home"));out = httpURLConnection.getOutputStream();// 清空缓冲区数据out.flush();// 获取HTTP状态码int httpStatusCode = httpURLConnection.getResponseCode();if(httpStatusCode!=200){throw new RuntimeException("异常");}in = httpURLConnection.getInputStream();// 获取文件长度int len = httpURLConnection.getContentLength();// 路径+文件名String pathAndName = dir + File.separator + fileName;// 保存文件saveFileByByte(in, pathAndName, len);} catch (Exception e) {e.printStackTrace();} finally {if (out != null) {try {out.close();} catch (Exception e) {e.printStackTrace();throw new RuntimeException(e.getMessage());}}if (in != null) {try {in.close();} catch (Exception e) {e.printStackTrace();}}if (httpURLConnection != null) {httpURLConnection.disconnect();httpURLConnection = null;}}}//写文件private static void saveFileByByte(InputStream in, String path, int len)throws Exception {byte[] byteDatas = new byte[len];BufferedOutputStream bw = null;try {// 创建文件对象File f = new File(path);// 创建文件路径if (!f.getParentFile().exists())f.getParentFile().mkdirs();// 写入文件bw = new BufferedOutputStream(new FileOutputStream(path));int bytesRead = 0;while ((bytesRead = in.read(byteDatas, 0, byteDatas.length)) != -1) {bw.write(byteDatas, 0, bytesRead);}} catch (Exception e) {e.printStackTrace();throw e;} finally {try {if (bw != null)bw.close();} catch (Exception e) {throw e;}}}}