通过HttpURLConnection 上传和下载文件（二）

HttpURLConnection文件上传

　　HttpURLConnection采用模拟浏览器上传的数据格式，上传给服务器

　　上传代码如下：

package com.util;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Iterator;
import java.util.Map;

/**
 * Java原生的API可用于发送HTTP请求，即java.net.URL、java.net.URLConnection，这些API很好用、很常用，
 * 但不够简便；
 * 
 * 1.通过统一资源定位器（java.net.URL）获取连接器（java.net.URLConnection） 2.设置请求的参数 3.发送请求
 * 4.以输入流的形式获取返回内容 5.关闭输入流
 * 
 * @author H__D
 *
 */
public class HttpConnectionUtil {


    /**
     * 多文件上传的方法
     * 
     * @param actionUrl：上传的路径
     * @param uploadFilePaths：需要上传的文件路径，数组
     * @return
     */
    @SuppressWarnings("finally")
    public static String uploadFile(String actionUrl, String[] uploadFilePaths) {
        String end = "
";
        String twoHyphens = "--";
        String boundary = "*****";

        DataOutputStream ds = null;
        InputStream inputStream = null;
        InputStreamReader inputStreamReader = null;
        BufferedReader reader = null;
        StringBuffer resultBuffer = new StringBuffer();
        String tempLine = null;

        try {
            // 统一资源
            URL url = new URL(actionUrl);
            // 连接类的父类，抽象类
            URLConnection urlConnection = url.openConnection();
            // http的连接类
            HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;

            // 设置是否从httpUrlConnection读入，默认情况下是true;
            httpURLConnection.setDoInput(true);
            // 设置是否向httpUrlConnection输出
            httpURLConnection.setDoOutput(true);
            // Post 请求不能使用缓存
            httpURLConnection.setUseCaches(false);
            // 设定请求的方法，默认是GET
            httpURLConnection.setRequestMethod("POST");
            // 设置字符编码连接参数
            httpURLConnection.setRequestProperty("Connection", "Keep-Alive");
            // 设置字符编码
            httpURLConnection.setRequestProperty("Charset", "UTF-8");
            // 设置请求内容类型
            httpURLConnection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);

            // 设置DataOutputStream
            ds = new DataOutputStream(httpURLConnection.getOutputStream());
            for (int i = 0; i < uploadFilePaths.length; i++) {
                String uploadFile = uploadFilePaths[i];
                String filename = uploadFile.substring(uploadFile.lastIndexOf("//") + 1);
                ds.writeBytes(twoHyphens + boundary + end);
                ds.writeBytes("Content-Disposition: form-data; " + "name="file" + i + "";filename="" + filename
                        + """ + end);
                ds.writeBytes(end);
                FileInputStream fStream = new FileInputStream(uploadFile);
                int bufferSize = 1024;
                byte[] buffer = new byte[bufferSize];
                int length = -1;
                while ((length = fStream.read(buffer)) != -1) {
                    ds.write(buffer, 0, length);
                }
                ds.writeBytes(end);
                /* close streams */
                fStream.close();
            }
            ds.writeBytes(twoHyphens + boundary + twoHyphens + end);
            /* close streams */
            ds.flush();
            if (httpURLConnection.getResponseCode() >= 300) {
                throw new Exception(
                        "HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
            }

            if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                inputStream = httpURLConnection.getInputStream();
                inputStreamReader = new InputStreamReader(inputStream);
                reader = new BufferedReader(inputStreamReader);
                tempLine = null;
                resultBuffer = new StringBuffer();
                while ((tempLine = reader.readLine()) != null) {
                    resultBuffer.append(tempLine);
                    resultBuffer.append("
");
                }
            }

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            if (ds != null) {
                try {
                    ds.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            if (inputStreamReader != null) {
                try {
                    inputStreamReader.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }

            return resultBuffer.toString();
        }
    }


    public static void main(String[] args) {

        // 上传文件测试
         String str = uploadFile("http://127.0.0.1:8080/image/image.do",new String[] { "/Users//H__D/Desktop//1.png","//Users/H__D/Desktop/2.png" });
         System.out.println(str);


    }

}

HttpURLConnection文件下载

　　下载代码如下：

package com.util;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Iterator;
import java.util.Map;

/**
 * Java原生的API可用于发送HTTP请求，即java.net.URL、java.net.URLConnection，这些API很好用、很常用，
 * 但不够简便；
 * 
 * 1.通过统一资源定位器（java.net.URL）获取连接器（java.net.URLConnection） 2.设置请求的参数 3.发送请求
 * 4.以输入流的形式获取返回内容 5.关闭输入流
 * 
 * @author H__D
 *
 */
public class HttpConnectionUtil {


    /**
     * 
     * @param urlPath
     *            下载路径
     * @param downloadDir
     *            下载存放目录
     * @return 返回下载文件
     */
    public static File downloadFile(String urlPath, String downloadDir) {
        File file = null;
        try {
            // 统一资源
            URL url = new URL(urlPath);
            // 连接类的父类，抽象类
            URLConnection urlConnection = url.openConnection();
            // http的连接类
            HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
            // 设定请求的方法，默认是GET
            httpURLConnection.setRequestMethod("POST");
            // 设置字符编码
            httpURLConnection.setRequestProperty("Charset", "UTF-8");
            // 打开到此 URL 引用的资源的通信链接（如果尚未建立这样的连接）。
            httpURLConnection.connect();

            // 文件大小
            int fileLength = httpURLConnection.getContentLength();

            // 文件名
            String filePathUrl = httpURLConnection.getURL().getFile();
            String fileFullName = filePathUrl.substring(filePathUrl.lastIndexOf(File.separatorChar) + 1);

            System.out.println("file length---->" + fileLength);

            URLConnection con = url.openConnection();

            BufferedInputStream bin = new BufferedInputStream(httpURLConnection.getInputStream());

            String path = downloadDir + File.separatorChar + fileFullName;
            file = new File(path);
            if (!file.getParentFile().exists()) {
                file.getParentFile().mkdirs();
            }
            OutputStream out = new FileOutputStream(file);
            int size = 0;
            int len = 0;
            byte[] buf = new byte[1024];
            while ((size = bin.read(buf)) != -1) {
                len += size;
                out.write(buf, 0, size);
                // 打印下载百分比
                // System.out.println("下载了-------> " + len * 100 / fileLength +
                // "%
");
            }
            bin.close();
            out.close();
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            return file;
        }

    }

    public static void main(String[] args) {

        // 下载文件测试
        downloadFile("http://localhost:8080/images/1467523487190.png", "/Users/H__D/Desktop");

    }

}

downloadFile

此文来源于 ：https://www.cnblogs.com/h--d/p/5638092.html