get Pdf from oss when 302 从第三方接口获取文件流生成PDF并存储到本地

原创已于 2022-06-17 23:55:22 修改 · 397 阅读

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#java #开发语言

于 2022-06-17 23:54:48 首次发布

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该代码示例展示了如何使用Java的HttpURLConnection处理HTTP 302重定向来下载PDF文件。程序首先发送GET请求，当遇到重定向时，获取新的Location并重新发送请求，同时处理Cookies，最终将PDF内容写入指定的文件路径。

 package http;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.function.Function;

class PdfUtil {
    public void getPdffrom302(String url, String filePath, Function<String, String> changeUtil){
        try {
            System.out.println("访问地址:" + url);
//发送get请求
            URL serverUrl = new URL(url);
            HttpURLConnection conn = (HttpURLConnection) serverUrl.openConnection();
            conn.setRequestMethod("GET");
//必须设置false，否则会自动redirect到重定向后的地址
            conn.setInstanceFollowRedirects(false);
            conn.addRequestProperty("Accept-Charset", "UTF-8;");
            conn.addRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2.8) Firefox/3.6.8");
            // conn.addRequestProperty("Referer", "http://matols.com/");
            conn.connect();
//判定是否会进行302重定向
            if (conn.getResponseCode() == 302) {

//如果会重定向，保存302重定向地址，以及Cookies,然后重新发送请求(模拟请求)
                String location = conn.getHeaderField("Location");
                location = changeUtil.apply(location);
                String cookies = conn.getHeaderField("Set-Cookie");
                serverUrl = new URL(location);
                conn = (HttpURLConnection) serverUrl.openConnection();
                conn.setRequestMethod("GET");
                conn.setRequestProperty("Cookie", cookies);
                conn.addRequestProperty("Accept-Charset", "UTF-8;");
                conn.addRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2.8) Firefox/3.6.8");
                //    conn.addRequestProperty("Referer", "http://matols.com/");
                conn.connect();
                System.out.println("跳转地址:" + location);
            }
//将返回的输入流转换成字符串
            InputStream is = conn.getInputStream();
            File f = new File(filePath);
            OutputStream os = new FileOutputStream(f);
            byte[] buffer = new byte[1024];
            int len;
            while ((len = is.read(buffer)) != -1) {
                os.write(buffer, 0, len);
            }
            os.flush();
            is.close();
            os.close();
// 释放资源
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    public static void main(String[] args) {
        PdfUtil p= new PdfUtil();
        String url="http://www ";

        p.getPdffrom302(url,"1.pdf", new Function<String, String>() {
            public String apply(String location) {
                return location.replace("files.xxxx.com", "128.0.0.1");
            }
        });
    }


}

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>