Java发送http请求以及下载图片

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原创最新推荐文章于 2026-05-25 10:23:17 发布 1.5k 阅读 AI 写同款· GEO 优化 ›

使用HttpClient库的下载程序下载蚂蜂窝的图片这个程序首先创建一个HttpClient实例，然后定义要下载的图片URL，并设置代理主机和代理端口。接着，它发送GET请求，并获取响应体。然后，它将响应体转换为字节数组，并将字节数组写入文件。最后，它关闭文件输出流、响应和HttpClient实例，并输出下载成功信息。希望这个程序能够满足你的需求！编写一个使用HttpClient库的下载程序。该程序将使用Java下载https://www.mafengwo.cn/的图片，并且代码必须使用以下代码：代理主机：www.duoip.cn，代理端口：8000。阅读详情

一、导入okHttp依赖

<dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp</artifactId>
    <version>3.8.1</version>
</dependency>

二、创建HttpUtil工具类

package net.***.util;

import okhttp3.*;

import java.io.IOException;
import java.util.concurrent.TimeUnit;

public class HttpUtils {
    
    private static OkHttpClient client = new OkHttpClient();
    public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");

    /**
     * http  post请求
     */
    public static String postRequest(String url, String param) {
        RequestBody body = RequestBody.create(JSON, param);
        Request request = new Request.Builder()
                .url(url)
                .post(body)
                .build();

        Response response = null;
        try {
            //设置等待时间
            client = new OkHttpClient.Builder()
                    .connectTimeout(20 * 1000, TimeUnit.SECONDS)
                    .writeTimeout(20 * 1000, TimeUnit.SECONDS)
                    .readTimeout(20 * 1000, TimeUnit.SECONDS)
                    .build();

            response = client.newCall(request).execute();
            return response.body().string();
        } catch (IOException e) {
            System.out.println(e);
            return null;
        }
    }

    /**
     * http  get请求
     */
    public static String getRequest(String url) {
        Request request = new Request.Builder()
                .url(url)
                .get()
                .build();

        Response response = null;
        try {
            //设置等待时间
            client = new OkHttpClient.Builder()
                    .connectTimeout(20 * 1000, TimeUnit.SECONDS)
                    .writeTimeout(20 * 1000, TimeUnit.SECONDS)
                    .readTimeout(20 * 1000, TimeUnit.SECONDS)
                    .build();

            response = client.newCall(request).execute();
            return response.body().string();
        } catch (IOException e) {
            System.out.println(e);
            return null;
        }
    }
}

三、根据图片http路径下载图片转换二进制

package net.***.util;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class Utils {
    /**
     * 获取图片二进制流
     */
    public byte[] getFileBytes(String urlMsg) {
        try {
            URL url = new URL(urlMsg);
            // 打开链接
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            // get请求
            connection.setRequestMethod("GET");
            // 超时响应时间
            connection.setConnectTimeout(5*1000);
            //获取流
            InputStream inputStream = connection.getInputStream();
            ByteArrayOutputStream outStream = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            //每次读取的字符串长度，如果为-1，代表全部读取完毕
            int len = 0;
            //使用一个输入流从buffer里把数据读取出来
            while( (len=inputStream.read(buffer)) != -1 ){
                outStream.write(buffer,0,len);
            }
            // 关闭输出流
            inputStream.close();
            // 获取流
            return outStream.toByteArray();
        }catch (Exception e){
            System.out.println(e);
        }
        return null;
    }
}