JAVA发送http GET/POST请求的两种方式+JAVA http 请求手动配置代理

java发送http get请求，有两种方式。

第一种用URLConnection：

 public static String get(String url) throws IOException {
        BufferedReader in = null;

        URL realUrl = new URL(url);
        // 打开和URL之间的连接
        URLConnection connection = realUrl.openConnection();
        // 设置通用的请求属性
        connection.setRequestProperty("accept", "*/*");
        connection.setRequestProperty("connection", "Keep-Alive");
        connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
        connection.setConnectTimeout(5000);
        connection.setReadTimeout(5000);
        // 建立实际的连接
        connection.connect();
        // 定义 BufferedReader输入流来读取URL的响应
        in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        StringBuffer sb = new StringBuffer();
        String line;
        while ((line = in.readLine()) != null) {
            sb.append(line);
        }

        in.close();
        return sb.toString();
    }

第二种用java HTTP客户端：HttpGet、HttpClient、HttpResponse等

public static String httpGet(String url, String charset)
            throws HttpException, IOException {
        String json = null;
        HttpGet httpGet = new HttpGet();
        // 设置参数
        try {
            httpGet.setURI(new URI(url));
        } catch (URISyntaxException e) {
            throw new HttpException("请求url格式错误。"+e.getMessage());
        }
        // 发送请求
        HttpClient client=HttpClients.createDefault();
        HttpResponse httpResponse = client.execute(httpGet);
        // 获取返回的数据
        HttpEntity entity = httpResponse.getEntity();
        byte[] body = EntityUtils.toByteArray(entity);
        StatusLine sL = httpResponse.getStatusLine();
        int statusCode = sL.getStatusCode();
        if (statusCode == 200) {
            json = new String(body, charset);
            entity.consumeContent();
        } else {
            throw new HttpException("statusCode="+statusCode);
        }
        return json;
    }

POST请求同理，这里只列出URLConnection方式：

public static String post(String url, String param, Map<String, String> header) throws IOException {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        URL realUrl = new URL(url);
        // 打开和URL之间的连接
        URLConnection conn = realUrl.openConnection();
        //设置超时时间
        conn.setConnectTimeout(5000);
        conn.setReadTimeout(15000);
        // 设置通用的请求属性
        if (header != null) {
            for (Map.Entry<String, String> entry : header.entrySet()) {
                conn.setRequestProperty(entry.getKey(), entry.getValue());
            }
        }
        conn.setRequestProperty("accept", "*/*");
        conn.setRequestProperty("connection", "Keep-Alive");
        conn.setRequestProperty("user-agent",
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");


        // 发送POST请求必须设置如下两行
        conn.setDoOutput(true);
        conn.setDoInput(true);
        // 获取URLConnection对象对应的输出流
        out = new PrintWriter(conn.getOutputStream());
        // 发送请求参数
        out.print(param);
        // flush输出流的缓冲
        out.flush();
        // 定义BufferedReader输入流来读取URL的响应
        in = new BufferedReader(
                new InputStreamReader(conn.getInputStream(), "utf8"));
        String line;
        while ((line = in.readLine()) != null) {
            result += line;
        }
        if (out != null) {
            out.close();
        }
        if (in != null) {
            in.close();
        }
        return result;
    }

代理

如果使用代理的话可以按如下编写一个设置代理的函数configProxy，然后在发送请求前调用一下这个函数就行了：

package com.tpot.DataDownload;

import java.util.Properties;

public class Configer {
    public static void configProxy(){
        Properties prop=System.getProperties();

        prop.setProperty("proxySet","true");
        prop.setProperty("http.proxyHost","proxy.xxxx.com");
        prop.setProperty("http.proxyPort","8080");
        prop.setProperty("http.proxyUser","xxxxx");
        prop.setProperty("http.proxyPassword","xxxxx");

        prop.setProperty("https.proxyHost","proxy.xxxxx.com");
        prop.setProperty("https.proxyPort","8080");
        prop.setProperty("https.proxyUser","xxxxx");
        prop.setProperty("https.proxyPassword","xxxxx");
    }
}