项目添加HttpClient jar包引用，下载地址：http://hc.apache.org/downloads.cgi
引用：

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

获取网页内容代码：

HttpClient httpclient = new DefaultHttpClient();
        HttpGet httpget = new HttpGet(request.getParameter("requestUrl"));
        HttpResponse res = httpclient.execute(httpget);
        HttpEntity entity = res.getEntity();
        //response.setCharacterEncoding("utf-8");
        //response.setContentType("application/json");
        OutputStream out = response.getOutputStream();

        if (entity != null) {

            InputStream instream = entity.getContent();
            int len;
            byte[] tmp = new byte[2048];
            while ((len = instream.read(tmp)) != -1) {
                out.write(tmp, 0, len);
            }
        }else{
            out.write(new byte[]{ '{','}' });
        }