/*******************************************************************************
* Copyright (c) 2005, 2014 springside.github.io
*
* Licensed under the Apache License, Version 2.0 (the "License");
*******************************************************************************/
package org.springside.examples.showcase.demos.web;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.http.HttpEntity;
import org.apache.http.client.HttpResponseException;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.fluent.Executor;
import org.apache.http.client.fluent.Request;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* 演示使用多线程安全且带连接池的Apache HttpClient和 JDK两种方案获取远程静态内容并进行展示的Servlet.
*
* 另外简单演示了轻量级更易用的Apache HttpClient Fluent API。
*
* 演示访问地址如下(contentUrl已经过URL编码):
* remote-content?contentUrl=http%3A%2F%2Flocalhost%3A8080%2Fshowcase%2Fimages%2Flogo.jpg
*
* @author calvin
*/
public class RemoteContentServlet extends HttpServlet {
private static final long serialVersionUID = -8483811141908827663L;
private static final int TIMEOUT_SECONDS = 20;
private static final int POOL_SIZE = 20;
private static Logger logger = LoggerFactory.getLogger(RemoteContentServlet.class);
private static CloseableHttpClient httpClient;
@Override
public void init(ServletConfig config) throws ServletException {
initApacheHttpClient();
}
@Override
public void destroy() {
destroyApacheHttpClient();
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 获取URL
String contentUrl = request.getParameter("contentUrl");
if (StringUtils.isBlank(contentUrl)) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "contentUrl parameter is required.");
}
// 基於配置，使用HttpClient或JDK 獲取URL內容
String client = request.getParameter("client");
if ("apache".equals(client)) {
fetchContentByApacheHttpClient(response, contentUrl);
} else {
fetchContentByJDKConnection(response, contentUrl);
}
}
private void fetchContentByApacheHttpClient(HttpServletResponse response, String contentUrl) throws IOException {
// 获取内容
HttpGet httpGet = new HttpGet(contentUrl);
CloseableHttpResponse remoteResponse = httpClient.execute(httpGet);
try {
// 判断返回值
int statusCode = remoteResponse.getStatusLine().getStatusCode();
if (statusCode >= 400) {
response.sendError(statusCode, "fetch image error from " + contentUrl);
return;
}
HttpEntity entity = remoteResponse.getEntity();
// 设置Header
response.setContentType(entity.getContentType().getValue());
if (entity.getContentLength() > 0) {
response.setContentLength((int) entity.getContentLength());
}
// 输出内容
InputStream input = entity.getContent();
OutputStream output = response.getOutputStream();
// 基于byte数组读取InputStream并直接写入OutputStream, 数组默认大小为4k.
IOUtils.copy(input, output);
output.flush();
} finally {
remoteResponse.close();
}
}
private void fetchContentByJDKConnection(HttpServletResponse response, String contentUrl) throws IOException {
HttpURLConnection connection = (HttpURLConnection) new URL(contentUrl).openConnection();
// 设置Socket超时
connection.setReadTimeout(TIMEOUT_SECONDS * 1000);
try {
connection.connect();
// 真正发出请求
InputStream input;
try {
input = connection.getInputStream();
} catch (FileNotFoundException e) {
response.sendError(HttpServletResponse.SC_NOT_FOUND, contentUrl + " is not found.");
return;
}
// 设置Header
response.setContentType(connection.getContentType());
if (connection.getContentLength() > 0) {
response.setContentLength(connection.getContentLength());
}
// 输出内容
OutputStream output = response.getOutputStream();
try {
// 基于byte数组读取InputStream并直接写入OutputStream, 数组默认大小为4k.
IOUtils.copy(input, output);
output.flush();
} finally {
// 保证InputStream的关闭.
IOUtils.closeQuietly(input);
}
} finally {
connection.disconnect();
}
}
// 创建包含connection pool与超时设置的client
private void initApacheHttpClient() {
RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(TIMEOUT_SECONDS * 1000)
.setConnectTimeout(TIMEOUT_SECONDS * 1000).build();
httpClient = HttpClientBuilder.create().setMaxConnTotal(POOL_SIZE).setMaxConnPerRoute(POOL_SIZE)
.setDefaultRequestConfig(requestConfig).build();
}
private void destroyApacheHttpClient() {
try {
httpClient.close();
} catch (IOException e) {
logger.error("httpclient close fail", e);
}
}
/**
* 演示FluentAPI。
*/
@SuppressWarnings("unused")
public void fluentAPIDemo(String contentUrl) throws IOException {
try {
// demo1: 获取文字 , 使用默认连接池(200 total/100 per route), returnContent()会自动获取全部内容后关闭inputstream。
String resultString = Request.Get(contentUrl).execute().returnContent().asString();
// demo2: 获取图片, 增加超时设定。
byte[] resultBytes = Request.Get(contentUrl).connectTimeout(TIMEOUT_SECONDS * 1000)
.socketTimeout(TIMEOUT_SECONDS * 1000).execute().returnContent().asBytes();
// demo3: 获取图片，使用之前设置好了的自定义连接池与超时的httpClient
Executor executor = Executor.newInstance(httpClient);
String resultString2 = executor.execute(Request.Get(contentUrl)).returnContent().asString();
} catch (HttpResponseException e) {
logger.error("Status code:" + e.getStatusCode(), e);
}
}
}