一、HttpClient 简介
HttpClient 是 Apache Jakarta Common 下的子项目，用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。Java后台使用httpclient主要目的是为了模拟客户端的请求。
2、HttpClient的请求类型
实现了所有的Http请求类型，相应的类为：HttpGet、HttpPost、HttpDelete、HttpPut
3、Http的使用流程
1）导包
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.5</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpmime</artifactId>
<version>4.5</version>
</dependency>
2）创建连接所需要的配置信息
public class HttpClientConfig {
static int httpConnectTimeout = 10000;//连接超时时间(单位毫秒)
static int httpSocketTimeout = 10000;//socket读写超时时间(单位毫秒)
static int httpMaxPoolSize = 100;
static int httpMonitorInterval = 3000;
static int httpIdelTimeout = 2000;
public static int getHttpIdelTimeout() {
return httpIdelTimeout;
}
public static int getHttpSocketTimeout() {
return httpSocketTimeout;
}
public static int getHttpMaxPoolSize() {
return httpMaxPoolSize;
}
public static int getHttpMonitorInterval() {
return httpMonitorInterval;
}
public static int getHttpConnectTimeout() {
return httpConnectTimeout;
}
}
3）封装HttpClientUtils类--包括连接池的信息
public class HttpClientUtils {
private final static Logger logger = Logger.getLogger(HttpClientUtils.class);
private static CloseableHttpClient httpClient;
private static PoolingHttpClientConnectionManager manager; // 连接池管理类
private static ScheduledExecutorService monitorExecutor; // 监控
private final static Object syncLock = new Object(); // 相当于线程锁,用于线程安全
private static final int CONNECT_TIMEOUT = HttpClientConfig.getHttpConnectTimeout();// 设置连接建立的超时时间为10s
private static final int SOCKET_TIMEOUT = HttpClientConfig.getHttpSocketTimeout();
private static final int MAX_CONN = HttpClientConfig.getHttpMaxPoolSize(); // 最大连接数
private static final int Max_PRE_ROUTE = HttpClientConfig.getHttpMaxPoolSize();
private static final int MAX_ROUTE = HttpClientConfig.getHttpMaxPoolSize();
/**
* 对http请求进行基本设置
*
* @param httpRequestBase
* http请求
*/
private static void setRequestConfig(HttpRequestBase httpRequestBase) {
RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(CONNECT_TIMEOUT)
.setConnectTimeout(CONNECT_TIMEOUT).setSocketTimeout(SOCKET_TIMEOUT).build();
httpRequestBase.setConfig(requestConfig);
}
public static CloseableHttpClient getHttpClient(String url) {
String hostName = url.split("/")[2];
// System.out.println(hostName);
int port = 80;
if (hostName.contains(":")) {
String[] args = hostName.split(":");
hostName = args[0];
port = Integer.parseInt(args[1]);
}
if (httpClient == null) {
// 多线程下多个线程同时调用getHttpClient容易导致重复创建httpClient对象的问题,所以加上了同步锁
synchronized (syncLock) {
if (httpClient == null) {
httpClient = createHttpClient(hostName, port);
// 开启监控线程,对异常和空闲线程进行关闭
monitorExecutor = Executors.newScheduledThreadPool(1);
monitorExecutor.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
// 关闭异常连接
manager.closeExpiredConnections();
// 关闭5s空闲的连接
manager.closeIdleConnections(HttpClientConfig.getHttpIdelTimeout(), TimeUnit.MILLISECONDS);
logger.debug("close expired and idle for over 5s connection");
}
}, HttpClientConfig.getHttpMonitorInterval(), HttpClientConfig.getHttpMonitorInterval(),
TimeUnit.MILLISECONDS);
}
}
}
return httpClient;
}
/**
* 根据host和port构建httpclient实例
*
* @param host
* 要访问的域名
* @param port
* 要访问的端口
* @return
*/
public static CloseableHttpClient createHttpClient(String host, int port) {
ConnectionSocketFactory plainSocketFactory = PlainConnectionSocketFactory.getSocketFactory();
LayeredConnectionSocketFactory sslSocketFactory = SSLConnectionSocketFactory.getSocketFactory();
Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory> create()
.register("http", plainSocketFactory).register("https", sslSocketFactory).build();
manager = new PoolingHttpClientConnectionManager(registry);
// 设置连接参数
manager.setMaxTotal(MAX_CONN); // 最大连接数
manager.setDefaultMaxPerRoute(Max_PRE_ROUTE); // 路由最大连接数
HttpHost httpHost = new HttpHost(host, port);
manager.setMaxPerRoute(new HttpRoute(httpHost), MAX_ROUTE);
// 请求失败时,进行请求重试
HttpRequestRetryHandler handler = new HttpRequestRetryHandler() {
@Override
public boolean retryRequest(IOException e, int i, HttpContext httpContext) {
if (i > 3) {
// 重试超过3次,放弃请求
logger.error("retry has more than 3 time, give up request");
return false;
}
if (e instanceof NoHttpResponseException) {
// 服务器没有响应,可能是服务器断开了连接,应该重试
logger.error("receive no response from server, retry");
return true;
}
if (e instanceof SSLHandshakeException) {
// SSL握手异常
logger.error("SSL hand shake exception");
return false;
}
if (e instanceof InterruptedIOException) {
// 超时
logger.error("InterruptedIOException");
return false;
}
if (e instanceof UnknownHostException) {
// 服务器不可达
logger.error("server host unknown");
return false;
}
if (e instanceof ConnectTimeoutException) {
// 连接超时
logger.error("Connection Time out");
return false;
}
if (e instanceof SSLException) {
logger.error("SSLException");
return false;
}
HttpClientContext context = HttpClientContext.adapt(httpContext);
HttpRequest request = context.getRequest();
if (!(request instanceof HttpEntityEnclosingRequest)) {
// 如果请求不是关闭连接的请求
return true;
}
return false;
}
};
CloseableHttpClient client = HttpClients.custom().setConnectionManager(manager).setRetryHandler(handler)
.build();
return client;
}
/**
* 关闭连接池
*/
public static void closeConnectionPool() {
try {
httpClient.close();
manager.close();
monitorExecutor.shutdown();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 对http请求进行基本设置
*
* @param httpRequestBase
* http请求
*/
private static void setRequestConfig(HttpRequestBase httpRequestBase) {
RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(CONNECT_TIMEOUT)
.setConnectTimeout(CONNECT_TIMEOUT).setSocketTimeout(SOCKET_TIMEOUT).build();
httpRequestBase.setConfig(requestConfig);
}
4）form表单提交
public static String doPostForm(String url, Map<String, String> params) {
HttpPost httpPost = new HttpPost(url);
setRequestConfig(httpPost);
String resultString = "";
CloseableHttpResponse response = null;
try {
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
if (params != null) {
for (String key : params.keySet()) {
builder.addPart(key,
new StringBody(params.get(key), ContentType.create("text/plain", Consts.UTF_8)));
}
}
HttpEntity reqEntity = builder.build();
httpPost.setEntity(reqEntity);
// 发起请求 并返回请求的响应
response = getHttpClient(url).execute(httpPost, HttpClientContext.create());
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (response != null)
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
5）File文件上传
public static String uploadFile(String url, String localFile, String fileParamName, Map<String, String> params) {
HttpPost httpPost = new HttpPost(url);
setRequestConfig(httpPost);
String resultString = "";
CloseableHttpResponse response = null;
try {
// 把文件转换成流对象FileBody
FileBody bin = new FileBody(new File(localFile));
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
// 相当于<input type="file" name="file"/>
builder.addPart("files", bin);
// 相当于<input type="text" name="userName" value=userName>
builder.addPart("filesFileName",
new StringBody(fileParamName, ContentType.create("text/plain", Consts.UTF_8)));
if (params != null) {
for (String key : params.keySet()) {
builder.addPart(key,
new StringBody(params.get(key), ContentType.create("text/plain", Consts.UTF_8)));
}
}
HttpEntity reqEntity = builder.build();
httpPost.setEntity(reqEntity);
// 发起请求 并返回请求的响应
response = getHttpClient(url).execute(httpPost, HttpClientContext.create());
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (response != null)
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
6) 传输Json数据
public static String doPostJson(String url, String json) {
HttpPost httpPost = new HttpPost(url);
setRequestConfig(httpPost);
String resultString = "";
CloseableHttpResponse response = null;
try {
// 设置ContentType(注:如果只是传普通参数的话,ContentType不一定非要用application/json)
// httpPost.setHeader("Content-Type",
// "application/json;charset=utf8");
httpPost.setHeader("Content-Type", "application/json");
// 创建请求内容
StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
httpPost.setEntity(entity);
// 执行http请求
response = getHttpClient(url).execute(httpPost, HttpClientContext.create());
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
logger.error("httpclient的get请求失败,url:" + url, e);
// e.printStackTrace();
} finally {
try {
if (response != null)
response.close();
} catch (IOException e) {
logger.error("IOException的错误", e);
// e.printStackTrace();
}
}
return resultString;
}
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