HttpClient设置连接超时时间

使用HttpClient，一般都需要设置连接超时时间和获取数据超时时间。这两个参数很重要，目的是为了防止访问其他http时，由于超时导致自己的应用受影响。

4.5版本中，这两个参数的设置都抽象到了RequestConfig中，由相应的Builder构建，具体的例子如下:

CloseableHttpClient httpclient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://www.baidu.com");
RequestConfig requestConfig = RequestConfig.custom()
        .setConnectTimeout(5000).setConnectionRequestTimeout(1000)
        .setSocketTimeout(5000).build();
httpGet.setConfig(requestConfig);
CloseableHttpResponse response = null;
try {
    response = httpclient.execute(httpGet);
} catch (IOException e) {
    e.printStackTrace();
}
System.out.println("得到的结果:" + response.getStatusLine());//得到请求结果
HttpEntity entity = response.getEntity();//得到请求回来的数据
String s = EntityUtils.toString(response.getEntity(), "UTF-8");
System.out.println(s);

setConnectTimeout：设置连接超时时间，单位毫秒。

setConnectionRequestTimeout：设置从connect Manager获取Connection 超时时间，单位毫秒。这个属性是新加的属性，因为目前版本是可以共享连接池的。

setSocketTimeout：请求获取数据的超时时间，单位毫秒。 如果访问一个接口，多少时间内无法返回数据，就直接放弃此次调用。

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一、连接超时：connectionTimeout

指的是连接一个url的连接等待时间。比如连google.

org.apache.http.conn.ConnectTimeoutException: Connect to www.google.com:80 [www.google.com/203.98.7.65] failed: connect timed out
    at org.apache.http.impl.conn.HttpClientConnectionOperator.connect(HttpClientConnectionOperator.java:132)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:318)
    at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:363)
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:219)
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:195)
    at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:86)
    at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:106)
    at Test.main(Test.java:22)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: java.net.SocketTimeoutException: connect timed out
    at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at org.apache.http.conn.socket.PlainConnectionSocketFactory.connectSocket(PlainConnectionSocketFactory.java:72)
    at org.apache.http.impl.conn.HttpClientConnectionOperator.connect(HttpClientConnectionOperator.java:123)
    ... 15 more

二、读取数据超时：SocketTimeout

指的是连接上一个url，获取response的返回等待时间。

测试的时候连接url可以是本地开启的一个url，http://localhost:8080/firstTest.htm?method=test

当访问到这个链接时，线程sleep一段时间，来模拟返回response超时。

@RequestMapping(params = "method=test")
public String testMethod(ModelMap model) {
    try {
        Thread.sleep(3000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    System.out.println("call testMethod method.");
    model.addAttribute("name", "test method");
    return "test";
}

参考：

http://blog.csdn.net/hi_kevin/article/details/32316171