1.连接池原理(待续)
2.httpclient连接池如何保证连接交回至连接池管理器
2.1 方式一
- HttpResponse response = (httpMethod);
- HttpEntity entity = response.getEntity();
- //这两段代码返回的entity是HttpEntity的实现类BasicManagedEntity。此时与本次请求关联的连接尚未归还至连接管理器。需要调用以下两条语句:
- InputStream instream = entity.getContent();//获得响应具体内容
- //处理响应:代码省略
- instream.close();//关闭输入流同时会将连接交回至连接处理器
2.2 方式二使用默认的响应处理器BasicResponseHandler
- httpClient Jar包中提供BasicResponseHandler。如果返回的类型能确定需要解码为String类型的话,推荐使用该响应处理器。
- 该处理器解码http连接响应字节流为String类型,对返回码>=300的响应进行了异常封装,并能够保证连接交还给连接池管理器。
- 该处理器将字节解码为字符的过程依次如下:
- 1)如果响应http报文Head部分由指定的charset,则使用该charset进行解码,否则进行下一步。例如使用UTF-8解码以下响应:DEBUG org.apache.http.headers - $amp;
- 2)如果响应报文未执行charset,则使用传入EntityUntils.toString()时指定的charset进行解码。否则进行下一步
- 3)使用ISO-8859-1进行解码。
3.实现连接池(待续)
4.遇到的问题
4.1 连接池阻塞,频繁的报以下错误信息
- pooling post() method executing IOException:java.net.SocketTimeoutException: Read timed out
- java.net.SocketTimeoutException: Read timed out
- at java.net.SocketInputStream.socketRead0(Native Method)
- at java.net.SocketInputStream.read(SocketInputStream.java:129)
- at org.apache.http.impl.io.SessionInputBufferImpl.streamRead(SessionInputBufferImpl.java:136)
- at org.apache.http.impl.io.SessionInputBufferImpl.fillBuffer(SessionInputBufferImpl.java:152)
- at org.apache.http.impl.io.SessionInputBufferImpl.readLine(SessionInputBufferImpl.java:270)
- at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:140)
- at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:57)
- at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:260)
- at org.apache.http.impl.DefaultBHttpClientConnection.receiveResponseHeader(DefaultBHttpClientConnection.java:161)
- at sun.reflect.GeneratedMethodAccessor96.invoke(Unknown Source)
- at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
- at java.lang.reflect.Method.invoke(Method.java:597)
- at org.apache.http.impl.conn.CPoolProxy.invoke(CPoolProxy.java:138)
- at com.sun.proxy.$Proxy43.receiveResponseHeader(Unknown Source)
- at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:271)
- at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:123)
- at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:254)
- at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:195)
- at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:85)
- at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108)
- at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:186)
- at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:72)
- at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:214)
- at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:160)
- at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:136)
上述问题主要问题是连接池中httpclient连接在遇到异常情况下未正常关闭导致,出问题时候连接池关于回收httpclient连接的代码如下:
- private ResponseHandler<String> responseHandler = new ResponseHandler<String>() {
- public String handleResponse(final HttpResponse response) throws ClientProtocolException, IOException {
- int status = response.getStatusLine().getStatusCode();
- if (status >= HttpStatus.SC_OK && status < HttpStatus.SC_MULTIPLE_CHOICES) {
- HttpEntity entity = response.getEntity();
- Charset charset = ContentType.getOrDefault(entity).getCharset();
- if (charset == null) {
- charset = Charset.forName("UTF-8");
- }
- return entity != null ? EntityUtils.toString(entity, charset) : null;
- } else {
- //注意这里没有告诉连接池要回收连接
- throw new ClientProtocolException("Unexpected response status: " + status);
- }
- };
修改后的代码如下:
- private ResponseHandler<String> responseHandler = new ResponseHandler<String>() {
- public String handleResponse(final HttpResponse response) throws ClientProtocolException, IOException {
- final StatusLine statusLine = response.getStatusLine();
- final HttpEntity entity = response.getEntity();
- if (statusLine.getStatusCode() >= HttpStatus.SC_MULTIPLE_CHOICES||statusLine.getStatusCode()<HttpStatus.SC_OK) {
- //主动回收httpclient连接
- EntityUtils.consume(entity);
- throw new HttpResponseException(statusLine.getStatusCode(),
- statusLine.getReasonPhrase());
- }
- Charset charset = ContentType.getOrDefault(entity).getCharset();
- if (charset == null) {
- charset = Charset.forName("UTF-8");
- }
- return entity != null ? EntityUtils.toString(entity, charset) : null;
- }
- };