RestTemplate的一个请求过程，mark一下

 来看下RestTemplate中默认的的ResponseErrorHandler:

package org.springframework.web.client;

import java.io.IOException;
import java.nio.charset.Charset;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.FileCopyUtils;

/**
 * Spring's default implementation of the {@link ResponseErrorHandler} interface.
 *
 * <p>This error handler checks for the status code on the {@link ClientHttpResponse}:
 * Any code with series {@link org.springframework.http.HttpStatus.Series#CLIENT_ERROR}
 * or {@link org.springframework.http.HttpStatus.Series#SERVER_ERROR} is considered to be
 * an error; this behavior can be changed by overriding the {@link #hasError(HttpStatus)}
 * method. Unknown status codes will be ignored by {@link #hasError(ClientHttpResponse)}.
 *
 * @author Arjen Poutsma
 * @author Rossen Stoyanchev
 * @author Juergen Hoeller
 * @since 3.0
 * @see RestTemplate#setErrorHandler
 */
public class DefaultResponseErrorHandler implements ResponseErrorHandler {

    /**
     * Delegates to {@link #hasError(HttpStatus)} with the response status code.
     */
    @Override
    public boolean hasError(ClientHttpResponse response) throws IOException {
        HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
        return (statusCode != null && hasError(statusCode));
    }

    /**
     * Template method called from {@link #hasError(ClientHttpResponse)}.
     * <p>The default implementation checks if the given status code is
     * {@link HttpStatus.Series#CLIENT_ERROR CLIENT_ERROR} or
     * {@link HttpStatus.Series#SERVER_ERROR SERVER_ERROR}.
     * Can be overridden in subclasses.
     * @param statusCode the HTTP status code
     * @return {@code true} if the response has an error; {@code false} otherwise
     */
    protected boolean hasError(HttpStatus statusCode) {
        return (statusCode.series() == HttpStatus.Series.CLIENT_ERROR ||
                statusCode.series() == HttpStatus.Series.SERVER_ERROR);
    }

    /**
     * Delegates to {@link #handleError(ClientHttpResponse, HttpStatus)} with the response status code.
     */
    @Override
    public void handleError(ClientHttpResponse response) throws IOException {
        HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
        if (statusCode == null) {
            throw new UnknownHttpStatusCodeException(response.getRawStatusCode(), response.getStatusText(),
                    response.getHeaders(), getResponseBody(response), getCharset(response));
        }
        handleError(response, statusCode);
    }

    /**
     * Handle the error in the given response with the given resolved status code.
     * <p>This default implementation throws a {@link HttpClientErrorException} if the response status code
     * is {@link org.springframework.http.HttpStatus.Series#CLIENT_ERROR}, a {@link HttpServerErrorException}
     * if it is {@link org.springframework.http.HttpStatus.Series#SERVER_ERROR},
     * and a {@link RestClientException} in other cases.
     * @since 5.0
     */
    protected void handleError(ClientHttpResponse response, HttpStatus statusCode) throws IOException {
        switch (statusCode.series()) {
            case CLIENT_ERROR:
                throw new HttpClientErrorException(statusCode, response.getStatusText(),
                        response.getHeaders(), getResponseBody(response), getCharset(response));
            case SERVER_ERROR:
                throw new HttpServerErrorException(statusCode, response.getStatusText(),
                        response.getHeaders(), getResponseBody(response), getCharset(response));
            default:
                throw new UnknownHttpStatusCodeException(statusCode.value(), response.getStatusText(),
                        response.getHeaders(), getResponseBody(response), getCharset(response));
        }
    }


    /**
     * Determine the HTTP status of the given response.
     * @param response the response to inspect
     * @return the associated HTTP status
     * @throws IOException in case of I/O errors
     * @throws UnknownHttpStatusCodeException in case of an unknown status code
     * that cannot be represented with the {@link HttpStatus} enum
     * @since 4.3.8
     * @deprecated as of 5.0, in favor of {@link #handleError(ClientHttpResponse, HttpStatus)}
     */
    @Deprecated
    protected HttpStatus getHttpStatusCode(ClientHttpResponse response) throws IOException {
        HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
        if (statusCode == null) {
            throw new UnknownHttpStatusCodeException(response.getRawStatusCode(), response.getStatusText(),
                    response.getHeaders(), getResponseBody(response), getCharset(response));
        }
        return statusCode;
    }

    /**
     * Read the body of the given response (for inclusion in a status exception).
     * @param response the response to inspect
     * @return the response body as a byte array,
     * or an empty byte array if the body could not be read
     * @since 4.3.8
     */
    protected byte[] getResponseBody(ClientHttpResponse response) {
        try {
            return FileCopyUtils.copyToByteArray(response.getBody());
        }
        catch (IOException ex) {
            // ignore
        }
        return new byte[0];
    }

    /**
     * Determine the charset of the response (for inclusion in a status exception).
     * @param response the response to inspect
     * @return the associated charset, or {@code null} if none
     * @since 4.3.8
     */
    @Nullable
    protected Charset getCharset(ClientHttpResponse response) {
        HttpHeaders headers = response.getHeaders();
        MediaType contentType = headers.getContentType();
        return (contentType != null ? contentType.getCharset() : null);
    }

}

 

    /**
     * Execute the given method on the provided URI.
     * <p>The {@link ClientHttpRequest} is processed using the {@link RequestCallback};
     * the response with the {@link ResponseExtractor}.
     * @param url the fully-expanded URL to connect to
     * @param method the HTTP method to execute (GET, POST, etc.)
     * @param requestCallback object that prepares the request (can be {@code null})
     * @param responseExtractor object that extracts the return value from the response (can be {@code null})
     * @return an arbitrary object, as returned by the {@link ResponseExtractor}
     */
    @Nullable
    protected <T> T doExecute(URI url, @Nullable HttpMethod method, @Nullable RequestCallback requestCallback,
            @Nullable ResponseExtractor<T> responseExtractor) throws RestClientException {

        Assert.notNull(url, "'url' must not be null");
        Assert.notNull(method, "'method' must not be null");
        ClientHttpResponse response = null;
        try {
            ClientHttpRequest request = createRequest(url, method);
            if (requestCallback != null) {
                requestCallback.doWithRequest(request);
            }
            response = request.execute();
            handleResponse(url, method, response);
            if (responseExtractor != null) {
                return responseExtractor.extractData(response);
            }
            else {
                return null;
            }
        }
        catch (IOException ex) {
            String resource = url.toString();
            String query = url.getRawQuery();
            resource = (query != null ? resource.substring(0, resource.indexOf('?')) : resource);
            throw new ResourceAccessException("I/O error on " + method.name() +
                    " request for "" + resource + "": " + ex.getMessage(), ex);
        }
        finally {
            if (response != null) {
                response.close();
            }
        }
    }

 

/**
 * Simple implementation of {@link ClientHttpRequest} that wraps another request.
 *
 * @author Arjen Poutsma
 * @since 3.1
 */
final class BufferingClientHttpRequestWrapper extends AbstractBufferingClientHttpRequest {

    private final ClientHttpRequest request;


    BufferingClientHttpRequestWrapper(ClientHttpRequest request) {
        this.request = request;
    }


    @Override
    @Nullable
    public HttpMethod getMethod() {
        return this.request.getMethod();
    }

    @Override
    public String getMethodValue() {
        return this.request.getMethodValue();
    }

    @Override
    public URI getURI() {
        return this.request.getURI();
    }

    @Override
    protected ClientHttpResponse executeInternal(HttpHeaders headers, byte[] bufferedOutput) throws IOException {
        this.request.getHeaders().putAll(headers);
        StreamUtils.copy(bufferedOutput, this.request.getBody());
        ClientHttpResponse response = this.request.execute();
        return new BufferingClientHttpResponseWrapper(response);
    }

}

org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://zkh-gbb-website/user": Connect to 172.16.5.45:8080 [/172.16.5.45] failed: connect timed out; nested exception is org.apache.http.conn.ConnectTimeoutException: Connect to 172.16.5.45:8080 [/172.16.5.45] failed: connect timed out

	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:741)
	at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:684)
	at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:332)
	at com.zkh360.api.TestObjectMapperControllerTest.testObjectMapper(TestObjectMapperControllerTest.java:27)
	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 org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:73)
	at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:83)
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.apache.http.conn.ConnectTimeoutException: Connect to 172.16.5.45:8080 [/172.16.5.45] failed: connect timed out
	at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:151)
	at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:373)
	at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:381)
	at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:237)
	at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185)
	at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89)
	at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:111)
	at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
	at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
	at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56)
	at org.springframework.http.client.HttpComponentsClientHttpRequest.executeInternal(HttpComponentsClientHttpRequest.java:87)
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
	at org.springframework.http.client.BufferingClientHttpRequestWrapper.executeInternal(BufferingClientHttpRequestWrapper.java:63)
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
	at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:108)
	at org.springframework.cloud.client.loadbalancer.LoadBalancerRequestFactory.lambda$createRequest$0(LoadBalancerRequestFactory.java:59)
	at org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient.execute(RibbonLoadBalancerClient.java:112)
	at org.springframework.cloud.client.loadbalancer.RetryLoadBalancerInterceptor.lambda$intercept$0(RetryLoadBalancerInterceptor.java:76)
	at org.springframework.retry.support.RetryTemplate.doExecute(RetryTemplate.java:287)
	at org.springframework.retry.support.RetryTemplate.execute(RetryTemplate.java:180)
	at org.springframework.cloud.client.loadbalancer.RetryLoadBalancerInterceptor.intercept(RetryLoadBalancerInterceptor.java:67)
	at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:92)
	at com.zkh360.core.config.LoggingClientHttpRequestInterceptor.intercept(RestTemplateConfig.java:290)
	at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:92)
	at org.springframework.http.client.InterceptingClientHttpRequest.executeInternal(InterceptingClientHttpRequest.java:76)
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:727)
	... 33 more
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:75)
	at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:142)
	... 62 more

17:14:36.979 [main] DEBUG org.springframework.web.client.RestTemplate - Created GET request for "http://localhost:8080/test/session/get"
17:14:36.992 [main] DEBUG org.springframework.web.client.RestTemplate - Setting request Accept header to [application/json, application/*+json]
17:14:37.007 [main] DEBUG org.apache.http.client.protocol.RequestAddCookies - CookieSpec selected: default
17:14:37.015 [main] DEBUG org.apache.http.client.protocol.RequestAuthCache - Auth cache not set in the context
17:14:37.016 [main] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection request: [route: {}->http://localhost:8080][total kept alive: 0; route allocated: 0 of 200; total allocated: 0 of 300]
17:14:37.028 [main] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection leased: [id: 0][route: {}->http://localhost:8080][total kept alive: 0; route allocated: 1 of 200; total allocated: 1 of 300]
17:14:37.030 [main] DEBUG org.apache.http.impl.execchain.MainClientExec - Opening connection {}->http://localhost:8080
17:14:37.037 [main] DEBUG org.apache.http.impl.conn.DefaultHttpClientConnectionOperator - Connecting to localhost/127.0.0.1:8080
17:14:37.038 [main] DEBUG org.apache.http.impl.conn.DefaultHttpClientConnectionOperator - Connection established 127.0.0.1:60552<->127.0.0.1:8080
17:14:37.038 [main] DEBUG org.apache.http.impl.conn.DefaultManagedHttpClientConnection - http-outgoing-0: set socket timeout to 5000
17:14:37.038 [main] DEBUG org.apache.http.impl.execchain.MainClientExec - Executing request GET /test/session/get HTTP/1.1
17:14:37.038 [main] DEBUG org.apache.http.impl.execchain.MainClientExec - Target auth state: UNCHALLENGED
17:14:37.038 [main] DEBUG org.apache.http.impl.execchain.MainClientExec - Proxy auth state: UNCHALLENGED
17:14:37.040 [main] DEBUG org.apache.http.headers - http-outgoing-0 >> GET /test/session/get HTTP/1.1
17:14:37.040 [main] DEBUG org.apache.http.headers - http-outgoing-0 >> Accept: application/json, application/*+json
17:14:37.040 [main] DEBUG org.apache.http.headers - http-outgoing-0 >> Content-Type: application/json;charset=UTF-8
17:14:37.040 [main] DEBUG org.apache.http.headers - http-outgoing-0 >> Host: localhost:8080
17:14:37.040 [main] DEBUG org.apache.http.headers - http-outgoing-0 >> Connection: Keep-Alive
17:14:37.040 [main] DEBUG org.apache.http.headers - http-outgoing-0 >> User-Agent: Apache-HttpClient/4.5.6 (Java/1.8.0_144)
17:14:37.040 [main] DEBUG org.apache.http.headers - http-outgoing-0 >> Accept-Encoding: gzip,deflate
17:14:37.040 [main] DEBUG org.apache.http.wire - http-outgoing-0 >> "GET /test/session/get HTTP/1.1[
][
]"
17:14:37.040 [main] DEBUG org.apache.http.wire - http-outgoing-0 >> "Accept: application/json, application/*+json[
][
]"
17:14:37.040 [main] DEBUG org.apache.http.wire - http-outgoing-0 >> "Content-Type: application/json;charset=UTF-8[
][
]"
17:14:37.040 [main] DEBUG org.apache.http.wire - http-outgoing-0 >> "Host: localhost:8080[
][
]"
17:14:37.040 [main] DEBUG org.apache.http.wire - http-outgoing-0 >> "Connection: Keep-Alive[
][
]"
17:14:37.040 [main] DEBUG org.apache.http.wire - http-outgoing-0 >> "User-Agent: Apache-HttpClient/4.5.6 (Java/1.8.0_144)[
][
]"
17:14:37.040 [main] DEBUG org.apache.http.wire - http-outgoing-0 >> "Accept-Encoding: gzip,deflate[
][
]"
17:14:37.040 [main] DEBUG org.apache.http.wire - http-outgoing-0 >> "[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "HTTP/1.1 200 [
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "X-Application-Context: application:dev,redis,log,flyway[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "ETag: "099914b932bd37a50b983c5e7c90ae93b"[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "X-Content-Type-Options: nosniff[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "X-XSS-Protection: 1; mode=block[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "X-Frame-Options: DENY[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "Set-Cookie: SESSION=36fed5e6-fe6d-4b9e-87a1-7f7aa5ef8bf0; Path=/; HttpOnly[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "Content-Type: application/json[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "Content-Length: 2[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "Date: Thu, 13 Dec 2018 09:14:37 GMT[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "[
][
]"
17:14:37.056 [main] DEBUG org.apache.http.wire - http-outgoing-0 << "{}"
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << HTTP/1.1 200 
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << X-Application-Context: application:dev,redis,log,flyway
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << ETag: "099914b932bd37a50b983c5e7c90ae93b"
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << X-Content-Type-Options: nosniff
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << X-XSS-Protection: 1; mode=block
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << X-Frame-Options: DENY
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << Set-Cookie: SESSION=36fed5e6-fe6d-4b9e-87a1-7f7aa5ef8bf0; Path=/; HttpOnly
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << Content-Type: application/json
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << Content-Length: 2
17:14:37.058 [main] DEBUG org.apache.http.headers - http-outgoing-0 << Date: Thu, 13 Dec 2018 09:14:37 GMT
17:14:37.061 [main] DEBUG org.apache.http.impl.execchain.MainClientExec - Connection can be kept alive indefinitely
17:14:37.066 [main] DEBUG org.apache.http.client.protocol.ResponseProcessCookies - Cookie accepted [SESSION="36fed5e6-fe6d-4b9e-87a1-7f7aa5ef8bf0", version:0, domain:localhost, path:/, expiry:null]
17:14:37.070 [main] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection [id: 0][route: {}->http://localhost:8080] can be kept alive indefinitely
17:14:37.070 [main] DEBUG org.apache.http.impl.conn.DefaultManagedHttpClientConnection - http-outgoing-0: set socket timeout to 0
17:14:37.070 [main] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection released: [id: 0][route: {}->http://localhost:8080][total kept alive: 1; route allocated: 1 of 200; total allocated: 1 of 300]
17:14:37.070 [main] INFO com.tangcheng.app.business.config.LoggingClientHttpRequestInterceptor - cost:[74]ms,GET url:http://localhost:8080/test/session/get. request:,
response:{},
17:14:37.072 [main] DEBUG org.springframework.web.client.RestTemplate - GET request for "http://localhost:8080/test/session/get" resulted in 200 ()
17:14:37.073 [main] DEBUG org.springframework.web.client.RestTemplate - Reading [java.util.Map<java.lang.String, java.lang.Object>] as "application/json" using [org.springframework.http.converter.json.MappingJackson2HttpMessageConverter@2dca0d64]
{}
17:14:37.098 [main] DEBUG org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate - Retrieved ApplicationContext from cache with key [[MergedContextConfiguration@481a15ff testClass = RestTemplateApiTest, locations = '{}', classes = '{class com.tangcheng.app.business.config.RestTemplateConfig}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{}', contextCustomizers = set[org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@6321e813, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@57855c9a, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5f282abb], contextLoader = 'org.springframework.test.context.support.DelegatingSmartContextLoader', parent = [null]]]
17:14:37.098 [main] DEBUG org.springframework.test.context.cache - Spring test ApplicationContext cache statistics: [DefaultContextCache@3f91b517 size = 1, maxSize = 32, parentContextCount = 0, hitCount = 2, missCount = 1]
17:14:37.098 [main] DEBUG org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate - Retrieved ApplicationContext from cache with key [[MergedContextConfiguration@481a15ff testClass = RestTemplateApiTest, locations = '{}', classes = '{class com.tangcheng.app.business.config.RestTemplateConfig}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{}', contextCustomizers = set[org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@6321e813, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@57855c9a, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5f282abb], contextLoader = 'org.springframework.test.context.support.DelegatingSmartContextLoader', parent = [null]]]
17:14:37.098 [main] DEBUG org.springframework.test.context.cache - Spring test ApplicationContext cache statistics: [DefaultContextCache@3f91b517 size = 1, maxSize = 32, parentContextCount = 0, hitCount = 3, missCount = 1]
17:14:37.099 [main] DEBUG org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate - Retrieved ApplicationContext from cache with key [[MergedContextConfiguration@481a15ff testClass = RestTemplateApiTest, locations = '{}', classes = '{class com.tangcheng.app.business.config.RestTemplateConfig}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{}', contextCustomizers = set[org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@6321e813, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@57855c9a, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5f282abb], contextLoader = 'org.springframework.test.context.support.DelegatingSmartContextLoader', parent = [null]]]
17:14:37.100 [main] DEBUG org.springframework.test.context.cache - Spring test ApplicationContext cache statistics: [DefaultContextCache@3f91b517 size = 1, maxSize = 32, parentContextCount = 0, hitCount = 4, missCount = 1]
17:14:37.100 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'org.springframework.boot.test.mock.mockito.MockitoBeans'
17:14:37.100 [main] DEBUG org.springframework.test.context.support.AbstractDirtiesContextTestExecutionListener - After test method: context [DefaultTestContext@646007f4 testClass = RestTemplateApiTest, testInstance = com.tangcheng.rest.RestTemplateApiTest@319b92f3, testMethod = givenApiWithGenericReturnType_thenUseExchange@RestTemplateApiTest, testException = [null], mergedContextConfiguration = [MergedContextConfiguration@481a15ff testClass = RestTemplateApiTest, locations = '{}', classes = '{class com.tangcheng.app.business.config.RestTemplateConfig}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{}', contextCustomizers = set[org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@6321e813, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@57855c9a, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5f282abb], contextLoader = 'org.springframework.test.context.support.DelegatingSmartContextLoader', parent = [null]]], class annotated with @DirtiesContext [false] with mode [null], method annotated with @DirtiesContext [false] with mode [null].
17:14:37.105 [main] DEBUG org.springframework.test.context.support.AbstractDirtiesContextTestExecutionListener - After test class: context [DefaultTestContext@646007f4 testClass = RestTemplateApiTest, testInstance = [null], testMethod = [null], testException = [null], mergedContextConfiguration = [MergedContextConfiguration@481a15ff testClass = RestTemplateApiTest, locations = '{}', classes = '{class com.tangcheng.app.business.config.RestTemplateConfig}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{}', contextCustomizers = set[org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@6321e813, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@57855c9a, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5f282abb], contextLoader = 'org.springframework.test.context.support.DelegatingSmartContextLoader', parent = [null]]], class annotated with @DirtiesContext [false] with mode [null].
17:14:37.106 [Thread-0] INFO com.tangcheng.app.business.config.RestTemplateConfig - closing http client
17:14:37.106 [Thread-1] INFO org.springframework.context.support.GenericApplicationContext - Closing org.springframework.context.support.GenericApplicationContext@3d0f8e03: startup date [Thu Dec 13 17:14:35 CST 2018]; root of context hierarchy
17:14:37.106 [Thread-0] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection manager is shutting down
17:14:37.106 [Thread-0] DEBUG org.apache.http.impl.conn.DefaultManagedHttpClientConnection - http-outgoing-0: Close connection
17:14:37.106 [Thread-1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'lifecycleProcessor'
17:14:37.106 [Thread-1] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@143640d5: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.event.internalEventListenerProcessor,org.springframework.context.event.internalEventListenerFactory,restTemplateConfig,org.springframework.boot.test.mock.mockito.MockitoPostProcessor$SpyPostProcessor,org.springframework.boot.test.mock.mockito.MockitoPostProcessor,restTemplate]; root of factory hierarchy
17:14:37.107 [Thread-0] DEBUG org.apache.http.impl.conn.PoolingHttpClientConnectionManager - Connection manager shut down
17:14:37.107 [Thread-0] INFO com.tangcheng.app.business.config.RestTemplateConfig - http client closed

感觉挺有意思的