org.springframework.web.client.RestTemplate Maven / Gradle / Ivy
/*
* Copyright 2002-2009 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.client;
import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpRequest;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.http.client.support.HttpAccessor;
import org.springframework.http.converter.ByteArrayHttpMessageConverter;
import org.springframework.http.converter.FormHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.http.converter.json.MappingJacksonHttpMessageConverter;
import org.springframework.http.converter.xml.SourceHttpMessageConverter;
import org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.web.util.UriTemplate;
/**
* The central class for client-side HTTP access. It simplifies communication with HTTP servers, and
* enforces RESTful principles. It handles HTTP connections, leaving application code to provide URLs (with possible
* template variables) and extract results.
*
* The main entry points of this template are the methods named after the six main HTTP methods:
HTTP
* method RestTemplate methods DELETE {@link #delete} GET {@link #getForObject} HEAD {@link #headForHeaders} OPTIONS {@link #optionsForAllow} POST {@link #postForLocation} {@link #postForObject} PUT {@link #put} any {@link #execute}
*
* For each of these HTTP methods, there are three corresponding Java methods in the {@code RestTemplate}. Two
* variant take a {@code String} URI as first argument (eg. {@link #getForObject(String, Class, Object[])}, {@link
* #getForObject(String, Class, Map)}), and are capable of substituting any {@linkplain UriTemplate URI templates} in
* that URL using either a {@code String} variable arguments array, or a {@code Map}. The string varargs
* variant expands the given template variables in order, so that
*
* String result = restTemplate.getForObject("http://example.com/hotels/{hotel}/bookings/{booking}", String.class,"42",
* "21");
*
* will perform a GET on {@code http://example.com/hotels/42/bookings/21}. The map variant expands the template based on
* variable name, and is therefore more useful when using many variables, or when a single variable is used multiple
* times. For example:
*
* Map<String, String> vars = Collections.singletonMap("hotel", "42");
* String result = restTemplate.getForObject("http://example.com/hotels/{hotel}/rooms/{hotel}", String.class, vars);
*
* will perform a GET on {@code http://example.com/hotels/42/rooms/42}. Alternatively, there are {@link URI} variant
* methods ({@link #getForObject(URI, Class)}), which do not allow for URI templates, but allow you to reuse a single,
* expanded URI multiple times.
*
* Furthermore, the {@code String}-argument methods assume that the URL String is unencoded. This means that
*
* restTemplate.getForObject("http://example.com/hotel list");
*
* will perform a GET on {@code http://example.com/hotel%20list}. As a result, any URL passed that is already encoded
* will be encoded twice (i.e. {@code http://example.com/hotel%20list} will become {@code
* http://example.com/hotel%2520list}). If this behavior is undesirable, use the {@code URI}-argument methods, which
* will not perform any URL encoding.
*
* Objects passed to and returned from these methods are converted to and from HTTP messages by {@link
* HttpMessageConverter} instances. Converters for the main mime types are registered by default, but you can also write
* your own converter and register it via the {@link #setMessageConverters messageConverters} bean property.
*
*
This template uses a {@link org.springframework.http.client.SimpleClientHttpRequestFactory} and a {@link
* DefaultResponseErrorHandler} as default strategies for creating HTTP connections or handling HTTP errors,
* respectively. These defaults can be overridden through the {@link #setRequestFactory(ClientHttpRequestFactory)
* requestFactory} and {@link #setErrorHandler(ResponseErrorHandler) errorHandler} bean properties.
*
* @author Arjen Poutsma
* @see HttpMessageConverter
* @see RequestCallback
* @see ResponseExtractor
* @see ResponseErrorHandler
* @since 3.0
*/
public class RestTemplate extends HttpAccessor implements RestOperations {
private static final boolean jaxb2Present =
ClassUtils.isPresent("javax.xml.bind.Binder", RestTemplate.class.getClassLoader());
private static final boolean jacksonPresent =
ClassUtils.isPresent("org.codehaus.jackson.map.ObjectMapper", RestTemplate.class.getClassLoader()) &&
ClassUtils.isPresent("org.codehaus.jackson.JsonGenerator", RestTemplate.class.getClassLoader());
private final ResponseExtractor headersExtractor = new HeadersExtractor();
private List> messageConverters = new ArrayList>();
private ResponseErrorHandler errorHandler = new DefaultResponseErrorHandler();
/** Create a new instance of the {@link RestTemplate} using default settings. */
public RestTemplate() {
this.messageConverters.add(new ByteArrayHttpMessageConverter());
this.messageConverters.add(new StringHttpMessageConverter());
this.messageConverters.add(new FormHttpMessageConverter());
this.messageConverters.add(new SourceHttpMessageConverter());
if (jaxb2Present) {
this.messageConverters.add(new Jaxb2RootElementHttpMessageConverter());
}
if (jacksonPresent) {
this.messageConverters.add(new MappingJacksonHttpMessageConverter());
}
}
/**
* Create a new instance of the {@link RestTemplate} based on the given {@link ClientHttpRequestFactory}.
* @param requestFactory HTTP request factory to use
* @see org.springframework.http.client.SimpleClientHttpRequestFactory
* @see org.springframework.http.client.CommonsClientHttpRequestFactory
*/
public RestTemplate(ClientHttpRequestFactory requestFactory) {
this();
setRequestFactory(requestFactory);
}
/**
* Set the message body converters to use. These converters are used to convert from and to HTTP requests and
* responses.
*/
public void setMessageConverters(List> messageConverters) {
Assert.notEmpty(messageConverters, "'messageConverters' must not be empty");
this.messageConverters = messageConverters;
}
/** Returns the message body converters. These converters are used to convert from and to HTTP requests and responses. */
public List> getMessageConverters() {
return this.messageConverters;
}
/** Set the error handler. */
public void setErrorHandler(ResponseErrorHandler errorHandler) {
Assert.notNull(errorHandler, "'errorHandler' must not be null");
this.errorHandler = errorHandler;
}
/** Return the error handler. By default, this is the {@link DefaultResponseErrorHandler}. */
public ResponseErrorHandler getErrorHandler() {
return this.errorHandler;
}
// GET
public T getForObject(String url, Class responseType, Object... urlVariables) throws RestClientException {
AcceptHeaderRequestCallback requestCallback = new AcceptHeaderRequestCallback(responseType);
HttpMessageConverterExtractor responseExtractor =
new HttpMessageConverterExtractor(responseType, getMessageConverters());
return execute(url, HttpMethod.GET, requestCallback, responseExtractor, urlVariables);
}
public T getForObject(String url, Class responseType, Map urlVariables) throws RestClientException {
AcceptHeaderRequestCallback requestCallback = new AcceptHeaderRequestCallback(responseType);
HttpMessageConverterExtractor responseExtractor =
new HttpMessageConverterExtractor(responseType, getMessageConverters());
return execute(url, HttpMethod.GET, requestCallback, responseExtractor, urlVariables);
}
public T getForObject(URI url, Class responseType) throws RestClientException {
AcceptHeaderRequestCallback requestCallback = new AcceptHeaderRequestCallback(responseType);
HttpMessageConverterExtractor responseExtractor =
new HttpMessageConverterExtractor(responseType, getMessageConverters());
return execute(url, HttpMethod.GET, requestCallback, responseExtractor);
}
// HEAD
public HttpHeaders headForHeaders(String url, Object... urlVariables) throws RestClientException {
return execute(url, HttpMethod.HEAD, null, this.headersExtractor, urlVariables);
}
public HttpHeaders headForHeaders(String url, Map urlVariables) throws RestClientException {
return execute(url, HttpMethod.HEAD, null, this.headersExtractor, urlVariables);
}
public HttpHeaders headForHeaders(URI url) throws RestClientException {
return execute(url, HttpMethod.HEAD, null, this.headersExtractor);
}
// POST
public URI postForLocation(String url, Object request, Object... urlVariables) throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request);
HttpHeaders headers = execute(url, HttpMethod.POST, requestCallback, this.headersExtractor, urlVariables);
return headers.getLocation();
}
public URI postForLocation(String url, Object request, Map urlVariables)
throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request);
HttpHeaders headers = execute(url, HttpMethod.POST, requestCallback, this.headersExtractor, urlVariables);
return headers.getLocation();
}
public URI postForLocation(URI url, Object request) throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request);
HttpHeaders headers = execute(url, HttpMethod.POST, requestCallback, this.headersExtractor);
return headers.getLocation();
}
public T postForObject(String url, Object request, Class responseType, Object... uriVariables)
throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request, responseType);
HttpMessageConverterExtractor responseExtractor =
new HttpMessageConverterExtractor(responseType, getMessageConverters());
return execute(url, HttpMethod.POST, requestCallback, responseExtractor, uriVariables);
}
public T postForObject(String url, Object request, Class responseType, Map uriVariables)
throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request, responseType);
HttpMessageConverterExtractor responseExtractor =
new HttpMessageConverterExtractor(responseType, getMessageConverters());
return execute(url, HttpMethod.POST, requestCallback, responseExtractor, uriVariables);
}
public T postForObject(URI url, Object request, Class responseType) throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request, responseType);
HttpMessageConverterExtractor responseExtractor =
new HttpMessageConverterExtractor(responseType, getMessageConverters());
return execute(url, HttpMethod.POST, requestCallback, responseExtractor);
}
// PUT
public void put(String url, Object request, Object... urlVariables) throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request);
execute(url, HttpMethod.PUT, requestCallback, null, urlVariables);
}
public void put(String url, Object request, Map urlVariables) throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request);
execute(url, HttpMethod.PUT, requestCallback, null, urlVariables);
}
public void put(URI url, Object request) throws RestClientException {
PostPutCallback requestCallback = new PostPutCallback(request);
execute(url, HttpMethod.PUT, requestCallback, null);
}
// DELETE
public void delete(String url, Object... urlVariables) throws RestClientException {
execute(url, HttpMethod.DELETE, null, null, urlVariables);
}
public void delete(String url, Map urlVariables) throws RestClientException {
execute(url, HttpMethod.DELETE, null, null, urlVariables);
}
public void delete(URI url) throws RestClientException {
execute(url, HttpMethod.DELETE, null, null);
}
// OPTIONS
public Set optionsForAllow(String url, Object... urlVariables) throws RestClientException {
HttpHeaders headers = execute(url, HttpMethod.OPTIONS, null, this.headersExtractor, urlVariables);
return headers.getAllow();
}
public Set optionsForAllow(String url, Map urlVariables) throws RestClientException {
HttpHeaders headers = execute(url, HttpMethod.OPTIONS, null, this.headersExtractor, urlVariables);
return headers.getAllow();
}
public Set optionsForAllow(URI url) throws RestClientException {
HttpHeaders headers = execute(url, HttpMethod.OPTIONS, null, this.headersExtractor);
return headers.getAllow();
}
// general execution
public T execute(String url, HttpMethod method, RequestCallback requestCallback,
ResponseExtractor responseExtractor, Object... urlVariables) throws RestClientException {
UriTemplate uriTemplate = new UriTemplate(url);
URI expanded = uriTemplate.expand(urlVariables);
return doExecute(expanded, method, requestCallback, responseExtractor);
}
public T execute(String url, HttpMethod method, RequestCallback requestCallback,
ResponseExtractor responseExtractor, Map urlVariables) throws RestClientException {
UriTemplate uriTemplate = new UriTemplate(url);
URI expanded = uriTemplate.expand(urlVariables);
return doExecute(expanded, method, requestCallback, responseExtractor);
}
public T execute(URI url, HttpMethod method, RequestCallback requestCallback,
ResponseExtractor responseExtractor) throws RestClientException {
return doExecute(url, method, requestCallback, responseExtractor);
}
/**
* Execute the given method on the provided URI. 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 null)
* @param responseExtractor object that extracts the return value from the response (can be null)
* @return an arbitrary object, as returned by the {@link ResponseExtractor}
*/
protected T doExecute(URI url, HttpMethod method, RequestCallback requestCallback,
ResponseExtractor 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();
if (!getErrorHandler().hasError(response)) {
logResponseStatus(method, url, response);
}
else {
handleResponseError(method, url, response);
}
if (responseExtractor != null) {
return responseExtractor.extractData(response);
}
else {
return null;
}
}
catch (IOException ex) {
throw new ResourceAccessException("I/O error: " + ex.getMessage(), ex);
}
finally {
if (response != null) {
response.close();
}
}
}
private void logResponseStatus(HttpMethod method, URI url, ClientHttpResponse response) {
if (logger.isDebugEnabled()) {
try {
logger.debug(
method.name() + " request for \"" + url + "\" resulted in " + response.getStatusCode() + " (" +
response.getStatusText() + ")");
}
catch (IOException e) {
// ignore
}
}
}
private void handleResponseError(HttpMethod method, URI url, ClientHttpResponse response) throws IOException {
if (logger.isWarnEnabled()) {
try {
logger.warn(
method.name() + " request for \"" + url + "\" resulted in " + response.getStatusCode() + " (" +
response.getStatusText() + "); invoking error handler");
}
catch (IOException e) {
// ignore
}
}
getErrorHandler().handleError(response);
}
/**
* Request callback implementation that prepares the request's accept headers.
*/
private class AcceptHeaderRequestCallback implements RequestCallback {
private final Class responseType;
private AcceptHeaderRequestCallback() {
responseType = null;
}
private AcceptHeaderRequestCallback(Class responseType) {
this.responseType = responseType;
}
@SuppressWarnings("unchecked")
public void doWithRequest(ClientHttpRequest request) throws IOException {
if (responseType != null) {
List allSupportedMediaTypes = new ArrayList();
for (HttpMessageConverter messageConverter : getMessageConverters()) {
if (messageConverter.canRead(responseType, null)) {
List supportedMediaTypes = messageConverter.getSupportedMediaTypes();
for (MediaType supportedMediaType : supportedMediaTypes) {
if (supportedMediaType.getCharSet() != null) {
supportedMediaType =
new MediaType(supportedMediaType.getType(), supportedMediaType.getSubtype());
}
allSupportedMediaTypes.add(supportedMediaType);
}
}
}
if (!allSupportedMediaTypes.isEmpty()) {
Collections.sort(allSupportedMediaTypes);
request.getHeaders().setAccept(allSupportedMediaTypes);
}
}
}
}
/**
* Request callback implementation that writes the given object to the request stream.
*/
private class PostPutCallback extends AcceptHeaderRequestCallback {
private final Object requestBody;
private final MediaType requestContentType;
private PostPutCallback(Object requestBody) {
this.requestBody = requestBody;
this.requestContentType = null;
}
private PostPutCallback(Object requestBody, Class responseType) {
super(responseType);
this.requestBody = requestBody;
this.requestContentType = null;
}
@Override
@SuppressWarnings("unchecked")
public void doWithRequest(ClientHttpRequest httpRequest) throws IOException {
super.doWithRequest(httpRequest);
if (requestBody != null) {
Class requestType = requestBody.getClass();
for (HttpMessageConverter messageConverter : getMessageConverters()) {
if (messageConverter.canWrite(requestType, requestContentType)) {
messageConverter.write(requestBody, requestContentType, httpRequest);
return;
}
}
String message = "Could not write request: no suitable HttpMessageConverter found for request type [" +
requestType.getName() + "]";
if (requestContentType != null) {
message += " and content type [" + requestContentType + "]";
}
throw new RestClientException(message);
}
else {
httpRequest.getHeaders().setContentLength(0L);
}
}
}
/**
* Response extractor that extracts the response {@link HttpHeaders}.
*/
private static class HeadersExtractor implements ResponseExtractor {
public HttpHeaders extractData(ClientHttpResponse response) throws IOException {
return response.getHeaders();
}
}
}