Spring for android RestTemplate 超时设置
spring for android是一个android平台下的网络框架，由大名鼎鼎的spring项目组开发。spring for android对于处理rest网络请求特别方便，这是我使用spring for android的主要原因。使用过程中，可能发现spring for android这套框架不好设置超时，有时甚至设置了也无效。如果使用了aa注解框架，设置超时更麻烦点。下面从源码角度解读这些问题。
常用解决方法
常用解决方法有两种
- 获取
requestFactory,然后设置超时。 - 继承一个已有的
requestFactory,构造RestTemplate时传入自己的requestfactory
第一种方式可以封装成如下代码:
public static void configTimeout(RestTemplate template, int readTimeout,
int connectTimeout) {
boolean updateReadTimeout = readTimeout >= 0;
boolean updateConnectTimeout = connectTimeout >= 0;
if (template == null || (!updateReadTimeout && !updateReadTimeout))
return;
ClientHttpRequestFactory factory = template.getRequestFactory();
if (factory instanceof SimpleClientHttpRequestFactory) {
SimpleClientHttpRequestFactory simple = (SimpleClientHttpRequestFactory) factory;
if (updateReadTimeout)
simple.setReadTimeout(readTimeout);
if (updateConnectTimeout)
simple.setConnectTimeout(connectTimeout);
} else if (factory instanceof HttpComponentsClientHttpRequestFactory) {
HttpComponentsClientHttpRequestFactory client = (HttpComponentsClientHttpRequestFactory) factory;
if (updateReadTimeout)
client.setReadTimeout(readTimeout);
if (updateConnectTimeout)
client.setConnectTimeout(connectTimeout);
}
}
如果使用aa框架，这样配置更麻烦，每次都需要获取restTemplate。如果使用aa框架，推荐使用第二种方式。
第二种方式，首先需要自定义一个类，继承一个RequestFactory,构造时设置超时。
public class MyHttpFactory extends SimpleClientHttpRequestFactory{
public MyHttpFactory(){
super();
setConnectTimeout(7*1000);
setReadTimeout(7*1000);
}
然后构造restTemplate
public void test(){
RestTemplate template = new RestTemplate(new MyHttpFactory());
// 网络请求
}
这种方式主要是在使用aa框架下使用，aa的rest接口可以传入requestFactory，我们自定义的factory就能用了,比如:
@Rest(converters = {FormHttpMessageConverter.class, GsonHttpMessageConverter.class,
StringHttpMessageConverter.class}, rootUrl = HttpURL.ROOT_URL + "tests/",
requestFactory = MyHttpFactory.class)
public interface TestApi extends RestClientSupport {
@Post("?name={name}")
public void test(String name);
}
设置超时无效原因
在使用上述第一种解决方案时，添加了拦截器之后，发现设置超时无效，什么原因呢，可以从spring for android源码看看。
RestTemplate继承InterceptingHttpAccessor类，在InterceptingHttpAccessor类里实现了一个方法getRequestFactory,这个方法作用就是获取RequestFactory,方法实现如下
@Override
public ClientHttpRequestFactory getRequestFactory() {
ClientHttpRequestFactory delegate = super.getRequestFactory();
if (!CollectionUtils.isEmpty(getInterceptors())) {
return new InterceptingClientHttpRequestFactory(delegate, getInterceptors());
}
else {
return delegate;
}
}
可以看到，如果RestTemplate有拦截器，则返回一个代理ReqeustFactory的InterceptingClientHttpRequestFactory，而InterceptingClientHttpRequestFactory并没有提显式提供什么方法获取真实的RequestTemplate。
超时无效的解决方法
从上例中方法我们可以看出解决方法，那就是先设置拦截器为空，然后设置超时，最后重新设置回拦截器。具体代码改动如下:
public static void configTimeout(RestTemplate template, int readTimeout,
int connectTimeout) {
boolean updateReadTimeout = readTimeout >= 0;
boolean updateConnectTimeout = connectTimeout >= 0;
if (template == null || (!updateReadTimeout && !updateReadTimeout))
return;
//这里是为了解决spring requestfactory不能获取到真实factory的问题，先设置过滤器为空，设置后超时后
//再重新设置回去
List<ClientHttpRequestInterceptor> interceptors = template.getInterceptors();
template.setInterceptors(null);
try {
ClientHttpRequestFactory factory = template.getRequestFactory();
// InterceptingClientHttpRequestFactory interceptingClientHttpRequestFactory;
if (factory instanceof SimpleClientHttpRequestFactory) {
SimpleClientHttpRequestFactory simple = (SimpleClientHttpRequestFactory) factory;
if (updateReadTimeout)
simple.setReadTimeout(readTimeout);
if (updateConnectTimeout)
simple.setConnectTimeout(connectTimeout);
} else if (factory instanceof HttpComponentsClientHttpRequestFactory) {
HttpComponentsClientHttpRequestFactory client = (HttpComponentsClientHttpRequestFactory) factory;
if (updateReadTimeout)
client.setReadTimeout(readTimeout);
if (updateConnectTimeout)
client.setConnectTimeout(connectTimeout);
}
} finally {
//重新设置回去
template.setInterceptors(interceptors);
}
}
如果你觉得这种方式好麻烦，那就来个简单暴力点的，通过无所不能的反射来设置超时
/**
* 配置RestTemplate超时时间,通过反射强制获取factry设置属性
*
* @param restTemplate
* @param readTimeout 读取超时，如果小于等于0，则不设置
* @param connectTimeout 连接超时时间，如果小于等于0，则不设置
*/
public static void configTimeoutByReflect(RestTemplate restTemplate, int readTimeout, int connectTimeout) {
ClientHttpRequestFactory factory = restTemplate.getRequestFactory();
boolean updateReadTimeout = readTimeout >= 0;
boolean updateConnectTimeout = connectTimeout >= 0;
if (factory instanceof InterceptingClientHttpRequestFactory) {
try {
factory = (ClientHttpRequestFactory) ReflectUtils.getFieledValue(factory, "requestFactory");
if(factory == null) return;
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
if (factory instanceof SimpleClientHttpRequestFactory) {
SimpleClientHttpRequestFactory simple = (SimpleClientHttpRequestFactory) factory;
if (updateReadTimeout)
simple.setReadTimeout(readTimeout);
if (updateConnectTimeout)
simple.setConnectTimeout(connectTimeout);
} else if (factory instanceof HttpComponentsClientHttpRequestFactory) {
HttpComponentsClientHttpRequestFactory client = (HttpComponentsClientHttpRequestFactory) factory;
if (updateReadTimeout)
client.setReadTimeout(readTimeout);
if (updateConnectTimeout)
client.setConnectTimeout(connectTimeout);
}
}
ReflectUtils代码如下:
package com.dreamliner.secretchat.utils;
import java.lang.reflect.Field;
/**
* Created by Administrator on 2015/5/12.
*/
public class ReflectUtils {
/**
* Gets fieled value.
*获取到Filed的值
* @param obj the obj
* @param fieldName the field name
* @return the fieled value
* @throws IllegalAccessException the illegal access exception
*/
public static Object getFieledValue(Object obj, String fieldName)
throws IllegalAccessException {
Field field = getFieldByRecursion(obj.getClass(), fieldName);
if (field != null) {
field.setAccessible(true);
return field.get(obj);
}
return null;
}
/**
* Sets field value.
*
* @param obj the obj
* @param fildName the fild name
* @param fieldValue the field value
* @return the field value
*/
public static boolean setFieldValue(Object obj, String fildName,
Object fieldValue) {
Field field = getFieldByRecursion(obj.getClass(), fildName);
boolean result = false;
if (field != null) {
field.setAccessible(true);
try {
field.set(obj, fieldValue);
result = true;
} catch (IllegalArgumentException | IllegalAccessException e) {
e.printStackTrace();
}
}
return result;
}
/**
* Gets field by recursion.
*
* @param classes the classes
* @param fildName the fild name
* @return the field by recursion
*/
// 用递归实现
public static Field getFieldByRecursion(Class<?> classes, String fildName) {
if (classes == null)
return null;
Field field = getFieldInCurrentClass(classes, fildName);
return field == null ? getFieldByRecursion(classes.getSuperclass(), fildName)
: field;
}
/**
* Gets field by loop.
*
* @param classes the classes
* @param fildName the fild name
* @return the field by loop
*/
// 用循环实现
public static Field getFieldByLoop(Class<?> classes, String fildName) {
boolean havaField = false;
Field field = null;
Class<?> currentClass = classes;
while (!havaField) {
if (currentClass == null)
break;
field = getFieldInCurrentClass(currentClass, fildName);
if (field != null)
break;
currentClass = currentClass.getSuperclass();
}
return field;
}
/**
* Gets field in current class.
*
* @param classes the classes
* @param fildName the fild name
* @return the field in current class
*/
public static Field getFieldInCurrentClass(Class<?> classes, String fildName) {
Field[] declaredFields = classes.getDeclaredFields();
for (Field field : declaredFields) {
if (field.getName().equals(fildName)) {
return field;
}
}
return null;
}
}