JAVA跨域、RestTemplate高并发下异常与配置、JSON数据Long转String

## 跨域支持

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;

@Configuration
public class CorsConfig {
/**
* 跨域支持
*
* @return
*/
@Bean
public CorsFilter corsFilter() {
final UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
final CorsConfiguration config = new CorsConfiguration();
config.setAllowCredentials(true); // 允许cookies跨域
config.addAllowedOrigin("*");// #允许向该服务器提交请求的URI，*表示全部允许
config.addAllowedHeader("*");// #允许访问的头信息,*表示全部
config.setMaxAge(18000L);// 预检请求的缓存时间（秒），即在这个时间段里，对于相同的跨域请求不会再预检了
config.addAllowedMethod("*");// 允许提交请求的方法，*表示全部允许
source.registerCorsConfiguration("/**", config);
return new CorsFilter(source);
}
}

## RestTemplate高并发下异常与配置

import org.apache.http.client.HttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.DefaultResponseErrorHandler;
import org.springframework.web.client.RestTemplate;

/**
*
* RestTemplate高并发下异常与配置说明
* 1、java.util.ConcurrentModificationException
* 2、java.net.SocketTimeoutException Connection timed out
*/
@Configuration
public class RestTemplateConfig {

@Bean
@LoadBalanced
public RestTemplate restTemplate() {
// 长连接
PoolingHttpClientConnectionManager pollingConnectionManager = new PoolingHttpClientConnectionManager();
// 总连接数
pollingConnectionManager.setMaxTotal(1000);
// 同路由的并发数
pollingConnectionManager.setDefaultMaxPerRoute(1000);

HttpClientBuilder httpClientBuilder = HttpClients.custom();
httpClientBuilder.setConnectionManager(pollingConnectionManager);
// 重试次数，默认是3次，没有开启
// httpClientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(3, true));
HttpClient httpClient = httpClientBuilder.build();

HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(
httpClient);
// 连接超时 ms
clientHttpRequestFactory.setConnectTimeout(12000);
// 数据读取超时时间，即SocketTimeout ms
clientHttpRequestFactory.setReadTimeout(12000);
// 连接不够用的等待时间，不宜过长，必须设置，比如连接不够用时，时间过长将是灾难性的
clientHttpRequestFactory.setConnectionRequestTimeout(200);
// 缓冲请求数据，默认值是true。通过POST或者PUT大量发送数据时，建议将此属性更改为false，以免耗尽内存。
// clientHttpRequestFactory.setBufferRequestBody(false);

RestTemplate restTemplate = new RestTemplate();
restTemplate.setRequestFactory(clientHttpRequestFactory);
restTemplate.setErrorHandler(new DefaultResponseErrorHandler());

return restTemplate;
}
}

## json数据Long为String

/**
*
* @description: 返回json是转换long为string
* @create: 2019-08-02 17:49
**/
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.util.List;

@EnableWebMvc
@Configuration
public class WebDataConvertConfig implements WebMvcConfigurer {
@Override
public void configureMessageConverters(List> converters) {
MappingJackson2HttpMessageConverter jackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
ObjectMapper objectMapper = new ObjectMapper();
/**
* 序列换成json时,将所有的long变成string
* 因为js中得数字类型不能包含所有的java long值
*/
SimpleModule simpleModule = new SimpleModule();
simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
simpleModule.addSerializer(Long.TYPE, ToStringSerializer.instance);
objectMapper.registerModule(simpleModule);
jackson2HttpMessageConverter.setObjectMapper(objectMapper);
converters.add(jackson2HttpMessageConverter);
}

}

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