ParameterizedTypeReference使用
超类型标记模式会捕获类信息中的泛型参数，以避免Java语言中类型擦除的限制。
The purpose of this class is to enable capturing and passing a generic Type. In order to capture the generic type and retain it at runtime, you need to create a subclass (ideally as anonymous inline class) as follows:
ParameterizedTypeReference<List<String>> typeRef = new ParameterizedTypeReference<List<String>>() {};
The resulting typeRef instance can then be used to obtain a Type instance that carries the captured parameterized type information at runtime. For more information on “super type tokens” see the link to Neal Gafter’s blog post.
- 一个控制器，返回类型为Map<String, String>
package greetings;import org.springframework.context.annotation.Profile;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;import java.security.Principal;
import java.util.Collections;
import java.util.Map;@Profile("secure")
@RestController
@RequestMapping(method = RequestMethod.GET, value = "/greet/{name}")
public class SecureGreetingsRestController {@RequestMappingMap<String, String> hi(@PathVariable String name, Principal p) {return Collections.singletonMap("greeting","Hello, " + name + " from " + p.getName() + "!");}
}
- 通过restTemplate请求
package greetings;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Profile;
import org.springframework.core.ParameterizedTypeReference;
import org.springframework.http.HttpMethod;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;import java.util.Map;@Profile({ "default", "insecure" })
@RestController
@RequestMapping("/api")
class RestTemplateGreetingsClientApiGateway {private final RestTemplate restTemplate;@AutowiredRestTemplateGreetingsClientApiGateway(@LoadBalanced RestTemplate restTemplate) { // <1>this.restTemplate = restTemplate;}@GetMapping("/resttemplate/{name}")Map<String, String> restTemplate(@PathVariable String name) {//@formatter:offParameterizedTypeReference<Map<String, String>> type =new ParameterizedTypeReference<Map<String, String>>() {};//@formatter:onResponseEntity<Map<String, String>> responseEntity = this.restTemplate.exchange("http://greetings-service/greet/{name}", HttpMethod.GET, null,type, name);return responseEntity.getBody();}
}
ParameterizedTypeReference使用
超类型标记模式会捕获类信息中的泛型参数，以避免Java语言中类型擦除的限制。
The purpose of this class is to enable capturing and passing a generic Type. In order to capture the generic type and retain it at runtime, you need to create a subclass (ideally as anonymous inline class) as follows:
ParameterizedTypeReference<List<String>> typeRef = new ParameterizedTypeReference<List<String>>() {};
The resulting typeRef instance can then be used to obtain a Type instance that carries the captured parameterized type information at runtime. For more information on “super type tokens” see the link to Neal Gafter’s blog post.
- 一个控制器，返回类型为Map<String, String>
package greetings;import org.springframework.context.annotation.Profile;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;import java.security.Principal;
import java.util.Collections;
import java.util.Map;@Profile("secure")
@RestController
@RequestMapping(method = RequestMethod.GET, value = "/greet/{name}")
public class SecureGreetingsRestController {@RequestMappingMap<String, String> hi(@PathVariable String name, Principal p) {return Collections.singletonMap("greeting","Hello, " + name + " from " + p.getName() + "!");}
}
- 通过restTemplate请求
package greetings;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Profile;
import org.springframework.core.ParameterizedTypeReference;
import org.springframework.http.HttpMethod;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;import java.util.Map;@Profile({ "default", "insecure" })
@RestController
@RequestMapping("/api")
class RestTemplateGreetingsClientApiGateway {private final RestTemplate restTemplate;@AutowiredRestTemplateGreetingsClientApiGateway(@LoadBalanced RestTemplate restTemplate) { // <1>this.restTemplate = restTemplate;}@GetMapping("/resttemplate/{name}")Map<String, String> restTemplate(@PathVariable String name) {//@formatter:offParameterizedTypeReference<Map<String, String>> type =new ParameterizedTypeReference<Map<String, String>>() {};//@formatter:onResponseEntity<Map<String, String>> responseEntity = this.restTemplate.exchange("http://greetings-service/greet/{name}", HttpMethod.GET, null,type, name);return responseEntity.getBody();}
}
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