英文:
get Values from Json List java
问题
以下是您提供的代码的翻译部分：
我有一个SpringBootApplication，类似于以下代码示例：
我有一个看起来像这样的Service：
package com.example.workflow;
import org.springframework.stereotype.Service;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
@Service
public class CallService {
private List<Call> callList = new ArrayList<>(Arrays.asList(new Call("33333301","61","Test",
"Test","Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test",
"Test","Test","Test"),new Call("33333302","61","Test",
"Test","Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test",
"Test","Test","Test")));
public List<Call> getAllCallList() {
return callList;
}
public void addCall(Call call) {
callList.add(call);
}
}
我的REST-Controller看起来像这样：
package com.example.workflow;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RestController
public class CallController {
@Autowired
private CallService callService;
@GetMapping("/calls")
public List<Call> getAllCalls(){
return callService.getAllCallList();
}
@PostMapping("/calls")
public void addCall(@RequestBody Call call){
callService.addCall(call);
}
}
然后，我想访问"variables"（变量）的值，如tcpident等等。
我的输出如下：
Output from GetCall[{"tcpident":"33333301","requestid":"61","mclass":"Test","mno":"Test","errorstate":"Test","datalength":"Test","resourceid":"Test","ono":"Test","opos":"Test","wpno":"Test","opno":"Test","bufno":"Test","bufpos":"Test","carrierid":"Test","palletid":"Test","palletpos":"Test","pno":"Test","oposid":"Test","stepno":"Test","maxrecords":"Test","boxid":"Test","boxpos":"Test","mainopos":"Test","beltno":"Test","cno":"Test","boxpno":"Test","palletpno":"Test","aux1int":"Test","aux2int":"Test","aux1dint":"Test","aux2dint":"Test","mainpno":"Test"},{"tcpident":"33333302","requestid":"61","mclass":"Test","mno":"Test","errorstate":"Test","datalength":"Test","resourceid":"Test","ono":"Test","opos":"Test","wpno":"Test","opno":"Test","bufno":"Test","bufpos":"Test","carrierid":"Test","palletid":"Test","palletpos":"Test","pno":"Test","oposid":"Test","stepno":"Test","maxrecords":"Test","boxid":"Test","boxpos":"Test","mainopos":"Test","beltno":"Test","cno":"Test","boxpno":"Test","palletpno":"Test","aux1int":"Test","aux2int":"Test","
<details>
<summary>英文:</summary>
I have a SpringBootApplication with REST-MVC like following Code examples:
I have a Service that looks like this:
package com.example.workflow;
import org.springframework.stereotype.Service;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
@Service
public class CallService {
private List<Call> callList = new ArrayList<>(Arrays.asList(new Call("33333301","61","Test",
"Test","Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test",
"Test","Test","Test"),new Call("33333302","61","Test",
"Test","Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test",
"Test","Test","Test","Test","Test","Test",
"Test","Test","Test")));
public List<Call> getAllCallList() {
return callList;
}
public void addCall(Call call) {
callList.add(call);
}
}
My REST-Controller looks like this:
package com.example.workflow;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RestController
public class CallController {
@Autowired
private CallService callService;
@GetMapping("/calls")
public List<Call> getAllCalls(){
return callService.getAllCallList();
}
@PostMapping("/calls")
public void addCall(@RequestBody Call call){
callService.addCall(call);
}
}
Then I want to access the values of the "variables" like tcpident, etc.
My output is like:
Output from GetCall[{"tcpident":"33333301","requestid":"61","mclass":"Test","mno":"Test","errorstate":"Test","datalength":"Test","resourceid":"Test","ono":"Test","opos":"Test","wpno":"Test","opno":"Test","bufno":"Test","bufpos":"Test","carrierid":"Test","palletid":"Test","palletpos":"Test","pno":"Test","oposid":"Test","stepno":"Test","maxrecords":"Test","boxid":"Test","boxpos":"Test","mainopos":"Test","beltno":"Test","cno":"Test","boxpno":"Test","palletpno":"Test","aux1int":"Test","aux2int":"Test","aux1dint":"Test","aux2dint":"Test","mainpno":"Test"},{"tcpident":"33333302","requestid":"61","mclass":"Test","mno":"Test","errorstate":"Test","datalength":"Test","resourceid":"Test","ono":"Test","opos":"Test","wpno":"Test","opno":"Test","bufno":"Test","bufpos":"Test","carrierid":"Test","palletid":"Test","palletpos":"Test","pno":"Test","oposid":"Test","stepno":"Test","maxrecords":"Test","boxid":"Test","boxpos":"Test","mainopos":"Test","beltno":"Test","cno":"Test","boxpno":"Test","palletpno":"Test","aux1int":"Test","aux2int":"Test","aux1dint":"Test","aux2dint":"Test","mainpno":"Test"}]
This I get if I do GET-Request on: http://localhost:8080/calls
like in following method:
public void get(){
try {
URL url = new URL("http://localhost:8080/calls");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : "
+ conn.getResponseCode());
}
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println("Output from GetCall"+output);
}
conn.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
How can I access to tcpident, requestid, and so on ?
I tried to make a Post-Request, but I got a NullPointerException. My Post Method looks like:
public void post(){
MultiValueMap<String, String> parameters = new LinkedMultiValueMap<>();
//headers.setContentType(MediaType.APPLICATION_JSON);
parameters.add("tcpident","1");
parameters.add("requestid","2");
parameters.add("mclass","3");
parameters.add("mno","4");
parameters.add("errorstate","5");
parameters.add("datalength","6");
parameters.add("resourceid","1");
parameters.add("ono","2");
parameters.add("opos","3");
parameters.add("wpno","23");
parameters.add("opno","ddsds");
parameters.add("bufno","d");
parameters.add("bufpos","ds");
parameters.add("carrierid","dsdd");
parameters.add("palletid","dsd");
parameters.add("palletpos","dsd");
parameters.add("pno","dsd");
parameters.add("oposid","ds");
parameters.add("stepno","dsd");
parameters.add("maxrecords","dsd");
parameters.add("boxid","dsd");
parameters.add("boxpos","dsd");
parameters.add("mainopos","dsds");
parameters.add("eltno","dsd");
parameters.add("cno","dsd");
parameters.add("boxpno","ds");
parameters.add("palletpno","dsd");
parameters.add("aux1int","ds");
parameters.add("aux2int","ds");
parameters.add("aux1dint","dsdsd");
parameters.add("aux2dint","dsd");
parameters.add("mainpno","dsod");
HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(parameters);
ResponseEntity<Call[]> response = restTemplate.postForEntity("http://localhost:8080/calls", request, Call[].class);
}
Error Message Edited:
org.springframework.web.client.HttpClientErrorException$BadRequest: 400 : [{"timestamp":"2020-08-05T13:05:24.741+0000","status":400,"error":"Bad Request","message":"Invalid JSON input: Cannot deserialize instance of `java.lang.String` out of START_ARRAY token; nested excepti... (484 bytes)]
at org.springframework.web.client.HttpClientErrorException.create(HttpClientErrorException.java:101) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:170) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:112) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:782) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:740) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:674) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
at org.springframework.web.client.RestTemplate.postForEntity(RestTemplate.java:449) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
at com.example.workflow.PostRequestDelegate.post(PostRequestDelegate.java:85) ~[classes/:na]
at com.example.workflow.PostRequestDelegate.execute(PostRequestDelegate.java:28) ~[classes/:na]
</details>
# 答案1
**得分**: 1
由于您正在使用Spring Boot，您应考虑使用RestTemplate。
```java
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<Call[]> response = restTemplate.getForEntity("http://localhost:8080/calls", Call[].class);
if (response.getStatusCode() != HttpStatus.OK) {
throw new RuntimeException("Failed : HTTP error code : " + response.getStatusCode());
}
Call[] output = response.getBody();
// 现在可以像output[0].getTcpIdent()这样使用output
请还为您的Call类提供一个默认构造函数。
您还可以使用RestTemplate来发送POST请求。
MultiValueMap<String, String> parameters = new LinkedMultiValueMap<>();
parameters.add("id", "1");
HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(parameters);
ResponseEntity<Object[]> response = restTemplate.postForEntity("http://localhost:8080/calls", request, Call[].class);
英文:
Since you are using Spring Boot you should consider to use RestTemplate.
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<Call[]> response = restTemplate.getForEntity("http://localhost:8080/calls", Call[].class);
if (response.getStatusCode() != HttpStatus.OK) {
throw new RuntimeException("Failed : HTTP error code : "
+ response.getStatusCode());
}
Call[] output = response.getBody();
// now use output like output[0].getTcpIdent()
Please also provide a default constructor for your Call class.
You can also use RestTemplate so send a POST call.
MultiValueMap<String, String> parameters = new LinkedMultiValueMap<>();
parameters.add("id", "1");
HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(parameters);
ResponseEntity<Object[]> response = restTemplate.postForEntity("http://localhost:8080/calls", request, Call[].class);
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