[JAVA] Behandelt verschiedene Fehler (Ausnahmen), die während der HTTP-Kommunikation mit RestTemplate auftreten

Überblick

• HTTP-Kommunikation mit der RestTemplate-Klasse von Spring Framework
• Führen Sie das Beispielprogramm aus, um verschiedene Ausnahmen zu überprüfen, die während der HTTP-Kommunikation auftreten

Vererbungsbeziehungsbaum für die Ausnahmeklasse RestClientException

In der Spring Framework-Dokumentation gibt RestTemplate an, dass org.springframework.web.client.RestClientException ausgelöst wird. Wenn Sie die Ausnahme abfangen und den Inhalt überprüfen, können Sie sehen, dass die Unterklasse von RestClientException tatsächlich ausgelöst wird.

--RestClientException (die Klasse, auf der die von RestTemplate ausgelöste Ausnahme basiert) --RestClientResponseException (Klasse, für die die Ausnahme HTTP-Antwortdaten enthält) --HttpStatusCodeException (abstrakte Ausnahmeklasse basierend auf Statuscode) --HttpClientErrorException (beim Empfang von HTTP 4xx-Serien) --Jede Ausnahmeklasse (Plural) des 4xx-Serienstatuscodes --HttpServerErrorException (beim Empfang von HTTP 5xx-Serien) --Jede Ausnahmeklasse (Plural) des Statuscodes der Serie 5xx --UnknownHttpStatusCodeException (wenn der Statuscode unbekannt ist) --ResourceAccessException (wenn ein E / A-Fehler auftritt)

Liste der Ausnahmen, die im Beispielprogramm aufgetreten sind

Für HTTP 404 nicht gefunden

--Ausnahme, die aufgetreten ist: org.springframework.web.client.HttpClientErrorException $ NotFound --HttpClientErrorException.NotFound ist eine Unterklasse von org.springframework.web.client.HttpClientErrorException

Für internen HTTP 500-Serverfehler

--Ausnahme, die aufgetreten ist: org.springframework.web.client.HttpServerErrorException $ InternalServerError --HttpServerErrorException.InternalServerError ist eine Unterklasse von org.springframework.web.client.HttpServerErrorException

Für unbekannten Statuscode

--Ausnahme, die aufgetreten ist: org.springframework.web.client.UnknownHttpStatusCodeException

Wenn nicht eine URL-Zeichenfolge

--Exception: java.lang.IllegalArgumentException

Wenn es nicht als URL-Zeichenfolge analysiert werden kann

--Ausnahme, die aufgetreten ist: java.net.URISyntaxException

Wenn der Schemaname der URL unbekannt ist

--Ausnahme, die aufgetreten ist: org.springframework.web.client.ResourceAccessException

• Ausnahmebedingung: java.net.MalformedURLException

Wenn die IP-Adresse nicht vom Hostnamen abgezogen werden kann

--Ausnahme, die aufgetreten ist: org.springframework.web.client.ResourceAccessException

• Ausnahme verursachen: java.net.UnknownHostException

Beim Zugriff auf einen Port, an dem der Webserver nicht gestartet ist (Verbindung abgelehnt)

--Ausnahme, die aufgetreten ist: org.springframework.web.client.ResourceAccessException

• Ausnahme verursachen: java.net.ConnectException

Für nicht vertrauenswürdige SSL-Serverzertifikate (selbstsigniertes Zertifikat, Oleore-Zertifikat)

--Ausnahme, die aufgetreten ist: org.springframework.web.client.ResourceAccessException

• Ursache verursachen: javax.net.ssl.SSLHandshakeException

Im Falle eines Verbindungszeitlimits (z. B. IP-Adresse, an der das Gerät nicht vorhanden ist)

--Ausnahme, die aufgetreten ist: org.springframework.web.client.ResourceAccessException

• Ursache: java.net.SocketTimeoutException

Im Falle eines Lesezeitlimits

--Ausnahme, die aufgetreten ist: org.springframework.web.client.ResourceAccessException

• Ursache: java.net.SocketTimeoutException

Betriebsüberprüfungsumgebung

• macOS Mojave
• OpenJDK 11.0.2
• Spring Framework 5.1.8

Quellcode des Beispielprogramms

Quellcodeliste

├── pom.xml
└── src
    └── main
        └── java
            └── com
                └── example
                    └── MyHttpClient.java

Maven Build-Datei pom.xml

Erstellen Sie dieses Mal das Beispielprogramm mit Maven. Die RestTemplate-Klasse ist im Spring Web des Spring Framework enthalten. Fügen Sie daher den Abhängigkeiten Spring-Web hinzu.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.example</groupId>
  <artifactId>my-http-client</artifactId>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <maven.compiler.source>11</maven.compiler.source>
    <maven.compiler.target>11</maven.compiler.target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <build>
    <plugins>
      <!-- http://maven.apache.org/plugins/maven-assembly-plugin/ -->
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>3.1.1</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <descriptorRefs>
            <descriptorRef>jar-with-dependencies</descriptorRef>
          </descriptorRefs>
          <archive>
            <manifest>
              <mainClass>com.example.MyHttpClient</mainClass>
            </manifest>
          </archive>
        </configuration>
      </plugin>
    </plugins>
  </build>

  <dependencies>
    <!-- https://mvnrepository.com/artifact/org.springframework/spring-web -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>5.1.8.RELEASE</version>
    </dependency>
  </dependencies>

</project>

MyHttpClient.java

Eine Klasse zum Überprüfen verschiedener Ausnahmen, die während der HTTP-Kommunikation auftreten.

package com.example;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.RequestEntity;
import org.springframework.http.ResponseEntity;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.web.client.ResourceAccessException;
import org.springframework.web.client.RestClientException;
import org.springframework.web.client.RestClientResponseException;
import org.springframework.web.client.RestTemplate;

import java.net.URI;
import java.net.URISyntaxException;

public class MyHttpClient {

  public static void main(String[] args) {

    RestTemplate restTemplate = new RestTemplate();

    //Timeout-Wert einstellen
    if(restTemplate.getRequestFactory() instanceof SimpleClientHttpRequestFactory) {
      SimpleClientHttpRequestFactory rf = (SimpleClientHttpRequestFactory)restTemplate.getRequestFactory();
      rf.setConnectTimeout(1000); //Stellen Sie das Verbindungszeitlimit auf 1000 Millisekunden ein
      rf.setReadTimeout(1000); //Stellen Sie das Lesezeitlimit auf 1000 Millisekunden ein
    }

    //Gibt den Klassennamen von ClientHttpRequestFactory aus, der intern von RestTemplate verwendet wird
    System.out.println("ClientHttpRequestFactory: " + restTemplate.getRequestFactory().getClass().getName());

    //Probieren Sie verschiedene Muster aus
    get("HTTP 200 OK", restTemplate, "http://localhost:8000/");
    get("HTTP 301 Moved Permanently (Weiterleitungen sollten automatisch behandelt werden)", restTemplate, "http://localhost:8000/?status=301&headers=%7B%22location%22%3A%22http%3A%2F%2Flocalhost%3A8000%2F%22%7D");
    get("HTTP 404 Not Found", restTemplate, "http://localhost:8000/?status=404");
    get("HTTP 500 Internal Server Error", restTemplate, "http://localhost:8000/?status=500");
    get("Unbekannter Statuscode", restTemplate, "http://localhost:8000/?status=599");
    get("Keine URL-Zeichenfolge", restTemplate, "foo");
    get("Kann nicht als URL-Zeichenfolge analysiert werden", restTemplate, "http://local host:8000/");
    get("Unbekannter URL-Schemaname", restTemplate, "foo://localhost:8000/");
    get("Die IP-Adresse kann nicht vom Hostnamen abgezogen werden", restTemplate, "http://localhostlocalhost:8000/");
    get("Port, an dem der Webserver nicht gestartet wird", restTemplate, "http://localhost:1234/");
    get("Nicht vertrauenswürdiges SSL-Serverzertifikat(Selbstsigniertes Zertifikat,Oreore-Zertifikat)", restTemplate, "https://localhost:8443/");
    get("Verbindungszeitüberschreitung(Connection Timeout)IP-Adresse, bei der das Gerät nicht vorhanden ist", restTemplate, "http://127.0.0.2/");
    get("Zeitüberschreitung lesen(Read Timeout)", restTemplate, "http://localhost:8000/?wait=10");
  }

  /**
   *Greifen Sie auf die angegebene URL zu und geben Sie die Informationen aus.
   *
   * @Param Titel Titel(Erklärung, welche Art von Muster)
   * @param restTemplate RestTemplate-Objekt, das für die HTTP-Kommunikation verwendet wird
   * @Parameter URL URL für den Zugriff
   */
  private static void get(String title, RestTemplate restTemplate, String url) {
    try {
      System.out.println("************************************************************");
      System.out.println(title);
      System.out.println("URL: " + url);
      URI uri = new URI(url);
      RequestEntity req = RequestEntity.get(uri).build();
      ResponseEntity<String> res = restTemplate.exchange(req, String.class);
      HttpStatus status = res.getStatusCode();
      HttpHeaders headers = res.getHeaders();
      String body = res.getBody();
      System.out.println("Status: " + status);
    } catch (RestClientResponseException e) {
      System.out.println("Class: " + e.getClass().getName());
      int statusCode = e.getRawStatusCode();
      String statusText = e.getStatusText();
      System.out.println("StatusCode: " + statusCode);
      System.out.println("StatusText: " + statusText);
      e.printStackTrace();
    } catch (ResourceAccessException e) {
      System.out.println("Class: " + e.getClass().getName());
      e.printStackTrace();
    } catch (RestClientException e) {
      System.out.println("Class: " + e.getClass().getName());
      e.printStackTrace();
    } catch (URISyntaxException e) {
      System.out.println("Class: " + e.getClass().getName());
      e.printStackTrace();
    } catch (Exception e) {
      System.out.println("Class: " + e.getClass().getName());
      e.printStackTrace();
    }
  }
}

Quellcode erstellen

Generieren Sie eine JAR-Datei mit dem Befehl mvn package.

$ mvn package

Ausführungsergebnis

Führen Sie das Beispielprogramm aus, um festzustellen, welche Ausnahmen in den einzelnen Mustern auftreten.

$ java -jar target/my-http-client-1.0-SNAPSHOT-jar-with-dependencies.jar 
ClientHttpRequestFactory: org.springframework.http.client.SimpleClientHttpRequestFactory
************************************************************
HTTP 200 OK
URL: http://localhost:8000/
Status: 200 OK
************************************************************
HTTP 301 Moved Permanently (Weiterleitungen sollten automatisch behandelt werden)
URL: http://localhost:8000/?status=301&headers=%7B%22location%22%3A%22http%3A%2F%2Flocalhost%3A8000%2F%22%7D
Status: 200 OK
************************************************************
HTTP 404 Not Found
URL: http://localhost:8000/?status=404
Class: org.springframework.web.client.HttpClientErrorException$NotFound
StatusCode: 404
StatusText: Not Found
org.springframework.web.client.HttpClientErrorException$NotFound: 404 Not Found
	at org.springframework.web.client.HttpClientErrorException.create(HttpClientErrorException.java:85)
	at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:122)
	at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:102)
	at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63)
	at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:778)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:736)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:35)
************************************************************
HTTP 500 Internal Server Error
URL: http://localhost:8000/?status=500
Class: org.springframework.web.client.HttpServerErrorException$InternalServerError
StatusCode: 500
StatusText: Internal Server Error
org.springframework.web.client.HttpServerErrorException$InternalServerError: 500 Internal Server Error
	at org.springframework.web.client.HttpServerErrorException.create(HttpServerErrorException.java:79)
	at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:124)
	at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:102)
	at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63)
	at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:778)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:736)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:36)
************************************************************
Unbekannter Statuscode
URL: http://localhost:8000/?status=599
Class: org.springframework.web.client.UnknownHttpStatusCodeException
StatusCode: 599
StatusText: null
org.springframework.web.client.UnknownHttpStatusCodeException: Unknown status code [599] null
	at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:100)
	at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63)
	at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:778)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:736)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:37)
************************************************************
Keine URL-Zeichenfolge
URL: foo
Class: java.lang.IllegalArgumentException
java.lang.IllegalArgumentException: URI is not absolute
	at java.base/java.net.URL.fromURI(URL.java:674)
	at java.base/java.net.URI.toURL(URI.java:1116)
	at org.springframework.http.client.SimpleClientHttpRequestFactory.createRequest(SimpleClientHttpRequestFactory.java:145)
	at org.springframework.http.client.support.HttpAccessor.createRequest(HttpAccessor.java:87)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:731)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:38)
************************************************************
Kann nicht als URL-Zeichenfolge analysiert werden
URL: http://local host:8000/
Class: java.net.URISyntaxException
java.net.URISyntaxException: Illegal character in authority at index 7: http://local host:8000/
	at java.base/java.net.URI$Parser.fail(URI.java:2915)
	at java.base/java.net.URI$Parser.parseAuthority(URI.java:3249)
	at java.base/java.net.URI$Parser.parseHierarchical(URI.java:3160)
	at java.base/java.net.URI$Parser.parse(URI.java:3116)
	at java.base/java.net.URI.<init>(URI.java:600)
	at com.example.MyHttpClient.get(MyHttpClient.java:60)
	at com.example.MyHttpClient.main(MyHttpClient.java:39)
************************************************************
Unbekannter URL-Schemaname
URL: foo://localhost:8000/
Class: org.springframework.web.client.ResourceAccessException
org.springframework.web.client.ResourceAccessException: I/O error on GET request for "foo://localhost:8000/": unknown protocol: foo; nested exception is java.net.MalformedURLException: unknown protocol: foo
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:744)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:40)
Caused by: java.net.MalformedURLException: unknown protocol: foo
	at java.base/java.net.URL.<init>(URL.java:634)
	at java.base/java.net.URL.fromURI(URL.java:701)
	at java.base/java.net.URI.toURL(URI.java:1116)
	at org.springframework.http.client.SimpleClientHttpRequestFactory.createRequest(SimpleClientHttpRequestFactory.java:145)
	at org.springframework.http.client.support.HttpAccessor.createRequest(HttpAccessor.java:87)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:731)
	... 3 more
************************************************************
Die IP-Adresse kann nicht vom Hostnamen abgezogen werden
URL: http://localhostlocalhost:8000/
Class: org.springframework.web.client.ResourceAccessException
org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://localhostlocalhost:8000/": localhostlocalhost; nested exception is java.net.UnknownHostException: localhostlocalhost
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:744)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:41)
Caused by: java.net.UnknownHostException: localhostlocalhost
	at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:220)
	at java.base/java.net.Socket.connect(Socket.java:591)
	at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569)
	at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1242)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1181)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1075)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1009)
	at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:76)
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:735)
	... 3 more
************************************************************
Port, an dem der Webserver nicht gestartet wird
URL: http://localhost:1234/
Class: org.springframework.web.client.ResourceAccessException
org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://localhost:1234/": Connection refused (Connection refused); nested exception is java.net.ConnectException: Connection refused (Connection refused)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:744)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:42)
Caused by: java.net.ConnectException: Connection refused (Connection refused)
	at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)
	at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)
	at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)
	at java.base/java.net.Socket.connect(Socket.java:591)
	at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569)
	at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1242)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1181)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1075)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1009)
	at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:76)
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:735)
	... 3 more
************************************************************
Nicht vertrauenswürdiges SSL-Serverzertifikat(Selbstsigniertes Zertifikat,Oreore-Zertifikat)
URL: https://localhost:8443/
Class: org.springframework.web.client.ResourceAccessException
org.springframework.web.client.ResourceAccessException: I/O error on GET request for "https://localhost:8443/": PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target; nested exception is javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:744)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:43)
Caused by: javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
	at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:128)
	at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:321)
	at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:264)
	at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:259)
	at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:642)
	at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.onCertificate(CertificateMessage.java:461)
	at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.consume(CertificateMessage.java:361)
	at java.base/sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:392)
	at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:444)
	at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:421)
	at java.base/sun.security.ssl.TransportContext.dispatch(TransportContext.java:178)
	at java.base/sun.security.ssl.SSLTransport.decode(SSLTransport.java:164)
	at java.base/sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1152)
	at java.base/sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1063)
	at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:402)
	at java.base/sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:567)
	at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
	at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:163)
	at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:76)
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:735)
	... 3 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
	at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:385)
	at java.base/sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:290)
	at java.base/sun.security.validator.Validator.validate(Validator.java:264)
	at java.base/sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:321)
	at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:221)
	at java.base/sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:129)
	at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:626)
	... 20 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
	at java.base/sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
	at java.base/sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
	at java.base/java.security.cert.CertPathBuilder.build(CertPathBuilder.java:297)
	at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
	... 26 more
************************************************************
Verbindungszeitüberschreitung(Connection Timeout)IP-Adresse, bei der das Gerät nicht vorhanden ist
URL: http://127.0.0.2/
Class: org.springframework.web.client.ResourceAccessException
org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://127.0.0.2/": connect timed out; nested exception is java.net.SocketTimeoutException: connect timed out
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:744)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:44)
Caused by: java.net.SocketTimeoutException: connect timed out
	at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)
	at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)
	at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)
	at java.base/java.net.Socket.connect(Socket.java:591)
	at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569)
	at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1242)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1181)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1075)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1009)
	at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:76)
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:735)
	... 3 more
************************************************************
Zeitüberschreitung lesen(Read Timeout)
URL: http://localhost:8000/?wait=10
Class: org.springframework.web.client.ResourceAccessException
org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://localhost:8000/": Read timed out; nested exception is java.net.SocketTimeoutException: Read timed out
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:744)
	at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:637)
	at com.example.MyHttpClient.get(MyHttpClient.java:62)
	at com.example.MyHttpClient.main(MyHttpClient.java:45)
Caused by: java.net.SocketTimeoutException: Read timed out
	at java.base/java.net.SocketInputStream.socketRead0(Native Method)
	at java.base/java.net.SocketInputStream.socketRead(SocketInputStream.java:115)
	at java.base/java.net.SocketInputStream.read(SocketInputStream.java:168)
	at java.base/java.net.SocketInputStream.read(SocketInputStream.java:140)
	at java.base/java.io.BufferedInputStream.fill(BufferedInputStream.java:252)
	at java.base/java.io.BufferedInputStream.read1(BufferedInputStream.java:292)
	at java.base/java.io.BufferedInputStream.read(BufferedInputStream.java:351)
	at java.base/sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:746)
	at java.base/sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:689)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1604)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1509)
	at java.base/java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:527)
	at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:82)
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:735)
	... 3 more

Referenzmaterial

• spring-framework/spring-web at master · spring-projects/spring-framework · GitHub
• RestTemplate (Spring Framework 5.1.8.RELEASE API)
• RestClientException (Spring Framework 5.1.8.RELEASE API)
• SimpleClientHttpRequestFactory (Spring Framework 5.1.8.RELEASE API)
• [5 \ .2 . REST-Client (HTTP-Client) - TERASOLUNA Server Framework für Java \ (5 \ .x ) Entwicklungsrichtlinie 5 \ .5 \ .1 \ .RELEASE-Dokumentation](http: //terasolunaorg.github) .io / guideline / 5.5.1.RELEASE / ja / ArchitectureInDetail / WebServiceDetail / RestClient.html)
• [Spring] Zusammenfassung der von RestTemplate \ -Qiita ausgelösten Ausnahmeklassen