無法從REST請求獲取響應 - Java NetBeans with Spring Beans

Question

我想了解如何在NetBeans中使用Spring進行REST服務。

在我的應用程序中，我創建了一個bean，並在我的pom.xml文件中放入依賴關係。

當我做了我的要求（我知道的作品，當我在瀏覽器中輸入它並取回JSON），我得到以下錯誤：

--- exec-maven-plugin:1.2.1:exec (default-cli) @ AutoNGplusAPITest --- 
Exception in thread "AWT-EventQueue-0" org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [interface java.util.Map] and content type [text/html;charset=utf-8] 
    at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:108) 
    at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:773) 
    at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:758) 
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:535) 
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:489) 
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:431) 
    at com.blackstonesoftwaretechnologies.startPage.sendURIActionPerformed(startPage.java:467) 
    at com.blackstonesoftwaretechnologies.startPage.access$800(startPage.java:26) 
    at com.blackstonesoftwaretechnologies.startPage$9.actionPerformed(startPage.java:218) 
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022) 
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348) 
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402) 
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259) 
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252) 
    at java.awt.Component.processMouseEvent(Component.java:6533) 
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324) 
    at java.awt.Component.processEvent(Component.java:6298) 
    at java.awt.Container.processEvent(Container.java:2236) 
    at java.awt.Component.dispatchEventImpl(Component.java:4889) 
    at java.awt.Container.dispatchEventImpl(Container.java:2294) 
    at java.awt.Component.dispatchEvent(Component.java:4711) 
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888) 
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525) 
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466) 
    at java.awt.Container.dispatchEventImpl(Container.java:2280) 
    at java.awt.Window.dispatchEventImpl(Window.java:2746) 
    at java.awt.Component.dispatchEvent(Component.java:4711) 
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758) 
    at java.awt.EventQueue.access$500(EventQueue.java:97) 
    at java.awt.EventQueue$3.run(EventQueue.java:709) 
    at java.awt.EventQueue$3.run(EventQueue.java:703) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) 
    at java.awt.EventQueue$4.run(EventQueue.java:731) 
    at java.awt.EventQueue$4.run(EventQueue.java:729) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) 
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) 
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) 
------------------------------------------------------------------------ 
BUILD SUCCESS 
------------------------------------------------------------------------ 
Total time: 19.966s 
Finished at: Wed Sep 14 11:15:07 EDT 2016 
Final Memory: 6M/106M 

---

這裏是我的Java代碼我正在運行通過REST調用的類文件：

private void sendURIActionPerformed(java.awt.event.ActionEvent evt) {           
     // TODO add your handling code here: 
     String link, api = null; 
     link = parseString(endpointAPI.getText()); 
     shortResults.setText("URI under Test is: " + String.valueOf(link) + ". \n" + "Please wait ..." + "\n\n\n" + "Results: " + "\n"); 
     //api = parseString(endpointAPI.getText()); 

     Object[] row = {link, "", "200", ""}; 
     DefaultTableModel model = (DefaultTableModel) parameterTable.getModel(); 
     model.addRow(row); 

     RestTemplate restTemplate = new RestTemplate(); 
     HttpHeaders requestHeaders = new HttpHeaders(); 

     requestHeaders.add("Content-Type","application/json"); 

     HttpEntity<String> request = new HttpEntity<>(requestHeaders); 

     String tokenaccess = ""; 
     String apiUndertest1 = restTemplate.exchange(link, HttpMethod.GET, request, String.class).getBody(); 
     Map result = restTemplate.exchange(link, HttpMethod.GET, request, Map.class).getBody(); 

     shortResults.append(apiUndertest1); 

    }          

我在想什麼？ 我假設在pom.xml文件中，我下載的彈簧依賴關係將負責JSON轉換。

我使用的示例網址：https://github.com和http://jsonplaceholder.typicode.com/posts/1

有人可以幫助我瞭解，我做了我的錯誤，並告訴我如何糾正它（缺碼，代碼結構，等等）。我真的很想正確地學習這一點。

感謝

Answer 1

彈簧安置模板不會自動JSON映射爲對象。你必須明確地定義它。使用傑克遜（核心，數據綁定，註釋）。在調度器servlet中輸入以下內容：

<beans:bean 
     class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"> 
     <beans:property name="messageConverters"> 
      <beans:list> 
       <beans:ref bean="jsonMessageConverter" /> 
      </beans:list> 
     </beans:property> 
    </beans:bean> 

    <!-- Configure bean to convert JSON to POJO and vice versa --> 
    <beans:bean id="jsonMessageConverter" 
     class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"> 
    </beans:bean> 

這將負責將JSON轉換爲Class對象，反之亦然。

這應該是最好的辦法。

Answer 2

您預計春節RestTemplate會自動解析您的結果爲Java對象（地圖你的情況）。事實並非如此。

您必須爲RestTemplate提供它應該嘗試使用的轉換器列表。在大多數情況下，你應該使用MappingJackson2HttpMessageConverter

RestTemplate restTemplate = new RestTemplate(); 
List<HttpMessageConverter> messageConverters = new ArrayList<>(); 
messageConverters.add(new MappingJackson2HttpMessageConverter()); 
restTemplate.setMessageConverters(messageConverters);  

要做到這也行你應該添加傑克遜你的pom.xml：

<dependency> 
    <groupId>com.fasterxml.jackson.core</groupId> 
    <artifactId>jackson-core</artifactId> 
    <version>2.8.2</version> 
</dependency>