在Servlet中使用org.json導致java.lang.ClassNotFoundException：org.json.JSONException

我想開發一個servlet來發送一些JSON對象，但我得到了一些異常。我相信我需要添加一些jar文件，但我不確定哪些。這裏是所有沿doGet方法我輸入：在Servlet中使用org.json導致java.lang.ClassNotFoundException：org.json.JSONException

import java.io.IOException; 
import java.io.PrintWriter; 

import javax.servlet.ServletException; 
import javax.servlet.annotation.WebServlet; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

import org.json.JSONException; 
import org.json.JSONObject; 

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
    response.setContentType("application/json"); 
    PrintWriter out = response.getWriter(); 

    JSONObject obj = new JSONObject(); 
    try { 
     obj.put("name", "jad"); 
    } catch (JSONException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
    out.println(obj.toString()); 
}

這是我的控制檯：

SEVERE: A child container failed during start 
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/CarpoolServer]] 
    at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source) 
    at java.util.concurrent.FutureTask.get(Unknown Source) 
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123) 
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:800) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559) 
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549) 
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source) 
    at java.util.concurrent.FutureTask.run(Unknown Source) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
    at java.lang.Thread.run(Unknown Source) 
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/CarpoolServer]] 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) 
    ... 7 more 
Caused by: java.lang.NoClassDefFoundError: org/json/JSONException 
    at java.lang.Class.getDeclaredFields0(Native Method) 
    at java.lang.Class.privateGetDeclaredFields(Unknown Source) 
    at java.lang.Class.getDeclaredFields(Unknown Source) 
    at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:106) 
    at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:261) 
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:140) 
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:67) 
    at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:405) 
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:881) 
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:369) 
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119) 
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90) 
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5269) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    ... 7 more 
Caused by: java.lang.ClassNotFoundException: org.json.JSONException 
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1713) 
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1558) 
    ... 21 more 

May 03, 2013 6:16:01 PM org.apache.catalina.core.ContainerBase startInternal 
SEVERE: A child container failed during start 
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]] 
    at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source) 
    at java.util.concurrent.FutureTask.get(Unknown Source) 
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123) 
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:302) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:732) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    at org.apache.catalina.startup.Catalina.start(Catalina.java:684) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
    at java.lang.reflect.Method.invoke(Unknown Source) 
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322) 
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:456) 
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]] 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) 
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559) 
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549) 
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source) 
    at java.util.concurrent.FutureTask.run(Unknown Source) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
    at java.lang.Thread.run(Unknown Source) 
Caused by: org.apache.catalina.LifecycleException: A child container failed during start 
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131) 
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:800) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    ... 7 more 

May 03, 2013 6:16:01 PM org.apache.catalina.startup.Catalina start 
SEVERE: Catalina.start: 
org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]] 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) 
    at org.apache.catalina.startup.Catalina.start(Catalina.java:684) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
    at java.lang.reflect.Method.invoke(Unknown Source) 
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322) 
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:456) 
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]] 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) 
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:732) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    ... 7 more 
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]] 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) 
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    ... 9 more 
Caused by: org.apache.catalina.LifecycleException: A child container failed during start 
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131) 
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:302) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    ... 11 more

來源

2013-05-03 Jad

你是如何編寫代碼的？編譯時缺少的jar在類路徑中。 – 2013-05-03 15:19:17

@JBNizet你是否推斷庫（json-jena.jar）包含在Tomcat運行時？ – 2013-05-03 15:22:20

使用ctrl-shift-T鍵入缺少的類名稱。在項目視圖中找到它的jar，並確保這個jar在web項目的WEB-INF/lib下。 WEB-INF/lib下的所有jar都位於webapp的運行時類路徑中的編譯類路徑AND中。您也可以從項目的構建路徑中找到jar。從構建路徑中將其刪除並將其添加到WEB-INF/lib。 – 2013-05-03 15:23:02

添加java-json.jar到Eclipse的展開組件。

enter image description here

來源

2013-05-03 15:19:50

它的工作！謝謝！當我在瀏覽器中寫入url時，我得到一個文件來下載，而不是出現在瀏覽器中的json對象字符串。這是正常的嗎？ – Jad 2013-05-03 16:08:45

@Jad謝謝JB他真的爲我打下了這一個。我認爲你得到的下載是因爲你在響應中設置了contenttype。不要只爲了好玩而嘗試。測試結束後，您會盡可能希望將其設置回去。 – 2013-05-03 16:14:12

是的你是對的 – Jad 2013-05-03 16:23:05

在Servlet中使用org.json導致java.lang.ClassNotFoundException：org.json.JSONException

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