我有这个类从我的表中选择一些行并生成一个String，用作我的do get servlet上的JSON：
package sql;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import connections.OrganiteRepository;
public class select {
// a conexão com o banco de dados
public Connection connection;
public select() {
super();
this.connection = new OrganiteRepository().getConnection();
}
public String createJsonFile() throws SQLException, JSONException, IOException {
PreparedStatement stmt = connection.prepareStatement("select * from contatos");
ResultSet rs = stmt.executeQuery();
JSONArray jArray = new JSONArray();
while (rs.next()) {
JSONObject jObj = new JSONObject();
jObj.put("ID", rs.getString("id"));
jObj.put("Nome", rs.getString("nome"));
jArray.put(jObj);
}
JSONObject jObjList = new JSONObject();
jObjList.put("list", jArray);
String resp = jArray.toString();
try (FileWriter file = new FileWriter("file1.txt")) {
file.write(jObjList.toString());
System.out.println("Successfully Copied JSON Object to File...");
System.out.println("\nJSON Object: " + jObjList);
}
stmt.close();
rs.close();
connection.close();
return resp;
}
}
一切正常，直到我创建我的servlet。
我似乎无法理解如何实际打印我的String，因为每当我启动Tomcat服务器时它都会出错，而且它甚至都没有启动。
我的servlet如下：
package servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
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 sql.select;
@WebServlet("/getTablesJSON")
public class GetTablesJSON extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// TODO Auto-generated method stub
try {
resp.setContentType("application/json");
select s = new select();
String str = s.createJsonFile();
PrintWriter out = resp.getWriter();
out.println(str);
} catch (IOException e) {
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
我似乎无法理解什么是错的。
提前谢谢大家！
PS：如果有人对任何方法的建议比这个更好，他们会很感激。尝试启动服务器时出现错误：
mar 03, 2016 1:08:15 AM org.apache.catalina.core.AprLifecycleListener init
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files\Java\jre1.8.0_73\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:/Program Files/Java/jre1.8.0_73/bin/server;C:/Program Files/Java/jre1.8.0_73/bin;C:/Program Files/Java/jre1.8.0_73/lib/amd64;C:\ProgramData\Oracle\Java\javapath;C:\Program Files (x86)\Common Files\Intel\Shared Libraries\redist\intel64\compiler;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\MySQL\MySQL Enterprise Backup 3.12\;C:\Program Files (x86)\MySQL\MySQL Fabric 1.5.4 and MySQL Utilities 1.5.4 1.5\;C:\Program Files (x86)\MySQL\MySQL Fabric 1.5.4 and MySQL Utilities 1.5.4 1.5\Doctrine extensions for PHP\;C:\Program Files\Microsoft DNX\Dnvm\;C:\Program Files (x86)\Windows Kits\8.1\Windows Performance Toolkit\;C:\Program Files (x86)\MiKTeX 2.9\miktex\bin\;C:\instant_client_oracle;C:\Python27;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\Python27\Scripts;C:\Program Files (x86)\MiKTeX 2.9.58\miktex\bin\;C:\Program Files (x86)\Skype\Phone\;C:\Program Files (x86)\Windows Live\Shared;C:\Program Files\nodejs\;C:\Program Files\Git\cmd;C:\Program Files\Git\mingw64\bin;C:\Program Files\Git\usr\bin;C:\oracle\instantclient;C:\Users\Asus\.dnx\bin;C:\Program Files (x86)\Microsoft VS Code\bin;C:\Users\Asus\AppData\Roaming\npm;C:\Users\Asus\eclipse\jee-mars\eclipse;;.
mar 03, 2016 1:08:16 AM org.apache.tomcat.util.digester.SetPropertiesRule begin
WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:organiteserver' did not find a matching property.
mar 03, 2016 1:08:16 AM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-bio-8080"]
mar 03, 2016 1:08:16 AM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
mar 03, 2016 1:08:16 AM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 816 ms
mar 03, 2016 1:08:16 AM org.apache.catalina.core.StandardService startInternal
INFO: Starting service Catalina
mar 03, 2016 1:08:16 AM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/7.0.47
mar 03, 2016 1:08:16 AM 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].StandardContext[/organiteserver]]
at java.util.concurrent.FutureTask.report(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.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[/organiteserver]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
... 6 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:263)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:142)
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:376)
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:5322)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
... 6 more
Caused by: java.lang.ClassNotFoundException: org.json.JSONException
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1702)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)
... 20 more
mar 03, 2016 1:08:16 AM 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.report(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:691)
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$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$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)
... 6 more
mar 03, 2016 1:08:16 AM org.apache.catalina.startup.Catalina start
SEVERE: The required Server component failed to start so Tomcat is unable to 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:691)
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
mar 03, 2016 1:08:16 AM org.apache.coyote.AbstractProtocol pause
INFO: Pausing ProtocolHandler ["http-bio-8080"]
mar 03, 2016 1:08:16 AM org.apache.coyote.AbstractProtocol pause
INFO: Pausing ProtocolHandler ["ajp-bio-8009"]
mar 03, 2016 1:08:16 AM org.apache.catalina.core.StandardService stopInternal
INFO: Stopping service Catalina
mar 03, 2016 1:08:16 AM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["http-bio-8080"]
mar 03, 2016 1:08:16 AM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["ajp-bio-8009"]