我有一个包含网络服务的动态网络项目。我已经把它导出为一个WAR文件,放在tomcat的webapps目录下。 Tomcat 显示 Web 应用程序正在运行。当我尝试调用我的服务的其中一项操作时,出现以下异常:
java.lang.NullPointerException
sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
java.lang.ClassLoader.loadClass(ClassLoader.java:247)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1629)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:461)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:931)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
java.lang.Thread.run(Thread.java:680)
知道这是什么意思吗?
这是我定义 Web 服务的类:
打包网络服务;
import java.sql.*;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.HeaderParam;
import javax.ws.rs.core.MediaType;
@Path("/operations")
public class NotifyWebService {
@Path("/insertNewPatron")
@GET
public String insertNewPatron(@QueryParam("cardNumber")String cardNumber,
@QueryParam("pin") String pin,
@QueryParam("nickname") String nickname,
@QueryParam("deviceID")String deviceID) throws Exception {
String connectionUrl = "jdbc:sqlserver://mssql.acpl.lib.in.us:1433;" +
"databaseName=MobileNotify;user=Mobile_Notification_User;password=xxxxxxx;";
Connection c = DriverManager.getConnection(connectionUrl);
String insertPatronStatement = "INSERT INTO dbo.Patron VALUES ('"+cardNumber+"','"+pin+"','"+nickname+"')";
String insertDeviceOwner = "INSERT INTO dbo.DeviceOwner VALUES ('"+deviceID+"','"+cardNumber+"')";
Statement state = null;
state = c.createStatement();
state.executeUpdate(insertPatronStatement);
state.executeUpdate(insertDeviceOwner);
c.close();
return "true";
}
@Path("/initializeDevice")
@GET
public String initializeDevice( @QueryParam("deviceID")String deviceID) throws Exception{
String connectionUrl = "jdbc:sqlserver://mssql.acpl.lib.in.us:1433;" +
"databaseName=MobileNotify;user=Mobile_Notification_User;password=xxxxxx;";
Connection c = DriverManager.getConnection(connectionUrl);
String insertDeviceStatement = "INSERT INTO dbo.Devices VALUES ('"+deviceID+"',1,3,1,3)";
Statement state = c.createStatement();
state.executeUpdate(insertDeviceStatement);
return "true";
}
@Path("/updateDevicePreferences")
@GET
public String updateDevicePreferences(@QueryParam("deviceID") String deviceID,
@QueryParam("dueDateNotice")String dueDateNotice,
@QueryParam("dueDateNoticeAdvance") String dueDateNoticeAdvance,
@QueryParam("holdsNotice") String holdsNotice,
@QueryParam("eventNoticeAdvance")String eventNoticeAdvance) throws Exception{
String connectionUrl = "jdbc:sqlserver://mssql.acpl.lib.in.us:1433;" +
"databaseName=MobileNotify;user=Mobile_Notification_User;password=xxxxxx;";
Connection c = DriverManager.getConnection(connectionUrl);
String updateDeviceStatement = "UPDATE dbo.Devices SET dueDateNotice="+dueDateNotice+", dueDateNoticeAdvance="+dueDateNoticeAdvance
+", holdsNotice="+holdsNotice+", eventNoticeAdvance="+eventNoticeAdvance+" WHERE deviceID='"+deviceID+"'";
Statement state = c.createStatement();
state.executeUpdate(updateDeviceStatement);
return "true";
}
@Path("/removeUser")
@GET
public String removeUser(@QueryParam("cardNumber")String cardNumber) throws Exception{
String connectionUrl = "jdbc:sqlserver://mssql.acpl.lib.in.us:1433;" +
"databaseName=MobileNotify;user=Mobile_Notification_User;password=xxxxxx;";
Connection c = DriverManager.getConnection(connectionUrl);
String removeStatement = "DELETE FROM dbo.Patron WHERE cardNumber='"+cardNumber+"'";
Statement state = c.createStatement();
state.executeUpdate(removeStatement);
return "true";
}
@Path("/addEvent")
@GET
public String addEvent(@QueryParam("deviceID")String deviceID, @QueryParam("eventID")String eventID) throws Exception{
String connectionUrl = "jdbc:sqlserver://mssql.acpl.lib.in.us:1433;" +
"databaseName=MobileNotify;user=Mobile_Notification_User;password=xxxxx;";
Connection c = DriverManager.getConnection(connectionUrl);
String eventStatement = "INSERT INTO dbo.Events VALUES ('"+deviceID+"','"+eventID+"')";
Statement state = c.createStatement();
state.executeUpdate(eventStatement);
return "true";
}
@Path("/removeEvent")
@GET
public String removeEvent(@QueryParam("deviceID")String deviceID, @QueryParam("eventID")String eventID) throws Exception{
String connectionUrl = "jdbc:sqlserver://mssql.acpl.lib.in.us:1433;" +
"databaseName=MobileNotify;user=Mobile_Notification_User;password=xxxxx;";
Connection c = DriverManager.getConnection(connectionUrl);
String eventStatement = "DELETE FROM dbo.Events WHERE deviceID='"+deviceID+"' AND eventID='"+eventID+"'";
Statement state = c.createStatement();
state.executeUpdate(eventStatement);
return "true";
}
@Path("/removeAllEvents")
@GET
public String removeAllEvents(@QueryParam("deviceID")String deviceID) throws Exception{
String connectionUrl = "jdbc:sqlserver://mssql.acpl.lib.in.us:1433;" +
"databaseName=MobileNotify;user=Mobile_Notification_User;password=xxxx;";
Connection c = DriverManager.getConnection(connectionUrl);
String eventStatement = "DELETE FROM dbo.Events WHERE deviceID='"+deviceID+"'";
Statement state = c.createStatement();
state.executeUpdate(eventStatement);
return "true";
}
}
这是我的 web.xml 文件:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>APNS_WebService</display-name>
<servlet>
<servlet-name>javax.ws.rs.core.Application</servlet-name>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>javax.ws.rs.core.Application</servlet-name>
<url-pattern>/rest/*</url-pattern>
</servlet-mapping>
</web-app>
如果需要更多信息,请告诉我!
最佳答案
我认为您的 NPE 的原因是缺少 <servlet-class>
你的 <servlet>
中的元素堵塞。然而,决定 servlet 类应该是什么会引发更大的问题......
您似乎没有选择 JAX-RS 框架。参见 JAX-RS Frameworks了解各种替代方案。
我目前正在使用 Jersey。 Jersey 的典型 web.xml 可能包含:
<servlet>
<servlet-name>WebService</servlet-name>
<servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>com.sun.jersey.config.property.packages</param-name>
<param-value>webservice</param-value>
</init-param>
<init-param>
<param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
<param-value>true</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>WebService</servlet-name>
<url-pattern>/api/rest/*</url-pattern>
</servlet-mapping>
对于许多 JAX-RS 框架,框架的选择将决定您应该输入什么作为 <servlet-class>
另请注意,由于您的根资源位于包 webservice
中, 我设置了 com.sun.jersey.config.property.packages
参数 webservice
因此 Jersey 将扫描您的包以查找任何 JAX-RS 注释类。
关于java - Tomcat:尝试访问 Web 服务时出现空指针异常,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13771236/