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java - "Resource not available"将数据库显示到 JSP 中时出错

转载 作者：行者123 更新时间：2023-11-30 22:55:15 25 4
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我想我已经成功连接到数据库，当我运行 Fetch.jsp 时，我确实得到了带有提交按钮的页面。但是，当我单击提交按钮时，它会显示 Tomcat 错误类型状态报告消息/样本描述请求的资源不可用。工具:Eclipse开普勒MySQL 工作台 6.1.7 Apache Tomcat 7.0.54

获取.jsp文件

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Database_Test</title>
</head>
<body>
<form action="Sample" method="post">
Fetch Data: <input type="submit"></input>  
</form>
</body>
</html>

示例.java

package testusecase;

import java.io.IOException;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet; 
import java.sql.Statement;
import java.util.Date;

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

public class Sample extends HttpServlet {
/**
 * 
 */
private static final long serialVersionUID = 8462790020399479519L;

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {


    @SuppressWarnings("unused")
    Sample instance = new Sample();
    final String URL = "jdbc:mysql://localhost:3306/samschema";
    final String USER = "root";
    final String PASSWORD = "password";
    final String DRIVER_CLASS = "com.mysql.jdbc.Driver";

    try {
        Class.forName(DRIVER_CLASS);
        Connection connection = null;
        connection = DriverManager.getConnection(URL, USER, PASSWORD);
        String query = "SELECT * FROM samschema.sample1";
        Statement st = connection.createStatement();
        ResultSet rs = st.executeQuery(query);
        while (rs.next()) {
            int serial_no = rs.getInt("serial_no");
            String first_name = rs.getString("first_name");
            String middle_name = rs.getString("middle_name");
            String last_name = rs.getString("last_name");
            String date_of_birth = rs.getString("date_of_birth");
            String contact_no = rs.getString("contact_no");
            String email_id = rs.getString("email_id");
            String residential_address = rs.getString("residential_address");
            String city = rs.getString("city");
            BigDecimal percentage_x = rs.getBigDecimal("percentage_x");
            Date yop_x = rs.getDate("yop_x");
            String board_x = rs.getString("board_x");
            String percentage_xii = rs.getString("percentage_xii");
            String yop_xii = rs.getString("yop_xii");
            String board_xii = rs.getString("board_xii");
            String btech_stream = rs.getString("btech_stream");
            String mtech_stream = rs.getString("mtech_stream");
            String other_stream = rs.getString("other_stream");
            String percentage_graduation = rs.getString("percentage_graduation");
            String mca_percentage = rs.getString("mca_percentage");
            String year_of_graduation = rs.getString("year_of_graduation");
            String d_to_d = rs.getString("d_to_d");
            String mtech_percentage = rs.getString("mtech_percentage");
            String yop_diploma = rs.getString("yop_diploma");
            String percentage_d_to_d = rs.getString("percentage_d_to_d");


            // print the results
            System.out.format("%d, %s, %s, %s, %s, %s, %s, %s, %s, %d, %d, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s\n", serial_no, first_name,
                    middle_name,last_name, date_of_birth,contact_no,email_id,residential_address,city, percentage_x, yop_x, board_x, percentage_xii, yop_xii, board_xii, btech_stream, mtech_stream, other_stream, percentage_graduation, mca_percentage, year_of_graduation, d_to_d, mtech_percentage, yop_diploma, percentage_d_to_d);
        }
        st.close();

    }

    catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

}

网络.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" 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>TestUseCase</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<security-constraint>
<web-resource-collection>
  <web-resource-name>TestUseCase</web-resource-name>
  <url-pattern>/*</url-pattern>
  <http-method>GET</http-method>
  <http-method>POST</http-method>
</web-resource-collection>
</security-constraint>
<servlet>
<description></description>
<display-name>Login</display-name>
<servlet-name>Login</servlet-name>
<jsp-file>/Login.jsp</jsp-file>
</servlet>
<servlet-mapping>
<servlet-name>Login</servlet-name>
<url-pattern>/Login</url-pattern>
</servlet-mapping>

<servlet>
<description></description>
<display-name>Sample</display-name>
<servlet-name>Sample</servlet-name>
<servlet-class>Sample</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Sample</servlet-name>
<url-pattern>/Sample</url-pattern>
</servlet-mapping>


</web-app>

控制台中的 Java 堆栈跟踪

Java Model Exception: Java Model Status [Unknown javadoc format for getAsciiStream(java.lang.String) [in ResultSet [in ResultSet.class [in java.sql [in U:\Miller\Eclipse\JDK\lib\rt.jar]]]]]
at org.eclipse.jdt.internal.core.JavadocContents.getMethodDoc(JavadocContents.java:158)
at org.eclipse.jdt.internal.core.BinaryMethod.getAttachedJavadoc(BinaryMethod.java:671)
at org.eclipse.jdt.internal.ui.text.javadoc.JavadocContentAccess2.getHTMLContent(JavadocContentAccess2.java:499)
at org.eclipse.jdt.internal.ui.text.java.ProposalInfo.extractJavadoc(ProposalInfo.java:93)
at org.eclipse.jdt.internal.ui.text.java.ProposalInfo.computeInfo(ProposalInfo.java:77)
at org.eclipse.jdt.internal.ui.text.java.ProposalInfo.getInfo(ProposalInfo.java:62)
at org.eclipse.jdt.internal.ui.text.java.AbstractJavaCompletionProposal.getAdditionalProposalInfo(AbstractJavaCompletionProposal.java:573)
at org.eclipse.jface.text.contentassist.AdditionalInfoController$3.run(AdditionalInfoController.java:106)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)

浏览器错误

HTTP Status 500 - Error instantiating servlet class Sample

type Exception report

message Error instantiating servlet class Sample

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: Error instantiating servlet class Sample
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:610)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source) 
root cause

java.lang.ClassNotFoundException: Sample
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:610)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.54 logs.

Apache Tomcat/7.0.54

最佳答案

在 servlet 标记中，<servlet-class> element 应该是您的 servlet 类的完全限定名称。例如:

<servlet-class>testusecase.Sample</servlet-class>

另请注意，您显示的堆栈跟踪似乎是针对您的应用程序启动时的，而不是针对指定问题发生时的。

关于java - "Resource not available"将数据库显示到 JSP 中时出错，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26689901/

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