我無法連接到MySQL數據庫寧靜

我正在開發一個寧靜的Web服務，實際上我正在使用一個文件，但我想做一個數據庫連接，所以我可以從數據庫中獲取數據一個文件，我試圖建立一個數據庫連接，但它無法工作，即使是癱瘓的服務器停止並停止部署該項目。這是使用即時通訊文件：我無法連接到MySQL數據庫寧靜

DBConnection.java文件

package com.TP6; 

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import java.sql.Statement; 

public class DBConnection { 

public static Connection dbCon; 
public Statement dbStmt; 
public ResultSet dbRst; 

public static Connection setDBConnection() throws SQLException { 
try { 

System.out.println("Inside DB Connection"); 

Class.forName("com.mysql.jdbc.Driver"); 
dbCon = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/usermangment", 
"root", ""); 

} catch (ClassNotFoundException e) 

{ 
System.out.println(e); 
} 
return dbCon; 
} 

public void getInsertResutlSet(String sqlQuery, Connection conn) 
throws SQLException { 

System.out.println(sqlQuery); 
String sqlquery = sqlQuery; 
dbCon = conn; 
try { 

dbStmt = dbCon.createStatement(); 
dbStmt.executeUpdate(sqlquery); 

} catch (SQLException se) { 
System.out.println(se); 
} 

} 

public ResultSet getResutlSet(String sqlQuery, Connection conn) 
throws SQLException { 

System.out.println(sqlQuery); 
String sqlquery = sqlQuery; 
dbCon = conn; 
try { 

dbStmt = dbCon.createStatement(); 
dbRst = dbStmt.executeQuery(sqlquery); 

} catch (SQLException se) { 
System.out.println(se); 
} 
return dbRst; 
} 
}

的userDao.java：獲取和插入數據

它使用一個文件IL

package com.TP6; 

import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.ObjectInputStream; 
import java.io.ObjectOutputStream; 
import java.util.ArrayList; 
import java.util.List; 

public class UserDao { 
    public List<User> getAllUsers(){ 
     List<User> userList = null; 
     try { 



     File file = new File("Users.dat"); 
     if (!file.exists()) { 
      User user = new User(1, "", ""); 
      userList = new ArrayList<User>(); 
      userList.add(user); 
      saveUserList(userList); 
     } 
     else{ 
      FileInputStream fis = new FileInputStream(file); 
      ObjectInputStream ois = new ObjectInputStream(fis); 
      userList = (List<User>) ois.readObject(); 
      ois.close(); 
     } 
     } catch (IOException e) { 
     e.printStackTrace(); 
     } catch (ClassNotFoundException e) { 
     e.printStackTrace(); 
     } 
     return userList; 
    } 

    public User getUser(int id){ 
     List<User> users = getAllUsers(); 

     for(User user: users){ 
     if(user.getId() == id){ 
      return user; 
     } 
     } 
     return null; 
    } 

    public int addUser(User pUser){ 
     List<User> userList = getAllUsers(); 
     boolean userExists = false; 
     for(User user: userList){ 
     if(user.getId() == pUser.getId()){ 
      userExists = true; 
      break; 
     } 
     } 
     if(!userExists){ 
     userList.add(pUser); 
     saveUserList(userList); 
     return 1; 
     } 
     return 0; 
    } 




    public int updateUser(User pUser){ 
     List<User> userList = getAllUsers(); 

     for(User user: userList){ 
     if(user.getId() == pUser.getId()){ 
      int index = userList.indexOf(user);  
      userList.set(index, pUser); 
      saveUserList(userList); 
      return 1; 
     } 
     } 
     return 0; 
    } 

    public int deleteUser(int id){ 
     List<User> userList = getAllUsers(); 

     for(User user: userList){ 
     if(user.getId() == id){ 
      int index = userList.indexOf(user);  
      userList.remove(index); 
      saveUserList(userList); 
      return 1;  
     } 
     } 
     return 0; 
    } 

    private void saveUserList(List<User> userList){ 
     try { 
     File file = new File("Users.dat"); 
     FileOutputStream fos; 

     fos = new FileOutputStream(file); 

     ObjectOutputStream oos = new ObjectOutputStream(fos); 
     oos.writeObject(userList); 
     oos.close(); 
     } catch (FileNotFoundException e) { 
     e.printStackTrace(); 
     } catch (IOException e) { 
     e.printStackTrace(); 
     } 
    } 
}

的userService.java

package com.TP6;  
import java.io.IOException; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import java.util.List; 
import javax.servlet.http.HttpServletResponse; 
import javax.ws.rs.Consumes; 
import javax.ws.rs.DELETE; 
import javax.ws.rs.FormParam; 
import javax.ws.rs.GET; 
import javax.ws.rs.OPTIONS; 
import javax.ws.rs.POST; 
import javax.ws.rs.PUT; 


import javax.ws.rs.Path; 
import javax.ws.rs.PathParam; 
import javax.ws.rs.Produces; 
import javax.ws.rs.core.Context; 
import javax.ws.rs.core.MediaType; 

import com.TP6.DBConnection; 
import com.mysql.jdbc.Connection; 
@Path("/UserService") 
public class UserService { 

    DBConnection dbCoN; 
    Connection conn; 
    ResultSet rslt; 
    String Iuser = "user inconnu "; 
    String query; 
    UserDao userDao = new UserDao(); 
    private static final String SUCCESS_RESULT="<result>success</result>"; 
    private static final String FAILURE_RESULT="<result>failure</result>"; 


    @GET 
    @Path("/user/ID") 
    @Produces(MediaType.APPLICATION_XML) 
    public String Usernom(@PathParam("id") String id) 

      throws SQLException { 

    query = "select nom from user where id=55"; 

// System.out.println("" + query); 
    dbCoN = new DBConnection(); 

    try { 
    conn = (Connection) DBConnection.setDBConnection(); 
    rslt = dbCoN.getResutlSet(query, conn); 

    if (rslt.next()) { 

    String nom = rslt.getString(2); 


    } else { 
    return Iuser; 
    } 

    } catch (Exception e) { 
    System.out.println(e); 
    } finally { 
    if (conn != null) { 
    conn.close(); 
    } 
    } 

    return Iuser; 

    } 

    @GET 
    @Path("/users") 
    @Produces(MediaType.APPLICATION_XML) 
    public List<User> getUsers(){ 
     return userDao.getAllUsers(); 
    } 

    @GET 
    @Path("https://stackoverflow.com/users/{userid}") 
    @Produces(MediaType.APPLICATION_XML) 
    public User getUser(@PathParam("userid") int userid){ 
     return userDao.getUser(userid); 
    } 

    @PUT 
    @Path("/users") 
    @Produces(MediaType.APPLICATION_XML) 
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED) 
    public String createUser(@FormParam("id") int id,@FormParam("nom") String nom,@FormParam("agence") String agence, @Context HttpServletResponse servletResponse) 
       throws IOException{ 
     User user = new User(id, nom, agence); 
     int result = userDao.addUser(user); 
     if(result == 1){ 
     return SUCCESS_RESULT; 
     } 
     return FAILURE_RESULT; 
    } 

    @POST 
    @Path("/users") 
    @Produces(MediaType.APPLICATION_XML) 
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED) 
    public String updateUser(@FormParam("id") int id, 
     @FormParam("nom") String nom, 
     @FormParam("agence") String agence, 
     @Context HttpServletResponse servletResponse) throws IOException{ 
     User user = new User(id, nom, agence); 
     int result = userDao.updateUser(user); 
     if(result == 1){ 
     return SUCCESS_RESULT; 
     } 
     return FAILURE_RESULT; 
    } 

    @DELETE 
    @Path("https://stackoverflow.com/users/{userid}") 
    @Produces(MediaType.APPLICATION_XML) 
    public String deleteUser(@PathParam("userid") int userid){ 
     int result = userDao.deleteUser(userid); 
     if(result == 1){ 
     return SUCCESS_RESULT; 
     } 
     return FAILURE_RESULT; 
    } 

    @OPTIONS 
    @Path("/users") 
    @Produces(MediaType.APPLICATION_XML) 
    public String getSupportedOperations(){ 
     return "<operations>GET, PUT, POST, DELETE</operations>"; 
    } 
}

其實我只是想要什麼ois問題爲什麼當im使數據庫連接停止工作。

此控制檯：

20:26:51,986 INFO [org.jboss.modules] (main) JBoss Modules version 1.3.0.Final 
20:26:52,235 INFO [org.jboss.msc] (main) JBoss MSC version 1.2.0.Final 
20:26:52,327 INFO [org.jboss.as] (MSC service thread 1-6) JBAS015899: WildFly 8.0.0.Final "WildFly" starting 
20:26:53,805 INFO [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - 1) JBAS015003: Found UserManagment.war in deployment directory. To trigger deployment create a file called UserManagment.war.dodeploy 
20:26:53,827 INFO [org.jboss.as.server] (Controller Boot Thread) JBAS015888: Creating http management service using socket-binding (management-http) 
20:26:53,856 INFO [org.xnio] (MSC service thread 1-7) XNIO version 3.2.0.Final 
20:26:53,868 INFO [org.xnio.nio] (MSC service thread 1-7) XNIO NIO Implementation Version 3.2.0.Final 
20:26:53,966 INFO [org.jboss.as.connector.subsystems.datasources] (ServerService Thread Pool -- 28) JBAS010403: Deploying JDBC-compliant driver class org.h2.Driver (version 1.3) 
20:26:53,976 INFO [org.jboss.as.connector.subsystems.datasources] (ServerService Thread Pool -- 28) JBAS010404: Deploying non-JDBC-compliant driver class com.mysql.jdbc.Driver (version 5.1) 
20:26:54,053 INFO [org.wildfly.extension.undertow] (ServerService Thread Pool -- 49) JBAS017502: Undertow 1.0.0.Final starting 
20:26:54,037 INFO [org.jboss.as.naming] (ServerService Thread Pool -- 41) JBAS011800: Activating Naming Subsystem 
20:26:54,060 INFO [org.jboss.as.security] (ServerService Thread Pool -- 46) JBAS013171: Activating Security Subsystem 
20:26:54,061 INFO [org.wildfly.extension.undertow] (MSC service thread 1-2) JBAS017502: Undertow 1.0.0.Final starting 
20:26:54,063 INFO [org.jboss.as.security] (MSC service thread 1-2) JBAS013170: Current PicketBox version=4.0.20.Final 
20:26:54,095 INFO [org.jboss.as.webservices] (ServerService Thread Pool -- 50) JBAS015537: Activating WebServices Extension 
20:26:54,099 INFO [org.jboss.as.jsf] (ServerService Thread Pool -- 39) JBAS012615: Activated the following JSF Implementations: [main] 
20:26:54,138 INFO [org.jboss.as.clustering.infinispan] (ServerService Thread Pool -- 33) JBAS010280: Activating Infinispan subsystem. 
20:26:54,180 INFO [org.jboss.as.connector.logging] (MSC service thread 1-3) JBAS010408: Starting JCA Subsystem (IronJacamar 1.1.3.Final) 
20:26:54,202 INFO [org.jboss.as.naming] (MSC service thread 1-5) JBAS011802: Starting Naming Service 
20:26:54,222 INFO [org.jboss.as.connector.deployers.jdbc] (MSC service thread 1-2) JBAS010417: Started Driver service with driver-name = mysql 
20:26:54,223 INFO [org.jboss.as.connector.deployers.jdbc] (MSC service thread 1-2) JBAS010417: Started Driver service with driver-name = h2 
20:26:54,214 INFO [org.jboss.as.mail.extension] (MSC service thread 1-5) JBAS015400: Bound mail session [java:jboss/mail/Default] 
20:26:54,505 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-4) JBAS010400: Bound data source [java:/DsBibliotheque] 
20:26:54,506 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-4) JBAS010400: Bound data source [java:/DsBanque] 
20:26:54,661 INFO [org.wildfly.extension.undertow] (ServerService Thread Pool -- 49) JBAS017527: Creating file handler for path C:\Users\Emel\wildfly-8.0.0.Final/welcome-content 
20:26:54,689 INFO [org.wildfly.extension.undertow] (MSC service thread 1-4) JBAS017525: Started server default-server. 
20:26:54,699 INFO [org.wildfly.extension.undertow] (MSC service thread 1-4) JBAS017531: Host default-host starting 
20:26:54,781 INFO [org.jboss.remoting] (MSC service thread 1-7) JBoss Remoting version 4.0.0.Final 
20:26:54,981 INFO [org.jboss.as.server.deployment.scanner] (MSC service thread 1-4) JBAS015012: Started FileSystemDeploymentService for directory C:\Users\Emel\wildfly-8.0.0.Final\standalone\deployments 
20:26:54,987 INFO [org.jboss.as.server.deployment] (MSC service thread 1-7) JBAS015876: Starting deployment of "UserManagment.war" (runtime-name: "UserManagment.war") 
20:26:55,191 INFO [org.wildfly.extension.undertow] (MSC service thread 1-8) JBAS017519: Undertow HTTP listener default listening on localhost/127.0.0.1:8180 
20:26:55,399 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-6) JBAS010400: Bound data source [java:jboss/datasources/ExampleDS] 
20:26:55,728 INFO [org.jboss.ws.common.management] (MSC service thread 1-8) JBWS022052: Starting JBoss Web Services - Stack CXF Server 4.2.3.Final 
20:26:56,055 ERROR [org.jboss.remoting.remote.connection] (XNIO-1 I/O-1) JBREM000200: Remote connection failed: java.io.IOException: Une connexion établie a été abandonnée par un logiciel de votre ordinateur hôte 
20:26:56,057 ERROR [org.jboss.remoting.remote.connection] (XNIO-1 I/O-2) JBREM000200: Remote connection failed: java.io.IOException: Une connexion établie a été abandonnée par un logiciel de votre ordinateur hôte 
20:26:56,571 INFO [org.jboss.resteasy.spi.ResteasyDeployment] (MSC service thread 1-3) Deploying javax.ws.rs.core.Application: class com.TP6.RestApplicationConfig 
20:26:56,615 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-3) MSC000001: Failed to start service jboss.undertow.deployment.default-server.default-host./UserManagment: org.jboss.msc.service.StartException in service jboss.undertow.deployment.default-server.default-host./UserManagment: Failed to start service 
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1904) [jboss-msc-1.2.0.Final.jar:1.2.0.Final] 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [rt.jar:1.8.0_91] 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [rt.jar:1.8.0_91] 
    at java.lang.Thread.run(Unknown Source) [rt.jar:1.8.0_91] 
Caused by: java.lang.NoClassDefFoundError: Lcom/mysql/jdbc/Connection; 
    at java.lang.Class.getDeclaredFields0(Native Method) [rt.jar:1.8.0_91] 
    at java.lang.Class.privateGetDeclaredFields(Unknown Source) [rt.jar:1.8.0_91] 
    at java.lang.Class.getDeclaredFields(Unknown Source) [rt.jar:1.8.0_91] 
    at org.jboss.resteasy.spi.metadata.ResourceBuilder.processDeclaredFields(ResourceBuilder.java:867) 
    at org.jboss.resteasy.spi.metadata.ResourceBuilder.processFields(ResourceBuilder.java:849) 
    at org.jboss.resteasy.spi.metadata.ResourceBuilder.fromAnnotations(ResourceBuilder.java:755) 
    at org.jboss.resteasy.spi.metadata.ResourceBuilder.rootResourceFromAnnotations(ResourceBuilder.java:700) 
    at org.jboss.resteasy.plugins.server.resourcefactory.POJOResourceFactory.<init>(POJOResourceFactory.java:29) 
    at org.jboss.resteasy.core.ResourceMethodRegistry.addPerRequestResource(ResourceMethodRegistry.java:75) 
    at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:400) 
    at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:241) 
    at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.init(ServletContainerDispatcher.java:112) 
    at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.init(HttpServletDispatcher.java:36) 
    at io.undertow.servlet.core.ManagedServlet$DefaultInstanceStrategy.start(ManagedServlet.java:208) 
    at io.undertow.servlet.core.ManagedServlet.createServlet(ManagedServlet.java:116) 
    at io.undertow.servlet.core.DeploymentManagerImpl.start(DeploymentManagerImpl.java:496) 
    at org.wildfly.extension.undertow.deployment.UndertowDeploymentService.startContext(UndertowDeploymentService.java:87) 
    at org.wildfly.extension.undertow.deployment.UndertowDeploymentService.start(UndertowDeploymentService.java:71) 
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1948) [jboss-msc-1.2.0.Final.jar:1.2.0.Final] 
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1881) [jboss-msc-1.2.0.Final.jar:1.2.0.Final] 
    ... 3 more 
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Connection from [Module "deployment.UserManagment.war:main" from Service Module Loader] 
    at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:197) [jboss-modules.jar:1.3.0.Final] 
    at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:443) [jboss-modules.jar:1.3.0.Final] 
    at org.jboss.modules.ConcurrentClassLoader.performLoadClassChecked(ConcurrentClassLoader.java:431) [jboss-modules.jar:1.3.0.Final] 
    at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:373) [jboss-modules.jar:1.3.0.Final] 
    at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:118) [jboss-modules.jar:1.3.0.Final] 
    ... 23 more 

20:26:56,630 ERROR [org.jboss.as.controller.management-operation] (Controller Boot Thread) JBAS014613: Operation ("deploy") failed - address: ([("deployment" => "UserManagment.war")]) - failure description: {"JBAS014671: Failed services" => {"jboss.undertow.deployment.default-server.default-host./UserManagment" => "org.jboss.msc.service.StartException in service jboss.undertow.deployment.default-server.default-host./UserManagment: Failed to start service 
    Caused by: java.lang.NoClassDefFoundError: Lcom/mysql/jdbc/Connection; 
    Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Connection from [Module \"deployment.UserManagment.war:main\" from Service Module Loader]"}} 
20:26:56,667 INFO [org.jboss.as.server] (ServerService Thread Pool -- 29) JBAS018559: Deployed "UserManagment.war" (runtime-name : "UserManagment.war") 
20:26:56,671 INFO [org.jboss.as.controller] (Controller Boot Thread) JBAS014774: Service status report 
JBAS014777: Services which failed to start:  service jboss.undertow.deployment.default-server.default-host./UserManagment: org.jboss.msc.service.StartException in service jboss.undertow.deployment.default-server.default-host./UserManagment: Failed to start service 

20:26:56,866 INFO [org.jboss.as] (Controller Boot Thread) JBAS015961: Http management interface listening on http://127.0.0.1:10090/management 
20:26:56,866 INFO [org.jboss.as] (Controller Boot Thread) JBAS015951: Admin console listening on http://127.0.0.1:10090 
20:26:56,867 ERROR [org.jboss.as] (Controller Boot Thread) JBAS015875: WildFly 8.0.0.Final "WildFly" started (with errors) in 5188ms - Started 257 of 314 services (2 services failed or missing dependencies, 90 services are lazy, passive or on-demand) 
20:26:56,931 INFO [org.hibernate.validator.internal.util.Version] (MSC service thread 1-2) HV000001: Hibernate Validator 5.0.3.Final 
20:26:56,982 INFO [org.jboss.as.server.deployment] (MSC service thread 1-6) JBAS015877: Stopped deployment UserManagment.war (runtime-name: UserManagment.war) in 81ms 
20:26:57,176 INFO [org.jboss.as.server] (DeploymentScanner-threads - 2) JBAS018558: Undeployed "UserManagment.war" (runtime-name: "UserManagment.war") 
20:26:57,178 INFO [org.jboss.as.controller] (DeploymentScanner-threads - 2) JBAS014774: Service status report 
JBAS014775: New missing/unsatisfied dependencies: 
     service jboss.deployment.unit."UserManagment.war".component."com.sun.faces.config.ConfigureListener".START (missing) dependents: [service jboss.deployment.unit."UserManagment.war".deploymentCompleteService] 
     service jboss.deployment.unit."UserManagment.war".component."javax.faces.webapp.FacetTag".START (missing) dependents: [service jboss.deployment.unit."UserManagment.war".deploymentCompleteService] 
     service jboss.deployment.unit."UserManagment.war".component."javax.servlet.jsp.jstl.tlv.PermittedTaglibsTLV".START (missing) dependents: [service jboss.deployment.unit."UserManagment.war".deploymentCompleteService] 
     service jboss.deployment.unit."UserManagment.war".component."javax.servlet.jsp.jstl.tlv.ScriptFreeTLV".START (missing) dependents: [service jboss.deployment.unit."UserManagment.war".deploymentCompleteService] 
     service jboss.undertow.deployment.default-server.default-host./UserManagment (missing) dependents: [service jboss.deployment.unit."UserManagment.war".deploymentCompleteService] 
JBAS014777: Services which failed to start:  service jboss.undertow.deployment.default-server.default-host./UserManagment 

20:27:01,705 INFO [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - 2) JBAS015003: Found UserManagment.war in deployment directory. To trigger deployment create a file called UserManagment.war.dodeploy

PS：使用IM日食，wildfly 8.0作爲服務器，郵遞員爲嘗試的URL，我已經創建了MySQL數據庫。當我刪除數據庫連接文件和用戶服務中的數據庫的代碼塊再次工作時，這就是爲什麼確保問題是在數據庫連接。

以防萬一你想知道我的目標是什麼開發一個android應用程序，它會消耗一個寧靜的web服務，從數據庫獲取數據就是了！

謝謝你幫助我！

來源

2017-03-08 Emél

你有沒有包含必要的庫？你使用任何構建工具（如maven例如）或只是Eclipse的Web項目？ – niceman

是的，我已經添加了mysql jar，不，我不認爲我有一個構建工具！我想也許我需要一個persistance.xml文件或類似的東西？ –

什麼是您的eclipse版本，您是如何創建該項目的？ – niceman

當我們看到像NoClassDefFoundError,ClassNotFoundException,NoSuchMethodException這樣的錯誤，這意味着JVM搜索的類/方法沒有找到它。

但是等一下，我的項目編譯好了，怎麼沒找到它們？

要回答我必須解釋運行時間依賴和編譯時間依賴之間的區別。當A使用B.jar（在你的情況下，A是你的項目，而B.jar是mysql.jar），我們說A依賴於B（B是A的依賴），如果A不能編譯，不需要B但是可以在沒有它的情況下運行我們說B是編譯時間依賴，通常IDE不會將這些庫複製到最終結果（jar或war文件）中。

當A不能沒有B運行時，我們說B是運行時依賴，通常IDE將這些包括到最終結果（jar或war文件）中。

在你的情況下，mysql.jar是一個運行時依賴項，但我希望你配置它爲編譯時間依賴項，這就是爲什麼你的項目編譯但無法運行。

爲了解決這個問題，我們在我們的IDE配置得當，月食我們做這樣（假設你已經添加的mysql.jar到庫）：

右鍵單擊該項目。
根據Build Path選擇Configure Build Path。
左鍵點擊Deployment Assembly。
點擊添加，會彈出一個對話框，選擇Java Build Path Entries。
從那裏

選擇mysql.jar如果這些步驟去如我所料蝕會複製到mysql.jar夾WEB-INF/lib和你的問題將去（我的Eclipse版本是霓虹燈，我希望這些說明與您當前的版本）。

幾點建議：

瞭解如何使用一個構建工具，我建議gradle這個，因爲我覺得這是對構建Java項目的現代方式，但其他人一樣好（gradle這個用於Android的:)）
你可能希望使用一些關於JDBC的抽象，特別是ORM，但並不是都同意它們。我仍然建議你看一看，它們有標準（即jpa和jdo），並且有許多符合標準的實現與通常的非標準擴展），Java中最流行的ORM是Hibernate（但這並不意味着它是最好的，因爲它的例外對於維護來說是非常可怕的）

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2017-03-09 15:51:45 niceman

非常感謝你是的它的工作！謝謝你的建議，我也會嘗試瞭解更多關於構建工具的信息，謝謝@niceman^_^ –

@Emél很高興幫助你^ _ ^ – niceman

我無法連接到MySQL數據庫寧靜

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