如何链接JDBC驱动程序到EJB项目缺少WEB-INF文件夹 [英] How to link JDBC driver to EJB project missing WEB-INF folder

问题描述

我在霓虹Eclipse中有企业应用解决方案，其中包含EJB和Servlet项目并部署到Wildfly 10服务器。

Servlet调用访问DB的EJB。

如果我把JDBC Servlet项目的WEB-INF文件夹中的驱动程序一切顺利，但是如果我将代码移动到EJB并将驱动程序作为外部JAR链接（见截图），我会收到错误：

  java.lang.ClassNotFoundException：com.mysql.jdbc.Driver从[Moduledeployment.NeoflexBank.ear.Neoflex.jar：mainfrom Service Module Loader] 
  

以下是我用于访问数据库的代码：

  public String test（）{
 String output =; 
 
 try {
 Class.forName（com.mysql.jdbc.Driver）。newInstance（）; 
} catch（Exception e）{
 e.printStackTrace（）; 
} 
 
 String url =jdbc：mysql：// localhost：3306 / neoflex; 
 String username =root; 
 String password =; 
 String query =select * from clients; 
连接conn; 
 try {
 conn =（Connection）DriverManager.getConnection（url，username，password）; 
语句stmt =（Statement）conn.createStatement（）; 
 ResultSet rs = stmt.executeQuery（query）; 
 
 while（rs.next（））
 {
输出+ = rs.getInt（id）; 
输出+ = rs.getString（username）; 
 output + = rs.getString（birth_date）; 
 output + = rs.getString（name）; 
 output + = rs.getString（surename）; 
} 
} catch（SQLException e）{
 // TODO自动生成的catch块
 return e.toString（）; 
} 
 
返回输出; 
} 
  

解决方案

在Java EE服务器中执行此操作的方法是定义一个DataSource，然后使用它来获取JDBC连接：

1. 将mysql-connector-java-5.1.40-bin.jar移动到 standalone\deployments 目录。




2. 启动WildFly服务器，并在 http：// localhost：9990 。您可能需要按照一些说明在此设置一些安全性。




3. 点击配置标签，然后点击：

   
   
   

   a。子系统

   
   
   

   b。数据源

   
   
   

   c。非XA




4. 点击蓝色添加按钮，然后按照提示进行操作。

现在，EJB中的代码看起来有点像：

  @Stateless 
 public class SomeEJB {
 
 @Resource（name =java：/ MySqlDS）
 private DataSource ds; 
 
 public String test（）{
 String output =; 
 
 String query =select * from clients; 
 
尝试{
 try（Connection conn = ds.getConnection（）; 
语句stmt = conn.createStatement（）; 
 ResultSet rs = stmt.executeQuery（query ））{
 
 while（rs.next（））
 {
输出+ = rs.getInt（id）; 
输出+ = rs.getString（username）; 
 output + = rs.getString（birth_date）; 
 output + = rs.getString（name）; 
 output + = rs.getString（surename）; 
} 
} 
} catch（SQLException e）{
 return e.toString（）; 
} 
 
返回输出; 
} 
} 
  

这将您的应用程序与数据库配置分离。 DataSource配置也可以从命令行脚本完成。

I have Enterprise Appilcation Solution in Neon Eclipse, which envelope EJB and Servlet projects and deployed to Wildfly 10 server.
Servlet calls EJB for access DB.
If I put JDBC driver in WEB-INF folder of Servlet project, all is going well, but if I move the code to EJB and link the driver as external JAR (see screenshot), I get error:

 java.lang.ClassNotFoundException: com.mysql.jdbc.Driver from [Module "deployment.NeoflexBank.ear.Neoflex.jar:main" from Service Module Loader]

Here is the code I use for access the DB:

    public String test() {
        String output = "";

        try {
            Class.forName("com.mysql.jdbc.Driver").newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }

        String url="jdbc:mysql://localhost:3306/neoflex";
        String username="root";
        String password="";
        String query="select * from clients";
        Connection conn;
        try {
            conn = (Connection) DriverManager.getConnection(url, username, password);
            Statement stmt = (Statement) conn.createStatement();
            ResultSet rs = stmt.executeQuery(query);

            while(rs.next())
            {
                output += rs.getInt("id");
                output += rs.getString("username");
                output += rs.getString("birth_date");
                output += rs.getString("name");
                output += rs.getString("surename");
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            return e.toString();
        }

        return output;
    }

解决方案

The way to do this in a Java EE server is to define a DataSource and then use that for getting JDBC connections:

1. move the mysql-connector-java-5.1.40-bin.jar into the standalone\deployments directory of your WildFly installation.

2. start up your WildFly server and open the admin console at http://localhost:9990. You may have to follow some instructions to set up a bit of security here.

3. click on the Configuration tab, and then click on:

   a. Subsystems

   b. Datasources

   c. Non-XA

4. Click the blue Add button and follow the prompts.

Now, the code in your EJB will look a bit like:

@Stateless
public class SomeEJB {

   @Resource(name="java:/MySqlDS")
   private DataSource ds;

   public String test() {
        String output = "";

        String query="select * from clients";

        try {
            try (Connection conn = ds.getConnection();
                 Statement stmt = conn.createStatement();
                 ResultSet rs = stmt.executeQuery(query)) {

                while(rs.next())
                {
                    output += rs.getInt("id");
                    output += rs.getString("username");
                    output += rs.getString("birth_date");
                    output += rs.getString("name");
                    output += rs.getString("surename");
                }
            } 
        } catch (SQLException e) {
            return e.toString();
        }

        return output;
    }
}

This decouples your application from the database configuration. The DataSource configuration can also be done from a command line script.

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