如何使用给定的 JNDI 名称连接到 Websphere 数据源?

2022-01-14 00:00:00 db2 java jndi websphere ibm-rational

我正在使用 Websphere Portal 7.0 并使用 RAD 8.0 创建一个 portlet.我的 portlet 正在尝试与远程服务器建立 db2 连接.我在本地编写了一个 java 程序来与服务器建立基本的 JDBC 连接并从表中获取记录.代码工作正常；但是，当我将代码添加到我的 portlet 以及 db2jcc4.jar 时，连接不起作用.我正在使用基本的:

I'm using Websphere Portal 7.0 and creating a portlet with RAD 8.0. My portlet is trying to make a db2 connection to a remote server. I wrote a java program locally to do a basic JDBC connection to the server and get records from a table. The code works fine; however, when I add the code to my portlet as well as the db2jcc4.jar, the connection doesn't work. I'm using the basic: 

Connection connection = DriverManager.getConnection("jdbc:db2://server:port/db:user=user;password=pw;");

我认为使用 Websphere 数据源是正确的方法.我知道数据源的 JNDI 名称，但我没有找到关于如何建立连接的明确示例.几个例子使用了一个 DataSource 类(我输入了这个，这似乎不是来自本地 java 包，所以我在这里使用什么导入?)加上一个 Context.我遇到过这样的代码:

I figure that using the Websphere datasource is the right way to go. I know the JNDI name for the datasource, but I'm not finding clear cut examples on how to make a connection. Several examples use a DataSource class (I typed this in and this doesn't seem like it comes from a native java package so what import do I use here?) coupled with a Context. I've come across code like: 

Context ctx = new InitialContext();
ctx.lookup("jdbc/xxxx");

...有人可以帮我分解一下吗?

... Can someone break this down for me?

编辑 1

我已根据列出的答案更新了我的代码.我真的觉得我越来越近了.这是我的 getConnection() 方法:

I've updated my code per the answers listed. I really think I'm getting closer. Here is my getConnection() method:

private Connection getConnection() throws SQLException {
    javax.naming.InitialContext ctx = null;
    javax.sql.DataSource ds = null;
    System.out.println("Attempting connection..." + DateUtil.now() );
    try {
        ctx = new javax.naming.InitialContext();
        ds = (javax.sql.DataSource) ctx.lookup("java:comp/env/jdbc/db");
        connection = ds.getConnection();
    } catch (NamingException e) {
        System.out.println("peformanceappraisalstatus: COULDN'T CREATE CONNECTION!");
        e.printStackTrace();
    }       
    System.out.println("connection: " + connection.getClass().getName() + " at " + DateUtil.now());
    return connection;
}

我的整个 web.xml 文件看起来像:

My entire web.xml file looks like: 

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <display-name>PeformanceAppraisalStatus</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>
    <resource-ref>
        <description>
        Datasource connection to Db</description>
        <res-ref-name>jdbc/db</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
        <res-sharing-scope>Shareable</res-sharing-scope>
    </resource-ref>
</web-app>

我看到一个错误，描述了你们告诉我的 Websphere 应该提示我做的事情，但没有:

I am seeing an error that describes the very thing you guys are telling me Websphere should prompt me to do, but doesn't:

SRVE0169I: Loading Web Module: PeformanceAppraisalStatus.
[8/23/11 18:08:02:166 CDT] 00000009 InjectionProc E   CWNEN0044E: A resource reference binding could not be found for the jdbc/db resource reference, defined for the PeformanceAppraisalStatus component.
[8/23/11 18:08:02:169 CDT] 00000009 InjectionEngi E   CWNEN0011E:  The injection engine failed to process bindings for the metadata.

是的，我知道我在整个应用程序中将性能拼写为性能.

Yes, I know that I've mispelled performance as peformance throughout the app.

解决方案

我是如此接近.以下是使其全部到位的缺失部分:

I was so very close. Here are the missing bits that made it all fall into place:

web.xml:
<resource-ref>      
    <description>
    Datasource connection to db</description>
    <res-ref-name>jdbc/db</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
    <res-sharing-scope>Shareable</res-sharing-scope>
    <mapped-name>jdbc/db</mapped-name>      
</resource-ref>

ibm-web-bnd.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-bnd 
    xmlns="http://websphere.ibm.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://websphere.ibm.com/xml/ns/javaee http://websphere.ibm.com/xml/ns/javaee/ibm-web-bnd_1_0.xsd"
    version="1.0">

    <virtual-host name="default_host" />


    <resource-ref name="jdbc/db" binding-name="jdbc/mydatasource" />
</web-bnd>

似乎 ibm-web-bnd.xml 文件处理了项目资源名称和 websphere 中的数据源之间的绑定.一旦我添加了这一行:

It appears that the ibm-web-bnd.xml file handles the binding between the project resource name and the datasource in websphere. Once I added the line:

<resource-ref name="jdbc/db" binding-name="jdbc/mydatasource" />

Websphere Portal 似乎得到了安抚.我的代码现在正在工作并连接到数据库.

Websphere Portal seemed appeased. My code is working and connecting to the database now.

推荐答案

您需要在您的应用程序中定义一个资源引用，然后在执行期间将该逻辑资源引用映射到物理资源(数据源)部署.

You need to define a resource reference in your application and then map that logical resource reference to the physical resource (data source) during deployment.

在您的 web.xml 中，添加以下配置(根据需要修改名称和属性):

In your web.xml, add the following configuration (modifying the names and properties as appropriate):

<resource-ref>
    <description>Resource reference to my database</description>
    <res-ref-name>jdbc/MyDB</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
    <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>

然后，在应用程序部署期间，WAS 会提示您将此资源引用(jdbc/MyDB)映射到您在 WAS 中创建的数据源.

Then, during application deployment, WAS will prompt you to map this resource reference (jdbc/MyDB) to the data source you created in WAS.

在您的代码中，您可以获得与您在示例中显示的方式类似的 DataSource；但是，用于查找的 JNDI 名称实际上应该是您定义的资源引用的名称 (res-ref-name)，而不是物理数据源的 JNDI 名称.此外，您需要在 res-ref-name 前面加上应用程序命名上下文 (java:comp/env/).

In your code, you can obtain the DataSource similar to how you've shown it in your example; however, the JNDI name you'll use to look it up should actually be the resource reference's name you defined (res-ref-name), rather than the JNDI name of the physical data source. Also, you'll need to prefix the res-ref-name with the application naming context (java:comp/env/).

Context ctx = new InitialContext();
DataSource dataSource = (DataSource) ctx.lookup("java:comp/env/jdbc/MyDB");

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