所以我在context.xml中有一个代码,其中包含数据库连接的信息
<?xml version="1.0" encoding="UTF-8"?>
<Resources name="jdbc/murach" auth="Containter"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/murach"
username="root" password="root"
maxActive="100" maxIdle="30" maxWait="10000"
logAbandoned="true" removeAbandoned="true"
removeAbandonedTimeout="60" type="javax.sql.DataSource" />
<ResourceLink name="jdbc/murach"
global="jdbc/mydb"
type="javax.sql.DataSource" />
对于连接池,我创建了一个类来启动并将其连接到数据库。错误从 getConnection()
方法开始。请问我应该在查找中真正添加什么才能使其工作。顺便说一下,在datasource.getConnection()
的返回中,错误是NullPointerException
。
package lars.data;
import java.sql.Connection;
import java.sql.SQLException;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
public class ConnectionPool {
private static ConnectionPool pool = null;
private static DataSource dataSource = null;
private ConnectionPool() {
try {
InitialContext ic = new InitialContext();
dataSource = (DataSource) ic.lookup("java:/comp/env/jdbc/murach");
System.out.print(dataSource);
} catch (NamingException e) {
System.out.println(e);
}
}
public static synchronized ConnectionPool getInstance() {
if (pool == null) {
pool = new ConnectionPool();
}
return pool;
}
public Connection getConnection() {
try {
return dataSource.getConnection();
} catch (SQLException e) {
System.out.println(e);
return null;
}
}
public void freeConnection(Connection c) {
try {
c.close();
} catch (SQLException e) {
System.out.println(e);
}
}
}
最佳答案
我相信您的问题在于 ResourceLink
的配置,尤其是属性 global
的值,该值应与 Resource< 中定义的值匹配
,应该是:
<ResourceLink name="jdbc/murach"
global="jdbc/murach"
type="javax.sql.DataSource" />
global: The name of the linked global resource in the global JNDI context.
name: The name of the resource link to be created, relative to the
java:comp/env
context.
注意事项1:定义资源的节点名称是Resource
,而不是Resources
。换句话说,它应该是:
<Resource name="jdbc/murach" ... />
NB 2:您应该尝试ic.lookup("java:comp/env/jdbc/murach")
关于java - 启动连接池时数据源出现NullPointerException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39170365/