Java 在tomcat上部署项目时JDBC数据源不工作
我开发了一个servlet，它通过JDNI数据源调用MariaDB数据库。当我在eclipse中运行的tomcat服务器上运行eclipse中的web项目时，这很好 但是，当我使用WAR文件在eclipse外部的tomcat服务器上部署项目时，同一个servlet不起作用。出于测试目的，该项目还包含另一个直接连接的servlet，即不使用JDNI数据源连接到同一个mariaDB，即使部署到eclipse外部的tomcat服务器上，它也可以正常工作。 关于什么可能是错误的，我已经没有什么想法了，如果有人能解释一下，我将不胜感激 配置信息： OS:macOS High Sierra tomcat版本：8.5 eclipse:Neon.2.，第4.6.2版 爪哇：8 MariaDB驱动程序：MariaDB-java-client-2.2.0 在eclipse之外，驱动程序位于两个位置： /tomcat文件夹/lib /WAR文件中的tomcat文件夹/webapps/my-app/WEB-INF/lib 我已将以下资源引用添加到应用程序web.xml文件：Java 在tomcat上部署项目时JDBC数据源不工作,java,mysql,eclipse,tomcat,mariadb,Java,Mysql,Eclipse,Tomcat,Mariadb,我开发了一个servlet，它通过JDNI数据源调用MariaDB数据库。当我在eclipse中运行的tomcat服务器上运行eclipse中的web项目时，这很好 但是，当我使用WAR文件在eclipse外部的tomcat服务器上部署项目时，同一个servlet不起作用。出于测试目的，该项目还包含另一个直接连接的servlet，即不使用JDNI数据源连接到同一个mariaDB，即使部署到eclipse外部的tomcat服务器上，它也可以正常工作。 关于什么可能是错误的，我已经没有什么想法了，如
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/MYDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
import javax.naming.InitialContext;
import javax.naming.Context;
import javax.naming.NamingException;
import javax.sql.DataSource;
public class DBConfigTest extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// JDBC driver name and database URL
// static final String JDBC_DRIVER = "org.mariadb.jdbc.Driver";
// static final String DB_URL="jdbc:mariadb://localhost/MYDB"+"?user=root&password=";
// Database credentials
// static final String USER = "root";
// static final String PASS = "";
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Database Result";
String docType =
"<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
out.println(docType +
"<html>\n" +
"<head><title>" + title + "</title></head>\n" +
"<body bgcolor = \"#f0f0f0\">\n" +
"<h1 align = \"center\">" + title + "</h1>\n");
// Execute SQL query
//Statement stmt=null;
//Connection conn=null;
Connection connection=null;
PreparedStatement statement=null;
try {
// Register JDBC driver
//Class.forName("org.mariadb.jdbc.Driver");
// Open a connection
//conn = DriverManager.getConnection("jdbc:mariadb://localhost/MYDB"+"?user=root&password=");
connection = getConnection();
String sql = "SELECT * FROM ingredient";
statement = connection.prepareStatement(sql);
ResultSet rs = statement.executeQuery();
// Execute SQL query
/*stmt = conn.createStatement();
String sql;
sql = "SELECT * FROM ingredient";
ResultSet rs = stmt.executeQuery(sql);*/
// Extract data from result set
while(rs.next()){
//Retrieve by column name
int id = rs.getInt("ingredient_id");
String code = rs.getString("ingredient_code");
String description = rs.getString("ingredient_description");
//Display values
out.println("ID: " + id + "<br>");
out.println(", Code: " + code + "<br>");
out.println(", Description: " + description + "<br>");
}
out.println("</body></html>");
// Clean-up environment
rs.close();
statement.close();
connection.close();
} catch(SQLException se) {
//Handle errors for JDBC
se.printStackTrace();
} catch(Exception e) {
//Handle errors for Class.forName
e.printStackTrace();
} finally {
//finally block used to close resources
try {
if(statement!=null)
statement.close();
} catch(SQLException se2) {
} // nothing we can do
try {
if(connection!=null)
connection.close();
} catch(SQLException se) {
se.printStackTrace();
} //end finally try
} //end try
}
private Connection getConnection() {
Connection connection = null;
try {
/*InitialContext context = new InitialContext();
DataSource dataSource = (DataSource) context.lookup("jdbc/MYDB");
connection = dataSource.getConnection();*/
Context initContext = new InitialContext();
Context envContext = (Context)initContext.lookup("java:/comp/env");
DataSource ds = (DataSource)envContext.lookup("jdbc/MYDB");
connection = ds.getConnection();
} catch (NamingException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return connection;
}
}
下面示例中的url应为url=jdbc：mariadb://localhost:3306/MYDB”. 一个冒号：在JDBCURL中，在mariadb之后和//之前，缺少
<Resource name="jdbc/MYDB” auth="Container" type="javax.sql.DataSource"
maxTotal="100" maxIdle="30" maxWaitMillis="10000"
username="root" password="" driverClassName="org.mariadb.jdbc.Driver"
url="jdbc:mariadb//localhost:3306/MYDB”/>
你确定org.mariadb.jdbc.Driver在类路径上吗？你在jdbc URL中缺少一个冒号：在mariadb之后和//之前。嗨，Steve和Andreas，谢谢你的快速回答。应用安德烈亚斯的答案解决了我的问题。我刚刚在tomcat服务器的context.xml中添加了：in。tomcat动态地考虑了这一点，并修复了资源定义的问题。
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
import javax.naming.InitialContext;
import javax.naming.Context;
import javax.naming.NamingException;
import javax.sql.DataSource;
public class DBConfigTest extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// JDBC driver name and database URL
// static final String JDBC_DRIVER = "org.mariadb.jdbc.Driver";
// static final String DB_URL="jdbc:mariadb://localhost/MYDB"+"?user=root&password=";
// Database credentials
// static final String USER = "root";
// static final String PASS = "";
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Database Result";
String docType =
"<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
out.println(docType +
"<html>\n" +
"<head><title>" + title + "</title></head>\n" +
"<body bgcolor = \"#f0f0f0\">\n" +
"<h1 align = \"center\">" + title + "</h1>\n");
// Execute SQL query
//Statement stmt=null;
//Connection conn=null;
Connection connection=null;
PreparedStatement statement=null;
try {
// Register JDBC driver
//Class.forName("org.mariadb.jdbc.Driver");
// Open a connection
//conn = DriverManager.getConnection("jdbc:mariadb://localhost/MYDB"+"?user=root&password=");
connection = getConnection();
String sql = "SELECT * FROM ingredient";
statement = connection.prepareStatement(sql);
ResultSet rs = statement.executeQuery();
// Execute SQL query
/*stmt = conn.createStatement();
String sql;
sql = "SELECT * FROM ingredient";
ResultSet rs = stmt.executeQuery(sql);*/
// Extract data from result set
while(rs.next()){
//Retrieve by column name
int id = rs.getInt("ingredient_id");
String code = rs.getString("ingredient_code");
String description = rs.getString("ingredient_description");
//Display values
out.println("ID: " + id + "<br>");
out.println(", Code: " + code + "<br>");
out.println(", Description: " + description + "<br>");
}
out.println("</body></html>");
// Clean-up environment
rs.close();
statement.close();
connection.close();
} catch(SQLException se) {
//Handle errors for JDBC
se.printStackTrace();
} catch(Exception e) {
//Handle errors for Class.forName
e.printStackTrace();
} finally {
//finally block used to close resources
try {
if(statement!=null)
statement.close();
} catch(SQLException se2) {
} // nothing we can do
try {
if(connection!=null)
connection.close();
} catch(SQLException se) {
se.printStackTrace();
} //end finally try
} //end try
}
private Connection getConnection() {
Connection connection = null;
try {
/*InitialContext context = new InitialContext();
DataSource dataSource = (DataSource) context.lookup("jdbc/MYDB");
connection = dataSource.getConnection();*/
Context initContext = new InitialContext();
Context envContext = (Context)initContext.lookup("java:/comp/env");
DataSource ds = (DataSource)envContext.lookup("jdbc/MYDB");
connection = ds.getConnection();
} catch (NamingException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return connection;
}
}
<Resource name="jdbc/MYDB” auth="Container" type="javax.sql.DataSource"
maxTotal="100" maxIdle="30" maxWaitMillis="10000"
username="root" password="" driverClassName="org.mariadb.jdbc.Driver"
url="jdbc:mariadb//localhost:3306/MYDB”/>