按照网上的教程配置好了MySQL数据库连接池。
1.Tomcat的context.xml文件下加了
<Resource name="jdbc/mysql"
auth="Container"
type="javax.sql.DataSource"
driverClassName="com.mysql.jdbc.Driver"
username="root"
password="123456"
maxActive="100"
maxIdle="30"
maxWait="10000"
url="jdbc:mysql://localhost:3306/blog "/>
2.在工程和Tomcat的lib文件夹下都加入了JAR包
3.servlet源程序:
package cn.com.seven.blog;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import javax.sql.DataSource;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class BlogServlet extends HttpServlet {
private static final long serialVersionUID=1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
String title=request.getParameter("title");
String content=request.getParameter("content");
String categoryId=request.getParameter("category");
//System.out.println(title);
//System.out.println(content);
//System.out.println(categoryId);
DataSource ds = null;
try {
// 通过在context.xml文件,设定的数据源对象的名字,获取数据源对象
Context context = new InitialContext();
ds = (DataSource) context.lookup("java:/comp/env/jdbc/mysqlds");
} catch (Exception e) {
System.out.println("获取数据源时出错");
}
Connection conn;
try {
conn=ds.getConnection();
String sql = "insert into blog (title,content,category_id,createdtime) values (?,?,?,now())";
PreparedStatement pstmt =conn.prepareStatement(sql);
pstmt.setString(1, title);
pstmt.setString(2, content);
pstmt.setInt(3,Integer.parseInt(categoryId));
int result=pstmt.executeUpdate();
System.out.println(result);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
然后在界面中输入信息后报错:
获取数据源时出错
十二月 01, 2017 6:50:08 下午 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet [BlogServlet] in context with path [/blog] threw exception
java.lang.NullPointerException
at cn.com.seven.blog.BlogServlet.doPost(BlogServlet.java:49)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2516)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2505)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
【不知道什么原因,请大神帮帮我~~~】