使用jdbc读取数据到页面

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通过maven部署jdbc驱动：

 <dependency>        <groupId>mysql</groupId>        <artifactId>mysql-connector-java</artifactId>        <version>5.1.9</version>    </dependency>

web.xml配置servlet信息

<servlet>  <servlet-name>HelloJavaWeb</servlet-name>  <servlet-class>javawebstudy.NewHelloJavaWeb</servlet-class>   <init-param> <param-name>url</param-name><param-value>jdbc:mysql://127.0.0.1:3306/mysql</param-value>  </init-param>  <init-param>  <param-name>user</param-name>  <param-value>root</param-value>  </init-param>  <init-param>  <param-name>password</param-name>  <param-value>123456</param-value>  </init-param>  </servlet>    <servlet-mapping>  <servlet-name>HelloJavaWeb</servlet-name>  <url-pattern>/hello</url-pattern>  </servlet-mapping>

创建jdbc驱动：

static final String JDBC_DRIVER="com.mysql.jdbc.Driver";

创建类，extends HttpServlet 。Override doGet方法，通过ServletConfig读取xml中配置的数据库信息。

ServletConfig mysqlcfg=this.getServletConfig();String mysqlurl=mysqlcfg.getInitParameter("url");String mysqlname=mysqlcfg.getInitParameter("user");String mysqlpassword=mysqlcfg.getInitParameter("password");

通过PrintWriter pw=resp.getWriter();创建向页面送信息。

链接数据库，然后通过pw.println打印出来

完整代码：

package javawebstudy;import java.io.IOException;import java.io.PrintWriter;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import javax.servlet.ServletConfig;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@SuppressWarnings("serial")public class NewHelloJavaWeb extends HttpServlet {static final String JDBC_DRIVER="com.mysql.jdbc.Driver";@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {// TODO Auto-generated method stubServletConfig mysqlcfg=this.getServletConfig();String mysqlurl=mysqlcfg.getInitParameter("url");String mysqlname=mysqlcfg.getInitParameter("user");String mysqlpassword=mysqlcfg.getInitParameter("password");PrintWriter pw=resp.getWriter();Connection conn=null;Statement stmt=null;ResultSet rs=null;try {Class.forName(JDBC_DRIVER);try {conn=DriverManager.getConnection(mysqlurl, mysqlname, mysqlpassword);stmt=conn.createStatement();rs=stmt.executeQuery("select user,password from user;");while(rs.next()){System.out.println(rs.getString("user"));pw.println(rs.getString("user")+" "+rs.getString("password"));}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}} catch (ClassNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}pw.close();}}

嗯，刚开始学习，希望跟C++一样，慢慢进步。

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