Java EE WEB工程师培训——JDBC+Servlet+JSP整合开发之21.Servlet_资源访问（访问数据库） 推荐
2010-03-31 13:53
961 查看
? B/S结构程序、B/A/S结构程序简介
? Servlet 资源访问
–Servlet 和 JDBC
? 实例
–维护客户列表
#######################################
? B/S结构程序、B/A/S结构程序简介
–B/S结构程序是指：Browser（客户端）/Server(服务器)两层结构
–B/A/S结构程序是指：Browser(客户端）/Application Server(应用程序服务器）/DB Server 三层结构
? Servlet 资源访问
–Servlet 和 JDBC
? Servlet作为控制器
–响应用户请求
? 获得表单数据
–调用后台逻辑
? 业务逻辑
? 数据逻辑
–页面导航
? JDBC
–使用DAO模式封装数据逻辑（封装持久层）
? 实例
–维护客户列表
DBServlet.java
package com.michael.servlet;
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.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DBServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public DBServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// jdbc
// get Connection
Connection conn = null;
// 加载驱动
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/Servlet_db", "root", "963963");
} catch (Exception e) {
e.printStackTrace();
}
// get Statement
ResultSet rs = null;
try {
Statement stmt = conn.createStatement();
String sql = "select * from customertbl";
rs = stmt.executeQuery(sql);
} catch (SQLException e) {
e.printStackTrace();
}
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out
.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.println(" <table>");
out.println(" <tr>");
out.println(" <th>");
out.println("ID");
out.println(" </th>");
out.println(" <th>");
out.println("Name");
out.println(" </th>");
out.println(" <th>");
out.println("Email");
out.println(" </th>");
try {
while (rs.next()) {
int id = rs.getInt(1);
String name = rs.getString(2);
String email = rs.getString(3);
out.println(" <tr>");
out.println(" <td>");
out.println(id);
out.println(" </td>");
out.println(" <td>");
out.println(name);
out.println(" </td>");
out.println(" <td>");
out.println(email);
out.println(" </td>");
out.println(" </tr>");
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
out.println(" </tr>");
out.println(" </table>");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException
* if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
web.xml
测试
以上代码实现了读取数据库数据功能，但是没有实现分层结构哈~下面我们实现分层结构来实现代码共用。
DBServlet.java
package com.michael.servlet;
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 java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.michael.dao.CustomerDao;
import com.michael.dao.impl.CustomerDaoImpl;
import com.michael.vo.Customer;
public class DBServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public DBServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
// jdbc
// get Connection
Connection conn = null;
// 加载驱动
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/Servlet_db", "root", "963963");
} catch (Exception e) {
e.printStackTrace();
}
// get Statement
ResultSet rs = null;
try {
Statement stmt = conn.createStatement();
String sql = "select * from customertbl";
rs = stmt.executeQuery(sql);
} catch (SQLException e) {
e.printStackTrace();
}
*/
CustomerDao dao = new CustomerDaoImpl();
List list = dao.getCustomerList();
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out
.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.println(" <table>");
out.println(" <tr>");
out.println(" <th>");
out.println("ID");
out.println(" </th>");
out.println(" <th>");
out.println("Name");
out.println(" </th>");
out.println(" <th>");
out.println("Email");
out.println(" </th>");
/*
try {
while (rs.next()) {
int id = rs.getInt(1);
String name = rs.getString(2);
String email = rs.getString(3);
out.println(" <tr>");
out.println(" <td>");
out.println(id);
out.println(" </td>");
out.println(" <td>");
out.println(name);
out.println(" </td>");
out.println(" <td>");
out.println(email);
out.println(" </td>");
out.println(" </tr>");
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
*/
for (int i=0;i<list.size();i++){
Customer c = (Customer) list.get(i);
out.println(" <tr>");
out.println(" <td>");
out.println(c.getId());
out.println(" </td>");
out.println(" <td>");
out.println(c.getName());
out.println(" </td>");
out.println(" <td>");
out.println(c.getEmail());
out.println(" </td>");
out.println(" </tr>");
}
out.println(" </tr>");
out.println(" </table>");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException
* if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
CustomerDaoImpl
ConnectionUtil
package com.michael.dao.impl;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;
public class ConnectionUtil {
/**
* @param args
*/
public static void main(String[] args) {
ConnectionUtil cu = new ConnectionUtil();
System.out.println(cu.openConnection());
}
public Connection openConnection() {
String url = "";
String driver = "";
String user = "";
String password = "";
Properties prop = new Properties();
try {
prop.load(this.getClass().getClassLoader().getResourceAsStream("DBConfig.properties"));
driver = prop.getProperty("driver");
url = prop.getProperty("url");
user = prop.getProperty("user");
password = prop.getProperty("password");
Class.forName(driver);
Connection conn = DriverManager.getConnection(
url, user, password);
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public Connection getConnection(String driver, String url, String user,
String password) {
// Class.forName()
try {
Class.forName(driver);
// DriverManager get connection
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public Connection getConnection() {
// Class.forName()
try {
Class.forName("com.mysql.jdbc.Driver");
// DriverManager get connection
Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/Servlet_db", "root", "963963");
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
DBConfig.properties
Customer
测试
############################################
? Servlet 资源访问
–Servlet 和 JDBC
? 实例
–维护客户列表
#######################################
? B/S结构程序、B/A/S结构程序简介
–B/S结构程序是指：Browser（客户端）/Server(服务器)两层结构
–B/A/S结构程序是指：Browser(客户端）/Application Server(应用程序服务器）/DB Server 三层结构
? Servlet 资源访问
–Servlet 和 JDBC
? Servlet作为控制器
–响应用户请求
? 获得表单数据
–调用后台逻辑
? 业务逻辑
? 数据逻辑
–页面导航
? JDBC
–使用DAO模式封装数据逻辑（封装持久层）
? 实例
–维护客户列表
DBServlet.java
package com.michael.servlet;
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.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DBServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public DBServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// jdbc
// get Connection
Connection conn = null;
// 加载驱动
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/Servlet_db", "root", "963963");
} catch (Exception e) {
e.printStackTrace();
}
// get Statement
ResultSet rs = null;
try {
Statement stmt = conn.createStatement();
String sql = "select * from customertbl";
rs = stmt.executeQuery(sql);
} catch (SQLException e) {
e.printStackTrace();
}
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out
.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.println(" <table>");
out.println(" <tr>");
out.println(" <th>");
out.println("ID");
out.println(" </th>");
out.println(" <th>");
out.println("Name");
out.println(" </th>");
out.println(" <th>");
out.println("Email");
out.println(" </th>");
try {
while (rs.next()) {
int id = rs.getInt(1);
String name = rs.getString(2);
String email = rs.getString(3);
out.println(" <tr>");
out.println(" <td>");
out.println(id);
out.println(" </td>");
out.println(" <td>");
out.println(name);
out.println(" </td>");
out.println(" <td>");
out.println(email);
out.println(" </td>");
out.println(" </tr>");
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
out.println(" </tr>");
out.println(" </table>");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException
* if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
web.xml
测试
以上代码实现了读取数据库数据功能，但是没有实现分层结构哈~下面我们实现分层结构来实现代码共用。
DBServlet.java
package com.michael.servlet;
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 java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.michael.dao.CustomerDao;
import com.michael.dao.impl.CustomerDaoImpl;
import com.michael.vo.Customer;
public class DBServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public DBServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
// jdbc
// get Connection
Connection conn = null;
// 加载驱动
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/Servlet_db", "root", "963963");
} catch (Exception e) {
e.printStackTrace();
}
// get Statement
ResultSet rs = null;
try {
Statement stmt = conn.createStatement();
String sql = "select * from customertbl";
rs = stmt.executeQuery(sql);
} catch (SQLException e) {
e.printStackTrace();
}
*/
CustomerDao dao = new CustomerDaoImpl();
List list = dao.getCustomerList();
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out
.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.println(" <table>");
out.println(" <tr>");
out.println(" <th>");
out.println("ID");
out.println(" </th>");
out.println(" <th>");
out.println("Name");
out.println(" </th>");
out.println(" <th>");
out.println("Email");
out.println(" </th>");
/*
try {
while (rs.next()) {
int id = rs.getInt(1);
String name = rs.getString(2);
String email = rs.getString(3);
out.println(" <tr>");
out.println(" <td>");
out.println(id);
out.println(" </td>");
out.println(" <td>");
out.println(name);
out.println(" </td>");
out.println(" <td>");
out.println(email);
out.println(" </td>");
out.println(" </tr>");
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
*/
for (int i=0;i<list.size();i++){
Customer c = (Customer) list.get(i);
out.println(" <tr>");
out.println(" <td>");
out.println(c.getId());
out.println(" </td>");
out.println(" <td>");
out.println(c.getName());
out.println(" </td>");
out.println(" <td>");
out.println(c.getEmail());
out.println(" </td>");
out.println(" </tr>");
}
out.println(" </tr>");
out.println(" </table>");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException
* if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
CustomerDaoImpl
ConnectionUtil
package com.michael.dao.impl;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;
public class ConnectionUtil {
/**
* @param args
*/
public static void main(String[] args) {
ConnectionUtil cu = new ConnectionUtil();
System.out.println(cu.openConnection());
}
public Connection openConnection() {
String url = "";
String driver = "";
String user = "";
String password = "";
Properties prop = new Properties();
try {
prop.load(this.getClass().getClassLoader().getResourceAsStream("DBConfig.properties"));
driver = prop.getProperty("driver");
url = prop.getProperty("url");
user = prop.getProperty("user");
password = prop.getProperty("password");
Class.forName(driver);
Connection conn = DriverManager.getConnection(
url, user, password);
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public Connection getConnection(String driver, String url, String user,
String password) {
// Class.forName()
try {
Class.forName(driver);
// DriverManager get connection
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public Connection getConnection() {
// Class.forName()
try {
Class.forName("com.mysql.jdbc.Driver");
// DriverManager get connection
Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/Servlet_db", "root", "963963");
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
DBConfig.properties
Customer
测试
############################################
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