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Servlet开发

Java web 
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1. Servlet开发

1) servlet引入 

HelloWorldServlet.java

package com.andrew.web;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorldServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("get");
        this.doPost(request, response);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setCharacterEncoding("gbk");
        PrintWriter out=response.getWriter();
        out.println("<html>");
        out.println("<head><title>问候</title></head>");
        out.println("Servlet你好！");
        out.println("</html>");
        out.close();
    }
}

web.xml

<servlet>
      <servlet-name>helloWorldServlet</servlet-name>
      <servlet-class>com.andrew.web.HelloWorldServlet</servlet-class>
</servlet>
<servlet-mapping>
      <servlet-name>helloWorldServlet</servlet-name>
      <url-pattern>/helloWorld</url-pattern>
</servlet-mapping>

http://localhost:8080/HeadFirstJspServletChap05/helloWorld
运行结果：
Servlet你好！


2) servlet生命周期 

servlet的生命周期，简单的概括这就分为四步：servlet类加载--->实例化--->服务--->销毁。



LifeServlet.java

package com.andrew.web;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LifeServlet extends HttpServlet {
    public void destroy() {
        System.out.println("LifeServlet destroy!");
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        System.out.println("LifeServlet doGet!");
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("LifeServlet doPost!");
    }
    public void init() throws ServletException {
        System.out.println("LifeServlet init!");
    }
}

web.xml

<servlet>
    <servlet-name>LifeServlet</servlet-name>
    <servlet-class>com.andrew.web.LifeServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>LifeServlet</servlet-name>
    <url-pattern>/LifeServlet</url-pattern>
</servlet-mapping>

http://localhost:8080/HeadFirstJspServletChap05/LifeServlet
控制台：
LifeServlet init!
LifeServlet doGet!


3) 客户端跳转 

response.sendRedirect("目标地址");



RedirectServlet.java

package com.andrew.web;
import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class RedirectServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setAttribute("requestKey", "request值");
        HttpSession session=request.getSession();
        session.setAttribute("sessionKey", "session值");
        ServletContext application=this.getServletContext();
        application.setAttribute("applicationKey", "application值");
        // 客户端跳转/重定向
        response.sendRedirect("target.jsp");
    }
}

web.xml

<servlet>
    <servlet-name>RedirectServlet</servlet-name>
    <servlet-class>com.andrew.web.RedirectServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>RedirectServlet</servlet-name>
    <url-pattern>/RedirectServlet</url-pattern>
</servlet-mapping>

target.jsp

<h1>目标地址</h1>
request值：<%=request.getAttribute("requestKey") %><br/>
session值：<%=session.getAttribute("sessionKey") %><br/>
application值：<%=application.getAttribute("applicationKey") %><br/>

http://localhost:8080/HeadFirstJspServletChap05/target.jsp
运行结果：
目标地址
request值：null
session值：session值
application值：application值


4) 服务器跳转 

RequestDispatcher rd = request.getRequestDispatcher("目标地址");
rd.forward(request, response);



ForwardServlet.java

package com.andrew.web;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class ForwardServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setAttribute("requestKey", "request值");
        HttpSession session=request.getSession();
        session.setAttribute("sessionKey", "session值");
        ServletContext application=this.getServletContext();
        application.setAttribute("applicationKey", "application值");
        // 服务器调转/转发
        RequestDispatcher rd=request.getRequestDispatcher("target.jsp");
        rd.forward(request, response);
    }
}

web.xml

<servlet>
    <servlet-name>ForwardServlet</servlet-name>
    <servlet-class>com.andrew.web.ForwardServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>ForwardServlet</servlet-name>
    <url-pattern>/ForwardServlet</url-pattern>
</servlet-mapping>

target.jsp

<h1>目标地址</h1>
request值：<%=request.getAttribute("requestKey") %><br/>
session值：<%=session.getAttribute("sessionKey") %><br/>
application值：<%=application.getAttribute("applicationKey") %><br/>

http://localhost:8080/HeadFirstJspServletChap05/ForwardServlet
运行结果：
目标地址
request值：request值
session值：session值
application值：application值


5) jsp&servlet用户登录功能实现

6) servlet过滤器

7) servlet监听器 

创建数据库db_jsp
创建表t_user
CREATE TABLE t_user (
  id int(11) NOT NULL AUTO_INCREMENT,
  userName varchar(20) DEFAULT NULL,
  password varchar(20) DEFAULT NULL,
  PRIMARY KEY (id)
) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;
insert into t_user(id,userName,password) values(1,'andrew','123456');

User.java

package com.andrew.model;
public class User {
    private int id;
    private String userName;
    private String password;
    public User() {
        super();
    }
    public User(String userName, String password) {
        super();
        this.userName = userName;
        this.password = password;
    }
    // getter and setter
}

DbUtil.java

package com.andrew.util;
import java.sql.Connection;
import java.sql.DriverManager;
public class DbUtil {
    private String dbUrl = "jdbc:mysql://localhost:3306/db_jsp";
    private String dbUserName = "root";
    private String dbPassword = "root";
    private String jdbcName = "com.mysql.jdbc.Driver";
    public Connection getCon() throws Exception {
        Class.forName(jdbcName);
        Connection con = DriverManager.getConnection(dbUrl, dbUserName, dbPassword);
        return con;
    }
    public void closeCon(Connection con) throws Exception {
        if (con != null) {
            con.close();
        }
    }
    public static void main(String[] args) {
        DbUtil dbUtil = new DbUtil();
        try {
            dbUtil.getCon();
            System.out.println("连接成功");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

UserDao.java

package com.andrew.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import com.andrew.model.User;
public class UserDao {
    public User login(Connection con,User user) throws Exception{
        User resultUser=null;
        String sql="select * from t_user where userName=? and password=?";
        PreparedStatement pstmt=con.prepareStatement(sql);
        pstmt.setString(1, user.getUserName());
        pstmt.setString(2, user.getPassword());
        ResultSet rs=pstmt.executeQuery();
        if(rs.next()){
            resultUser=new User();
            resultUser.setUserName(rs.getString("userName"));
            resultUser.setPassword(rs.getString("password"));
        }
        return resultUser;
    }
}

LoginServlet.java

package com.andrew.web;
import java.io.IOException;
import java.sql.Connection;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.andrew.dao.UserDao;
import com.andrew.model.User;
import com.andrew.util.DbUtil;
public class LoginServlet extends HttpServlet {
    DbUtil dbUtil = new DbUtil();
    UserDao userDao = new UserDao();
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String userName=request.getParameter("userName");
        String password=request.getParameter("password");
        Connection con = null;
        try {
            User user = new User(userName,password);
            con = dbUtil.getCon();
            User currentUser = userDao.login(con, user);
            if (currentUser == null) {
                request.setAttribute("error", "用户名或密码错误");
                request.setAttribute("userName", userName);
                request.setAttribute("password", password);
                request.getRequestDispatcher("login.jsp").forward(request, response);
            } else {
                HttpSession session = request.getSession();
                session.setAttribute("currentUser", currentUser);
                response.sendRedirect("main.jsp");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

LogoutServlet.java

package com.andrew.web;
import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class RedirectServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setAttribute("requestKey", "request值");
        HttpSession session=request.getSession();
        session.setAttribute("sessionKey", "session值");
        ServletContext application=this.getServletContext();
        application.setAttribute("applicationKey", "application值");
        // 客户端跳转/重定向
        response.sendRedirect("target.jsp");
    }
}

LoginFilter.java

package com.andrew.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
public class LoginFilter implements Filter {
    public void destroy() {}
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
            FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpSession session = request.getSession();
        Object o = session.getAttribute("currentUser");
        String path = request.getServletPath();
        if (o == null && path.indexOf("login") < 0) {
            request.getRequestDispatcher("login.jsp").forward(servletRequest, servletResponse);
        } else {
            filterChain.doFilter(servletRequest, servletResponse);
        }
    }
    public void init(FilterConfig arg0) throws ServletException {}
}

SessionAttributeListener.java

package com.andrew.listener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
public class SessionAttributeListener implements HttpSessionAttributeListener {
    public void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) {
        System.out.println("添加的属性名：" + httpSessionBindingEvent.getName() + ",属性值：" + httpSessionBindingEvent.getValue());
    }
    public void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) {
        System.out.println("删除的属性名：" + httpSessionBindingEvent.getName() + ",属性值：" + httpSessionBindingEvent.getValue());
    }
    public void attributeReplaced(
            HttpSessionBindingEvent httpSessionBindingEvent) {
    }
}

web.xml

<servlet>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>com.andrew.web.LoginServlet</servlet-class>
</servlet>
<servlet>
    <servlet-name>LogoutServlet</servlet-name>
    <servlet-class>com.andrew.web.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>LogoutServlet</servlet-name>
    <url-pattern>/logout</url-pattern>
</servlet-mapping>
<filter>
    <filter-name>loginFilter</filter-name>
    <filter-class>com.andrew.filter.LoginFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>loginFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<listener>
    <listener-class>
        com.andrew.listener.SessionAttributeListener
    </listener-class>
</listener>

login.jsp

<form action="login" method="post">
<table>
    <tr><th colspan="2">用户登录</th></tr>
    <tr><td>用户名：</td><td><input type="text" id="userName" name="userName" value="${userName }"/></td></tr>
    <tr><td>密码：</td><td><input type="password" id="password" name="password" value="${password }"/></td></tr>
    <tr><td><input type="submit" value="登录"/></td>
    <td><font color="red">${error }</font></td></tr>
</table>
</form>

main.jsp

主页！当前登录用户：${currentUser.userName } &nbsp;&nbsp;<a href="logout">注销</a>

http://localhost:8080/HeadFirstJspServletChap05/login.jsp
andrew
123456 sbumit
运行结果：
主页！当前登录用户：andrew   注销 
控制台：
添加的属性名：currentUser,属性值：com.andrew.model.User@4bdf7b12
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