年轻人的第一个WEB下载案例
2018-07-11 本文已影响0人
北冥有鱼_很好吃
1.项目环境的搭建
项目的搭建.PNG
2.loginFilter 登陆验证过滤器(验证用户是否登陆)
package com.itheima.expand.Filter;
import com.itheima.expand.entity.User;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* description:<登陆验证过滤器>
* create by Richard on 2018-07-11
*/
@WebFilter(urlPatterns = { "/queryResourceServlet","/listResourceServlet","/downloadServlet"})
public class loginFilter implements Filter {
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
request.setCharacterEncoding("utf-8");
User existUser = (User)request.getSession().getAttribute("login_succeed");
if (existUser!=null){
chain.doFilter(request, response);
}else {
response.sendRedirect("/index.html");
}
}
public void init(FilterConfig config) throws ServletException {
}
}
登陆界面效果图：
登陆显示界面.PNG
资源下载界面效果图：
资源下载界面.PNG
3.Code(Servlet)验证码生成器(可以在登陆的时候加上验证码，但这里没用到验证码)
package com.itheima.expand.servlet;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
/**
* create by Richard on 2018-07-06
*/
@WebServlet("/CodeServlet")
public class Code extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// gui 生成图片
// 1 高和宽
int height = 30;
int width = 60;
String data = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
Random random = new Random();
// 2 创建一个图片
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 3 获得画板
Graphics g = image.getGraphics();
// 4 填充一个矩形
// * 设置颜色
g.setColor(Color.BLACK);
g.fillRect(0, 0, width, height);
g.setColor(Color.WHITE);
g.fillRect(1, 1, width - 2, height - 2);
// * 设置字体
g.setFont(new Font("宋体", Font.BOLD | Font.ITALIC, 25));
StringBuffer sb = new StringBuffer();
// 5 写随机字
for (int i = 0; i < 4; i++) {
// 设置颜色--随机数
g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));
// 获得随机字
int index = random.nextInt(data.length());
String str = data.substring(index, index + 1);
// 写入
g.drawString(str, width / 6 * (i + 1), 20);
sb.append(str);// 获取验证码数据
}
// 验证码保存到session中
request.getSession().setAttribute("code",sb.toString());
// 6 干扰线
for (int i = 0; i < 3; i++) {
// 设置颜色--随机数
g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));
// 随机绘制先
g.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width), random.nextInt(height));
// 随机点
g.drawOval(random.nextInt(width), random.nextInt(height), 2, 2);
}
// end 将图片响应给浏览器
ImageIO.write(image, "jpg", response.getOutputStream());
}
}
4. DownloadServlet下载器的核心代码
package com.itheima.expand.servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;
/**
* description:<下载服务器>
* create by Richard on 2018-07-06
*/
@WebServlet(name = "DownloadServlet", urlPatterns = "/downloadServlet")
public class DownloadServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取用户提交的文件名
String filename = request.getParameter("filename");
System.out.println("用户下载了"+filename);
//下载资源 ： 一个流 两个头 （附件弹窗，文件类型）
ServletContext servletContext = getServletContext();
String path = servletContext.getRealPath("/WEB-INF/"+filename);
File file = new File(path);
if(file.exists()) {
FileInputStream in = new FileInputStream(file);
ServletOutputStream out = response.getOutputStream();
int len = -1;
byte[] bytes = new byte[1024 * 4];
while ((len = in.read(bytes))!=-1) {
//响应头1.弹窗附件 2.文件的MIME类型
response.setHeader("Content-Disposition","attachment;filename="+new String(filename.getBytes("gbk"), "ISO8859-1"));
//设置下载时文件名编码 解决乱码问题
String mimeType = servletContext.getMimeType(filename);
response.setContentType(mimeType);
out.write(bytes,0,len);
}
in.close();
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
doPost(request, response);
}
}
5.ListResourceServlet资源下载展示页面（最low的手动UI😂）
package com.itheima.expand.servlet;
import com.itheima.expand.entity.MyResource;
import com.itheima.expand.entity.User;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
/**
* description:<ListResourceServlet 职责:response将List<Resource>获取 显示资源列表页面>
* create by Richard on 2018-07-06
*/
@WebServlet(name = "ListResourceServlet", urlPatterns = "/listResourceServlet")
public class ListResourceServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
List<MyResource> resources = (List<MyResource>) request.getAttribute("list");
PrintWriter out = response.getWriter();
out.print("<html>");
User user = (User)request.getSession().getAttribute("login_succeed");
out.print("<h1>Welcome "+user.getNickname()+" to load musics</h1>");
for (MyResource resource : resources) {
String filename = resource.getFilename();
String str = "<a href='downloadServlet?filename="+filename+"'>"+filename+"</a><br>";
out.print(str);
}
out.print("</html>");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
doPost(request, response);
}
}
6. LoginServlet 登陆服务
package com.itheima.expand.servlet;
import com.itheima.expand.entity.User;
import com.itheima.expand.utils.DruidUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* description:<登陆服务：用户登陆成功后跳转（转发）到queryResourceServlet 查询服务；登陆失败提醒用户"登陆失败请检查用户名和密码">
* create by Richard on 2018-07-06
*/
@WebServlet(name = "LoginServlet", urlPatterns = "/loginServlet")
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
//获取用户信息与数据库用户表users比较是否存在
String username = request.getParameter("username");
String password = request.getParameter("password");
//1. 创建JdbcTemplate对象，传入数据源
JdbcTemplate jdbcTemplate = new JdbcTemplate(DruidUtils.getDataSource());
//2. 编写SQL语句
String sql = "select * from users where username=? and password=?";
//3. 使用JdbcTemplate对象的queryForObject方法查询结果
User user = null;
try {
user = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<User>(User.class), username, password);
} catch (DataAccessException e) {
System.out.println("someone error_login");
}
if (null==user){
//登陆失败重新跳转到登陆界面
response.sendRedirect("re_index.html");
}else{
//登陆成功 跳转到 queryResourceServlet
//response.sendRedirect("/queryResourceServlet");
//绑定转发
/* request.setAttribute("login_succeed",user.getNickname());
request.getRequestDispatcher("/queryResourceServlet").forward(request,response);*/
request.getSession().setAttribute("login_succeed",user);
response.sendRedirect("/queryResourceServlet");
System.out.println(user.getNickname()+" login succeed");
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
doPost(request, response);
}
}
7.查询服务，查询资源，将歌曲名称存到集合
package com.itheima.expand.servlet;
import com.itheima.expand.entity.MyResource;
import com.itheima.expand.entity.User;
import com.itheima.expand.utils.DruidUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;
/**
* description:<查询服务,查询数据库resources资源 获取List<Resource> 转发到ListResourceServlet >
* create by Richard on 2018-07-06
*/
@WebServlet(name = "QueryResourceServlet", urlPatterns = "/queryResourceServlet")
public class QueryResourceServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
JdbcTemplate jdbcTemplate = new JdbcTemplate(DruidUtils.getDataSource());
String sql = "select * from resources";
List<MyResource> myResources = null;
try {
myResources = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(MyResource.class));
} catch (DataAccessException e) {
e.printStackTrace();
}
//绑定转发
request.setAttribute("list", myResources);
request.getRequestDispatcher("/listResourceServlet").forward(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
doPost(request, response);
}
}
