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JavaWeb项目实战之表白墙和在线相册

作者：独一无二的哈密瓜

这篇文章主要给大家介绍了关于JavaWeb项目实战之表白墙和在线相册的相关资料,JavaWeb表白墙是一款基于JavaWeb技术开发的表白墙应用,用户可以在上面发布表白信息,也可以查看其他用户的表白信息,需要的朋友可以参考下

一. 案例: 表白墙 (使用模板引擎)

1. 首先创建 maven 项目

引入需要的依赖,创建必要的目录

2. 创建好模板文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>表白墙</title>
</head>
<body>
    <form action="confession" method="post">
        <div class="parent">
            <div id="wall">表白墙</div>
            <div id="remind">输入后点击提交,会将信息显示在表格中</div>
            <div class="one"><span class="two">谁:</span><input type="text" class="text" name="from"></div>
            <div class="one"><span class="two">对谁:</span><input type="text" class="text" name="to"></div>
            <div class="one"><span class="two">说什么:</span><input type="text" class="text" name="message"></div>
            <div class="one"><input type="submit" value="提 交" class="press"></div>
            <div class="elem" th:each="message : ${messages}">
                <span th:text="${message.from}">wz</span>对<span th:text="${message.to}">zw</span>说: <span th:text="${message.message}">wzz</span>
            </div>
        </div>
    </form>
    
    <style>
        /* 去除浏览器默认样式 */
        * {
            margin: 0;
            padding: 0;
        }
        /* 设置总宽度 */
        .parent {
            width: 400px;
            margin: 0 auto;
        }
        /* 设置表白墙样式 */
        #wall {
            font-size: 30px;
            font-weight: 700;
            text-align: center;
            margin: 5px;
        }
        /* 设置提示信息样式 */
        #remind{
            font-size:13px;
            text-align: center;
            color:gray;
            margin: 5px;
        }
        /* 设置弹性布局 */
        .one {
            display: flex;
            justify-content: center;
            align-items: center;
            height: 40px;
        }
        /* 设置文字内容 */
        .two {
            width: 100px;
            line-height: 40px;
        }
        /* 设置输入框 */
        .one .text{
            width: 200px;
            height: 20px;
            padding-left: 3px;
        }
        /* 提交按钮的设置 */
        .one .press{
            width: 304px;
            height: 40px;
            color:white;
            background-color: orange;
            border-radius: 5px;
            border: none;
        } 
        /* 设置鼠标点击的时候改变颜色 */
        .one .press:active{
            background-color: red;
        }
        /* 提交之后内容的设置 */
        .elem {
            text-align: center;
            margin: 15px;
        }
    </style>
</body>
</html>

3. 使用数据库存储数据.创建一个类用于数据库连接

ConnectionDB 类

import com.mysql.cj.jdbc.MysqlDataSource;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class ConnectionDB {
    private static final String URL = "jdbc:mysql://127.0.0.1:3306/confessionWall2?characterEncoding=utf-8&useSSL=true&serverTimezone=UTC";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "0000";

    private static volatile DataSource dataSource = null;

    public static DataSource getDataSource() {
        if(dataSource == null){
            synchronized (ConnectionDB.class){
                if(dataSource == null) {
                    dataSource = new MysqlDataSource();
                    ((MysqlDataSource) dataSource).setURL(URL);
                    ((MysqlDataSource) dataSource).setUser(USERNAME);
                    ((MysqlDataSource) dataSource).setPassword(PASSWORD);

                }
            }
        }
        return dataSource;

    }

    public static Connection getConnection() throws SQLException {
        return getDataSource().getConnection();
    }

    public static void close(Connection connection, PreparedStatement statement, ResultSet resultSet){
        if(resultSet != null){
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(statement != null){
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(connection != null){
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

4. 使用 监视器 来初始化 Thymeleaf

ThymeleafConfig 类

注意加上注解

import org.thymeleaf.TemplateEngine;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
public class ThymeleafConfig implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        System.out.println("ServletContext 初始化完毕!");
        ServletContext context = servletContextEvent.getServletContext();
        TemplateEngine engine = new TemplateEngine();
        ServletContextTemplateResolver resolver = new ServletContextTemplateResolver(context);
        resolver.setPrefix("/WEB-INF/template/");
        resolver.setSuffix(".html");
        resolver.setCharacterEncoding("utf-8");
        engine.setTemplateResolver(resolver);
        context.setAttribute("engine",engine);
    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {

    }
}

5. 编写 Servlet 代码

首先创建一个 Confession 类

class Confession{
    public String from;
    public String to;
    public String message;
}

① 重写 doGet 方法

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        List<Confession> list = load();

        TemplateEngine engine = (TemplateEngine) getServletContext().getAttribute("engine");
        WebContext webContext = new WebContext(req,resp,getServletContext());
        webContext.setVariable("messages",list);
        engine.process("confessionwall",webContext, resp.getWriter());
    }

② 重写 doPost 方法

        resp.setContentType("text/html;charset=utf-8");
        Confession confession = new Confession();
        confession.from = req.getParameter("from");
        confession.to = req.getParameter("to");
        confession.message = req.getParameter("message");

        save(confession);
        resp.sendRedirect("confession");

③ 实现 load 方法

    private List<Confession> load() {
        List<Confession> list = new ArrayList<>();
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            connection = ConnectionDB.getConnection();
            String sql = "select * from confession";
            statement = connection.prepareStatement(sql);
            resultSet = statement.executeQuery();
            while(resultSet.next()){
                Confession confession = new Confession();
                confession.from =resultSet.getString("from");
                confession.to = resultSet.getString("to");
                confession.message = resultSet.getString("message");
                list.add(confession);
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            ConnectionDB.close(connection,statement,resultSet);
        }
        return list;
    }

④ 实现 save 方法

    private void save(Confession confession) {
        Connection connection = null;
        PreparedStatement statement = null;
        try{
            connection = ConnectionDB.getConnection();
            String sql = "insert into confession values (?,?,?)";
            statement = connection.prepareStatement(sql);
            statement.setString(1,confession.from);
            statement.setString(2, confession.to);
            statement.setString(3,confession.message);
            int ret = statement.executeUpdate();
            if(ret == 1){
                System.out.println("插入成功");
            }else{
                System.out.println("插入失败");
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            ConnectionDB.close(connection,statement,null);
        }
    }

6. 注意事项

注意模板引擎

注意 乱码的情况,要添加utf-8

用数据库的方法存数据,要先创建好数据库

create database confessionWall2;

use confessionWall2;

create table confession(
    `from` varchar(1024),
    `to` varchar(1024),
    `message` varchar(1024)
);

还有一些必要的注解也要加上.

7. 部署之后 运行截图

浏览器输入对应的URL

在数据库为空的时候界面如下

在输入几个数据之后 如下

此时的数据库中表的内容

重新部署再进入URL发现数据还是存在.

二. 案例: 在线相册 (使用模板引擎)

1. 首先创建 maven 项目

引入必要的依赖,已经必要的目录

2. 创建好模板文件

image.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>相册</title>
    <link rel="stylesheet" href="./style.css">
</head>
<body>
    <div class="nav">
        <form action="upload" method="POST" enctype="multipart/form-data" >
            <input type="file" name="myImage">
            <input type="submit" value="上传图片">
        </form>
    </div>
    <div class="parent">
            <!-- 第一组图片 -->
        <figure class="sample" th:each="image : ${images}"> 
            <img th:src="${image.url}" alt="sample1" />
            <figcaption>
                <div>
                    <h2 th:text="${image.name}">Deconovo</h2>
                </div>
            </figcaption>
            <a th:href="${image.url}"></a>
        </figure>
    </div>
    
</body>
</html>

style.css

/* 引入文字样式库 */
@import url(https://fonts.googleapis.com/css?family=Raleway:400,700);
*{
    margin: 0 auto;
    padding: 0 auto;
    box-sizing: border-box;
}
html,body{
    width: 100%;
    height: calc(100% - 50px);
    background-color: #212121;
}
.parent{
    display: flex;
    justify-content: center;
    align-items: center;
    flex-flow: wrap;
    margin: 0;
    height: 100%;
}
.nav{
    background-color: rgba(255,255,255,0.3);
    height: 50px;
    width: 100%;
    display: flex;
    justify-content: left;
    align-items: center;
}
/* sample 部分的整体样式 */
.sample {
    font-family: 'Raleway', Arial, sans-serif;
    position: relative;
    overflow: hidden;
    margin: 10px;
    min-width: 230px;
    max-width: 315px;
    width: 100%;
    color: #ffffff;
    text-align: center;
    font-size: 16px;
    background-color: #000000;
}
.sample *,
.sample *:before,
.sample *:after {
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
    /* 当过了 0.55s 过渡效果 */
    -webkit-transition: all 0.55s ease;
    transition: all 0.55s ease;
}
/* 图片部分的样式 */
.sample img {
    max-width: 100%;
    backface-visibility: hidden;
    vertical-align: top;
}
/* figcaption 用作文档中插图的图像，带有一个标题 */
.sample figcaption {
    position: absolute;
    bottom: 25px;
    right: 25px;
    padding: 5px 10px 10px;
}
/* 绘制线条 */
.sample figcaption:before,
.sample figcaption:after {
    height: 2px;
    width: 400px;
    position: absolute;
    content: '';
    background-color: #ffffff;
}
/* 上面一条线 */
.sample figcaption:before {
    top: 0;
    left: 0;
    -webkit-transform: translateX(100%);
    transform: translateX(100%);
}
/* 下面一条线 */
.sample figcaption:after {
    bottom: 0;
    right: 0;
    -webkit-transform: translateX(-100%);
    transform: translateX(-100%);
}
/* 绘制线条 */
.sample figcaption div:before,
.sample figcaption div:after {
    width: 2px;
    height: 300px;
    position: absolute;
    content: '';
    background-color: #ffffff;
}
/* 左面一条线 */
.sample figcaption div:before {
    top: 0;
    left: 0;
    -webkit-transform: translateY(100%);
    transform: translateY(100%);
}
/* 右面一条线 */
.sample figcaption div:after {
    bottom: 0;
    right: 0;
    -webkit-transform: translateY(-100%);
    transform: translateY(-100%);
}
/* 文字部分 */
.sample h2,
.sample h4 {
    margin: 0;
    text-transform: uppercase;
}
.sample h2 {
    font-weight: 400;
}
.sample h4 {
    display: block;
    font-weight: 700;
    background-color: #ffffff;
    padding: 5px 10px;
    color: #000000;
}
.sample a {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
}
/* 当鼠标放到图片时的效果, .hover 仅演示需要，可自行取消 */
.sample:hover img,
.sample.hover img {
    zoom: 1;
    filter: alpha(opacity=50);
    -webkit-opacity: 0.5;
    opacity: 0.5;
}
.sample:hover figcaption:before,
.sample.hover figcaption:before,
.sample:hover figcaption:after,
.sample.hover figcaption:after,
.sample:hover figcaption div:before,
.sample.hover figcaption div:before,
.sample:hover figcaption div:after,
.sample.hover figcaption div:after {
    -webkit-transform: translate(0, 0);
    transform: translate(0, 0);
}
.sample:hover figcaption:before,
.sample.hover figcaption:before,
.sample:hover figcaption:after,
.sample.hover figcaption:after {
    /* 过渡延时 0.15s */
    -webkit-transition-delay: 0.15s;
    transition-delay: 0.15s;
}
/* 背景仅演示作用 */

3. 这是通过访问文件夹里的图片的

在webapp下创建一个文件夹 image,里面存放图片.

通过 getServletContext().getRealPath("/image") 来获取绝对路径

4. 使用 监视器 来初始化 Thymeleaf

这里的代码不变

import org.thymeleaf.TemplateEngine;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
public class ThymeleafConfig implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        System.out.println("ServletContext 初始化完毕");
        ServletContext context = servletContextEvent.getServletContext();
        TemplateEngine engine = new TemplateEngine();
        ServletContextTemplateResolver resolver = new ServletContextTemplateResolver(context);
        resolver.setPrefix("/WEB-INF/template/");
        resolver.setSuffix(".html");
        resolver.setCharacterEncoding("utf-8");
        engine.setTemplateResolver(resolver);

        context.setAttribute("engine",engine);
    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {

    }
}

5. 编写加载页面的 Servlet代码

创建一个 Image 类

class Image {
    public String name;
    public String url;
}

创建一个类,重写 doGet 方法

@WebServlet("/Image")
public class OnlineImageServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        // 1. 扫描指定路径 /webapp/image 路径
        List<Image> images = loadImage();
        // 2. 构造到模板页面
        TemplateEngine engine = (TemplateEngine) getServletContext().getAttribute("engine");
        WebContext webContext = new WebContext(req,resp,getServletContext());
        webContext.setVariable("images",images);
        String html = engine.process("image",webContext);
        resp.getWriter().write(html);
    }
}

实现 loadImage 方法

注意使用 getRealPath 方法

以及注意使用 file.listFiles()方法

    private List<Image> loadImage() {
        List<Image> images = new ArrayList<>();
        // 首先得到 /webapp/image 的绝对路径
        ServletContext context = this.getServletContext();
        // 这里是将 webapp下的目录转换成一个绝对路径
        String path = context.getRealPath("/image");
        // 根据路径 看里面有哪些图片.
        File file = new File(path);
        File[] files = file.listFiles();
        for(File f:files){
            Image image = new Image();
            image.name = f.getName();
            image.url = "image/"+f.getName();
            images.add(image);
        }
        return images;
    }

6. 编写提交图片的 Servlet 代码

① 创建一个类,重写 doPost 方法

注意一定要加上注解@MultipartConfig

import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.IOException;

// 这个注解在上传文件的功能中是必要的
@MultipartConfig
@WebServlet("/upload")
public class UploadServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String path = getServletContext().getRealPath("/image");
        Part part = req.getPart("myImage");
        part.write(path + "/" + part.getSubmittedFileName());
        resp.sendRedirect("Image");
    }
}

7. 注意事项

主要是得到文件夹,找到路径的步骤复杂点.重点掌握这几种方法的使用

前后端约定好的名称要对应.

传文件需要加上注解,否则会报500的错误.@MultipartConfig

8. 部署之后 运行截图

文件中已经存了两个图片,一运行就可以看到这些图片

点击图片还能放大

上传图片,上传两个图片

总结 

到此这篇关于JavaWeb项目实战之表白墙和在线相册的文章就介绍到这了,更多相关JavaWeb表白墙和在线相册内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

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