自定义MVC增删改查(终极篇)-阿里云开发者社区

1.框架配置

1.1将框架达成jar包，然后导入新工程，并且把框架的依赖jar包导入进去

将我们前面写的代码打成一个jar包然后导入我们的项目：

点击导出后我们搜索jar，点击JAR file(第一个选项)：

然后自己把jar包放在自己清楚的路径里：

之后我们把导出的jar包copy到WEB-INF安全目录下的lib文件夹中即可使用jar包中的方法。

1.2在这之后呢我们只需要导入其他的和依赖（助手类、baseDao······）

tag：

package com.Kissship.tag;
import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;
import com.Kissship.util.PageBean;
public class PageTag extends BodyTagSupport{
  private PageBean pageBean;// 包含了所有分页相关的元素
  public PageBean getPageBean() {
    return pageBean;
  }
  public void setPageBean(PageBean pageBean) {
    this.pageBean = pageBean;
  }
  @Override
  public int doStartTag() throws JspException {
//    没有标签体，要输出内容
    JspWriter out = pageContext.getOut();
    try {
      out.print(toHTML());
    } catch (IOException e) {
      e.printStackTrace();
    }
    return super.doStartTag();
  }
  private String toHTML() {
    StringBuffer sb = new StringBuffer();
//    隐藏的form表单---这个就是上一次请求下次重新发的奥义所在
//    上一次请求的URL
    sb.append("<form action='"+pageBean.getUrl()+"' id='pageBeanForm' method='post'>");
    sb.append(" <input type='hidden' name='page'>");
//    上一次请求的参数
    Map<String, String[]> paramMap = pageBean.getParamMap();
    if(paramMap != null && paramMap.size() > 0) {
      Set<Entry<String, String[]>> entrySet = paramMap.entrySet();
      for (Entry<String, String[]> entry : entrySet) {
//        参数名
        String key = entry.getKey();
//        参数值
        for (String value : entry.getValue()) {
//          上一次请求的参数，再一次组装成了新的Form表单
//          注意：page参数每次都会提交，我们需要避免
          if(!"page".equals(key)) {
            sb.append(" <input type='hidden' name='"+key+"' value='"+value+"' >");
          }
        }
      }
    }
    sb.append("</form>");
//    分页条
    sb.append("<ul class='pagination justify-content-center'>");
    sb.append(" <li class='page-item "+(pageBean.getPage() == 1 ? "disabled" : "")+"'><a class='page-link'");
    sb.append(" href='javascript:gotoPage(1)'>首页</a></li>");
    sb.append(" <li class='page-item "+(pageBean.getPage() == 1 ? "disabled" : "")+"'><a class='page-link'");
    sb.append(" href='javascript:gotoPage("+pageBean.previousPage()+")'>&lt;</a></li>");// less than 小于号
//    sb.append(" <li class='page-item'><a class='page-link' href='#'>1</a></li>");
//    sb.append(" <li class='page-item'><a class='page-link' href='#'>2</a></li>");
    sb.append(" <li class='page-item active'><a class='page-link' href='#'>"+pageBean.getPage()+"</a></li>");
    sb.append(" <li class='page-item "+(pageBean.getPage() == pageBean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pageBean.nextPage()+")'>&gt;</a></li>");
    sb.append(" <li class='page-item "+(pageBean.getPage() == pageBean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pageBean.maxPage()+")'>尾页</a></li>");
    sb.append(" <li class='page-item go-input'><b>到第</b><input class='page-link'");
    sb.append(" type='text' id='skipPage' name='' /><b>页</b></li>");
    sb.append(" <li class='page-item go'><a class='page-link'");
    sb.append(" href='javascript:skipPage()'>确定</a></li>");
    sb.append(" <li class='page-item'><b>共"+pageBean.getTotal()+"条</b></li>");
    sb.append("</ul>");
//    分页执行的JS代码
    sb.append("<script type='text/javascript'>");
    sb.append(" function gotoPage(page) {");
    sb.append("   document.getElementById('pageBeanForm').page.value = page;");
    sb.append("   document.getElementById('pageBeanForm').submit();");
    sb.append(" }");
    sb.append(" function skipPage() {");
    sb.append("   var page = document.getElementById('skipPage').value;");
    sb.append("   if (!page || isNaN(page) || parseInt(page) < 1 || parseInt(page) > "+pageBean.maxPage()+") {");
    sb.append("     alert('请输入1~"+pageBean.maxPage()+"的数字');");
    sb.append("     return;");
    sb.append("   }");
    sb.append("   gotoPage(page);");
    sb.append(" }");
    sb.append("</script>");
    return sb.toString();
  }
}

BaseDao：

package com.Kissship.util;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
/**
 * BaseDao 所有Dao类的父亲
 * @author jj
 *
 * @param <T>
 */
public class BaseDao<T> {
  /*
   * 通用增删改方法
   * sql---->增删改SQL
   * t---->SQL中的表对应的实体类
   * attrs---->实体类对应的属性
   * 
   */
  public int executeUpdate(String sql, T t, String[] attrs) throws Exception {
    Connection conn = DBAccess.getConnection();
    PreparedStatement ps = conn.prepareStatement(sql);
    for (int i = 0; i < attrs.length; i++) {
      Field f = t.getClass().getDeclaredField(attrs[i]);
      f.setAccessible(true);
      ps.setObject(i+1, f.get(t));
    }
    return ps.executeUpdate();
  }
  /**
   * 通用分页查询
   * @param sql
   * @param clz
   * @return
   * @throws Exception
   */
  public List<T> executeQuery(String sql,Class<T> clz,PageBean pageBean) throws Exception{
    List<T> list = new ArrayList<T>();
    Connection con = DBAccess.getConnection();;
    PreparedStatement pst = null;
    ResultSet rs = null;
    /*
     * 是否需要分页？
     *  无需分页（项目中的下拉框，查询条件教员下拉框，无须分页）  
     *  必须分页（项目中列表类需求、订单列表、商品列表、学生列表...）
     */
    if(pageBean != null && pageBean.isPagination()) {
//      必须分页（列表需求）
      String countSQL = getCountSQL(sql);
      pst = con.prepareStatement(countSQL);
      rs = pst.executeQuery();
      if(rs.next()) {
        pageBean.setTotal(String.valueOf(rs.getObject(1)));
      }
//      挪动到下面，是因为最后才处理返回的结果集
//      -- sql=SELECT * FROM t_mvc_book WHERE bname like '%圣墟%'
//      -- pageSql=sql limit (page-1)*rows,rows   对应某一页的数据
//      -- countSql=select count(1) from (sql) t  符合条件的总记录数
      String pageSQL = getPageSQL(sql,pageBean);//符合条件的某一页数据
      pst = con.prepareStatement(pageSQL);
      rs = pst.executeQuery();
    }else {
//      不分页（select需求）
      pst = con.prepareStatement(sql);//符合条件的所有数据
      rs = pst.executeQuery();
    }
    while (rs.next()) {
      T t = clz.newInstance();
      Field[] fields = clz.getDeclaredFields();
      for (Field f : fields) {
        f.setAccessible(true);
        f.set(t, rs.getObject(f.getName()));
      }
      list.add(t);
    }
    return list;
  }
  /**
   * 将原生SQL转换成符合条件的总记录数countSQL
   * @param sql
   * @return
   */
  private String getCountSQL(String sql) {
//    -- countSql=select count(1) from (sql) t  符合条件的总记录数
    return "select count(1) from ("+sql+") t";
  }
  /**
   * 将原生SQL转换成pageSQL
   * @param sql
   * @param pageBean
   * @return
   */
  private String getPageSQL(String sql,PageBean pageBean) {
//    (this.page - 1) * this.rows
//    pageSql=sql limit (page-1)*rows,rows
    return sql + " limit "+ pageBean.getStartIndex() +","+pageBean.getRows();
  }
}

PageBean：

package com.Kissship.util;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
/**
 * 分页工具类
 *
 */
public class PageBean {
  private int page = 1;// 页码
  private int rows = 10;// 页大小
  private int total = 0;// 总记录数
  private boolean pagination = true;// 是否分页
  private String url; //保存上一次请求的URL
  private Map<String,String[]> paramMap = new HashMap<>();// 保存上一次请求的参数
  /**
   * 初始化pagebean的，保存上一次请求的重要参数
   * @param req
   */
  public void setRequest(HttpServletRequest req) {
//    1.1 需要保存上一次请求的URL
    this.setUrl(req.getRequestURL().toString());
//    1.2 需要保存上一次请求的参数  bname、price
    this.setParamMap(req.getParameterMap());
//    1.3 需要保存上一次请求的分页设置  pagination
    this.setPagination(req.getParameter("pagination"));
//    1.4 需要保存上一次请求的展示条目数
    this.setRows(req.getParameter("rows"));
//    1.5  初始化请求的页码 page
    this.setPage(req.getParameter("page"));
  }
  public void setPage(String page) {
    if(StringUtils.isNotBlank(page))
      this.setPage(Integer.valueOf(page));
  }
  public void setRows(String rows) {
    if(StringUtils.isNotBlank(rows))
      this.setRows(Integer.valueOf(rows));
  }
  public void setPagination(String pagination) {
//    只有在前台jsp填写了pagination=false，才代表不分页
    if(StringUtils.isNotBlank(pagination))
      this.setPagination(!"false".equals(pagination));
  }
  public String getUrl() {
    return url;
  }
  public void setUrl(String url) {
    this.url = url;
  }
  public Map<String, String[]> getParamMap() {
    return paramMap;
  }
  public void setParamMap(Map<String, String[]> paramMap) {
    this.paramMap = paramMap;
  }
  public PageBean() {
    super();
  }
  public int getPage() {
    return page;
  }
  public void setPage(int page) {
    this.page = page;
  }
  public int getRows() {
    return rows;
  }
  public void setRows(int rows) {
    this.rows = rows;
  }
  public int getTotal() {
    return total;
  }
  public void setTotal(int total) {
    this.total = total;
  }
  public void setTotal(String total) {
    this.total = Integer.parseInt(total);
  }
  public boolean isPagination() {
    return pagination;
  }
  public void setPagination(boolean pagination) {
    this.pagination = pagination;
  }
  /**
   * 获得起始记录的下标
   * 
   * @return
   */
  public int getStartIndex() {
    return (this.page - 1) * this.rows;
  }
  /**
   * 最大页
   * @return
   */
  public int maxPage() {
//    total % rows == 0 ? total / rows : total / rows +1
    return this.total % this.rows == 0 ? this.total / this.rows : this.total / this.rows + 1;
  }
  /**
   * 下一页
   * @return
   */
  public int nextPage() {
//    如果当前页小于最大页，那就下一页为当前页+1；如果不小于，说明当前页就是最大页，那就无需+1
    return this.page < this.maxPage() ? this.page + 1 : this.page;
  }
  /**
   * 上一页
   * @return
   */
  public int previousPage() {
    return this.page > 1 ? this.page - 1 : this.page;
  }
  @Override
  public String toString() {
    return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]";
  }
}

DBAccess：

package com.Kissship.util;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
/**
 * 提供了一组获得或关闭数据库对象的方法
 * 
 */
public class DBAccess {
  private static String driver;
  private static String url;
  private static String user;
  private static String password;
  static {// 静态块执行一次，加载 驱动一次
    try {
      InputStream is = DBAccess.class
          .getResourceAsStream("config.properties");
      Properties properties = new Properties();
      properties.load(is);
      driver = properties.getProperty("driver");
      url = properties.getProperty("url");
      user = properties.getProperty("user");
      password = properties.getProperty("pwd");
      Class.forName(driver);
    } catch (Exception e) {
      e.printStackTrace();
      throw new RuntimeException(e);
    }
  }
  /**
   * 获得数据连接对象
   * 
   * @return
   */
  public static Connection getConnection() {
    try {
      Connection conn = DriverManager.getConnection(url, user, password);
      return conn;
    } catch (SQLException e) {
      e.printStackTrace();
      throw new RuntimeException(e);
    }
  }
  public static void close(ResultSet rs) {
    if (null != rs) {
      try {
        rs.close();
      } catch (SQLException e) {
        e.printStackTrace();
        throw new RuntimeException(e);
      }
    }
  }
  public static void close(Statement stmt) {
    if (null != stmt) {
      try {
        stmt.close();
      } catch (SQLException e) {
        e.printStackTrace();
        throw new RuntimeException(e);
      }
    }
  }
  public static void close(Connection conn) {
    if (null != conn) {
      try {
        conn.close();
      } catch (SQLException e) {
        e.printStackTrace();
        throw new RuntimeException(e);
      }
    }
  }
  public static void close(Connection conn, Statement stmt, ResultSet rs) {
    close(rs);
    close(stmt);
    close(conn);
  }
  public static boolean isOracle() {
    return "oracle.jdbc.driver.OracleDriver".equals(driver);
  }
  public static boolean isSQLServer() {
    return "com.microsoft.sqlserver.jdbc.SQLServerDriver".equals(driver);
  }
  public static boolean isMysql() {
    return "com.mysql.cj.jdbc.Driver".equals(driver);
  }
  public static void main(String[] args) {
    Connection conn = DBAccess.getConnection();
    System.out.println(conn);
    DBAccess.close(conn);
    System.out.println("isOracle：" + isOracle());
    System.out.println("isSQLServer：" + isSQLServer());
    System.out.println("isMysql：" + isMysql());
    System.out.println("数据库连接(关闭)成功");
  }
}

过滤器：

package com.Kissship.util;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
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.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * 中文乱码处理
 * 
 */
@WebFilter("*.action")
public class EncodingFiter implements Filter {
  private String encoding = "UTF-8";// 默认字符集
  public EncodingFiter() {
    super();
  }
  public void destroy() {
  }
  public void doFilter(ServletRequest request, ServletResponse response,
      FilterChain chain) throws IOException, ServletException {
    HttpServletRequest req = (HttpServletRequest) request;
    HttpServletResponse res = (HttpServletResponse) response;
    // 中文处理必须放到 chain.doFilter(request, response)方法前面
    res.setContentType("text/html;charset=" + this.encoding);
    if (req.getMethod().equalsIgnoreCase("post")) {
      req.setCharacterEncoding(this.encoding);
    } else {
      Map map = req.getParameterMap();// 保存所有参数名=参数值(数组)的Map集合
      Set set = map.keySet();// 取出所有参数名
      Iterator it = set.iterator();
      while (it.hasNext()) {
        String name = (String) it.next();
        String[] values = (String[]) map.get(name);// 取出参数值[注：参数值为一个数组]
        for (int i = 0; i < values.length; i++) {
          values[i] = new String(values[i].getBytes("ISO-8859-1"),
              this.encoding);
        }
      }
    }
    chain.doFilter(request, response);
  }
  public void init(FilterConfig filterConfig) throws ServletException {
    String s = filterConfig.getInitParameter("encoding");// 读取web.xml文件中配置的字符集
    if (null != s && !s.trim().equals("")) {
      this.encoding = s.trim();
    }
  }
}

StringUtils：

package com.Kissship.util;
public class StringUtils {
  // 私有的构造方法，保护此类不能在外部实例化
  private StringUtils() {
  }
  /**
   * 如果字符串等于null或去空格后等于""，则返回true，否则返回false
   * 
   * @param s
   * @return
   */
  public static boolean isBlank(String s) {
    boolean b = false;
    if (null == s || s.trim().equals("")) {
      b = true;
    }
    return b;
  }
  /**
   * 如果字符串不等于null或去空格后不等于""，则返回true，否则返回false
   * 
   * @param s
   * @return
   */
  public static boolean isNotBlank(String s) {
    return !isBlank(s);
  }
}

1.3框架的配置文件添加、以及web.xml的配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>Kissship_mvc_crud</display-name>
  <servlet>
    <servlet-name>mvc</servlet-name>
    <servlet-class>com.zking.framework.DispatchServlet</servlet-class>
    <init-param>
      <param-name>configurationLocation</param-name>
      <param-value>/mvc.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>mvc</servlet-name>
    <url-pattern>*.action</url-pattern>
  </servlet-mapping>
</web-app>

2.通用增删改

通过最近的学习，发现我之前写增删改查的代码很繁琐而且有待改进。可以利用自定义MVC框架来做到简化冗余代码的同时实现与之相同的功能。这是我的学习代码(以书籍管理系统为例)，如下：

首先我们要新建一个Book实体类：

package com.Kissship.entity;
public class Book {
  private int bid;
  private String bname;
  private float price;
  public int getBid() {
    return bid;
  }
  public void setBid(int bid) {
    this.bid = bid;
  }
  public String getBname() {
    return bname;
  }
  public void setBname(String bname) {
    this.bname = bname;
  }
  public float getPrice() {
    return price;
  }
  public void setPrice(float price) {
    this.price = price;
  }
  public Book(int bid, String bname, float price) {
    super();
    this.bid = bid;
    this.bname = bname;
    this.price = price;
  }
  public Book() {
    super();
  }
  @Override
  public String toString() {
    return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
  }
}

在实体类完成后我们就可以编写Dao方法了，这里我注释的是繁琐的代码，没注释的则是优化后的代码，如下：

Dao方法：

package com.Kissship.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;
import com.Kissship.entity.Book;
import com.Kissship.util.BaseDao;
import com.Kissship.util.DBAccess;
import com.Kissship.util.PageBean;
import com.Kissship.util.StringUtils;
public class BookDao extends BaseDao<Book> {
  public List<Book> list(Book book, PageBean pageBean) throws Exception {
    String sql = "select * from t_mvc_book where 1=1";
    String bname = book.getBname();
    int bid = book.getBid();
    if (StringUtils.isNotBlank(bname)) {
      sql += "and bname like '%" + bname + "%'";
    }
    // bid == 0 意味着前台没有传递bid值
    if (bid != 0) {
      sql += "and bid = " + bid;
    }
    return super.executeQuery(sql, Book.class, pageBean);
  }
  /*
   * 1.重复的代码 Connection conn = DBAccess.getConnection(); PreparedStatement ps =
   * conn.prepareStatement(sql); 2.代码的逻辑是重复的------->就是将sql中占位符?赋值 ps.setObject(1,
   * book.getBid()); ps.setObject(2, book.getBname()); ps.setObject(3,
   * book.getPrice());
   */
  // 增加
  // public int add(Book book) throws Exception {
  // String sql = "insert into t_mvc_book values(?,?,?)";
  // Connection conn = DBAccess.getConnection();
  // PreparedStatement ps = conn.prepareStatement(sql);
  // ps.setObject(1, book.getBid());
  // ps.setObject(2, book.getBname());
  // ps.setObject(3, book.getPrice());
  // return ps.executeUpdate();
  // }
  // 删除
  // public int del(Book book) throws Exception {
  // String sql = "delete from t_mvc_book where bid = ?";
  // Connection conn = DBAccess.getConnection();
  // PreparedStatement ps = conn.prepareStatement(sql);
  // ps.setObject(1, book.getBid());
  // return ps.executeUpdate();
  // }
  // 修改
  // public int edit(Book book) throws SQLException {
  // String sql = "update t_mvc_book set bname = ?,price = ? where bid = ?";
  // Connection conn = DBAccess.getConnection();
  // PreparedStatement ps = conn.prepareStatement(sql);
  // ps.setObject(1, book.getBname());
  // ps.setObject(2, book.getPrice());
  // ps.setObject(3, book.getBid());
  // return ps.executeUpdate();
  // }
  // 新增
  public int add(Book book) throws Exception {
    String sql = "insert into t_mvc_book values(?,?,?)";
    return super.executeUpdate(sql, book, new String[] { "bid", "bname", "price" });
  }
  // 删除
  public int del(Book book) throws Exception {
    String sql = "delete from t_mvc_book where bid = ?";
    return super.executeUpdate(sql, book, new String[] { "bid" });
  }
  // 修改
  public int edit(Book book) throws Exception {
    String sql = "update t_mvc_book set bname = ?,price = ? where bid = ?";
    return super.executeUpdate(sql, book, new String[] { "bname", "price", "bid" });
  }
}

可以看到优化后的代码很明显变得简短很多。紧接着我们用JUnit来测试一下：

BookDAoTest：

package com.Kissship.dao;
import static org.junit.Assert.*;
import java.util.List;
import org.junit.Test;
import com.Kissship.entity.Book;
import com.Kissship.util.PageBean;
public class BookDaoTest {
  private BookDao bookDao = new BookDao();
  @Test
  public void testList() {
    Book book = new Book();
//    book.setBname("圣墟");
    PageBean pageBean = new PageBean();
//    pageBean.setPage(3);
    pageBean.setPagination(false);
    try {
      List<Book> lst = bookDao.list(book, pageBean);
      for (Book b : lst) {
        System.out.println(b);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
//  @Test
//  public void testAdd() {
//    Book book = new Book(150141318,"嘿嘿",99);
//    try {
//      bookDao.add(book);
//    } catch (Exception e) {
//      e.printStackTrace();
//    }
//  }
//  @Test
//  public void testDel() {
//    Book book = new Book();
//    book.setBid(150141318);//删除id为150141318的数据
//    try {
//      bookDao.del(book);
//    } catch (Exception e) {
//      e.printStackTrace();
//    }
//  }
  @Test
  public void testEdit() {
    Book book = new Book(150141318,"被修改了啊啊啊",999);
    try {
      bookDao.edit(book);
    } catch (Exception e) {
      e.printStackTrace();
  }
  }
}

可以看到我们添加了一条名字为"嘿嘿"的数据，效果图如下：

接着我们试着删除它，如下：

最后试着修改：

经过测试之后没问题，我们通用增删改也就编写完成了。

3.后台代码

新建一个BookAction类：

package com.Kissship.web;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.Kissship.dao.BookDao;
import com.Kissship.entity.Book;
import com.Kissship.util.PageBean;
import com.zking.framework.ActionSupport;
import com.zking.framework.ModelDriven;
public class BookAction extends ActionSupport implements ModelDriven<Book> {
  private Book book = new Book();
  private BookDao bookDao = new BookDao();
  // 查询--bookList.jsp
  public String list(HttpServletRequest req, HttpServletResponse resp) {
    PageBean pageBean = new PageBean();
    pageBean.setRequest(req);
    try {
      List<Book> lst = bookDao.list(book, pageBean);
      req.setAttribute("lst", lst);
      req.setAttribute("pageBean", pageBean);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "list";
  }
  // 编辑界面跳转--bookEdit.jsp
  public String toEdit(HttpServletRequest req, HttpServletResponse resp) {
    try {
      if (book.getBid() != 0) {
        List<Book> lst = bookDao.list(book, null);
        req.setAttribute("lst", lst.get(0));
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toEdit";
  }
  // 增加--重定向到http://localhost:8080/mvc/book.action?methodName=list
  public String add(HttpServletRequest req, HttpServletResponse resp) {
    try {
      bookDao.add(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toList";
  } 
  // 删除
  public String del(HttpServletRequest req, HttpServletResponse resp) {
    try {
      bookDao.del(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toList";
  } 
  // 修改
  public String edit(HttpServletRequest req, HttpServletResponse resp) {
    try {
      bookDao.edit(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toList";
  } 
  @Override
  public Book getModel() {
    return book;
  }
}

在写完BookAction类之后把它的路径名放进我们的xml配置文件中，如下：

mvc.xml：

<?xml version="1.0" encoding="UTF-8"?>
<config>
  <action path="/book" type="com.Kissship.web.BookAction">
    <forward name="list" path="/bookList.jsp" redirect="false" />
    <forward name="toList" path="/book.action?methodName=list" redirect="true" />
    <forward name="toEdit" path="/bookEdit.jsp" redirect="false" />
  </action>
</config>

4.前端代码

在我们的后台代码写完之后，需要把我们的效果在浏览器上显示出来，也就需要我们完善前端的代码，如下：

copy我们之前写过的bookList.jsp：

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<%@ taglib uri="http://jsp.veryedu.cn" prefix="z"%> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> 
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link
  href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.css"
  rel="stylesheet">
<script
  src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/js/bootstrap.js"></script>
<title>书籍列表</title>
<style type="text/css">
.page-item input {
  padding: 0;
  width: 40px;
  height: 100%;
  text-align: center;
  margin: 0 6px;
}
.page-item input, .page-item b {
  line-height: 38px;
  float: left;
  font-weight: 400;
}
.page-item.go-input {
  margin: 0 10px;
}
</style>
</head>
<body>
  <form class="form-inline"
    action="${pageContext.request.contextPath }/book.action?methodName=list" method="post">
    <div class="form-group mb-2">
      <input type="text" class="form-control-plaintext" name="bname"
        placeholder="请输入书籍名称">
<!--      <input name="rows" value="20" type="hidden"> -->
<!-- 不想分页 -->
        <input name="pagination" value="false" type="hidden">
    </div>
    <button type="submit" class="btn btn-primary mb-2">查询</button>
    <a class="btn btn-primary mb-2" href="${pageContext.request.contextPath }/book.action?methodName=toEdit">新增</a>
  </form>
  <table class="table table-striped bg-success">
    <thead>
      <tr>
        <th scope="col">书籍ID</th>
        <th scope="col">书籍名</th>
        <th scope="col">价格</th>
        <th scope="col">操作</th>
      </tr>
    </thead>
    <tbody>
      <c:forEach  var="b" items="${lst }">
      <tr>
        <td>${b.bid }</td>
        <td>${b.bname }</td>
        <td>${b.price }</td>
        <td>
          <a href="${pageContext.request.contextPath }/book.action?methodName=toEdit&bid=${b.bid}">修改</a>
          <a href="${pageContext.request.contextPath }/book.action?methodName=del&bid=${b.bid}">删除</a>
        </td>
      </tr>
      </c:forEach>
    </tbody>
  </table>
  <!-- 这一行代码就相当于前面分页需求前端的几十行了 -->
  <z:page pageBean="${pageBean }"></z:page>
</body>
</html>

bookEdit：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>编辑界面</title>
</head>
<body>
<form action="${pageContext.request.contextPath }/book.action?methodName=${empty b ? 'add' : 'edit'}" method="post">
  编号:<input type="text" name="bid" value="${b.bid }"><br>
  名称:<input type="text" name="bname" value="${b.bname }"><br>
  价格:<input type="text" name="price" value="${b.price }"><br>
  <input type="submit"><br>
</form>
</body>
</html>

效果图：

最后自定义MVC增删改查(终极篇)就到这里，祝大家在敲代码的路上一路通畅!

感谢大家的观看 !

自定义MVC增删改查(终极篇)

1.框架配置

1.1将框架达成jar包，然后导入新工程，并且把框架的依赖jar包导入进去

1.2在这之后呢我们只需要导入其他的和依赖（助手类、baseDao······）

1.3框架的配置文件添加、以及web.xml的配置

2.通用增删改

3.后台代码

4.前端代码

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