JavaWeb项目实践
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JavaWeb项目实践
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連接數(shù)據(jù)庫無非就是和數(shù)據(jù)庫建立連接，和前面的python連接數(shù)據(jù)庫差不多。
首先在連接Java數(shù)據(jù)庫的時候需要數(shù)據(jù)庫的jar包，這點(diǎn)不同于python連接數(shù)據(jù)庫
mysql的jar包
下面讓我們來看看數(shù)據(jù)庫是如何讓連接的，是如何完成數(shù)據(jù)庫的一系列操作，增刪改查等…
Java連接數(shù)據(jù)庫。
1、注冊驅(qū)動
Class.forName("com.mysql.jdbc.Driver");2、獲取連接
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/shop", "root", "123456");注意：獲取連接很重要，數(shù)據(jù)的一點(diǎn)點(diǎn)錯誤都會導(dǎo)致你連接不上數(shù)據(jù)庫。
1、localhost代表本機(jī)不用變
2、3306是端口號，即port,一般默認(rèn)都是3306。
3、root一般指管理員，不用變，直接用即可。
4、"123456"指的是密碼，一般大家常用的密碼就123、111111、root或者123456幾種。
3、獲取數(shù)據(jù)庫操作對象
stmt = conn.createStatement();4、//執(zhí)行sql
String sql = "select id,name,num,price from testmodel_car";rs = stmt.executeQuery(sql);while (rs.next()) {String id = rs.getString("id");String name = rs.getString("name");String num = rs.getString("num");String price = rs.getString("price");System.out.println(id + "," + name + "," + num + "," + price);}} catch (Exception e) {e.printStackTrace();} finally {注意：
😃1、java"select id,name,num,price from testmodel_car";，從表 testmodel_car中查詢 id,name,num,price四列數(shù)據(jù)
😃2、rs = stmt.executeQuery(sql);，獲取的對象編譯一下sql語句
😃3、String id = rs.getString("id");，取出id那一列的值賦值給id(String id 中的id可以隨便換，只要不和其他變量沖突都是可以的)
5、釋放資源
if (rs != null) {try {rs.close();} catch (Exception e) {e.printStackTrace();}}if (stmt != null) {try {stmt.close();} catch (Exception e) {e.printStackTrace();}}if (conn != null) {try {conn.close();} catch (Exception e) {e.printStackTrace();}}不釋放資源也行，在上面拋出異常也可以解決
6、完整代碼
import com.mysql.jdbc.Driver;import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement;public class Test2 {public static void main(String[] args) {Connection conn = null;Statement stmt = null;ResultSet rs = null;try {//注冊驅(qū)動Class.forName("com.mysql.jdbc.Driver");//獲取連接conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/shop", "root", "123456");//獲取數(shù)據(jù)庫操作對象stmt = conn.createStatement();//執(zhí)行sqlString sql = "select id,name,num,price from testmodel_car";rs = stmt.executeQuery(sql);while (rs.next()) {String id = rs.getString("id");String name = rs.getString("name");String num = rs.getString("num");String price = rs.getString("price");System.out.println(id + "," + name + "," + num + "," + price);}} catch (Exception e) {e.printStackTrace();} finally {//釋放資源if (rs != null) {try {rs.close();} catch (Exception e) {e.printStackTrace();}}if (stmt != null) {try {stmt.close();} catch (Exception e) {e.printStackTrace();}}if (conn != null) {try {conn.close();} catch (Exception e) {e.printStackTrace();}}}} }連接數(shù)據(jù)庫------增加操作
add.jsp
<%--Created by IntelliJ IDEA.User: 17331Date: 2022/3/5Time: 15:40To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html lang="en"> <head><meta charset="UTF-8"><link href="h/favicon2.ico" rel="icon" type="image/x-icon"/><title>添加信息</title><style>body {background-color:#FDF5E6;}</style><style>body {width: 100%;height: 100%;background: url('./img/olypic.jpg');background-repeat: no-repeat;background-size: 100% 100%;background-attachment: fixed;}</style><style>input{width: 20%;padding: 12px 20px;margin: 8px 0;box-sizing: border-box;border: 1px solid #555;outline: none;}input:focus {background-color: lightblue;}</style><style>#boxshadow {position: relative;-moz-box-shadow: 1px 2px 4px rgba(0, 0, 0,0.5);-webkit-box-shadow: 1px 2px 4px rgba(0, 0, 0, .5);box-shadow: 1px 2px 4px rgba(0, 0, 0, .5);padding: 10px;background:#F0F8FF;border-radius:8px;}/* Make the image fit the box */#boxshadow img {width: 50%;border: 0px solid #8a4419;border-style: inset;}#boxshadow::after {content: '';position: absolute;z-index: -1; /* hide shadow behind image */-webkit-box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);-moz-box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);width: 70%;left: 15%; /* one half of the remaining 30% */height: 100px;bottom: 0;}</style><style>.button {background-color:#337AB7; /* Green */border: none;color: white;padding: 16px 32px;text-align: center;text-decoration: none;display: inline-block;font-size: 16px;margin: 4px 2px;-webkit-transition-duration: 0.4s; /* Safari */transition-duration: 0.4s;cursor: pointer;}.button1 {background-color: white;color: black;border: 2px solid #337AB7;}.button1:hover {background-color: #337AB7;color: white;box-shadow: 0 12px 16px 0 rgba(0,0,0,0.24),0 17px 50px 0 rgba(0,0,0,0.19);}</style></head> <body><div style="padding:2px;width:1080px;height:470px;margin-top:10%;margin-left:20%;opacity: 0.8" id="boxshadow"><div><img src="img/olypic.jpg" style="float:left;margin-top:5%;"></div><div style="float:right;"><form action="add" method="post"><p style="margin-right:200px;">國家名稱   <input type="text" name="Country" style="border-radius:8px;width:150px;height:30px;"></p><p>  金牌數(shù)     <input type="text" name="Glod_num" style="border-radius:8px;width:150px;height:30px;margin-top:1%"></p><p>  銀牌數(shù)     <input type="text" name="Silver_num" style="border-radius:8px;width:150px;height:30px;margin-top:1%"></p><p>  銅牌數(shù)     <input type="text" name="Copper_num" style="border-radius:8px;width:150px;height:30px;margin-top:1%"></p><p>     id           <input type="text" name="id" style="border-radius:8px;width:150px;height:30px;margin-top:1%"></p><input type="submit" value="保存"/><br/></form></form></div> </div> </body> </html>Add.java
package com.bjpowernode.javaweb.servlet;import com.bjpowernode.javaweb.utils.DButil;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.sql.*;@WebServlet(name = "add", value = "/add") public class Add extends HttpServlet {@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");request.setCharacterEncoding("UTF-8");//獲取信息，前端頁面注冊的信息String country=request.getParameter("Country"); // String logo=request.getParameter("logo");String Glod_num=request.getParameter("Glod_num");String Silver_num=request.getParameter("Silver_num");String Copper_num=request.getParameter("Copper_num");String id =request.getParameter("id"); // String Sum=request.getParameter("Sum");//連接數(shù)據(jù)庫，執(zhí)行insert插入語句Connection conn = null;PreparedStatement ps = null;int count=0;try {//注冊驅(qū)動try {Class.forName("com.mysql.jdbc.Driver");} catch (ClassNotFoundException e) {e.printStackTrace();}//獲取連接conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mofa", "root", "123456");// TODO 2、開啟事務(wù) 默認(rèn)開啟 我們將它關(guān)閉（）自動提交機(jī)制關(guān)閉String sql = "insert ignore into medals_table(Country,Glod_num,Silver_num,Copper_num,id) values (?,?,?,?,?);";ps = conn.prepareStatement(sql);ps.setString(1, country); // ps.setString(2, logo);ps.setString(2, Glod_num);ps.setString(3, Silver_num);ps.setString(4, Copper_num);ps.setString(5, id); // ps.setString(7, Sum);//返回一個值，指的是 影響了數(shù)據(jù)庫中多少條記錄 主要是判斷是否大于0 就是是否印象數(shù)據(jù)庫count = ps.executeUpdate();}catch (SQLException e){e.printStackTrace();}finally {DButil.close(conn,ps,null);}if(count==1){//增加成功 任然跳到列表頁面request.getRequestDispatcher("Take_01").forward(request,response);}else{//刪除失敗request.getRequestDispatcher("error.jsp").forward(request,response);}} }
增加功能就是通過前端jsp文件text填寫數(shù)據(jù)，然后通過submit提交數(shù)據(jù)，傳遞給后端servlet，也就是上面的Add，注意Java文件不要小寫，我就沒少挨罵
步驟：
😘1、前端jsp文件text寫入通過submit提交
😘2、<form action="add" method="post">通過form表單提交給后端的servel(Add)
😘3、String country=request.getParameter("Country");通過getParameter取到前端的值然后賦值給country，為后面刷數(shù)據(jù)做準(zhǔn)備
😘4、后端servlet訪問數(shù)據(jù)庫，步驟訪問上面第一個標(biāo)題《Java連接數(shù)據(jù)庫》
😘5、成功將前端傳來的數(shù)據(jù)刷如數(shù)據(jù)庫
💖連接數(shù)據(jù)庫------刪除操作
package com.bjpowernode.javaweb.servlet;import com.bjpowernode.javaweb.utils.DButil;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.sql.*;@WebServlet(name = "delete", value = "/delete") public class Delete extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//根據(jù)部門編號刪除部門//獲取部門編號String country = request.getParameter("name");//連接數(shù)據(jù)庫Connection conn = null;PreparedStatement ps = null;ResultSet rs = null;int count=0;try {//注冊驅(qū)動Class.forName("com.mysql.jdbc.Driver");//獲取連接conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mofa", "root", "123456");// TODO 2、開啟事務(wù) 默認(rèn)開啟 我們將它關(guān)閉（）自動提交機(jī)制關(guān)閉conn.setAutoCommit(false);String sql = "delete from medals_table where Country=?";ps = conn.prepareStatement(sql);ps.setString(1,country);//返回一個值，指的是 影響了數(shù)據(jù)庫中多少條記錄 主要是判斷是否大于0 就是是否印象數(shù)據(jù)庫count= ps.executeUpdate();//事務(wù)提交conn.commit();} catch (SQLException e) {if(conn!=null){try {conn.rollback();} catch (SQLException ex) {ex.printStackTrace();}}e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();}finally {DButil.close(conn,ps,null);}if(count==1){PrintWriter out = response.getWriter();out.println("<script>");out.println("alert('Dear, the deletion is unrecoverable. Are you sure you deleted it？');");out.println("location.href='Take_01'");//跳轉(zhuǎn)到用戶列表頁面out.println("</script>"); // //刪除成功 任然跳到列表頁面 // request.getRequestDispatcher("Take_01").forward(request,response);}else{//刪除失敗request.getRequestDispatcher("error.jsp").forward(request,response);}} }String country = request.getParameter("name");，老規(guī)矩，前端取值進(jìn)行操作
💖連接數(shù)據(jù)庫------修改操作
edit.jsp
<%--Created by IntelliJ IDEA.User: 17331Date: 2022/3/6Time: 17:39To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head><title><%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head><title>新增</title> </head> <body> <h1>新增國家獎牌信息</h1> <hr color="red" width="100%"> <form action="edit" method="post">國家名稱 :<input type='text' name='Country' value='"+country+"'/><br/> <%-- logo :<input type='text' name='logo' value='"+logo+"'/><br/>--%>金牌數(shù) :<input type='text' name='Glod_num' value='"+Glod+"'/><br/>銀牌數(shù) :<input type='text' name='Silver_num' value='"+Silver+"'/><br/>銅牌數(shù) :<input type='text' name='Copper_num' value='"+Copper+"'/><br/>id : <input type='text' name='Sum' value='"+sum+"'/><br/>總數(shù) : <input type='text' name='id' value='"+id+"'/><br/><input type="submit" value="保存"/><br/> </form> </body> </html>Edit.java
package com.bjpowernode.javaweb.servlet;import com.bjpowernode.javaweb.utils.DButil;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.sql.*;@WebServlet(name = "edit",value = "/edit") public class Edit extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String contextPath = request.getContextPath();response.setContentType("text/html;charset=UTF-8");request.setCharacterEncoding("UTF-8");PrintWriter out =response.getWriter();//jsp文檔out.println("<html lang='en'>");out.println("<head>");out.println(" <meta charset='UTF-8'>");out.println(" <link href='h/favicon2.ico' rel='icon' type='image/x-icon'/>");out.println(" <title>添加信息</title>");out.println(" <style>");out.println(" body {");out.println(" background-color:#FDF5E6;");out.println(" }");out.println(" </style>");out.println(" <style>");out.println(" body {");out.println(" width: 100%;");out.println(" height: 100%;");out.println(" background: url('./img/olypic.jpg');");out.println(" background-repeat: no-repeat;");out.println(" background-size: 100% 100%;");out.println(" background-attachment: fixed;");out.println(" }");out.println(" </style>");out.println(" <style>");out.println(" input{");out.println(" width: 20%;");out.println(" padding: 12px 20px;");out.println(" margin: 8px 0;");out.println(" box-sizing: border-box;");out.println(" border: 1px solid #555;");out.println(" outline: none;");out.println(" }");out.println("");out.println(" input:focus {");out.println(" background-color: lightblue;");out.println(" }");out.println(" </style>");out.println(" <style>");out.println(" #boxshadow {");out.println(" position: relative;");out.println(" -moz-box-shadow: 1px 2px 4px rgba(0, 0, 0,0.5);");out.println(" -webkit-box-shadow: 1px 2px 4px rgba(0, 0, 0, .5);");out.println(" box-shadow: 1px 2px 4px rgba(0, 0, 0, .5);");out.println(" padding: 10px;");out.println(" background:#F0F8FF;");out.println(" border-radius:8px;");out.println(" }");out.println("");out.println(" /* Make the image fit the box */");out.println(" #boxshadow img {");out.println(" width: 50%;");out.println(" border: 0px solid #8a4419;");out.println(" border-style: inset;");out.println(" }");out.println("");out.println(" #boxshadow::after {");out.println(" content: '';");out.println(" position: absolute;");out.println(" z-index: -1; /* hide shadow behind image */");out.println(" -webkit-box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);");out.println(" -moz-box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);");out.println(" box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);");out.println(" width: 70%;");out.println(" left: 15%; /* one half of the remaining 30% */");out.println(" height: 100px;");out.println(" bottom: 0;");out.println(" }");out.println(" </style>");out.println(" <style>");out.println(" .button {");out.println(" background-color:#337AB7; /* Green */");out.println(" border: none;");out.println(" color: white;");out.println(" padding: 16px 32px;");out.println(" text-align: center;");out.println(" text-decoration: none;");out.println(" display: inline-block;");out.println(" font-size: 16px;");out.println(" margin: 4px 2px;");out.println(" -webkit-transition-duration: 0.4s; /* Safari */");out.println(" transition-duration: 0.4s;");out.println(" cursor: pointer;");out.println(" }");out.println("");out.println(" .button1 {");out.println(" background-color: white;");out.println(" color: black;");out.println(" border: 2px solid #337AB7;");out.println(" }");out.println(" .button1:hover {");out.println(" background-color: #337AB7;");out.println(" color: white;");out.println(" box-shadow: 0 12px 16px 0 rgba(0,0,0,0.24),0 17px 50px 0 rgba(0,0,0,0.19);");out.println(" }");out.println(" </style>");out.println("");out.println("</head>");out.println("<body>");out.println("");out.println("<div style='padding:2px;width:1080px;height:470px;margin-top:10%;margin-left:20%;opacity: 0.8' id='boxshadow'>");out.println(" <div>");out.println(" <img src='img/olypic.jpg' style='float:left;margin-top:5%;'>");out.println(" </div>");out.println(" <div style='float:right;'>");out.println(" <form action='"+contextPath+"/update' method='post'>");//獲取國家名稱String country=request.getParameter("name");//連接數(shù)據(jù)庫Connection conn=null;PreparedStatement ps=null;ResultSet rs=null;try {try {Class.forName("com.mysql.jdbc.Driver");} catch (ClassNotFoundException e) {e.printStackTrace();}//獲取連接conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mofa", "root", "123456");String sql = "select * from medals_table where Country=?";//編譯sql語句ps = conn.prepareStatement(sql);//賦值 第一個問好賦值 country 國家名稱ps.setString(1, country);//查詢返回結(jié)果集 這個結(jié)果集只有一條記錄 ，國家名稱是主鍵 ， 故只有一條數(shù)據(jù)rs = ps.executeQuery();if(rs.next()){String logo=rs.getString("logo");String Glod = rs.getString("Glod_num");String Silver = rs.getString("Silver_num");String Copper = rs.getString("Copper_num");String sum=rs.getString("Sum");String id=rs.getString("id");System.out.println("你好，你好，你好，齊天大圣！！！");//輸出動態(tài)網(wǎng)頁out.println("<p style='margin-right:200px;'>");out.println(" 國家名稱   <input type='text' name='Country' value='"+country+"' style='border-radius:8px;width:150px;height:30px;'>");out.println(" </p>"); // out.println(" <p>"); // out.println("    logo      <input type='text' name='logo' value='"+logo+"' style='border-radius:8px;width:150px;height:30px;margin-top:1%'>"); // out.println(" </p>");out.println(" <p>");out.println("   金牌數(shù)     <input type='text' name='Glod_num' value='"+Glod+"' style='border-radius:8px;width:150px;height:30px;margin-top:1%'>");out.println(" </p>");out.println("");out.println(" <p>");out.println("   銀牌數(shù)     <input type='text' name='Silver_num' value='"+Silver+"' style='border-radius:8px;width:150px;height:30px;margin-top:1%'>");out.println(" </p>");out.println(" <p>");out.println("   銅牌數(shù)     <input type='text' name='Copper_num' value='"+Copper+"' style='border-radius:8px;width:150px;height:30px;margin-top:1%'>");out.println(" </p>");out.println(" <p>");out.println("      id           <input type='text' name='id' value='"+id+"' style='border-radius:8px;width:150px;height:30px;margin-top:1%'>");out.println(" </p>");}} catch (SQLException e) {e.printStackTrace();}finally {DButil.close(conn,ps,rs);}out.println(" <input type='submit' value='保存'/><br/>"); out.println(" </form>"); out.println(" </form>"); out.println(" </div>"); out.println("</div>"); out.println("</body>"); out.println("</html>");} }Update.java
package com.bjpowernode.javaweb.servlet;import com.bjpowernode.javaweb.utils.DButil;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.sql.*;@WebServlet(name = "update",value = "/update") public class Update extends HttpServlet {@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");request.setCharacterEncoding("UTF-8");//解決中文亂碼問題String country=request.getParameter("Country");String logo=request.getParameter("logo");String Glod_num=request.getParameter("Glod_num");String Silver_num=request.getParameter("Silver_num");String Copper_num=request.getParameter("Copper_num");String id=request.getParameter("id");//連接數(shù)據(jù)庫執(zhí)行更新操作Connection conn = null;PreparedStatement ps = null;ResultSet rs = null;int count=0;try {try {Class.forName("com.mysql.jdbc.Driver");} catch (ClassNotFoundException e) {e.printStackTrace();}//獲取連接conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mofa", "root", "123456");String sql = "update medals_table set Glod_num=?,Silver_num=?,Copper_num=?,id=? where Country=?";//編譯sql語句ps = conn.prepareStatement(sql); // ps.setString(1, logo);ps.setString(1, Glod_num);ps.setString(2, Silver_num);ps.setString(3, Copper_num);ps.setString(4, id);ps.setString(5, country); // System.out.println(logo);count=ps.executeUpdate();System.out.println(count);} catch (SQLException e) {e.printStackTrace();} finally {DButil.close(conn, ps, rs);}if(count==1){//更新成功request.getRequestDispatcher("Take_01").forward(request,response);}else{//更新失敗request.getRequestDispatcher("error.jsp").forward(request,response);}} }**``` 前端傳輸數(shù)據(jù)給后端edit,edit通過getParameter取到前端值完成后面的操作。** 為了讓修改的時候可以顯示修改前的值，我們在Edit.java中寫入前端代碼。** Edit.jav中代碼通過form表單把數(shù)據(jù)傳輸給Update.java。** Update.java通過getParameter取到由Edit.java中傳來的值。** 把取到的值存進(jìn)數(shù)據(jù)庫，完成刷入操作。******`注意：我這里有個bug，就是不能修改國家名稱，因?yàn)槭仲v的我為了讓數(shù)據(jù)庫看著好看就把國家名設(shè)置為主鍵了，，，，，，，`** *** *** 連接數(shù)據(jù)庫------查詢操作 **`Select.java`**```java package com.bjpowernode.javaweb.servlet;import com.bipowernode.pojo.Olypic; import com.bjpowernode.javaweb.utils.DButil;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.sql.*; import java.util.ArrayList; import java.util.List;@WebServlet(name = "select",value = "/select") public class Select extends HttpServlet {@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");request.setCharacterEncoding("UTF-8");String name = request.getParameter("select_name");System.out.println(name);//連接數(shù)據(jù)庫Connection conn = null;PreparedStatement ps = null;ResultSet rs = null;List<Olypic> olypicList=new ArrayList<>();try {Class.forName("com.mysql.jdbc.Driver");//獲取連接conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mofa", "root", "123456");String sql = "select * from medals_table where Country=?";//編譯sql語句ps = conn.prepareStatement(sql);//賦值 第一個問好賦值 country 國家名稱ps.setString(1, name);//查詢返回結(jié)果集 這個結(jié)果集只有一條記錄 ，國家名稱是主鍵 ， 故只有一條數(shù)據(jù)rs = ps.executeQuery();if (rs.next()) {String country = rs.getString("Country");String Glod = rs.getString("Glod_num");String Silver = rs.getString("Silver_num");String Copper = rs.getString("Copper_num");String id=rs.getString("id");String logo=rs.getString("logo");System.out.println("這是數(shù)據(jù)");System.out.println(country);System.out.println("Glod"); // String Sum=rs.getString("Sum");int G = Integer.valueOf(Glod).intValue();int S = Integer.valueOf(Silver).intValue();int C = Integer.valueOf(Copper).intValue();int A=G+S+C;String Sum=String.valueOf(A);//將數(shù)據(jù)封裝程Java對象Olypic olpic=new Olypic();olpic.setCountry(country);olpic.setGlod_num(Glod);olpic.setSilver_num(Silver);olpic.setCopper_num(Copper);olpic.setId(id);olpic.setSum(Sum);olpic.setLogo(logo);// TODO 將數(shù)據(jù)放入上面定義好的容器olypicList.add(olpic);}} catch (SQLException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();} finally {DButil.close(conn, ps, rs);}request.setAttribute("olypicList",olypicList);request.getRequestDispatcher("./take_03.jsp").forward(request,response);} }可以從前端或者后端傳值，完成搜索操作。但是一般是要通過前端搜索框輸入值，通過form表單傳走，后端通過getParameter取值完成一些列操作。
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