myEclipse,web项目连接数据库
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下面的结构图
1.在src你创建com.hqyj.wj.model建立model包,model里放数据库的元素,User.java的截图
package com.hqyj.wj.model;
//用户信息表
public class User {
private int id;
private String name;
private String birthday;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getBirthday() {
return birthday;
}
public void setBirthday(String birthday) {
this.birthday = birthday;
}
}
2.在src你创建com.hqyj.wj.dao.inf建立包,这个包是放接口类,这是UserDaoInf的截图
package com.hqyj.wj.dao.inf;
import java.util.List;
import com.hqyj.wj.model.User;
/**
* 数据访问层的接口定义数据接口的方法
*
*/
public interface UserDaoInf {
//定义一个查询方法
List<User> search();
}
3.在src你创建com.hqyj.wj.dao建立包,这个包连接数据库,及实现上面的接口类
package com.hqyj.wj.dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import com.hqyj.wj.dao.inf.UserDaoInf;
import com.hqyj.wj.model.User;
/**
*
* @author wl 数据访问接口
*/
public class UserDao implements UserDaoInf {
// 数据访问数据库的连接对象
protected Connection con = null;
//预编译你写的sql语句
protected PreparedStatement ps=null;
//查询预编译的sql语句
protected ResultSet rs=null;
// 获取数据库链接
@SuppressWarnings("finally")
public Connection getCon() {
try {
// 加载mysql驱动
Class.forName("com.mysql.jdbc.Driver");
//获取数据库链接
con=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/image?characterEncoding=utf8", "root", "root");
System.out.println("链接成功");
return con;
} catch (Exception e) {
System.out.println("链接失败"+e.getMessage());
return null;
// } finally {
// try {
// con.close();
// } catch (SQLException e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// return null;
// }
//
}
}
/**
* 查询方法
*/
public List<User> search() {
List<User> list=new ArrayList<User>();
try {
//定义一个sql语句
//String sql="SELECT a.id as 序号,a.salary as \'薪水\',b.`name` as \'姓名\' from salary a LEFT JOIN `user` b on a.u_id=b.id";
String sql="SELECT * from user";
//获取数据库连接
con=getCon();
//预编译sql语句
ps=con.prepareStatement(sql);
//把编译出来的结果集装载到ResultSet对象里面
rs=ps.executeQuery();
// rs=statement.executeQuery(sql);
//取出ResultSet里的结果集装载到数据模型里
while(rs.next()){
User user=new User();
user.setName(rs.getString("name"));
user.setBirthday(rs.getString("birthday"));
user.setId(Integer.parseInt(rs.getString("id")));
list.add(user);
}
} catch (Exception e) {
System.out.println("查询错误"+e.getMessage());
}finally{
try {
rs.close();
ps.close();
con.close();
} catch (Exception e2) {
e2.printStackTrace();
}
}
return list;
}
}
5.要引入数据库包mysql-connector-java-commercial-5.1.25-bin.jar,和json-lib-2.2.3-jdk15.jar在项目名字上右键->properties->java Build Path->Libraries->Add External Jars然后选择你下载的包
6.在src下面创建测试类
import java.util.List;
import com.hqyj.wj.dao.UserDao;
import com.hqyj.wj.model.User;
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
//获取数据库访问类对象
UserDao dao=new UserDao();
dao.getCon();
List<User> list=dao.search();
for(int i=0;i<list.size();i++){
System.out.println("id=="+list.get(i).getId());
System.out.println("name=="+list.get(i).getName());
System.out.println("birthday=="+list.get(i).getBirthday());
}
}
}
7.成功显示
8.src创建服务类和接口,UserServiceInf和UserService
package com.hqyj.wj.service.inf;
import java.util.List;
import com.hqyj.wj.model.User;
public interface UserServiceInf {
List<User> search();
}
package com.hqyj.wj.service;
import java.util.List;
import com.hqyj.wj.dao.UserDao;
import com.hqyj.wj.dao.inf.UserDaoInf;
import com.hqyj.wj.model.User;
import com.hqyj.wj.service.inf.UserServiceInf;
/**
*逻辑服务层实现类
*/
public class UserService implements UserServiceInf{
UserDaoInf us=new UserDao();
public List<User> search() {
return us.search();
}
}
9.src创建控制层 ,下新建个服务
package com.hqyj.wj.controller;
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;
import net.sf.json.JSONArray;
import com.hqyj.wj.service.*;
import com.hqyj.wj.service.inf.*;
import com.hqyj.wj.model.*;
import java.util.List;
import java.util.ArrayList;
public class OneServlet extends HttpServlet {
public OneServlet() {
super();
}
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
//doget对应的是ajax的$.get()方法
//request是装载请求数据
//response响应数据到前端对象
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//解决中文乱码的问题
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
//在服务器端设置允许在其他域名下访问，及响应类型、响应头设置
System.out.println("这是");
response.setHeader("Access-Control-Allow-Origin", "*");
response.setHeader("Access-Control-Allow-Methods","POST");
response.setHeader("Access-Control-Allow-Headers","x-requested-with,content-type");
//响应的文本格式
response.setContentType("text/html");
//获取响应的输出对象
PrintWriter out = response.getWriter();
// out.print("nissssss");
// out.print("您好呀");
//创建服务器层实现类
UserServiceInf service=new UserService();
List<User> list=service.search();
//把list数据解析成前端页面能读取的数据
JSONArray json=JSONArray.fromObject(list);
out.print(json.toString());
out.flush();
out.close();
}
//doget对应的是ajax的$.post()方法
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \\"-//W3C//DTD HTML 4.01 Transitional//EN\\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
public void init() throws ServletException {
// Put your code here
}
}
10.新建一个html,获取数据库数据
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>ajax获取集合</title> <script src="../js/jquery-3.1.1.min.js"></script> </head> <body> <table> <thead> <tr><th>id</th> <th>姓名</th> <th>生日</th></tr> </thead> <tbody> </tbody> </table> <script> $(function(){ $.get("http://localhost:8080/jquery/servlet/OneServlet",function(data){ var num=eval(data); var str; // for(var o in num){ // console.log(num[o].name); // str+=" <tr> <td>"+num[o].id+"</td> <td>"+num[o].name+"</td> <td>"+num[o].birthday+"</td></tr>"; // $("tbody").html(str) // } for(var i=0;i<num.length;i++){ str+=" <tr> <td>"+num[i].id+"</td> <td>"+num[i].name+"</td> <td>"+num[i].birthday+"</td></tr>"; } $("tbody").html(str) }) }) </script> </body> </html>
11.就可以运行成功了,我最开始运行失败了,把tomcat7换为tomcat6就正确了
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