使用dbutils和c3p0连接数据库进行简单的增删改查操作

直接上代码：

要引入jar包：

 然后写xml文件：

<?xml version="1.0" encoding="UTF-8" ?>
<c3p0-config>
    <default-config>
        <property name="user">root</property>
        <property name="password">root</property>
        <property name="driverClass">com.mysql.cj.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql:///db13?serverTimezone=UTC&amp;characterEncoding=UTF8</property>
    </default-config> 
</c3p0-config> 

bean层：

package com.user.bean;

public class Bean {
    private String name;
    private String id;
    private String sex;
    
    public Bean(String name, String id, String sex) {
        super();
        this.name = name;
        this.id = id;
        this.sex = sex;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public Bean() {
        // TODO Auto-generated constructor stub
    }

}

dao层：

package com.user.dao;

import java.sql.SQLException;
import java.util.List;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import com.user.bean.Bean;
import com.user.utils.DBUtils;

public class Dao {
    
    public  static boolean insertUser(Bean b) {
        System.out.println(b.getSex());
        QueryRunner qr=new QueryRunner(DBUtils.getDataSource());
        String sql="insert into user values(?,?,?)";
        try {
            int i=qr.update(sql,b.getName(),b.getId(),b.getSex());
            if(i>0) return true;
            else return false;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return false;
    } 
    public  static boolean updateUser(Bean b) {
        QueryRunner qr=new QueryRunner(DBUtils.getDataSource());
        String sql="update user set name=?,sex=? where id=?";
        try {
            int i=qr.update(sql,b.getName(),b.getSex(),b.getId());
            if(i>0) return true;
            else return false;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return false;
        
    } 
    
    
    public  static boolean deleteUser(Bean b) {
        QueryRunner qr=new QueryRunner(DBUtils.getDataSource());
        String sql="delete from user where id=?";
        try {
            int i=qr.update(sql,b.getId());
            if(i>0) return true;
            else return false;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return false;
        
    } 
    
    public  static List<Bean> queryUser() {
        QueryRunner qr=new QueryRunner(DBUtils.getDataSource());
        String sql="select * from user";
        try {
            List<Bean> list =qr.query(sql, new BeanListHandler<Bean>(Bean.class));
            return list;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    } 
    
    
    public Dao() {
        // TODO Auto-generated constructor stub
    }

}

发现同DBUtils比正常的dao要简单得多，代码量比较少

servlet层

package com.user.servlet;

import java.io.IOException;
import java.util.List;

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 com.user.bean.Bean;
import com.user.dao.Dao;

/**
 * Servlet implementation class servlet
 */
@WebServlet("/servlet")
public class servlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public servlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
//        response.getWriter().append("Served at: ").append(request.getContextPath());
        response.setCharacterEncoding("UTF-8");
        String method =request.getParameter("method");
        if("update".equals(method)) {
            try {
                update(request,response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        else if("insert".equals(method)) {
            try {
                insert(request,response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        else if("delete".equals(method)) {
            try {
                delete(request,response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        else if("list".equals(method)) {
            try {
                list(request,response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    private void list(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("UTF-8");
        List<Bean> list =Dao.queryUser();
        request.setAttribute("list", list);
        if(!list.isEmpty()) {
            request.setAttribute("message", "遍历成功");
            request.getRequestDispatcher("list.jsp").forward(request, response);
        }else {
            request.setAttribute("message", "遍历失败，即将返回主页");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }
        
        
        
    }

    private void delete(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("UTF-8");
        String name=request.getParameter("name");
        String id=request.getParameter("id");
        String sex=request.getParameter("sex");
        Bean b=new Bean();
        b.setName(name);
        b.setId(id);
        b.setSex(sex);
        if(Dao.deleteUser(b)) {
            request.setAttribute("message", "删除成功");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }else {
            request.setAttribute("message", "删除失败，即将返回主页");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }
    }

    private void insert(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        String name=request.getParameter("name");
        String id=request.getParameter("id");
        String sex=request.getParameter("sex");
        System.out.println(name+id+sex);
        Bean b=new Bean(name,id,sex);
        if(Dao.insertUser(b)) {
            request.setAttribute("message", "添加成功");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }else {
            request.setAttribute("message", "添加失败，即将返回主页");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }
        
    }

    private void update(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("UTF-8");
        String name=request.getParameter("name");
        String id=request.getParameter("id");
        String sex=request.getParameter("sex");
        Bean b=new Bean();
        b.setName(name);
        b.setId(id);
        b.setSex(sex);
        if(Dao.updateUser(b)){
            request.setAttribute("message", "修改成功");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }else {
            request.setAttribute("message", "修改失败，即将返回主页");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        doGet(request, response);
    }

}

dbutil：

package com.user.utils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DBUtils {

    private static DataSource dataSource = new ComboPooledDataSource();

    private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();

    // 直接可以获取一个连接池
    public static DataSource getDataSource() {
        return dataSource;
    }
    
    public static Connection getConnection() throws SQLException{
        return dataSource.getConnection();
    }

    // 获取连接对象
    public static Connection getCurrentConnection() throws SQLException {

        Connection con = tl.get();
        if (con == null) {
            con = dataSource.getConnection();
            tl.set(con);
        }
        return con;
    }

    // 开启事务
    public static void startTransaction() throws SQLException {
        Connection con = getCurrentConnection();
        if (con != null) {
            con.setAutoCommit(false);
        }
    }

    // 事务回滚
    public static void rollback() throws SQLException {
        Connection con = getCurrentConnection();
        if (con != null) {
            con.rollback();
        }
    }

    // 提交并且 关闭资源及从ThreadLocall中释放
    public static void commitAndRelease() throws SQLException {
        Connection con = getCurrentConnection();
        if (con != null) {
            con.commit(); // 事务提交
            con.close();// 关闭资源
            tl.remove();// 从线程绑定中移除
        }
    }

    // 关闭资源方法
    public static void closeConnection() throws SQLException {
        Connection con = getCurrentConnection();
        if (con != null) {
            con.close();
        }
    }

    public static void closeStatement(Statement st) throws SQLException {
        if (st != null) {
            st.close();
        }
    }

    public static void closeResultSet(ResultSet rs) throws SQLException {
        if (rs != null) {
            rs.close();
        }
    }
}

与之前的增删改查相比 代码量减少了很多，进而在有限的时间写出更多的功能，进行更多的操作。

大家可以看我之前的简单的增删改查，真的代码量很多。

但是我也遇到了乱码的问题，向数据库中写的中文全是乱码，曾经测试过，发现写入servelt层和dao层都不是乱码，所以感觉是数据库出了问题，因此百度，发现了上述xml文件中数据库名字后面的限制，但是应该注意&在xml文件中编译不通过，所以要用转义字符&但是即使这样在之前的测试中还是乱码，问了同学发现，要改数据库的时区，因此在这中条件下终于成功了。

测试结果：

因为之前有乱码所以写的全是中文来测试。