第一个servlet项目:pro07-javaweb-begin

第一级目录：src包，web包，pro07-javaweb-begin.iml
pro07-javaweb-begin.iml
pro07-javaweb-begin.src.com.atguigu.fruit
pro07-javaweb-begin.src.com.atguigu.fruit.dao
pro07-javaweb-begin.src.com.atguigu.fruit.dao.base.BaseDAO.java
package com.atguigu.fruit.dao.base;

import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public abstract class BaseDAO {
    public final String DRIVER = "com.mysql.jdbc.Driver" ;
    public final String URL = "jdbc:mysql://localhost:3306/fruitdb?useUnicode=true&characterEncoding=utf-8&useSSL=false";
    public final String USER = "root";
    public final String PWD = "123456" ;

    protected Connection conn ;
    protected PreparedStatement psmt ;
    protected ResultSet rs ;

    //T的Class对象
    private Class entityClass ;

    public BaseDAO(){
        //getClass() 获取Class对象，当前我们执行的是new FruitDAOImpl() , 创建的是FruitDAOImpl的实例
        //那么子类构造方法内部首先会调用父类（BaseDAO）的无参构造方法
        //因此此处的getClass()会被执行，但是getClass获取的是FruitDAOImpl的Class
        //所以getGenericSuperclass()获取到的是BaseDAO的Class
        Type genericType = getClass().getGenericSuperclass();
        //ParameterizedType 参数化类型
        Type[] actualTypeArguments = ((ParameterizedType) genericType).getActualTypeArguments();
        //获取到的中的T的真实的类型
        Type actualType = actualTypeArguments[0];
        try {
            entityClass = Class.forName(actualType.getTypeName());
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    protected Connection getConn(){
        try {
            //1.加载驱动
            Class.forName(DRIVER);
            //2.通过驱动管理器获取连接对象
            return DriverManager.getConnection(URL, USER, PWD);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
        return null ;
    }

    protected void close(ResultSet rs , PreparedStatement psmt , Connection conn){
        try {
            if (rs != null) {
                rs.close();
            }
            if(psmt!=null){
                psmt.close();
            }
            if(conn!=null && !conn.isClosed()){
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    //给预处理命令对象设置参数
    private void setParams(PreparedStatement psmt , Object... params) throws SQLException {
        if(params!=null && params.length>0){
            for (int i = 0; i < params.length; i++) {
                psmt.setObject(i+1,params[i]);
            }
        }
    }

    //执行更新，返回影响行数
    protected int executeUpdate(String sql , Object... params){
        boolean insertFlag = false ;
        insertFlag = sql.trim().toUpperCase().startsWith("INSERT");
        try {
            conn = getConn();
            if(insertFlag){
                psmt = conn.prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);
            }else {
                psmt = conn.prepareStatement(sql);
            }
            setParams(psmt,params);
            int count = psmt.executeUpdate() ;

            rs = psmt.getGeneratedKeys();
            if(rs.next()){
                return ((Long)rs.getLong(1)).intValue();
            }
            return count ;
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            close(rs,psmt,conn);
        }
        return 0;
    }

    //通过反射技术给obj对象的property属性赋propertyValue值
    private void setValue(Object obj ,  String property , Object propertyValue){
        Class clazz = obj.getClass();
        try {
            //获取property这个字符串对应的属性名 ， 比如 "fid"  去找 obj对象中的 fid 属性
            Field field = clazz.getDeclaredField(property);
            if(field!=null){
                field.setAccessible(true);
                field.set(obj,propertyValue);
            }
        } catch (NoSuchFieldException | IllegalAccessException e) {
            e.printStackTrace();
        }
    }

    //执行复杂查询，返回例如统计结果
    protected Object[] executeComplexQuery(String sql , Object... params){
        try {
            conn = getConn() ;
            psmt = conn.prepareStatement(sql);
            setParams(psmt,params);
            rs = psmt.executeQuery();

            //通过rs可以获取结果集的元数据
            //元数据：描述结果集数据的数据 , 简单讲，就是这个结果集有哪些列，什么类型等等

            ResultSetMetaData rsmd = rs.getMetaData();
            //获取结果集的列数
            int columnCount = rsmd.getColumnCount();
            Object[] columnValueArr = new Object[columnCount];
            //6.解析rs
            if(rs.next()){
                for(int i = 0 ; i executeQuery(String sql , Object... params){
        List list = new ArrayList<>();
        try {
            conn = getConn() ;
            psmt = conn.prepareStatement(sql);
            setParams(psmt,params);
            rs = psmt.executeQuery();

            //通过rs可以获取结果集的元数据
            //元数据：描述结果集数据的数据 , 简单讲，就是这个结果集有哪些列，什么类型等等

            ResultSetMetaData rsmd = rs.getMetaData();
            //获取结果集的列数
            int columnCount = rsmd.getColumnCount();
            //6.解析rs
            while(rs.next()){
                T entity = (T)entityClass.newInstance();

                for(int i = 0 ; i 
pro07-javaweb-begin.src.com.atguigu.fruit.dao.impl 
package com.atguigu.fruit.dao.impl;

import com.atguigu.fruit.dao.FruitDAO;
import com.atguigu.fruit.dao.base.BaseDAO;
import com.atguigu.fruit.pojo.Fruit;

import java.util.List;

public class FruitDAOImpl extends BaseDAO implements FruitDAO {
    @Override
    public List getFruitList() {
        return super.executeQuery("select * from t_fruit");
    }

    @Override
    public boolean addFruit(Fruit fruit) {
        String sql = "insert into t_fruit values(null,?,?,?,?)";
        int count = super.executeUpdate(sql,fruit.getFname(),fruit.getPrice(),fruit.getFcount(),fruit.getRemark()) ;
        //insert语句返回的是自增列的值，而不是影响行数
        //System.out.println(count);
        return count>0;
    }

    @Override
    public boolean updateFruit(Fruit fruit) {
        String sql = "update t_fruit set fcount = ? where fid = ? " ;
        return super.executeUpdate(sql,fruit.getFcount(),fruit.getFid())>0;
    }

    @Override
    public Fruit getFruitByFname(String fname) {
        return super.load("select * from t_fruit where fname like ? ",fname);
    }

    @Override
    public boolean delFruit(String fname) {
        String sql = "delete from t_fruit where fname like ? " ;
        return super.executeUpdate(sql,fname)>0;
    }
} 
pro07-javaweb-begin.src.com.atguigu.fruit.dao.FruitDAO.java 
package com.atguigu.fruit.dao;

import com.atguigu.fruit.pojo.Fruit;

import java.util.List;

public interface FruitDAO {
    //查询库存列表
    List getFruitList();

    //新增库存
    boolean addFruit(Fruit fruit);

    //修改库存
    boolean updateFruit(Fruit fruit);

    //根据名称查询特定库存
    Fruit getFruitByFname(String fname);

    //删除特定库存记录
    boolean delFruit(String fname);
} 
pro07-javaweb-begin.src.com.atguigu.fruit.pojo.Fruit.java 
package com.atguigu.fruit.pojo;

public class Fruit {
    private Integer fid ;
    private String fname ;
    private Integer price ;
    private Integer fcount ;
    private String remark ;

    public Fruit(){}

    public Fruit(Integer fid, String fname, Integer price, Integer fcount, String remark) {
        this.fid = fid;
        this.fname = fname;
        this.price = price;
        this.fcount = fcount;
        this.remark = remark;
    }

    public Integer getFid() {
        return fid;
    }

    public void setFid(Integer fid) {
        this.fid = fid;
    }

    public String getFname() {
        return fname;
    }

    public void setFname(String fname) {
        this.fname = fname;
    }

    public Integer getPrice() {
        return price;
    }

    public void setPrice(Integer price) {
        this.price = price;
    }

    public Integer getFcount() {
        return fcount;
    }

    public void setFcount(Integer fcount) {
        this.fcount = fcount;
    }

    public String getRemark() {
        return remark;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }

    @Override
    public String toString() {
        return fid + "tt" + fname + "tt" + price +"tt" + fcount +"tt" + remark ;
    }
} 
pro07-javaweb-begin.src.com.atguigu.servlets.AddServlet.java 
package com.atguigu.servlets;

import com.atguigu.fruit.dao.FruitDAO;
import com.atguigu.fruit.dao.impl.FruitDAOImpl;
import com.atguigu.fruit.pojo.Fruit;

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;
@WebServlet(urlPatterns = "/Add")
public class AddServlet extends HttpServlet {
    @Override
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        //post方式下，设置编码，防止中文乱码
        //需要注意的是，设置编码这一句代码必须在所有的获取参数动作之前
        request.setCharacterEncoding("UTF-8");
        String fname = request.getParameter("fname");
        String priceStr = request.getParameter("price");
        Integer price = Integer.parseInt(priceStr);
        String fcountStr = request.getParameter("fcount");
        Integer fcount = Integer.parseInt(fcountStr);
        String remark = request.getParameter("remark");

        FruitDAO fruitDAO = new FruitDAOImpl();
        boolean flag = fruitDAO.addFruit(new Fruit(0 , fname , price , fcount , remark));

        System.out.println(flag ? "添加成功！" : "添加失败！");
    }
} 
pro07-javaweb-begin.web.add.html 



    
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        价格：

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pro07-javaweb-begin.web.WEB-INF.web.xml
第一个servlet项目:pro07-javaweb-begin

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