User表及相关操作

1、创建EncryptUtil.Java工具类：

package cn.edu.mju.project1.util;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class EncryptUtil {
        public static String md5(String plainText){
            String encryStr = null;
            if(plainText != null && !"".equals(plainText)) {
                try {
                    byte[] ret = MessageDigest.getInstance("md5").digest(plainText.getBytes());
                    String md5Code = new BigInteger(1, ret).toString(16);
                    for (int i = 0; i < 32 - md5Code.length(); i++) {
                        md5Code = "0" + md5Code;
                    }
                    encryStr = md5Code;
                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                }
            }
            return encryStr;
    }
}

创建对应的测试类TestEncrypt.Java：

import cn.edu.mju.project1.util.EncryptUtil;
import org.junit.Test;

public class TestEncrypt {
    @Test
    public void testMd5(){
        System.out.println(EncryptUtil.md5("123"));
    }

}

测试该类的加密方法，结果如下：

2、创建User表：


创建User类：

package cn.edu.mju.project1.entity;

public class User {
    private Integer id;
    private String loginName;
    private String loginPwd;
    private String salt;
    private Byte gender;
    private String phone;
    private Byte  status;

    public User(){

    }
    public User(Integer id) {
        this.id = id;
    }

    public User(Integer id, String loginName, String loginPwd, String salt, Byte gender, String phone, Byte status) {
        this.id = id;
        this.loginName = loginName;
        this.loginPwd = loginPwd;
        this.salt = salt;
        this.gender = gender;
        this.phone = phone;
        this.status = status;
    }

    public Integer getId() {
        return id;
    }

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

    public String getLoginName() {
        return loginName;
    }

    public void setLoginName(String loginName) {
        this.loginName = loginName;
    }

    public String getLoginPwd() {
        return loginPwd;
    }

    public void setLoginPwd(String loginPwd) {
        this.loginPwd = loginPwd;
    }

    public String getSalt() {
        return salt;
    }

    public void setSalt(String salt) {
        this.salt = salt;
    }

    public Byte getGender() {
        return gender;
    }

    public void setGender(Byte gender) {
        this.gender = gender;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public Byte getStatus() {
        return status;
    }

    public void setStatus(Byte status) {
        this.status = status;
    }
}
创建IUserDao接口类（就先写了一个方法）：

```java
package cn.edu.mju.project1.persiste;


import cn.edu.mju.project1.entity.User;

public interface IUserDao {
        public User findByLoginName(String loginName);
}

创建IUserDao接口类的实现类UserDao（也先写了接口的一个抽象方法）:

package cn.edu.mju.project1.persiste.impl;

import cn.edu.mju.project1.entity.User;
import cn.edu.mju.project1.persiste.IUserDao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class UserDao implements IUserDao {
    @Override
    public User findByLoginName(String loginName) {
        User user = null;
        try {
            Connection conn = MySqlDbUtil.getConnection();
            String sql = "SELECT * FROM user WHERE login_name=?";
            PreparedStatement pst = conn.prepareStatement(sql);
            pst.setString(1, loginName);
            ResultSet rs = pst.executeQuery();
            if(rs.next()){
                user = new User();
                user.setId(rs.getInt("id"));

            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return user;
    }
}