JDBC

JDBC

2024 年 11 月 11 日

278 次浏览

2423字数

### UserDAO
```
package com.svse.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.svse.entity.UserEntity;

public class UserDAO {

// 全查询
	public List<UserEntity> getAll() {

List<UserEntity> ar = new ArrayList<UserEntity>();
		/************* 第一步：得到数据库的连接 *****************/
		String driver = "com.mysql.jdbc.Driver";
		String url = "jdbc:mysql://localhost:3306/test";
		String user = "root";
		String password = "root";
		Connection conn = null;
		try {
			Class.forName(driver);
			conn = DriverManager.getConnection(url, user, password);
		} catch (Exception e) {
			e.printStackTrace();
		}
		/***************** 第二步：开始查询 **************************/
		try {
			// 第一小步：写查询的SQL语句
			String sql = "select * from userinfo";
			// 第二小步：写预处理语句
			PreparedStatement pre = conn.prepareStatement(sql);
			// 第三小步：发送到数据库中去执行，并得到返回结果
			ResultSet rs = pre.executeQuery();
			// 第四小步：循环取出每一条
			while (rs.next()) {
				int uid = rs.getInt("uid");
				String uname = rs.getString("uname");
				String upsw = rs.getString("upsw");
				// 第五小步：一 一封装到实体----ar
				UserEntity u = new UserEntity();
				u.setUid(uid);
				u.setUname(uname);
				u.setUpsw(upsw);
				ar.add(u);
			}

} catch (SQLException e) {
			e.printStackTrace();
		}
		return ar;
	}
}

```
### UserEntity
```
package com.svse.entity;

public class UserEntity {
	
	//编号 
	private int uid;
	//姓名 
	private String uname;
	//密码
	private String upsw;
	
	
	public int getUid() {
		return uid;
	}
	public void setUid(int uid) {
		this.uid = uid;
	}
	public String getUname() {
		return uname;
	}
	public void setUname(String uname) {
		this.uname = uname;
	}
	public String getUpsw() {
		return upsw;
	}
	public void setUpsw(String upsw) {
		this.upsw = upsw;
	}

}

```
### Test

```
package com.svse.test;

import java.util.List;

import com.svse.dao.UserDAO;
import com.svse.entity.UserEntity;

public class Test {

public static void main(String[] args) {
		System.out.println("编号\t姓名\t密码");
		//调用全查询
		UserDAO dao=new UserDAO();
		List<UserEntity> ar=dao.getAll();
		for (int i = 0; i < ar.size(); i++) {
			System.out.println(ar.get(i).getUid()+"\t"+ar.get(i).getUname()+"\t"+ar.get(i).getUpsw());
		}
	}
}

```

JDBC