文章目录
I know, i know
地球另一端有你陪我
一、继续优化
1、引入 redis 作为缓冲层
RedisUtil Redis工具
需要导包
Jedis 3.0.0
使用连接池
/*
redis 工具类
*/
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;
public class RedisUtil {
private static JedisPool jedisPool;
static{
//连接池设置
JedisPoolConfig jpc = new JedisPoolConfig();
//连接池数量
jpc.setMaxTotal(5);
//最大等待时间
jpc.setMaxWaitMillis(100);
//创建连接池
jedisPool = new JedisPool(jpc,"master",6379);
}
public static Jedis getJedis(){
return jedisPool.getResource();
}
}
dao ：持久层 / 连接SQL
接口自己写
import com.fgh.spring.mvc.bean.Student;
import com.fgh.spring.mvc.bean.User;
import com.fgh.spring.util.JDBCUtil;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class UserDaoMySqlImpl implements UserDao{
//连接数据库
//按照输入的name从数据库中获得对应的数据
//存储到 user 对象之中，并返回
public User getuser(String username){
User user=null;
try {
Connection conn = JDBCUtil.getConn();
String sql = "select * from user where username=?";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1,username);
ResultSet rs = ps.executeQuery();
if(rs.next()){
user = new User();
user.setId(rs.getString("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
rs.close();
ps.close();
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
return user;
}
public Student select(String id){
Student student = null;
try {
Connection conn = JDBCUtil.getConn();
PreparedStatement ps =
conn.prepareStatement("select * from Student where id=?");
ps.setString(1,id);
ResultSet rs = ps.executeQuery();
if(rs.next()){
student = new Student();
student.setId(rs.getString("id"));
student.setName(rs.getString("name"));
student.setBirth(rs.getString("birth"));
student.setSex(rs.getString("sex"));
rs.close();
ps.close();
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
return student;
}
}
service ：业务逻辑层 / 逻辑验证
接口自己写
import com.fgh.spring.mvc.bean.Student;
import com.fgh.spring.mvc.dao.UserDaoMySqlImpl;
import com.fgh.spring.util.RedisUtil;
import redis.clients.jedis.Jedis;
import java.util.HashMap;
import java.util.Map;
public class UserService2Impl implements UserService {
@Override
public String checkUser(String username, String password) {
if (username == null) {
return "请填写用户名";
}
UserDaoMySqlImpl ud = new UserDaoMySqlImpl();
com.fgh.spring.mvc.bean.User user = ud.getuser(username);
if (user == null) {
return "用户名不存在";
}
if (!user.getPassword().equals(password)) {
return "用户名或密码错误";
}
return "登陆成功";
}
/*
* 连接redis
* hash作为缓存数据结构
* 通过id查询获取一个map结果
* map=有数据加TTL map={}没数据
* HashMap<String, User> map = new HashMap<String, User>();
*/
//提前创建对象
//此处 jedis 不能是静态的，否则一关全关了
Jedis jedis = RedisUtil.getJedis();
static UserDaoMySqlImpl userdao=new UserDaoMySqlImpl();
@Override
public String selectUser(String id) {
//使用 try catch 保证当 redis 数据库断开后
//依然可以通过连接池，再次连上数据库
try{
Map<String, String> map = jedis.hgetAll("student:" + id);
// map不等于null 并且map不等于空
//查到了，先刷新生存时限ttl，再返回数据
if(map!=null&&!map.isEmpty()){
jedis.expire("student:"+id,30);
return "redis---"+map.toString();
}
}catch (Exception e){
e.printStackTrace();
}finally {
jedis.close();
}
//如果没有数据，就去 mysql 查
Student student = userdao.select(id);
//没查到直接返回
if(student==null){
return "无此用户";
}
try{
//查到了先存到redis，再返回
HashMap<String, String> u = new HashMap<>();
u.put("id",student.getId());
u.put("name",student.getName());
u.put("birth",student.getBirth());
u.put("sex",student.getSex());
//存到redis，并为其添加生存时限ttl 30s
//最后返回
jedis.hmset("student:"+id,u);
jedis.expire("student:"+id,30);
}catch (Exception e){
e.printStackTrace();
}finally {
jedis.close();
}
return "mysql---"+student.toString();
}
}
controller ：表现层 / 前端交互
import com.fgh.spring.mvc.service.UserService2Impl;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class UserController {
@RequestMapping("/login")
public String login(String username,String password){
UserService2Impl us = new UserService2Impl();
String message = us.checkUser(username, password);
return message;
}
@RequestMapping("/select")
public String select(String id){
UserService2Impl us = new UserService2Impl();
String message = us.selectUser(id);
return message;
}
}
总结
1、在类中方法外，使用带返回值的静态方法，需要先写变量名，才能用 “.” 带出方法