数据模型（Model），视图（View），控制器（Controller）
HTTP请求发送到控制器，控制层与业务层数据模型进行交互、获取数据，使用视图响应请求。
2. 使用 @RequestMapping映射请求Controller层通过@RequestMapping映射请求：
package com.example.demo.controller;
import com.example.demo.pojo.User;
import com.example.demo.service.JdbcService;
import com.example.demo.service.JdbcTemplateService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import java.sql.SQLException;
import java.util.List;
@Controller
@RequestMapping("/jdbc")
public class JdbcController {
@Autowired
private JdbcTemplateService jdbcService;
@RequestMapping("/insert")
@ResponseBody
public String insert(String id, String name, int age) throws SQLException, ClassNotFoundException {
User user = new User(name, id, age);
int i = jdbcService.insert(user);
String msg = "新增了" + i + "条数据";
return msg;
}
@RequestMapping("/update")
@ResponseBody
public String update(String id, String name, int age) throws SQLException, ClassNotFoundException {
User user = new User(name, id, age);
int i = jdbcService.update(user);
String msg = "更新了" + i + "条数据";
return msg;
}
@RequestMapping("/delete")
@ResponseBody
public String delete(String id) throws SQLException, ClassNotFoundException {
int i = jdbcService.delete(id);
String msg = "删除了" + i + "条数据";
return msg;
}
@RequestMapping("/search")
@ResponseBody
public User search(String id) throws SQLException, ClassNotFoundException {
User user = jdbcService.search(id);
return user;
}
}
服务层编写服务接口：
package com.example.demo.service;
import com.example.demo.pojo.User;
import java.util.List;
public interface JdbcTemplateService {
public User search(String id);
public int insert(User user);
public int update(User user) ;
public int delete(String id);
}
服务层接口实现类：
package com.example.demo.service.impl;
import com.example.demo.pojo.User;
import com.example.demo.service.JdbcTemplateService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Service;
import java.sql.ResultSet;
@Service
@Slf4j
public class JdbcTemplateServiceImpl implements JdbcTemplateService {
@Autowired
private JdbcTemplate jdbcTemplate;
// 获取映射关系
private RowMapper getUserMapper() {
RowMapper userRowMapper = (ResultSet rs, int rownum) -> {
User user = new User();
user.setId(rs.getString("id"));
user.setName(rs.getString("name"));
user.setAge(rs.getInt("age"));
return user;
};
return userRowMapper;
}
@Override
public User search(String id) {
String sql = " select * from user where id = ?";
User user = jdbcTemplate.queryForObject(sql, getUserMapper(), id);
log.info("查询到数据" + user.toString());
return user;
}
@Override
public int insert(User user) {
String sql = " insert into user values( ?, ?, ?)";
int i = jdbcTemplate.update(sql, user.getName(), user.getId(), user.getAge());
return i;
}
@Override
public int update(User user) {
String sql = " update user set name = ?, age = ? where id = ?";
return jdbcTemplate.update(sql, user.getName(), user.getAge(), user.getId());
}
@Override
public int delete(String id) {
String sql = " delete from user where id = ?";
return jdbcTemplate.update(sql, id);
}
}
启动服务器，浏览器访问http://localhost:8080/jdbc/insert?id=111&name=R&age=1，得到：
新增了1条数据3. 视图和视图解析器、处理方法的数据绑定
视图解析器通过路径定位到视图，视图将数据模型进行渲染亿响应用户的请求。
数据绑定方法声明的参数可以与请求参数中名称相同的属性进行绑定
@RequestMapping("/insert")
@ResponseBody
// 方法参数中的id，name，age可以与请求参数中的id，name，age绑定
// http://localhost:8080/jdbc/insert?id=111&name=R&age=1
public String insert(String id, String name, int age) {
User user = new User(name, id, age);
int i = jdbcService.insert(user);
String msg = "新增了" + i + "条数据";
return msg;
}
绑定数组：
@RequestMapping("/list")
public String printUser(Long[] ids) {
return "ok";
}
// http://localhost:8080/user/list?ids=111,222,333
4. JSON处理
对于较复杂的数据，可以通过将数据封装成数据类进行json传递
使用@RequestBody注解可以接受从前端接收的json数据，json会根据字符串中的key来匹配对应实体类的属性。
@RequestMapping("/print")
public String (@RequestBody User user) {
System.out.println(user);
return "ok";
}
5. 拦截器学习
自定义拦截器：
package com.example.demo.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("拦截器前方法......");
// 返回true，不会拦截后续处理
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("拦截器后方法......");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("拦截器完成方法......");
}
}
拦截器控制方法：
package com.example.demo.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@RequestMapping("/interceptor")
public class InterceptorController {
@RequestMapping("/start")
@ResponseBody
public String start() {
System.out.println("执行拦截器");
return "Over";
}
}
注册拦截器：
package com.example.demo;
import com.example.demo.interceptor.MyInterceptor;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.format.FormatterRegistry;
import org.springframework.web.servlet.config.annotation.InterceptorRegistration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@SpringBootApplication
public class DemoApplication implements WebMvcConfigurer {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
// 注册拦截器
@Override
public void addInterceptors(InterceptorRegistry registry) {
InterceptorRegistration interceptor = registry.addInterceptor(new MyInterceptor());
interceptor.addPathPatterns("/interceptor/*");
}
}
启动服务器，访问http://localhost:8080/interceptor/start，控制台得到
拦截器前方法...... 执行拦截器 拦截器后方法...... 拦截器完成方法......
