springBoot常用注解

概述

  记录一些springBoot在web开发中常用的一些注解和介绍

@SpringBootApplication

springBootApplication自动给程序进行必要配置,等同于 @Configuration,@EnableAutoConfiguration和@ComponentScan 三个注解配置

package com.xmlxy.firstspringbootproject;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.PropertySource;

@SpringBootApplication
@PropertySource(value = "classpath:jdbc.properties",encoding = "utf-8")
public class FirstSpringbootProjectApplication {

    public static void main(String[] args) {
        SpringApplication.run(FirstSpringbootProjectApplication.class, args);
    }

}

@ResponseBody

这个注解表示返回结果直接写入HTTP response body中,异步获取json数据,一般配合@RequestMapping一起使用

package com.xmlxy.firstspringbootproject;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;


@Controller
public class TestController {

    @ResponseBody
    @RequestMapping(value = "/demo6",method = RequestMethod.GET)
    public String demo6()
    {
        return "demo";
    }
}

@Controller和@RequestMapping

定义控制类,负责将用户发来URL转发到对应的服务接口,通常配合@RequestMapping使用,@RequestMapping负责URL和Controller的具体还是映射

package com.xmlxy.firstspringbootproject;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;


@Controller
@RequestMapping(value = "/testDemo")
public class TestController {

    @ResponseBody
    @RequestMapping(value = "/demo6",method = RequestMethod.GET)
    public String demo6()
    {
        return "demo";
    }
}

@RestController

等同于@ResponseBody和@Controller的配置

package com.xmlxy.firstspringbootproject;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;


@Controller
@RequestMapping(value = "/testDemo")
public class TestController {

    @ResponseBody
    @RequestMapping(value = "/demo6",method = RequestMethod.GET)
    public String demo6()
    {
        return "demo";
    }
}

@ComponentScan

主要定义扫描路径从中找出需要标识了需要装配的类自动装配到spring的bean容器中,不管是@Controller还是@Service注解,都有一个共同的注解就是@Component,而@ComponentScan注解默认装配标识@Controller,@Service,@Component注解的类到容器中。

springBoot常用注解_第1张图片

@Autowired

自动导入依赖的bean

package com.xmlxy.firstspringbootproject;

import com.xmlxy.bean.TestData;
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.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping(value = "/testDemo")
public class TestController {

    @Autowired
    TestData testData;

    @ResponseBody
    @RequestMapping(value = "/demo6",method = RequestMethod.GET)
    public String demo6()
    {
        return "demo";
    }
}

 @Value

注入springboot配置的属性值

package com.xmlxy.firstspringbootproject;

import com.xmlxy.bean.TestData;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping(value = "/testDemo")
public class TestController {

    @Value("${date.value}")
    String value;

    @Autowired
    TestData testData;

    @ResponseBody
    @RequestMapping(value = "/demo6",method = RequestMethod.GET)
    public String demo6()
    {
        return "demo";
    }
}

@Service

对应的是业务层Bean,用于修饰service层的组件

public interface UserService
{
    void printf();
}
UserServiceImpl.java
package com.xmlxy.service;

import org.springframework.stereotype.Service;

@Service("userService")
public class UserServiceImpl implements UserService {
    @Override
    public void printf() {
        System.out.printf("2019-7-30 14:34");
    }
}

@Repository

数据访问层Bean,确保dao提供异常转译

package com.xmlxy.dao;

import com.xmlxy.bean.TestData;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
import org.springframework.stereotype.Repository;

import java.util.HashMap;
import java.util.Map;

@Repository(value = "testDao")
public class TestDaoImp implements TestDao
{
    @Autowired
    private NamedParameterJdbcTemplate jdbcTemplate;
    @Override
    public int add(TestData testData) {

        String sql = "INSERT t_hwc_db(name,age) VALUES(:name,:age)";
        Map param = new HashMap<>();
        System.out.printf("本次插入的值===>" + testData.getName() + ",年龄为==>" + testData.getAge());
        param.put("name",testData.getName());
        param.put("age",testData.getAge());
        return jdbcTemplate.update(sql,param);
    }
}
  @Resource(name = "testDao")
    private TestDao testDao;

@WebFilter

用于将一个类声明为拦截器

package com.xmlxy.firstspringbootproject;


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
@WebFilter(filterName = "customFilter",urlPatterns = "/*")
public class CustomFilter implements Filter {

    private static final Logger log = LoggerFactory.getLogger(CustomFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("fifter初始化");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("doFilter请求处理");
    }

    @Override
    public void destroy() {
        log.info("fifter销毁");
    }
}

 @ExceptionHandler 异常处理器,当出现其定义的异常时进行处理的方法

JPA注解

@Entity:@Table(name=”“):表明这是一个实体类。一般用于jpa这两个注解一般一块使用,但是如果表名和实体类名相同的话,@Table可以省略

@MappedSuperClass:用在确定是父类的entity上。父类的属性子类可以继承。

@NoRepositoryBean:一般用作父类的repository,有这个注解,spring不会去实例化该repository。

@Column:如果字段名与列名相同,则可以省略。

@Id:表示该属性为主键。

@GeneratedValue(strategy = GenerationType.SEQUENCE,generator = “repair_seq”):表示主键生成策略是sequence(可以为Auto、IDENTITY、native等,Auto表示可在多个数据库间切换),指定sequence的名字是repair_seq。

@SequenceGeneretor(name = “repair_seq”, sequenceName = “seq_repair”, allocationSize = 1):name为sequence的名称,以便使用,sequenceName为数据库的sequence名称,两个名称可以一致。

@Transient:表示该属性并非一个到数据库表的字段的映射,ORM框架将忽略该属性。如果一个属性并非数据库表的字段映射,就务必将其标示为@Transient,否则,ORM框架默认其注解为@Basic。@Basic(fetch=FetchType.LAZY):标记可以指定实体属性的加载方式

@JsonIgnore:作用是json序列化时将Java bean中的一些属性忽略掉,序列化和反序列化都受影响。

@JoinColumn(name=”loginId”):一对一:本表中指向另一个表的外键。一对多:另一个表指向本表的外键。

@OneToOne、@OneToMany、@ManyToOne:对应hibernate配置文件中的一对一,一对多,多对一。

 

你可能感兴趣的:(springBoot常用注解)