Spring常用注解介绍【经典总结】

Spring常用注解介绍【经典总结】

Spring的一个核心功能是IOC，就是将Bean初始化加载到容器中，Bean是如何加载到容器的，可以使用Spring注解方式或者Spring XML配置方式。
Spring注解方式减少了配置文件内容，更加便于管理，并且使用注解可以大大提高了开发效率！

下面讲解Spring中常用的一些注解。

注解类介绍

@Component ：标准一个普通的spring Bean类。
@Repository：标注一个DAO组件类。
@Service：标注一个业务逻辑组件类。
@Controller：标注一个控制器组件类。

这些都是注解在平时的开发过程中出镜率极高，@Component、@Repository、@Service、@Controller实质上属于同一类注解，用法相同，功能相同，区别在于标识组件的类型。@Component可以代替@Repository、@Service、@Controller，因为这三个注解是被@Component标注的。如下代码

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Controller {
    String value() default "";
}

（1）当一个组件代表数据访问层（DAO）的时候，我们使用@Repository进行注解，如下

@Repository
public class HappyDaoImpl implements HappyDao{
private final static Logger LOGGER = LoggerFactory.getLogger(HappyDaoImpl .class);
public void  club(){
        //do something ,like drinking and singing
    }
}

（2）当一个组件代表业务层时，我们使用@Service进行注解，如下

项目实际应用：

@Service
@Transactional(readOnly = true)
public class ChartChineseOceanService extends CrudService<ChartChineseOceanDao, ChartChineseOcean> {

    public ChartChineseOcean get(String id) {
        return super.get(id);
    }
    
    public List<ChartChineseOcean> findList(ChartChineseOcean chartChineseOcean) {
        return super.findList(chartChineseOcean);
    }
    
    public Page<ChartChineseOcean> findPage(Page<ChartChineseOcean> page, ChartChineseOcean chartChineseOcean) {
        return super.findPage(page, chartChineseOcean);
    }
    
    @Transactional(readOnly = false)
    public void save(ChartChineseOcean chartChineseOcean) {
        super.save(chartChineseOcean);
    }
    
    @Transactional(readOnly = false)
    public void delete(ChartChineseOcean chartChineseOcean) {
        super.delete(chartChineseOcean);
    }
    
}

（3）当一个组件作为前端交互的控制层，使用@Controller进行注解，如下

@Controller
public class HappyController {
    @Autowired //下面进行讲解
    private ClubService clubService;

    // Control the people entering the Club
    // do something
}
/*Controller相关的注解下面进行详细讲解，这里简单引入@Controller*/

实际应用：

/**
 * Copyright &copy; 2012-2016 <a href="https://github.com/thinkgem/jeesite">JeeSite</a> All rights reserved.
 */
package com.thinkgem.jeesite.modules.tpydg.chart.web;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.shiro.authz.annotation.RequiresPermissions;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

import com.thinkgem.jeesite.common.config.Global;
import com.thinkgem.jeesite.common.persistence.Page;
import com.thinkgem.jeesite.common.web.BaseController;
import com.thinkgem.jeesite.common.utils.StringUtils;
import com.thinkgem.jeesite.modules.tpydg.chart.entity.ChartSchoolEnrolment;
import com.thinkgem.jeesite.modules.tpydg.chart.service.ChartSchoolEnrolmentService;

import java.util.List;

/**
 * 岛国入学率Controller
 * @author zkx
 * @version 2018-05-15
 */
@Controller
@RequestMapping(value = "${adminPath}/chart/chartSchoolEnrolment")
public class ChartSchoolEnrolmentController extends BaseController {

    @Autowired
    private ChartSchoolEnrolmentService chartSchoolEnrolmentService;
    
    @ModelAttribute
    public ChartSchoolEnrolment get(@RequestParam(required=false) String id) {
        ChartSchoolEnrolment entity = null;
        if (StringUtils.isNotBlank(id)){
            entity = chartSchoolEnrolmentService.get(id);
        }
        if (entity == null){
            entity = new ChartSchoolEnrolment();
        }
        return entity;
    }
    
    @RequiresPermissions("chart:chartSchoolEnrolment:view")
    @RequestMapping(value = {"list", ""})
    public String list(ChartSchoolEnrolment chartSchoolEnrolment, HttpServletRequest request, HttpServletResponse response, Model model) {
        Page<ChartSchoolEnrolment> enrolmentPage = new Page<ChartSchoolEnrolment>(request, response);
        enrolmentPage.setOrderBy("year DESC");
        Page<ChartSchoolEnrolment> page = chartSchoolEnrolmentService.findPage(enrolmentPage, chartSchoolEnrolment);
        model.addAttribute("page", page);
        return "tpydg/chart/chartSchoolEnrolmentList";
    }

    @RequiresPermissions("chart:chartSchoolEnrolment:view")
    @RequestMapping(value = "form")
    public String form(ChartSchoolEnrolment chartSchoolEnrolment, Model model) {
        model.addAttribute("chartSchoolEnrolment", chartSchoolEnrolment);
        return "tpydg/chart/chartSchoolEnrolmentForm";
    }

    @RequiresPermissions("chart:chartSchoolEnrolment:edit")
    @RequestMapping(value = "save")
    public String save(ChartSchoolEnrolment chartSchoolEnrolment, Model model, RedirectAttributes redirectAttributes) {
        if (!beanValidator(model, chartSchoolEnrolment)){
            return form(chartSchoolEnrolment, model);
        }
        ChartSchoolEnrolment schoolEnrolment = new ChartSchoolEnrolment();
        schoolEnrolment.setYear(chartSchoolEnrolment.getYear());
        List<ChartSchoolEnrolment> list = chartSchoolEnrolmentService.findList(schoolEnrolment);
        if(StringUtils.isBlank(chartSchoolEnrolment.getId())&&! list.isEmpty()){
            addMessage(redirectAttributes, "添加失败，"+chartSchoolEnrolment.getYear()+"年数据已经存在！");
        } else{
            chartSchoolEnrolmentService.save(chartSchoolEnrolment);
            addMessage(redirectAttributes, "添加成功");
        }
        return "redirect:"+Global.getAdminPath()+"/chart/chartSchoolEnrolment/?repage";
    }
    
    @RequiresPermissions("chart:chartSchoolEnrolment:edit")
    @RequestMapping(value = "delete")
    public String delete(ChartSchoolEnrolment chartSchoolEnrolment, RedirectAttributes redirectAttributes) {
        chartSchoolEnrolmentService.delete(chartSchoolEnrolment);
        addMessage(redirectAttributes, "删除岛国入学率成功");
        return "redirect:"+Global.getAdminPath()+"/chart/chartSchoolEnrolment/?repage";
    }

}

4.@Autowired   @Autowired：属于Spring 的org.springframework.beans.factory.annotation包下,可用于为类的属性、构造器、方法进行注值

实际应用：

　　 @Autowired
    private ChartPopulationGrowthService chartPopulationGrowthService;
    @Autowired
    private ChartSchoolEnrolmentService chartSchoolEnrolmentService;
    @Autowired
    private ChartExportRateService chartExportRateService;
    @Autowired
    private ChartForeignInvestmentService chartForeignInvestmentService;
    @Autowired
    private  ChartGdpCompositionService chartGdpCompositionService;
    @Autowired
    private ChartGdpGrowthRateService chartGdpGrowthRateService;
    @Autowired
    private ChartGdpPurchaseDiscountService chartGdpPurchaseDiscountService;

5.@RequestMapping ： 这个注解用于将url映射到整个处理类或者特定的处理请求的方法。可以只用通配符！

@RequestMapping 既可以作用在类级别，也可以作用在方法级别。当它定义在类级别时，标明该控制器处理所有的请求都被映射到 /favsoft 路径下。@RequestMapping中可以使用 method 属性标记其所接受的方法类型，如果不指定方法类型的话，可以使用 HTTP GET/POST 方法请求数据，但是一旦指定方法类型，就只能使用该类型获取数据。

实际应用：

@RequestMapping(value = {"list", ""})
    public String list(ChartPopulationGrowth chartPopulationGrowth, HttpServletRequest request, HttpServletResponse response, Model model) {
        Page<ChartPopulationGrowth> growthPage = new Page<ChartPopulationGrowth>(request, response);
        growthPage.setOrderBy("year DESC");
        Page<ChartPopulationGrowth> page = chartPopulationGrowthService.findPage(growthPage, chartPopulationGrowth);
        model.addAttribute("page", page);
        return "tpydg/chart/chartPopulationGrowthList";
    }

    @RequiresPermissions("chart:chartPopulationGrowth:view")
    @RequestMapping(value = "form")
    public String form(ChartPopulationGrowth chartPopulationGrowth, Model model) {
        model.addAttribute("chartPopulationGrowth", chartPopulationGrowth);
        return "tpydg/chart/chartPopulationGrowthForm";
    }

    @RequiresPermissions("chart:chartPopulationGrowth:edit")
    @RequestMapping(value = "save")
    public String save(ChartPopulationGrowth chartPopulationGrowth, Model model, RedirectAttributes redirectAttributes) {
        if (!beanValidator(model, chartPopulationGrowth)){
            return form(chartPopulationGrowth, model);
        }

        ChartPopulationGrowth search = new ChartPopulationGrowth();
        search.setYear(chartPopulationGrowth.getYear());
        List<ChartPopulationGrowth> list = chartPopulationGrowthService.findList(search);
        if(StringUtils.isBlank(chartPopulationGrowth.getId())&&!list.isEmpty()){
            addMessage(redirectAttributes,"添加失败，"+chartPopulationGrowth.getYear()+"年数据已经存在！");
        }else{
            chartPopulationGrowthService.save(chartPopulationGrowth);
            addMessage(redirectAttributes, "添加成功");
        }
        return "redirect:"+Global.getAdminPath()+"/chart/chartPopulationGrowth/?repage";
    }
    
    @RequiresPermissions("chart:chartPopulationGrowth:edit")
    @RequestMapping(value = "delete")
    public String delete(ChartPopulationGrowth chartPopulationGrowth, RedirectAttributes redirectAttributes) {
        chartPopulationGrowthService.delete(chartPopulationGrowth);
        addMessage(redirectAttributes, "删除岛国 人口增长成功");
        return "redirect:"+Global.getAdminPath()+"/chart/chartPopulationGrowth/?repage";
    }

    @RequiresPermissions("chart:chartPopulationGrowth:edit")
    @RequestMapping(value = "import")

6.@RequestParam ：将请求的参数绑定到方法中的参数上，有required参数，默认情况下，required=true，也就是改参数必须要传。如果改参数可以传可不传，可以配置required=false。

 @RequestMapping("/happy")
  public String sayHappy(
  @RequestParam(value = "name", required = false) String name,
  @RequestParam(value = "age", required = true) String age) {
  //age参数必须传 ，name可传可不传
  ...
  }

以上就是开发中用的最多的注解啦 

参照博客：

https://blog.csdn.net/u010648555/article/details/76299467