controller level

method-level

package spittr.web;
import static org.springframework.web.bind.annotation.RequestMethod.*;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller 
public class HomeController {
  @RequestMapping(value="/", method=GET)
  public String home() {
    return "home"; 
  }
}

class-level

@Controller
@RequestMapping("/")  //@RequestMapping({"/", "/homepage"})
public class HomeController {
  @RequestMapping(method=GET)
  public String home() {
    return "home";
    } 
}

passing model data to the view

• 数据流： controller --> view resolver --> view
• 数据的类型： Model，本质上是一个map
• controller函数中始终返回的是view 名称，Model 数据的传递由框架来实现
• 在前端的jsp中，可以通过key来访问数据

传递模型数据的几种形式

返回view name， 数据保存在model中

• 返回的view名称"spittles", 传递的数据保存在Model（map）中
• Model 不明确指定key，默认自动推导可以为"spittleList"(List<Spittle> 推导而来)

@Controller
@RequestMapping("/spittles")
public class SpittleController {
    private SpittleRepository spittleRepository;
    @Autowired
    public SpittleController(
    SpittleRepository spittleRepository) {
        this.spittleRepository = spittleRepository;
    }
    @RequestMapping(method=RequestMethod.GET)
    public String spittles(Model model) {
      model.addAttribute(spittleRepository.findSpittles(Long.MAX_VALUE, 20));//model.addAttribute("spittleList", spittleRepository.findSpittles(Long.MAX_VALUE, 20));
      return "spittles";
    } 
}

返回view name, 数据使用java.util.Map保存

@RequestMapping(method=RequestMethod.GET)
public String spittles(Map model) {
  model.put("spittleList",
          spittleRepository.findSpittles(Long.MAX_VALUE, 20));
  return "spittles";
}

返回数据，view name让框架自动推导（最好别这么做）

@RequestMapping(method=RequestMethod.GET)
public List<Spittle> spittles() {
  return spittleRepository.findSpittles(Long.MAX_VALUE, 20));
}

• 返回的数据会保存到Model中，Model key也是自动推导
• view name 根据request path推到而来， 比例：http://xxx/spittles, view name就是spittles

request input

获取参数

@RequestMapping(method=RequestMethod.GET)
public List<Spittle> spittles(
  @RequestParam(value="max", defaultValue=MAX_LONG_AS_STRING) long max,
  @RequestParam(value="count", defaultValue="20") int count) {
  return spittleRepository.findSpittles(max, count);
}

resource-orientation 资源化的url

  @RequestMapping(value="/{spittleId}", method=RequestMethod.GET)
  public String spittle(
      @PathVariable("spittleId") long spittleId, 
      Model model) {
    model.addAttribute(spittleRepository.findOne(spittleId));
    return "spittle";
  }

• @PathVariable 可以省略参数，默认和函数的参数相同， 即spittleId (long spittleId)

processing forms

form controller

@RequestMapping(value="/register", method=POST)
public String processRegistration(Spitter spitter) {
    spitterRepository.save(spitter);
    return "redirect:/spitter/" +
           spitter.getUsername();
}

validating forms

import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

public class SpittleForm {

  @NotNull
  @Size(min=1, max=140)
  private String message;
  
  @Min(-180)
  @Max(180)
  private Double longitude;
  
  @Min(-90)
  @Max(90)
  private Double latitude;
  .....
}

• controller 对应的处理函数中必须增加一个org.springframework.validation.Errors 参数

  @RequestMapping(value="/register", method=POST)
  public String processRegistration(
      @Valid Spitter spitter, 
      Errors errors) {
    if (errors.hasErrors()) {
      return "registerForm";
    }
    
    spitterRepository.save(spitter);
    return "redirect:/spitter/" + spitter.getUsername();
  }