#J: Java Spring - 搭建Spring MVC (2)

Accept request parameter

Spring MVC允許多種方式將client的data傳到controller method中

Query parameter
Form parameter
Path variable

處理Query parameter

翻頁功能，讓使用者可以選擇要看哪一頁
假設要查看某一頁的Spittle列表，則這個list會按照最新的Spittle在前進行排序，因此下一頁的第一筆ID早於前一頁的最後一筆ID
為了顯示下一頁的Spittle，需要將一個Spittle的ID傳入
也可以傳入一個parameter確定要展現的Spittle counts
需要寫的controller method要處理以下參數

before parameter
count parameter

將spittles() method替換為使用上述兩個parameter的新spittles() method

先寫測試：

  @Test
  public void shouldShowPagedSpittles() throws Exception {
    List<Spittle> expectedSpittles = createSpittleList(50);
    SpittleRepository mockRepository = mock(SpittleRepository.class);
    when(mockRepository.findSpittles(238900, 50)) // expected的max及count parameter
        .thenReturn(expectedSpittles);
    
    SpittleController controller = new SpittleController(mockRepository);
    MockMvc mockMvc = standaloneSetup(controller)
        .setSingleView(new InternalResourceView("/WEB-INF/views/spittles.jsp"))
        .build();

    mockMvc.perform(get("/spittles?max=238900&count=50")) // 傳入的參數
      .andExpect(view().name("spittles"))
      .andExpect(model().attributeExists("spittleList"))
      .andExpect(model().attribute("spittleList", 
                 hasItems(expectedSpittles.toArray())));
  }

這個測試傳入parameters
測試了這個parameter存在時的controller method

新的spittles controller (同時處理有參數及沒有參數時的情境)

  @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);
  }

從path parameter中取得input

最簡單的方法就是在controller method中加上@RequestParam("spittle_id")

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

這個method可以處理類似/spittles/show?spittle_id=12345的request
從resource-orientation 角度來看，這個方法不好。/spittles/12345比/spittles/show?spittle_id=12345來得好

/spittles/12345: 能夠識別要查詢的resource
/spittles/show?spittle_id=12345: 只是一個有parameter的操作

以下是一個測試:

@Test
    public void testSpittle() throws Exception {
        Spittle expectedSpittle = new Spittle("Hello", new Date()); //expected
        SpittleRepository mockRepository = mock(SpittleRepository.class);
        when(mockRepository.findOne(12345)).thenReturn(expectedSpittle);

        SpittleController controller = new SpittleController(mockRepository);
        MockMvc mockMvc = standaloneSetup(controller).build();

        mockMvc.perform(get("/spittles/12345")).andExpect(view().name("spittle")) // 透過路徑取得資源
                        .andExpect(model().attributeExists("spittle"))
                        .andExpect(model().attribute("spittle", expectedSpittle));
    }

如果要處理例如spittle_id=12345的request，可以使用placeholder。

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

使用@PathVariable表示不管placeholder的值是什麼，都會傳到spittleId的parameter中
若@RequestMapping內的value name與@PathVariable相同(這邊都是spittleId)，則@PathVariable內名稱可以省略

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

也就是如果@PathVariable裡面沒有值，會假設與placeholder parameter name相同
傳到model的key是spittle
如此，就能加上jsp 取得內容及時間

<div class="spittleView">
  <div class="spittleMessage"><c:out value="${spittle.message}" /></div>
  <div>
    <span class="spittleTime"><c:out value="${spittle.time}" /></span>
  </div>
</div>

如果傳送的data是少量得，則Query parameters and path parameters是合理的。但通常都會傳送大量data，那麼使用Query parameters就不是個好選擇

Processing forms

新建一個SpitterController來接受request展現registerForm

@Controller
@RequestMapping("/spitter")
public class SpitterController {
    @RequestMapping(value = "/register", method = GET)
    public String showRegistrationForm() {
        return "registerForm";
    }
}

兩個@RequestMapping要組合起來，所以變成處理/spitter/register的request
測試，確認view name是對的

@Test
public void shouldShowRegistration() throws Exception {
  SpitterController controller = new SpitterController();
  MockMvc mockMvc = standaloneSetup(controller).build();
  mockMvc.perform(get("/spitter/register"))
         .andExpect(view().name("registerForm"));
}

JSP:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ page session="false"%>
<html>
<head>
<title>Spittr</title>
<link rel="stylesheet" type="text/css"
  href="<c:url value="/resources/style.css" />">
</head>
<body>
  <h1>Register</h1>
  <form method="POST">
    First Name: <input type="text" name="firstName" /><br /> Last Name:
    <input type="text" name="lastName" /><br /> Username: <input
      type="text" name="username" /><br /> Password: <input
      type="password" name="password" /><br /> <input type="submit"
      value="Register" />
  </form>
</body>
</html>

Form內沒有action，因此會當表單提交時，會直接提交到與當時的URL相同的path上

form-handling controller

當form submit發出post request後，controller需要接受form data且將之保存為Spitter object。且為了避免重複提交，browser 應該要重新到嚮導新的頁面
controller

  @RequestMapping(method=RequestMethod.POST)
  public String saveSpittle(SpittleForm form, Model model) throws Exception {
    spittleRepository.save(new Spittle(null, form.getMessage(), new Date(), 
        form.getLongitude(), form.getLatitude()));
    return "redirect:/spittles";
  }

測試：

@Test
    public void shouldProcessRegistration() throws Exception {
        SpitterRepository mockRepository = mock(SpitterRepository.class);
        Spitter unsaved = new Spitter("jbauer", "24hours", "Jack", "Bauer", "jbauer@ctu.gov");
        Spitter saved = new Spitter(24L, "jbauer", "24hours", "Jack", "Bauer", "jbauer@ctu.gov"); // return ID
        when(mockRepository.save(unsaved)).thenReturn(saved);

        SpitterController controller = new SpitterController(mockRepository);
        MockMvc mockMvc = standaloneSetup(controller).build();

        mockMvc.perform(post("/spitter/register").param("firstName", "Jack").param("lastName", "Bauer")
 .param("username", "jbauer").param("password", "24hours").param("email", "jbauer@ctu.gov"))
                        .andExpect(redirectedUrl("/spitter/jbauer"));

        verify(mockRepository, atLeastOnce()).save(unsaved); // 確認save狀況
    }

建立提交表單後的controller

package spittr.web;

import static org.springframework.web.bind.annotation.RequestMethod.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import spittr.Spitter;
import spittr.data.SpitterRepository;

@Controller
@RequestMapping("/spitter")
public class SpitterController {
    private SpitterRepository spitterRepository;

    @Autowired
    public SpitterController(SpitterRepository spitterRepository) {
        this.spitterRepository = spitterRepository;
    }

    @RequestMapping(value = "/register", method = GET)
    public String showRegistrationForm() {
        return "registerForm";
    }

    @RequestMapping(value = "/register", method = POST)
    public String processRegistration(Spitter spitter) { // 接受一個spitter當作parameter
        spitterRepository.save(spitter); // spitterRepository是被injects的parameter
        return "redirect:/spitter/" + spitter.getUsername();
    }
}

當看到redirect: 前綴時，就知道要重新定向。假如spitter.getUsername()是miii，則會傳送到/spitter/miii
還可以使用forward前綴，當發現是forward，就會前往指定的URL path
接著就新增method到controller，針對後綴有username的做處理

    @RequestMapping(value = "/{username}", method = GET)
    public String showSpitterProfile(@PathVariable String username, Model model) {
        Spitter spitter = spitterRepository.findByUsername(username);
        model.addAttribute(spitter);
        return "profile";
    }

profile view:

<h1>Your Profile</h1>
<c:out value="${spitter.username}" /><br/>
<c:out value="${spitter.firstName}" />
<c:out value="${spitter.lastName}" />

問題：應該要為表單提交進行validation，以避免值為空或太長

Validating forms

要處理username/password是空的情況，否則會出現安全問題，不管是誰只要提交空表單就能register
方法可以是保持value在合理的長度範圍內，避免這些input field的誤用
可以是把邏輯放在controller程式碼內。但，與其讓校驗邏輯弄亂controller method，不如使用Spring對Java validation API(JSP-303)。

從Spring3.0開始，在Spring只要使用Java validation API，不需要額為配置，只要保證在class path下有這個Java API，比如Hibernate Validator
只要將annotation放到property上，從而限制這些property的值
annotation都在javax.validation.constrains package中

Java提供validation annotation

@AssertFalse
@AssertTrue
@DecimalMax: 值要<=給定的BigDecimalString
@DecimalMin: 值要>=給定的BigDecimalString
@Digits: 有指定的位數
@Future: 需要是將來的日期
@Max: 值要<=給定的值
@Min: 值要>=給定的值
@NotNull
@Null
@Past: 需要是過去的日期
@Pattern: 直要是給訂的正規表示法
@Size: 值必須是String, collection或data，且給定的長度要符合給定的範圍

範例：

package spittr;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;
Annotation
Description
 
public class Spitter {
  private Long id;
  @NotNull
  @Size(min=5, max=16) // 不能是空的，且5-16個字
  private String username;
  @NotNull
  @Size(min=5, max=25) // 不能是空的，且5-25個字
  private String password;
  @NotNull
  @Size(min=2, max=30) // 不能是空的，且2-30個字
  private String firstName;
  @NotNull
  @Size(min=2, max=30) // 不能是空的，且2-30個字
  private String lastName;
... }

開啟validate，修改controller的method processRegistration

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

重要：Errors parameter要緊跟著帶有@Valid annotation的parameter後面

#J

2017年12月25日星期一

Java Spring - 搭建Spring MVC (2)

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張貼留言

2017年12月25日 星期一

Java Spring - 搭建Spring MVC (2)

沒有留言:

張貼留言

2017年12月25日星期一