Implementing Controllers

spring配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="org.springframework.samples.petclinic.web"/>

    <!-- ... -->

</beans>

@Controller
public class HelloWorldController {

    @RequestMapping("/helloWorld")
    public String helloWorld(Model model) {
        model.addAttribute("message", "Hello World!");
        return "helloWorld";
    }
}

@Controller
@RequestMapping("/appointments")
public class AppointmentsController {

    private final AppointmentBook appointmentBook;

    @Autowired
    public AppointmentsController(AppointmentBook appointmentBook) {
        this.appointmentBook = appointmentBook;
    }

    @RequestMapping(method = RequestMethod.GET)
    public Map<String, Appointment> get() {
        return appointmentBook.getAppointmentsForToday();
    }

    @RequestMapping(path = "/{day}", method = RequestMethod.GET)
    public Map<String, Appointment> getForDay(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date day, Model model) {
        return appointmentBook.getAppointmentsForDay(day);
    }

    @RequestMapping(path = "/new", method = RequestMethod.GET)
    public AppointmentForm getNewForm() {
        return new AppointmentForm();
    }

    @RequestMapping(method = RequestMethod.POST)
    public String add(@Valid AppointmentForm appointment, BindingResult result) {
        if (result.hasErrors()) {
            return "appointments/new";
        }
        appointmentBook.addAppointment(appointment);
        return "redirect:/appointments";
    }

    @RequestMapping("/vets")
    public ModelMap vetsHandler() {
        return new ModelMap(this.clinic.getVets());
    }
}

Spring4.3开始支持

@GetMapping
@PostMapping
@PutMapping
@DeleteMapping
@PatchMapping
URI Template Patterns

@GetMapping("/owners/{ownerId}")
public String findOwner(@PathVariable String ownerId, Model model) {
    Owner owner = ownerService.findOwner(ownerId);
    model.addAttribute("owner", owner);
    return "displayOwner";
}

@GetMapping("/owners/{ownerId}/pets/{petId}")
public String findPet(@PathVariable String ownerId, @PathVariable String petId, Model model) {
    Owner owner = ownerService.findOwner(ownerId);
    Pet pet = owner.getPet(petId);
    model.addAttribute("pet", pet);
    return "displayPet";
}

//正则
@RequestMapping("/spring-web/{symbolicName:[a-z-]+}-{version:\\d\\.\\d\\.\\d}{extension:\\.[a-z]+}")
public void handle(@PathVariable String version, @PathVariable String extension) {
    // ...
}

Consumable Media Types

@PostMapping(path = "/pets", consumes = "application/json")
public void addPet(@RequestBody Pet pet, Model model) {
    // implementation omitted
}

Producible Media Types

@GetMapping(path = "/pets/{petId}", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
@ResponseBody
public Pet getPet(@PathVariable String petId, Model model) {
    // implementation omitted
}

Request Parameters and Header Values

@Controller
@RequestMapping("/owners/{ownerId}")
public class RelativePathUriTemplateController {

    @GetMapping(path = "/pets/{petId}", params = "myParam=myValue")
    public void findPet(@PathVariable String ownerId, @PathVariable String petId, Model model) {
        // implementation omitted
    }

    @GetMapping(path = "/pets", headers = "myHeader=myValue")
    public void findPet(@PathVariable String ownerId, @PathVariable String petId, Model model) {
        // implementation omitted
    }

@RequestMapping("/displayHeaderInfo.do")
public void displayHeaderInfo(@RequestHeader("Accept-Encoding") String encoding,
        @RequestHeader("Keep-Alive") long keepAlive) {
    //...
}
}

Matrix Variables

spring配置如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <mvc:annotation-driven enable-matrix-variables="true"/>

</beans>

// GET /pets/42;q=11;r=22

@GetMapping("/pets/{petId}")
public void findPet(@PathVariable String petId, @MatrixVariable int q) {

    // petId == 42
    // q == 11

}

// GET /owners/42;q=11/pets/21;q=22

@GetMapping("/owners/{ownerId}/pets/{petId}")
public void findPet(
        @MatrixVariable(name="q", pathVar="ownerId") int q1,
        @MatrixVariable(name="q", pathVar="petId") int q2) {

    // q1 == 11
    // q2 == 22

}

// GET /pets/42

@GetMapping("/pets/{petId}")
public void findPet(@MatrixVariable(required=false, defaultValue="1") int q) {

    // q == 1

}

// GET /owners/42;q=11;r=12/pets/21;q=22;s=23

@GetMapping("/owners/{ownerId}/pets/{petId}")
public void findPet(
        @MatrixVariable MultiValueMap<String, String> matrixVars,
        @MatrixVariable(pathVar="petId"") MultiValueMap<String, String> petMatrixVars) {

    // matrixVars: ["q" : [11,22], "r" : 12, "s" : 23]
    // petMatrixVars: ["q" : 11, "s" : 23]

}

BindingResult

使用demo：

public class User {
    @XStreamAlias("username")
    @Pattern(regexp = "\\w{4,30}")
    private String username;
    @XStreamAlias("passwd")
    @Pattern(regexp = "\\S{6,30}")
    private String password;
    @XStreamAsAttribute
    @XStreamAlias("addr")
    private String address;
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    @XStreamAlias("birthday")
    @Past
    private Date birthday;
    @NumberFormat(pattern = "##,###.##")
    @DecimalMax(value = "100000.00")
    @DecimalMin(value="1000.00")
    private long salary;

 @RequestMapping("validator")
    public String validate(@Valid @ModelAttribute("user") User user, BindingResult bindingResult) {
        if (bindingResult.hasErrors()) {
            System.out.println(bindingResult.getAllErrors());
            return "user/register";
        } else {
            return "user/success";
        }
    }

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<html>
<head>
  <title>失败</title>
</head>
<body>
  验证失败
  <form:form modelAttribute="user" action="/user/validator.html">
      <form:errors path="*"> </form:errors>
      <form:errors path="username" cssClass="errorClass"/>
      <form:input path="username"/>
  </form:form>
</body>
</html>

下面是错误的做法

@PostMapping public String processSubmit(@ModelAttribute("pet") Pet pet, Model model, BindingResult result) { ... }

下面是正确的，这个要放在pet后面

@PostMapping
public String processSubmit(@ModelAttribute("pet") Pet pet, BindingResult result, Model model) { ... }

@RequestParam

@Controller
@RequestMapping("/pets")
@SessionAttributes("pet")
public class EditPetForm {

    // ...

    @GetMapping
    public String setupForm(@RequestParam("petId") int petId, ModelMap model) {
        Pet pet = this.clinic.loadPet(petId);
        model.addAttribute("pet", pet);
        return "petForm";
    }

    // ...

}

@RequestBody

HTTP request body

ByteArrayHttpMessageConverter 转为字节数组从HTTP请求和响应读取和写入字节数组；读/，写Content-Type为 application/octet-stream
StringHttpMessageConverter 转为字符串读text/*，写Content-Type 为 text/plain
FormHttpMessageConverter 表单转为 MultiValueMap<String, String>. 读写application/x-www-form-urlencoded，转化为 MultiValueMap<String, String>
SourceHttpMessageConverter 转为 javax.xml.transform.Source. text/xml和 application/xml；只有DOMSource, SAXSource和StreamSource被支持
其他
MarshallingHttpMessageConverter text/xml和 application/xml
MappingJackson2HttpMessageConverter application/json ；ObjectMapper
MappingJackson2XmlHttpMessageConverter application/xml；XmlMapper
BufferedImageHttpMessageConverter java.awt.image.BufferedImage

@PutMapping("/something")
public void handle(@RequestBody String body, Writer writer) throws IOException {
    writer.write(body);
}

@ResponseBody

@GetMapping("/something")
@ResponseBody
public String helloWorld() {
    return "Hello World";
}

@ModelAttribute

@PostMapping("/owners/{ownerId}/pets/{petId}/edit")
public String processSubmit(@ModelAttribute Pet pet) { }

@PutMapping("/accounts/{account}")
public String save(@ModelAttribute("account") Account account) {
    // ...
}

@PostMapping("/owners/{ownerId}/pets/{petId}/edit")
public String processSubmit(@ModelAttribute("pet") Pet pet, BindingResult result) {

    if (result.hasErrors()) {
        return "petForm";
    }

    // ...

}

@PostMapping("update")
public String update(@Valid AccountUpdateForm form, BindingResult result,
        @ModelAttribute(binding=false) Account account) {

    // ...
}

REST Controllers

HttpEntity

@RequestMapping("/something")
public ResponseEntity<String> handle(HttpEntity<byte[]> requestEntity) throws UnsupportedEncodingException {
    String requestHeader = requestEntity.getHeaders().getFirst("MyRequestHeader"));
    byte[] requestBody = requestEntity.getBody();

    // do something with request header and body

    HttpHeaders responseHeaders = new HttpHeaders();
    responseHeaders.set("MyResponseHeader", "MyValue");
    return new ResponseEntity<String>("Hello World", responseHeaders, HttpStatus.CREATED);
}

Asynchronous Request Processing 异步的请求处理

Spring MVC 3.2引入了基于Servlet 3异步请求处理。像往常一样,返回一个值,而是一个控制器方法可以返回一个java . util . concurrent。可生产从Spring MVC托管线程的返回值。同时主Servlet容器线程退出和释放,允许处理其他请求。Spring MVC调用调用在一个单独的线程的帮助下TaskExecutor调用返回时,请求被分配回Servlet容器的简历处理使用由可调用的返回值。这里是这样的控制器方法的一个例子: web.xml要加上<async-supported>true</async-supported>

@PostMapping
public Callable<String> processUpload(final MultipartFile file) {

    return new Callable<String>() {
        public String call() throws Exception {
            // ...
            return "someView";
        }
    };

}

HTTP Streaming

控制器方法可以使用DeferredResult和Callable 生成它的返回值,可用于实现技术,如长轮询服务器可以推动事件尽快给客户端。如果你想把多个事件在一个HTTP响应?这是一个技术与“长轮询”,被称为“HTTP流”。Spring MVC使之成为可能通过ResponseBodyEmitter返回值类型可以用来发送多个对象,而不是一个通常是@ResponseBody一样,其中每个对象发送写入响应HttpMessageConverter。

@RequestMapping("/events")
public ResponseBodyEmitter handle() {
    ResponseBodyEmitter emitter = new ResponseBodyEmitter();
    // Save the emitter somewhere..
    return emitter;
}

// In some other thread
emitter.send("Hello once");

// and again later on
emitter.send("Hello again");

// and done at some point
emitter.complete();

HTTP Streaming With Server-Sent Events

SseEmitterResponseBodyEmitter的子类提供支持服务器发送的事件。服务器发送的事件只是一个变化在同一“HTTP流”技术除了格式化事件从服务器推出根据W3C规范服务器发送的事件。服务器发送的事件可以用于自己的目的,这是推动事件从服务器转移到客户机。很容易在Spring MVC和SseEmitter需要简单地返回一个值的类型。注意但是,ie浏览器不支持服务器发送的事件,为更先进的web应用程序消息传递场景如网络游戏、合作金融applicatinos,其他人最好考虑Spring的WebSocket支持,包括SockJS-style WebSocket模拟回落到一个非常广泛的浏览器(包括Internet Explorer)和更高级别的消息传递模式也与客户进行交互通过发布-订阅模型在一个更messaging-centric架构。为进一步在这看到下面的博客背景。

HTTP Streaming Directly To The OutputStream

ResponseBodyEmitter允许发送事件通过HttpMessageConverter通过编写对象的响应。这可能是最常见的情况下,例如当编写JSON数据。然而有时是有用的绕过消息转换和直接写响应OutputStream例如一个文件下载。这样做可以的帮助下StreamingResponseBody返回值类型。

@RequestMapping("/download")
public StreamingResponseBody handle() {
    return new StreamingResponseBody() {
        @Override
        public void writeTo(OutputStream outputStream) throws IOException {
            // write...
        }
    };
}

配置异步请求

web.xml

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            http://java.sun.com/xml/ns/javaee
            http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    version="3.0">

  <filter>
        <filter-name>Spring OpenEntityManagerInViewFilter</filter-name>
        <filter-class>org.springframework.~.OpenEntityManagerInViewFilter</filter-class>
        <async-supported>true</async-supported>
    </filter>

    <filter-mapping>
        <filter-name>Spring OpenEntityManagerInViewFilter</filter-name>
        <url-pattern>/*</url-pattern>
        <dispatcher>REQUEST</dispatcher>
        <dispatcher>ASYNC</dispatcher>
    </filter-mapping>

</web-app>

@initbinder

在BaseController里实现 @InitBinder

    public void initBinder(ServletRequestDataBinder binder) {
        /**
         * 自动转换日期类型的字段格式
         */
        binder.registerCustomEditor(Date.class, new CustomDateEditor(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"), true));

        /**
         * 防止XSS攻击
         */
        binder.registerCustomEditor(String.class, new StringEscapeEditor(true, false));
    }

public class StringEscapeEditor extends PropertyEditorSupport {

    private boolean escapeHTML;// 编码HTML
    private boolean escapeJavaScript;// 编码javascript

    public StringEscapeEditor() {
        super();
    }

    public StringEscapeEditor(boolean escapeHTML, boolean escapeJavaScript) {
        super();
        this.escapeHTML = escapeHTML;
        this.escapeJavaScript = escapeJavaScript;
    }

    @Override
    public String getAsText() {
        Object value = getValue();
        return value != null ? value.toString() : "";
    }

    @Override
    public void setAsText(String text) throws IllegalArgumentException {
        if (text == null) {
            setValue(null);
        } else {
            String value = text;
            if (escapeHTML) {
                value = HtmlUtils.htmlEscape(value);
            }
            if (escapeJavaScript) {
                value = JavaScriptUtils.javaScriptEscape(value);
            }
            setValue(value);
        }
    }

}

www1350 / javaweb

SpringMVC #60