自定义校验器

Author: seaswalker

note/spring-mvc.md

@@ -1389,7 +1389,49 @@ private static final boolean javaxValidationPresent =
     ClassUtils.isPresent("javax.validation.Validator", AnnotationDrivenBeanDefinitionParser.class.getClassLoader());
 ```
 
-OptionalValidatorFactoryBean实现了InitializingBean接口，所以afterPropertiesSet方法是其初始化的入口，具体的校验过程不再展开。
+ 实现了InitializingBean接口，所以afterPropertiesSet方法是其初始化的入口，具体的校验过程不再展开。
+ 除此之外还有一个有意思的问题，就是上面提到的校验器是如何进入到DataBinder中去的呢?答案是WebDataBinderFactory创建DataBinder对象时会利用WebBindingInitializer对DataBinder进行初始化，正是在这里
+ 将容器中存在的校验器设置到DataBinder中，至于WebBindingInitializer又是从哪里来的，不再探究了，否则这细节实在是太麻烦了，意义不大。
 
 #### 自定义校验器
 
+我们可以实现Spring提供的Validator接口，然后在Controller里边这样设置我们要是用的校验器:
+
+```java
+@InitBinder
+public void initBinder(DataBinder dataBinder) {
+    dataBinder.setValidator(new SimpleModelValidator());
+    //如果有多个可以使用setValidators方法
+}
+```
+
+我们的Controller方法依然可以如此定义:
+
+```java
+@RequestMapping("/echoAgain")
+public String echo(@Validated SimpleModel simpleModel, Model model) {
+    return "echo";
+}
+```
+
+如果有错误，会直接返回400.
+
+#### 一个有意思的问题
+
+如果我们把Controller方法这样定义会怎样?
+
+```java
+@RequestMapping(value = "/echoAgain", method = RequestMethod.POST)
+public String echo(@Validated @RequestBody SimpleModel simpleModel, Model model) {}
+```
+
+答案是@RequestBody注解根本就没有起作用?why?
+
+RequestMappingHandlerAdapter.getDefaultArgumentResolvers相关源码:
+
+```java
+resolvers.add(new ServletModelAttributeMethodProcessor(false));
+resolvers.add(new RequestResponseBodyMethodProcessor(getMessageConverters(), this.requestResponseBodyAdvice));
+```
+
+仅仅就是因为ServletModelAttributeMethodProcessor的声明比RequestResponseBodyMethodProcessor早了一行!

pom.xml

@@ -94,11 +94,11 @@
             <version>3.2.5</version>
         </dependency>
 
-        <dependency>
+        <!--<dependency>
             <groupId>org.hibernate.validator</groupId>
             <artifactId>hibernate-validator</artifactId>
             <version>6.0.2.Final</version>
-        </dependency>
+        </dependency>-->
 
     </dependencies>
 

src/main/java/controller/SimpleController.java

@@ -3,8 +3,13 @@
 import model.SimpleModel;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
+import org.springframework.validation.DataBinder;
 import org.springframework.validation.annotation.Validated;
+import org.springframework.web.bind.annotation.InitBinder;
+import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import validator.SimpleModelValidator;
 
 /**
  * 简单的Spring {@link org.springframework.stereotype.Controller}.
@@ -14,14 +19,20 @@
 @Controller
 public class SimpleController {
 
+    @InitBinder
+    public void initBinder(DataBinder dataBinder) {
+        //dataBinder.setValidator(new SimpleModelValidator());
+        dataBinder.addValidators(new SimpleModelValidator());
+    }
+
     @RequestMapping("/echo")
     public String echo(String name, Model model) {
         model.addAttribute("echo", "hello " + name);
         return "echo";
     }
 
-    @RequestMapping("/echoAgain")
-    public String echo(@Validated SimpleModel simpleModel, Model model) {
+    @RequestMapping(value = "/echoAgain", method = RequestMethod.POST)
+    public String echo(@Validated @RequestBody SimpleModel simpleModel, Model model) {
         model.addAttribute("echo", "hello " + simpleModel.getName() + ", your age is " + simpleModel.getAge() + ".");
         System.out.println(model.asMap().get("simpleModel"));
         return "echo";

src/main/java/model/SimpleModel.java

@@ -1,15 +1,12 @@
 package model;
 
-import javax.validation.constraints.NotBlank;
-
 /**
  * 简单的model.
  *
  * @author skywalker
  */
 public class SimpleModel {
 
-    @NotBlank
     private String name;
     private Integer age;
 

src/main/java/validator/SimpleModelValidator.java

@@ -1,7 +1,28 @@
 package validator;
 
+import model.SimpleModel;
+import org.springframework.validation.Errors;
+import org.springframework.validation.Validator;
+
 /**
+ * 自定义Spring校验器.
+ *
  * @author skywalker
  */
-public class SimpleModelValidator {
+public class SimpleModelValidator implements Validator {
+
+    @Override
+    public boolean supports(Class<?> clazz) {
+        return (clazz == SimpleModel.class);
+    }
+
+    @Override
+    public void validate(Object target, Errors errors) {
+        SimpleModel simpleModel = (SimpleModel) target;
+        Integer age = simpleModel.getAge();
+        if (age == null || age < 1 || age > 200) {
+            errors.reject("100", "年龄不合法");
+        }
+    }
+
 }