OpenRewrite：精确定位与修改特定方法参数的教程

type: specs.openrewrite.org/v1beta/recipe
name: org.example.MandatoryRequestParameter
displayName: Make Spring `RequestParam` mandatory
description: Add `required` attribute to `RequestParam` and set the value to `true`.
recipeList:
  - org.openrewrite.java.AddOrUpdateAnnotationAttribute:
      annotationType: org.springframework.web.bind.annotation.RequestParam
      attributeName: required
      attributeValue: "true"

<plugin>
  <groupId>org.openrewrite.maven</groupId>
  <artifactId>rewrite-maven-plugin</artifactId>
  <version>4.38.0</version> <!-- 使用最新版本 -->
  <configuration>
    <activeRecipes>
      <recipe>org.example.MandatoryRequestParameter</recipe>
    </activeRecipes>
  </configuration>
</plugin>

import org.openrewrite.ExecutionContext;
import org.openrewrite.Recipe;
import org.openrewrite.TreeVisitor;
import org.openrewrite.java.AddOrUpdateAnnotationAttribute;
import org.openrewrite.java.JavaIsoVisitor;
import org.openrewrite.java.JavaVisitor;
import org.openrewrite.java.UsesType;
import org.openrewrite.java.tree.J;
import org.openrewrite.java.tree.JavaType;
import org.openrewrite.java.tree.TypeUtils;
import org.openrewrite.internal.lang.Nullable;
import javax.validation.constraints.NotNull;

public class MandatoryRequestParameter extends Recipe {

    private static final String REQUEST_PARAM_FQ_NAME = "org.springframework.web.bind.annotation.RequestParam";
    private static final String NOT_NULL_FQ_NAME = "javax.validation.constraints.NotNull"; // 用于演示如何检查NotNull注解

    @Override
    public @NotNull String getDisplayName() {
        return "Make Spring `RequestParam` mandatory conditionally";
    }

    @Override
    public String getDescription() {
        return "Add `required` attribute to `RequestParam` and set the value to `true` based on specific conditions.";
    }

    /**
     * 优化：仅当源文件包含 `RequestParam` 注解时才运行此配方。
     */
    @Override
    protected @Nullable TreeVisitor<?, ExecutionContext> getSingleSourceApplicableTest() {
        return new UsesType<>(REQUEST_PARAM_FQ_NAME);
    }

    @Override
    protected @NotNull JavaVisitor<ExecutionContext> getVisitor() {

        // 创建一个用于添加或更新注解属性的内部访问器
        JavaIsoVisitor<ExecutionContext> addAttributeVisitor = new AddOrUpdateAnnotationAttribute(
                REQUEST_PARAM_FQ_NAME, "required", "true", false
        ).getVisitor();

        return new JavaIsoVisitor<ExecutionContext>() {
            @Override
            public J.Annotation visitAnnotation(J.Annotation annotation, ExecutionContext ctx) {
                J.Annotation a = super.visitAnnotation(annotation, ctx);

                // 1. 检查当前注解是否是 @RequestParam
                if (!TypeUtils.isOfClassType(a.getType(), REQUEST_PARAM_FQ_NAME)) {
                    return a;
                }

                // 2. 使用 Cursor 向上导航，获取父级 J.VariableDeclarations (即方法参数声明)
                // 解决原始问题中 IllegalStateException 的关键点：
                // AddOrUpdateAnnotationAttribute 需要正确的父级上下文。
                // 通过 getCursor().getParent().getValue() 确保我们是在正确地操作注解的父级。
                J.VariableDeclarations variableDeclaration = getCursor().getParent().getValue();

                // 3. 定义条件：
                // 示例条件一：参数类型是 java.lang.Number 或其子类型
                // 示例条件二：参数名称是 "fred"
                // 扩展条件：检查参数是否也带有 @NotNull 注解
                boolean shouldApply = false;
                JavaType paramType = variableDeclaration.getType();
                if (TypeUtils.isAssignableTo("java.lang.Number", paramType) ||
                    variableDeclaration.getVariables().get(0).getSimpleName().equals("fred")) {
                    shouldApply = true;
                }

                // 检查是否存在 @NotNull 注解 (根据原始问题需求扩展)
                // 遍历参数声明上的所有注解，查找 @NotNull
                boolean hasNotNullAnnotation = variableDeclaration.getLeadingAnnotations().stream()
                    .anyMatch(ann -> TypeUtils.isOfClassType(ann.getType(), NOT_NULL_FQ_NAME));

                if (hasNotNullAnnotation && TypeUtils.isOfClassType(a.getType(), REQUEST_PARAM_FQ_NAME)) {
                    // 如果同时有 @NotNull 和 @RequestParam，则应用修改
                    shouldApply = true;
                }

                // 4. 如果满足条件，则委托给内部的 addAttributeVisitor 进行修改
                if (shouldApply) {
                    // 将当前注解 'a' 和其正确的 Cursor 上下文传递给内部访问器
                    return (J.Annotation) addAttributeVisitor.visit(a, ctx, getCursor());
                }
                return a;
            }
        };
    }
}

import org.junit.jupiter.api.Test;
import org.openrewrite.java.JavaParser;
import org.openrewrite.test.RecipeSpec;
import org.openrewrite.test.RewriteTest;

import static org.openrewrite.java.Assertions.java;

class MandatoryRequestParameterTest implements RewriteTest {

    @Override
    public void defaults(RecipeSpec spec) {
        spec.recipe(new MandatoryRequestParameter())
            .parser(JavaParser.fromJavaVersion().classpath("spring-web", "validation-api")); // 确保classpath包含相关依赖
    }

    @Test
    void requiredRequestParam() {
        rewriteRun(
            java(
                """
                  import org.springframework.web.bind.annotation.RequestParam;
                  import javax.validation.constraints.NotNull;

                  class ControllerClass {
                    public String sayHello (
                      @NotNull @RequestParam(value = "name") String name, // 期望修改
                      @RequestParam(value = "lang") String lang, // 不期望修改 (无 @NotNull)
                      @NotNull @RequestParam(value = "aNumber") Long aNumber, // 期望修改 (有 @NotNull 且类型为 Number)
                      @NotNull @RequestParam(value = "fred") String fred // 期望修改 (有 @NotNull 且名称为 "fred")
                    ) {
                      return "Hello";
                    }
                  }
                """,
                """
                  import org.springframework.web.bind.annotation.RequestParam;
                  import javax.validation.constraints.NotNull;

                  class ControllerClass {
                    public String sayHello (
                      @NotNull @RequestParam(required = true, value = "name") String name,
                      @RequestParam(value = "lang") String lang,
                      @NotNull @RequestParam(required = true, value = "aNumber") Long aNumber,
                      @NotNull @RequestParam(required = true, value = "fred") String fred
                    ) {
                      return "Hello";
                    }
                  }
                """
            )
        );
    }
}