Spring @MatrixVariable 教程展示了如何使用@MatrixVariable 解析 URL 参数。
Spring 是用于创建企业应用的流行 Java 应用框架。
@MatrixVariable
@MatrixVariable用于解析路径段中的名称-值对，并将它们绑定到方法参数。 多对用分号分隔。 必须首先启用矩阵变量。
Spring @MatrixVariable示例
以下应用解析 URL 路径段中的名称/值对。
pom.xmlsrc├───main│ ├───java│ │ └───com│ │ └───zetcode│ │ ├───config│ │ │ MyWebInitializer.java│ │ │ WebConfig.java│ │ └───controller│ │ MyController.java│ ├───resources│ └───webapp│ index.html└───test └───java
这是项目结构。
pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.zetcode</groupId> <artifactId>matrixvariableex</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> <spring-version>5.1.3.RELEASE</spring-version> </properties> <dependencies> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring-version}</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>3.2.2</version> </plugin> <plugin> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-maven-plugin</artifactId> <version>9.4.14.v20181114</version> </plugin> </plugins> </build></project>在pom.xml文件中，我们具有项目依赖项。
com/zetcode/config/MyWebInitializer.java
package com.zetcode.config;import org.springframework.context.annotation.Configuration;import org.springframework.web.context.WebApplicationContext;import org.springframework.web.servlet.DispatcherServlet;import org.springframework.web.servlet.FrameworkServlet;import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;@Configurationpublic class MyWebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer { @Override protected Class<?>[] getRootConfigClasses() { return null; } @Override protected Class<?>[] getServletConfigClasses() { return new Class[]{WebConfig.class}; } @Override protected String[] getServletMappings() { return new String[]{"/"}; }}MyWebInitializer初始化 Spring Web 应用。 它包含一个配置类：WebConfig。
com/zetcode/config/WebConfig.java
package com.zetcode.config;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;import org.springframework.web.servlet.config.annotation.EnableWebMvc;import org.springframework.web.servlet.config.annotation.PathMatchConfigurer;import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;import org.springframework.web.util.UrlPathHelper;@Configuration@EnableWebMvc@ComponentScan(basePackages = {"com.zetcode"})public class WebConfig implements WebMvcConfigurer { @Override public void configurePathMatch(PathMatchConfigurer configurer) { var urlPathHelper = new UrlPathHelper(); urlPathHelper.setRemoveSemicolonContent(false); configurer.setUrlPathHelper(urlPathHelper); } @Override public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) { configurer.enable(); }}WebConfig配置 Spring Web 应用。
@Overridepublic void configurePathMatch(PathMatchConfigurer configurer) { var urlPathHelper = new UrlPathHelper(); urlPathHelper.setRemoveSemicolonContent(false); configurer.setUrlPathHelper(urlPathHelper);}在这里，我们启用矩阵变量。
com/zetcode/controller/MyController.java
package com.zetcode.controller;import org.springframework.http.MediaType;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.MatrixVariable;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RestController;import java.util.Map;@RestControllerpublic class MyController { @GetMapping(value = "/user/{first}/{last}", produces = MediaType.TEXT_PLAIN_VALUE) public String handler1(@MatrixVariable("first") String first, @MatrixVariable("last") String last) { return String.format("Hello %s %s", first, last); } @GetMapping(value = "/data/{user:.*}", produces = MediaType.TEXT_PLAIN_VALUE) public String handler2(@MatrixVariable Map<String, String> data) { return String.format("Id: %s\nFirst name: %s\nLast Name: %s\nEmail: %s\n", data.get("id"), data.get("first"), data.get("last"), data.get("email")); } @GetMapping(value = "/geo/{continent}", produces = MediaType.TEXT_PLAIN_VALUE) public String handler3(@PathVariable("continent") String continent, @MatrixVariable("country") String country, @MatrixVariable("capital") String capital) { return String.format("Continent: %s\nCountry: %s\nCapital: %s\n", continent, country, capital); }}MyController包含请求路径到处理程序方法的映射。
@GetMapping(value = "/user/{first}/{last}", produces = MediaType.TEXT_PLAIN_VALUE)public String handler1(@MatrixVariable("first") String first, @MatrixVariable("last") String last) { return String.format("Hello %s %s", first, last);}在这里，我们使用@MatrixVariable将多个矩阵变量绑定到方法参数。
@GetMapping(value = "/data/{user:.*}", produces = MediaType.TEXT_PLAIN_VALUE)public String handler2(@MatrixVariable Map<String, String> data) { return String.format("Id: %s\nFirst name: %s\nLast Name: %s\nEmail: %s\n", data.get("id"), data.get("first"), data.get("last"), data.get("email"));}在这里，我们将多个名称/值对映射到一个映射中。
@GetMapping(value = "/geo/{continent}", produces = MediaType.TEXT_PLAIN_VALUE)public String handler3(@PathVariable("continent") String continent, @MatrixVariable("country") String country, @MatrixVariable("capital") String capital) { return String.format("Continent: %s\nCountry: %s\nCapital: %s\n", continent, country, capital);}在第三种情况下，我们将@MatrixVariable与@PathVariable结合在一起。
webapp/index.html
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Home page</title></head><body><p> <a href="http://localhost:8080/user/first=John/last=Doe">Greet user</a></p><p> <a href="http://localhost:8080/data/id=1;first=John;last=Doe;email=johndoe@gmail.com">Show user data</a></p><p> <a href="http://localhost:8080/geo/Europe;country=Slovakia;capital=Bratislava">Show country info</a></p></body></html>
这是主页。 我们有三个链接，这些链接包含使用@MatrixVariable注解解析的名称/值对。
在本教程中，我们使用@MatrixVariable解析路径段上的名称/值对并将其绑定到方法参数。
