wpcap 找不到指定的模块

Question

Miron

Asked:2020-05-15 18:06:18 +0000 UTC2020-05-15 18:06:18 +0000 UTC 2020-05-15 18:06:18 +0000 UTC

无法从spring xml上下文中的属性文件中获取属性getEnvironment

772

文件内容people.properties：

knight.age=34  
knight.name=Pedro

文件内容annotationsBased.xml：

<context:property-placeholder location="classpath:people.properties"/>
<bean class="ru.miron.SOWithDocs.Entities.Person" id="knightCreatedUsingPropertiesFile">
    <constructor-arg name="age" value="${knight.age}"/>
    <constructor-arg name="name" value="${knight.name}"/>
</bean>

收到后：

ApplicationContext XMLcontext = new ClassPathXmlApplicationContext("annotationsBased.xml");
System.out.println("Knight created using properties file - " + XMLcontext.getBean("knightCreatedUsingPropertiesFile"));

输出如下：

Knight created using properties file - Person [age=34, name=Pedro]

这意味着文件中的属性已成功加载到SpEL.

为什么在下一步执行以下代码时：

System.out.println(XMLcontext.getEnvironment().getProperty("knight.age"));

结论—— null？

2 个回答

Voted

Miron · Answer 1 · 2020-05-24T17:40:45Z

有两种接口方法Environment可以使用以下方法获取此类属性SpEL：

.resolveRequiredPlaceholders(文本);
.resolvePlaceholders(文本);

它们略有不同。

.resolveRequiredPlaceholders(text)：

抛出： IllegalArgumentException - 如果给定文本为 null 或任何占位符无法解析

resolvePlaceholders(text)：

抛出： IllegalArgumentException - 如果给定文本为空

执行以下代码行时：

System.out.println(context.getEnvironment().resolvePlaceholders("${knight.age}"));
System.out.println(context.getEnvironment().resolvePlaceholders("${knight.name}"));

我们得到输出：

34
佩德罗

这是最简单的让。您还可以使用注释检查这一点@PropertySource：

@Component
@PropertySource("classpath:people.properties") // can include many .properties files
public class EnvironmentFabric {
    @Autowired
    public Environment en;

    @Value("${knight.name}")
    public String knightName;
    @Value("${knight.age}")
    public int knightAge;

    public Environment getEnvironment() {
        return en;
    }

    public void printKnight() {
        System.out.println("knight name: " + knightName + ", knight age: " + knightAge);
    }
}

并且在执行以下代码时：

EnvironmentFabric enF = context.getBean("environmentFabric", EnvironmentFabric.class);
System.out.println(enF.getEnvironment().getProperty("knight.name"));
System.out.println(enF.getEnvironment().getProperty("knight.age"));
enF.printKnight();

输出将是：

佩德罗
34
骑士姓名：佩德罗，骑士年龄：34

答案基于这篇文章。
文章对题目进行了更详细的分析。

user328896 · Answer 2 · 2020-05-24T20:59:13Z

该文件properties连接到spring配置类中的上下文并写入 bean Environment。请参阅Spring 和 Spring Boot 的属性。然后可以将这个 bin 注入到任何其他 bin 中。

例如，在同一个地方，在配置类中：

@Bean(name = "knight1")
public Person knight(Environment environment) {
    Person knight1 = new Person();
    knight1.setAge(environment.getProperty("knight.age"));
    knight1.setName(environment.getProperty("knight.name"));
    return knight1;
}

或者在控制器类的构造函数中：

@Autowired
public Controller(Environment environment) {
    Person knight2 = new Person();
    knight2.setAge(environment.getProperty("knight.age"));
    knight2.setName(environment.getProperty("knight.name"));

    this.knight2 = knight2;
}

如果有很多带有属性的文件，那么在连接每个文件时，我们为其指定一个名称：

@PropertySource(name = "knight1.properties", value = "classpath:resources/knight1.properties", encoding = "UTF-8")
@PropertySource(name = "knight2.properties", value = "classpath:resources/knight2.properties", encoding = "UTF-8")

添加豆propertySources：

@Bean
public PropertySources propertySources(ConfigurableEnvironment environment) {
    return environment.getPropertySources();
}

然后我们从这个bean中获取属性：

@Bean(name = "knight1")
public Person knight(@Value("#{propertySources.get('knight1.properties')}")
                                 ResourcePropertySource propertySource) {
    Person knight1 = new Person();
    knight1.setAge(propertySource.getProperty("knight.age"));
    knight1.setName(propertySource.getProperty("knight.name"));
    return knight1;
}

示例：骑士项目

项目结构：

knights-project
├── src
│   └── main
│       ├── java
│       │   └── knights
│       │       ├── Controller.java
│       │       ├── Person.java
│       │       └── WebAppConfig.java
│       └── resources
│           ├── knight1.properties
│           └── knight2.properties
└── pom.xml

控制器.java

@RestController
public class Controller {
    private final HashMap<String, Person> band;

    @Autowired
    public Controller(@Qualifier("knight1") Person knight1,
                      @Value("#{propertySources.get('knight2.properties')}")
                              ResourcePropertySource propertySource) {

        Person knight2 = new Person();
        knight2.setAge(propertySource.getProperty("knight.age"));
        knight2.setName(propertySource.getProperty("knight.name"));

        this.band = new HashMap<>();
        this.band.put("knight1", knight1);
        this.band.put("knight2", knight2);
    }

    @RequestMapping(value = {"/", "/index.html"})
    public ResponseEntity<?> mainPage() {
        return ResponseEntity.ok(band);
    }
}

客户端： index.html

{
  "knight2": {
    "age": 35,
    "name": "González"
  },
  "knight1": {
    "age": 34,
    "name": "Pedro"
  }
}

人.java

public class Person {
    private int age;
    private String name;

    public Person() {
    }

    public int getAge() {
        return age;
    }

    public void setAge(Object age) {
        this.age = Integer.parseInt(String.valueOf(age));
    }

    public String getName() {
        return name;
    }

    public void setName(Object name) {
        this.name = String.valueOf(name);
    }
}

WebAppConfig.java

@Configuration
@ComponentScan
@EnableWebMvc
@PropertySource(name = "knight1.properties", value = "classpath:resources/knight1.properties", encoding = "UTF-8")
@PropertySource(name = "knight2.properties", value = "classpath:resources/knight2.properties", encoding = "UTF-8")
public class WebAppConfig implements WebApplicationInitializer {
    @Override
    public void onStartup(ServletContext servletContext) {
        CharacterEncodingFilter encodingFilter = new CharacterEncodingFilter();
        encodingFilter.setEncoding("UTF-8");
        encodingFilter.setForceEncoding(true);

        servletContext
                .addFilter("encoding-filter", encodingFilter)
                .addMappingForUrlPatterns(null, false, "/*");

        AnnotationConfigWebApplicationContext applicationContext = new AnnotationConfigWebApplicationContext();
        applicationContext.register(WebAppConfig.class);
        applicationContext.setServletContext(servletContext);

        ServletRegistration.Dynamic servlet =
                servletContext.addServlet("dispatcher", new DispatcherServlet(applicationContext));

        servlet.setLoadOnStartup(1);
        servlet.addMapping("/");
    }

    @Bean
    public PropertySources propertySources(ConfigurableEnvironment environment) {
        return environment.getPropertySources();
    }

    @Bean(name = "knight1")
    public Person knight(@Value("#{propertySources.get('knight1.properties')}")
                                     ResourcePropertySource propertySource) {
        Person knight1 = new Person();
        knight1.setAge(propertySource.getProperty("knight.age"));
        knight1.setName(propertySource.getProperty("knight.name"));
        return knight1;
    }
}

骑士1.properties

knight.age=34
knight.name=Pedro

骑士2.properties

knight.age=35
knight.name=González

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>knights-project</groupId>
    <artifactId>knights-project</artifactId>
    <name>knights-project</name>
    <version>1.0.0</version>
    <packaging>war</packaging>

    <properties>
        <java.version>14</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>

    <build>
        <defaultGoal>package</defaultGoal>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <targetPath>resources</targetPath>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.2.3</version>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <!-- spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.11.0</version>
        </dependency>

        <!-- common -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
</project>

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无法从spring xml上下文中的属性文件中获取属性getEnvironment

2 个回答

示例：骑士项目

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