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Spring框架讀取property屬性文件常用5種方法

更新時(shí)間：2020年09月27日 10:17:45 作者：愛笑的berg

這篇文章主要介紹了Spring框架讀取property屬性文件常用5種方法,文中通過示例代碼介紹的非常詳細(xì)，對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值,需要的朋友可以參考下

1、方式一：通過spring框架 PropertyPlaceholderConfigurer 工具實(shí)現(xiàn)

<bean id="propertyConfig" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="ignoreUnresolvablePlaceholders" value="true"/>
    <property name="locations">
      <value>classpath:conf/jdbc.properties</value>
    </property>
    <property name="fileEncoding">
      <value>UTF-8</value>
    </property>
    <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />
  </bean>
  
  <!-- 數(shù)據(jù)源配置 -->
  <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
     destroy-method="close">
    <property name="driverClassName" value="${database.connection.driver}"/>
    <property name="url" value="${database.connection.url}"/>
    <property name="username" value="${database.connection.username}"/>
    <property name="password" value="${database.connection.password}"/>
  </bean>
  <!-- DAL客戶端接口實(shí)現(xiàn)->
  <bean id="dalClient" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="dataSource"/>
  </bean>

2、方式二：簡(jiǎn)化配置

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
  http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee.xsd
  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
  http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
  http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
  ">
  <context:property-placeholder location="classpath:conf/jdbc.properties" ignore-unresolvable="true"/>
  <!-- 數(shù)據(jù)源配置 -->
  <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
     destroy-method="close">
    <property name="driverClassName" value="${database.connection.driver}"/>
    <property name="url" value="${database.connection.url}"/>
    <property name="username" value="${database.connection.username}"/>
    <property name="password" value="${database.connection.password}"/>
  </bean>
  <!-- DAL客戶端接口實(shí)現(xiàn)-->
  <bean id="dalClient" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="dataSource"/>
  </bean>
  <!--備注：如果${} 這種寫法無法讀取到，或者編譯出錯(cuò)，則增加ignore-unresolvable="true"的屬性信息，并添加上文的 命名空間信息-->
  
  jdbc.properties文件：
  database.connection.driver=com.mysql.jdbc.Driver
  database.connection.url=jdbc:mysql://*.*.*.*:3306/mysql?characterEncoding=utf-8
  database.connection.username=*
  database.connection.password=*

上述配置理解：

1）ignore-unresolvable屬性的示意：

<xsd:documentation><![CDATA[
Specifies if failure to find the property value to replace a key should be ignored.
Default is "false", meaning that this placeholder configurer will raise an exception
if it cannot resolve a key. Set to "true" to allow the configurer to pass on the key
to any others in the context that have not yet visited the key in question.
]]>

翻譯后：指定是否應(yīng)忽略未能找到用于替換鍵的屬性值。默認(rèn)值為“false”，表示如果它無法解析密鑰，此占位符配置程序?qū)⒁l(fā)異常。設(shè)置為“true”以允許配置程序傳遞密鑰對(duì)于上下文中尚未訪問相關(guān)密鑰的任何其他用戶。

2) 為簡(jiǎn)化 PropertyPlaceholderConfigurer 的使用，Spring提供了<context:property-placeholder location="classpath:jdbc.properties" />元素,啟用它后，開發(fā)者便不用配置PropertyPlaceholderConfigurer對(duì)象了。

PropertyPlaceholderConfigurer內(nèi)置的功能非常豐富，如果它未找到${xxx}中定義的xxx鍵，它還會(huì)去JVM系統(tǒng)屬性(System.getProperty())和環(huán)境變量(System.getenv())中尋找。其通過啟用systemPropertiesMode和searchSystemEnvironment屬性，開發(fā)者能夠控制這一行為。context:property-placeholder大大的方便了我們數(shù)據(jù)庫(kù)的配置。這樣就可以為spring配置的bean的屬性設(shè)置值了。

備注：spring容器中最多只能定義一個(gè) context:property-placeholder，否則會(huì)報(bào)錯(cuò)：Could not resolve placeholder XXX,但如果想引入多個(gè)屬性文件怎么辦那，可以使用通配符：<context:property-placeholder location="classpath*:conf*.properties"/>

3、方式三：通過對(duì)spring PropertyPlaceholderConfigurer bean工廠后置處理器的實(shí)現(xiàn)，在java程序中進(jìn)行屬性文件的讀取

<bean id="propertyConfigurer" class="com.weblearn.utils.PropertyConfigurer">
    <property name="locations">
      <list>
        <value>classpath:conf/web-sys-relation.properties</value>
        <value>classpath:conf/jdbc.properties</value>
        <value>classpath:conf/main-setting-web.properties</value>
      </list>
    </property>
    <property name="fileEncoding" value="UTF-8"/>
  </bean>
  <!-- DAL客戶端接口實(shí)現(xiàn)-->
  <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
     destroy-method="close">
    <property name="driverClassName" value="${database.connection.driver}"/>
    <property name="url" value="${database.connection.url}"/>
    <property name="username" value="${database.connection.username}"/>
    <property name="password" value="${database.connection.password}"/>
  </bean>
  
  <bean id="dalClient" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="dataSource"/>
  </bean>

public class PropertyConfigurer extends PropertyPlaceholderConfigurer {
    /* 
      PropertyPlaceholderConfigurer 是個(gè)bean工廠后置處理器的實(shí)現(xiàn)，也就是 BeanFactoryPostProcessor 接口的一個(gè)實(shí)現(xiàn)。
      在Spring中，使用PropertyPlaceholderConfigurer可以在XML配置文件中加入外部屬性文件，當(dāng)然也可以指定外部文件的編碼。PropertyPlaceholderConfigurer可以將上下文
    （配置文 件）中的屬性值放在另一個(gè)單獨(dú)的標(biāo)準(zhǔn)java Properties文件中去。在XML文件中用${key}替換指定的properties文件中的值。這樣的話，只需要對(duì)properties文件進(jìn)
    行修改，而不用對(duì)xml配置文件進(jìn)行修改。
      引入外部文件后，就可以在xml中用${key}替換指定的properties文件中的值，通常項(xiàng)目中都會(huì)將jdbc的配置放在properties文件中。
      在啟動(dòng)容器時(shí)，初始化bean時(shí)，${key}就會(huì)替換成properties文件中的值。
    */

    //存取properties配置文件key-value結(jié)果
    private Properties props;

    @Override
    protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)
        throws BeansException {
      super.processProperties(beanFactoryToProcess, props);
      this.props = props;
    }

    public String getProperty(String key) {
      return this.props.getProperty(key);
    }

    public String getProperty(String key, String defaultValue) {
      return this.props.getProperty(key, defaultValue);
    }

    public Object setProperty(String key, String value) {
      return this.props.setProperty(key, value);
    }

  }

  @Controller
  @RequestMapping("/")
  public class TestController {
    @Autowired
    PropertyConfigurer propertyConfigurer;

    @RequestMapping("/index.do")
    public String getIndex(HttpServletRequest request, HttpServletResponse response, Model model) {
      Map map = new HashMap<String, Object>();
      map.put("orderNo", "111");

      String address1 = propertyConfigurer.getProperty("static.picture.address1");
      String resRoot = propertyConfigurer.getProperty("resRoot");
      String envName = propertyConfigurer.getProperty("database.connection.username");
      String keyzjbceshi = propertyConfigurer.getProperty("keyceshi");


      map.put("address1", address1);
      map.put("resRoot", resRoot);
      map.put("envName", envName);
      map.put("keyzjbceshi", keyzjbceshi);

      model.addAllAttributes(map);
      return "index/index.ftl";
    }
  }

4、方式四：通過ClassPathResource類進(jìn)行屬性文件的讀取使用

public class ReadPropertiesUtils1 {
    private static final Logger LOGGER = LoggerFactory.getLogger(ReadPropertiesUtils1.class);

    private static Properties props = new Properties();

    static {
      ClassPathResource cpr = new ClassPathResource("conf/ref-system-relation.properties");// 會(huì)重新加載spring框架
      try {
        props.load(cpr.getInputStream());
      } catch (IOException exception) {
        LOGGER.error("ReadPropertiesUtils1 IOException", exception);
      }
    }

    private ReadPropertiesUtils1() {

    }

    public static String getValue(String key) {
      return (String) props.get(key);
    }

    public static void main(String[] args) {
      System.out.println("static.picture.address1>>>"+ ReadPropertiesUtils1.getValue("static.picture.address1"));
      System.out.println("static.picture.address2>>>"+ ReadPropertiesUtils1.getValue("static.picture.address2"));
    }

  }

5、方式五：通過ContextClassLoader進(jìn)行屬性文件的讀取使用

public class ReadPropertiesUtils2 {
    private static final Logger LOGGER = LoggerFactory.getLogger(ReadPropertiesUtils2.class);

    public static String getValue(String key) {
      Properties properties = new Properties();
      try {
        InputStream inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("conf/ref-system-relation.properties");
        properties.load(inputStream);
      } catch (FileNotFoundException e) {
        LOGGER.error("conf/web-sys-relation.properties文件沒有找到異常", e);
      } catch (IOException e) {
        LOGGER.error("IOException", e);
      }
      return properties.getProperty(key);
    }

    public static void main(String[] args) {
      System.out.println("static.picture.address1>>>" + ReadPropertiesUtils2.getValue("static.picture.address1"));
      System.out.println("static.picture.address2>>>" + ReadPropertiesUtils2.getValue("static.picture.address2"));
    }
  }

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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