Spring框架读取property属性文件常用5种方法

<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>
  
  <!-- 数据源配置 -->
  <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客户端接口实现->
  <bean id="dalClient" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="dataSource"/>
  </bean>

<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"/>
  <!-- 数据源配置 -->
  <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客户端接口实现-->
  <bean id="dalClient" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="dataSource"/>
  </bean>
  <!--备注：如果${} 这种写法无法读取到，或者编译出错，则增加ignore-unresolvable="true"的属性信息，并添加上文的 命名空间信息-->
  
  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=*

<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客户端接口实现-->
  <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 是个bean工厂后置处理器的实现，也就是 BeanFactoryPostProcessor 接口的一个实现。
      在Spring中，使用PropertyPlaceholderConfigurer可以在XML配置文件中加入外部属性文件，当然也可以指定外部文件的编码。PropertyPlaceholderConfigurer可以将上下文
    （配置文 件）中的属性值放在另一个单独的标准java Properties文件中去。在XML文件中用${key}替换指定的properties文件中的值。这样的话，只需要对properties文件进
    行修改，而不用对xml配置文件进行修改。
      引入外部文件后，就可以在xml中用${key}替换指定的properties文件中的值，通常项目中都会将jdbc的配置放在properties文件中。
      在启动容器时，初始化bean时，${key}就会替换成properties文件中的值。
    */

    //存取properties配置文件key-value结果
    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";
    }
  }

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");// 会重新加载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"));
    }

  }

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文件没有找到异常", 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"));
    }
  }