Three ways spring loads the properties configuration file

One, through the Context:property-placeholder tag implementation configuration file load 1) Usage:

1. Add tags to the spring.xml configuration file

<ignore-unresolvable= "true"  location= "Classpath: Redis-key.properties "/>

2. Using the profile property in Spring.xml: $

<!--Basic Property URL, user, password -< Propertyname= "url"value= "${jdbc.url}" />< Propertyname= "username"value= "${jdbc.username}" />< Propertyname= "Password"value= "${jdbc.password}" /

3. Use in Java files:

@Value ("${jdbc.url}")  private  //  Note: Here the variable cannot be defined as static

2) Note: Step over the Pit

When importing a configuration file using the <context:property-placeholderlocation> tag in XML in spring, you want to import multiple properties profiles, as follows:

<context:property-placeholderlocation= "Classpath:db.properties"/>

<context:property-placeholderlocation= "Classpath:zxg.properties"/>

It turns out that no, the second profile is never read, and theSpring container is a discovery mechanism that uses a reflection scan to instantiate an instance through the namespace of a tag, when Spring detects that there is a Org.springframework.beans.factory.config.PropertyPlaceholderConfigurer beans will stop on the remaining Propertyplaceholderconfigurer Scan, i.e. only one instance can exist

If you have more than one configuration file, you can use the "," Partition

< context:property-placeholderlocation = "Classpath:db.properties,classpath:monitor.properties" />

You can use a wildcard character *

< context:property-placeholderlocation = "Classpath:*.properties" />

3) Attribute Usage

Ignore-resource-not-found//If the property file is not found, ignore, default false, not ignore, file not found and no exception is thrown. Ignore-unresolvable//Whether the unresolved properties are ignored, and if not ignored, an exception will be thrown. But the main reason it is set to True is:

Second, through the util:properties tag implementation configuration file load 1) usage

1. Usage example: Adding tags to the spring.xml configuration file

<?XML version= "1.0" encoding= "UTF-8"?>Xmlns:util= "Http://www.springframework.org/schema/util"xsi:schemalocation= "Http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd" >
<!--Load configuration file -<util:propertiesID= "jdbc" local-override="true"  Location= "Classpath:properties/jdbc.properties"/>

2. Using profile properties in Spring.xml: #

<!--DataSource -<BeanID= "DataSource"class= "Com.mchange.v2.c3p0.ComboPooledDataSource">    < Propertyname= "Driverclass"value= "#{jdbc.driverclass}" />    < Propertyname= "Jdbcurl"value= "#{jdbc.jdbcurl}" />    < Propertyname= "User"value= "#{jdbc.user}" />    < Propertyname= "Password"value= "#{jdbc.password}" /></Bean>

3.java file, let spring inject the value of the property read from the resource file, and for the sake of simplicity, write several injected methods directly into a file to show:

@Component    Public class sysconf {        @Value ("#{jdbc.url}")      private  String url;  

    @Value ("#{jdbc}")      publicvoid  setjdbcconf (Properties jdbc) {          URL= sys.getproperty ("url");      }  }  

Note: The #{jdbc} here corresponds to the 1th step of the id= "JDBC"

Third, through the @PropertySource annotations to implement the configuration file loading

The use is similar to Context:property-placeholder

1. Usage Example: Using Propertysource annotations in Java class files

@PropertySource (value={"Classpath:mail.properties"})publicclass  readproperties {@ Value (Value= "${mail.username}"private  String user_name;}

Three ways spring loads the properties configuration file