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This article introduces the knowledge of "how to customize the attributes of spring". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

About spring Custom attributes (schema)

When developing Dubbo applications, we will do the following similar configuration in xml:

After spring starts, the local runtime environment of Dubbo will get this information and complete the registration service based on this information. Today, our practical content is to develop a similar custom property, and then use this property in the spring project.

An overview of the full text

The whole actual combat process is divided into the following steps:

Create a web project

Create a bean for configuration properties

Create a XSD file

Create a custom BeanDefinitionParser and make rules for parsing configuration information

Create a custom NamespaceHandler that specifies the parser for configuration information

Add a spring.handlers file

Add a spring.schemas file

Configure such a property in the project

Start the web project to verify the configuration

Source code download

If you do not intend to encode, you can also download the actual combat source code at GitHub. The address is https://github.com/zq2599/blog_demos, in which there are several projects. This time, springschemademo is used, as shown in the red box below:

Next, let's start the actual combat:

Create a web project

Create a maven project. The content of pom.xml is as follows, mainly to introduce spring-related dependencies:

4.0.0 com.bolingcavalry springschemademo war 0.0.1-SNAPSHOT app Maven Webapp http://maven.apache.org 4.0.2.RELEASE junit junit 4.11 test org.springframework spring-core ${spring.version} org.springframework spring-web ${spring.version} org.springframework Spring-oxm ${spring.version} org.springframework spring-tx ${spring.version} org.springframework spring-jdbc ${spring.version} org.springframework spring-webmvc ${spring.version} org.springframework spring-aop ${spring.version} org.springframework spring-context-support ${spring.version} org.springframework spring-test ${spring.version} org.springframework spring-beans ${spring.version} javax javaee-api 7.0 jstl jstl 1.2 org.codehaus.jackson jackson-mapper-asl 1.9.13 Commons-fileupload commons-fileupload 1.3.1 commons-io commons-io 2.4 commons-codec commons-codec 1.9 {project.artifactId} src/main/java * * / * .properties * * / .xml False src/main/resources org.apache.tomcat.maven tomcat7-maven-plugin 2.2 http://localhost:8080/manager/text tomcat7 / ${project.artifactId} true

Add the configuration of spring mvc to web.xml:

SpringMVC org.springframework.web.servlet.DispatcherServlet contextConfigLocation classpath:spring-mvc.xml 1 true SpringMVC /

There is also a configuration file for spring, plus comments related to the configuration:

The rest of the configuration can be set on your own, or refer to the source code I uploaded to git

Create a bean for configuration properties

The actual combat example of this time, taking "computer" as an example, has two attributes: operating system and memory size, as follows:

Package com.bolingcavalry;/** * Description: * * @ author willzhao * @ email zq2599@gmail.com * @ date 22:15 on 2017-7-1 * / public class Computer {/ * * operating system * / private String os; / * memory size * / private int ram; public String getOs () {return os } public void setOs (String os) {this.os = os;} public int getRam () {return ram;} public void setRam (int ram) {this.ram = ram;}} create a XSD file

Create a computer.xsd file in the src\ main\ resources\ META-INF\ computer.xsd directory of the project, as follows:

Note that the contents of xmlns and targetNamespace are also used for external use, and there is the xsd:element node, which restricts the two attributes of computer.

Create a custom BeanDefinitionParser and make rules for parsing configuration information

Next, you need to write a BeanDefinitionParser. After getting the computer node in xml, how to get valid information from this node to the spring environment. The source code is as follows:

Public class ComputerBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {@ Override protected Class getBeanClass (Element element) {return Computer.class;} @ Override protected void doParse (Element element, BeanDefinitionBuilder builder) {String os = element.getAttribute ("os"); String ramStr = element.getAttribute ("ram"); if (StringUtils.hasText (os)) {builder.addPropertyValue ("os", os) } if (StringUtils.hasText (ramStr)) {builder.addPropertyValue ("ram", Integer.valueOf (ramStr));}

The getBeanClass method determines the type of bean returned after parsing the node; the computer node is received in the input parameter of the doParse method, and the "os" and "ram" nodes are parsed in the method, and then the parsing result can be passed into the builder by calling builder.addPropertyValue.

Create a custom NamespaceHandler that specifies the parser for configuration information

For a custom NamespaceHandler, you can tell the spring environment that when you encounter the configuration information of computer, you should use ComputerBeanDefinitionParser to parse it. There is very little code, as follows:

Public class ComputerNamespaceHandler extends NamespaceHandlerSupport {public void init () {registerBeanDefinitionParser ("computer", new ComputerBeanDefinitionParser ());}} add a spring.handlers file

Under the src\ main\ resources\ META-INF\ directory, add the spring.handlers file with only one line, as follows:

Http\: / / blog.csdn.net/boling_cavalry/schema/computer=com.bolingcavalry.ComputerNamespaceHandler add spring.schemas file

Under the src\ main\ resources\ META-INF\ directory, add the spring.schemas file with only one line, as follows:

Http\: / / blog.csdn.net/boling_cavalry/schema/computer.xsd=META-INF/computer.xsd configure such a property in the project

You are almost ready to verify that if you want to use this property in the spring configuration file, you can write as follows:

In addition to the configuration of bolingcavalry:computer, but also pay attention to the configuration of xmlns:bolingcavalry, and the "http://blog.csdn.net/boling_cavalry/schema/computer"" and "http://blog.csdn.net/boling_cavalry/schema/computer.xsd"" in xsi:schemaLocation should not be omitted.

Start the web project to verify the configuration

To verify that the configuration is valid, we write a controller to display the configuration information in the browser as follows:

@ Controllerpublic class HelloController {private static SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss"); @ Autowired Computer computer; @ RequestMapping ("/ hello") @ ResponseBody public String toIndex (HttpServletRequest request, Model model) {return "hello 001 [" + sdf.format (new Date ()) + "], computer os [" + computer.getOs () + "], ram [" + computer.getRam () + "]" }}

Computer provides autowire injection, and outputs its two properties when web responds. Now launch tomcat and deploy the webapp. Type http://localhost:8080/springschemademo/hello in the browser, and you will see the following output:

This is the end of the content of "how to customize the properties of spring". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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