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POInstantiationException using Spring injection
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    copied!<p>I am experimenting with Spring injection for the first time. I am surely forgetting something obvious but I don't know what it is.</p> <p>Under src/main/java, I have a package 'example' containing Hello, Animal, Cat.</p> <p>Under src/main/webapp/WEB-INF, I have web.xml and springapp-servlet.xml.</p> <p>When I deploy my app with Tomcat, I get a: </p> <pre><code>javax.servlet.ServletException: Error instantiating servlet class example.Hello org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) </code></pre> <p>What am I missing for the injection to work?</p> <p>Source below:</p> <p>Hello.java</p> <pre><code>package example; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service public class Hello extends HttpServlet { private final Animal animal; @Autowired public Hello(final Animal animal) { this.animal = animal; } @Override protected void doGet(final HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException { resp.getWriter().write(animal.sound()); } } </code></pre> <p>Cat.java </p> <pre><code>package example; import org.springframework.stereotype.Service; @Service public class Cat implements Animal { public String sound() { return "Miaou"; } } </code></pre> <p>Animal.java </p> <pre><code>package example; public interface Animal { public String sound() ; } </code></pre> <p>web.xml </p> <pre><code>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt; &lt;web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"&gt; &lt;context-param&gt; &lt;param-name&gt;contextConfigLocation&lt;/param-name&gt; &lt;param-value&gt;/WEB-INF/springapp-servlet.xml&lt;/param-value&gt; &lt;/context-param&gt; &lt;listener&gt; &lt;listener-class&gt;org.springframework.web.context.ContextLoaderListener&lt;/listener-class&gt; &lt;/listener&gt; &lt;servlet&gt; &lt;servlet-name&gt;Hello&lt;/servlet-name&gt; &lt;servlet-class&gt;example.Hello&lt;/servlet-class&gt; &lt;/servlet&gt; &lt;servlet-mapping&gt; &lt;servlet-name&gt;Hello&lt;/servlet-name&gt; &lt;url-pattern&gt;/hello&lt;/url-pattern&gt; &lt;/servlet-mapping&gt; &lt;/web-app&gt; </code></pre> <p>springapp-servlet.xml</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation=" http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"&gt; &lt;context:component-scan base-package="example" /&gt; &lt;mvc:annotation-driven /&gt; &lt;/beans&gt; </code></pre> <p>I initially thought that perhaps my springapp-servlet.xml was not even read, but if I make a typo on the name springapp-servlet.xml in my web.xml, I do get an error at deployment time, so I clearly have the correct path for springapp-servlet.xml. It is being but yet the injection isn't working. </p> <p>UPDATE:</p> <p>I am showing below the solution that worked for me thanks to the answers below. All code remains the same except for Hello:</p> <p>Hello.java</p> <pre><code>public class Hello extends HttpServlet { @Inject private Animal animal; @Override public void init(final ServletConfig config) throws ServletException { super.init(config); SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this, config.getServletContext()); } @Override protected void doGet(final HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException { resp.getWriter().write(animal.sound()); } } </code></pre>
 

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