自定义annotation实现注入

1.工程所需要的jar，struts版本struts：1.2.6
commons-beanutils.jar
commons-digester.jar
commons-logging.jar
struts.jar
2.工程代码

package sun.com.struts.action;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.actions.MappingDispatchAction;
import sun.com.struts.pojo.LoginForm;
import sun.com.struts.service.ServiceLocator;
import sun.com.struts.service.UserService;
/**
 * user login action
 * @author fengyilin
 * @version $Revision: 64555 $ $Date: 2012-04-19 15:01:28 +0800 (Thu, 19 Apr 2012) $
 * @since 2012/04/26
 *
 */
public class LoginAction extends MappingDispatchAction {
    /** get the serviceLocator */
    private static ServiceLocator locator = ServiceLocator.getInstance();
    /** user service*/
    private UserService userService = (UserService) locator
            .getService("UserService");
    /**
     * login
     *
     * @param map ActionMapping  
     * @param form ActionForm
     * @param request HttpServletRequest
     * @param response HttpServletResponse
     * @return actionForward
    */
    public ActionForward login(ActionMapping map, ActionForm form,
            HttpServletRequest request, HttpServletResponse response) {
        LoginForm loginForm = (LoginForm) form;  
        String name = loginForm.getName();
        String passWord = loginForm.getPassWord();
        String userName = userService.findUserByName(name);
        if ("lin".equals(userName) && "lin".equals(passWord)) {
            return map.findForward("success");
        } else {
            return map.findForward("input");
        }
    }
}

这个action和普通的struts action的区别在于里面有如下src

 /** get the serviceLocator */
    private static ServiceLocator locator = ServiceLocator.getInstance();
    /** user service*/
    private UserService userService = (UserService) locator
            .getService("UserService");

即用到的service是由serviceLocator这个类提供的，ServiceLocator是自己定义的一个类扫描类，代码会在下面给出。

/**
 * 
 */
package sun.com.struts.annotation.service;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
 * @author fengyilin
 *
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Service {
    /** service name */
    String value();
}

 /**
 * 
 */
package sun.com.struts.pojo;
import org.apache.struts.action.ActionForm;
/**
 * user login action
 * @author fengyilin
 * @version $Revision: 64555 $ $Date: 2012-04-19 15:01:28 +0800 (Thu, 19 Apr 2012) $
 * @since 2011/08/05
 *
 */
public class LoginForm extends ActionForm {
    /**
     * 
     */
    private static final long serialVersionUID = 7260629305234876476L;
    private String name;
    private String passWord;
    /**
     * @param name
     *            the name to set  
     */
    public void setName(String name) {
        this.name = name;
    }
    /**
     * @return name name
     */
    public String getName() {
        return name;
    }
    /**
     * @param passWord
     *            the passWord to set
     */
    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }
    /**
     * @return the passWord
     */
    public String getPassWord() {
        return passWord;
    }
}

BaseService接口编写，所有的service接口都要继承自这个接口。

/**
 * 
 */
package sun.com.struts.service;
/**
 * @author fengyilin
 *
 */
public interface BaseService {
    /**
     * init the service
     */
    void init ();
    /**
     * destory the service
     */
    void destory();
}

UserService接口编写

/**
 * 
 */
package sun.com.struts.service;
/**
 * @author fengyilin
 *
 */
public interface UserService extends BaseService {
    /**
     * find the user
     * @param name userName
     * @return user
     */
    public String findUserByName(String name);
}

UserServiceImpl编写，该类的特别之处在于声明了Service这个annotation

/**
 * 
 */
package sun.com.struts.service.impl;
import sun.com.struts.annotation.service.Service;
import sun.com.struts.service.UserService;
/**
 * @author fengyilin
 *
 */
@Service("UserService")
public class UserServiceImpl implements UserService {
    @Override
    public void destory() {
    }
    @Override
    public void init() {
    }
    /**
     * find the user
     * @param name userName
     * @return user
     */
    @Override
    public String findUserByName(String name) {
        if ("gaofeng".equals(name)) {
            return "lin";
        } else {
            return "";
        }
    }
}
 

编写本文的重点类，类扫描器，这个类将对src\sun\com\struts\service这个包下的所有的类，然后会判断哪个类定义了Service的annotation，如果定义了，就将该类的一个实例保存到services这个map中。这样我们在action中想用哪一个service，直接从services中get出来就可以了。

/**
 * 
 */
package sun.com.struts.service;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
 * @author fengyilin
 *
 */
public final class ServiceLocator {
    /**
     * annotation path
     *
     * the class witch is belong to this path will be read
     */
    private static final String TARGET_PATH = "sun/com/struts/service/";
  //----------------------------------------------------------------- static 変数
    /** the unique system Locator instance */
    private static ServiceLocator locator = new ServiceLocator();
    /** construct method */
    private ServiceLocator() {}
    /** put the service instance to cache */
    private Map<String, BaseService> services;
    /** Log instance */
    private static Log log = LogFactory.getLog(ServiceLocator.class);
    /**
     * get the unique system Locator instance
     *
     * @return Locator instance
     */
    public static ServiceLocator getInstance() {
        return locator;
    }
    /** type of the class file */
    private static final String CLASS_EXTENSION = ".class";
    /**
     * get the service.
     *
     * @param <T> service type
     * @param name service name
     * @return service
     * @see #load()
     */
    public <T extends BaseService> T getService(String name) {
        if (name == null) {
            return null;
        }
        if (services == null) {
            try {
                log.debug("reade the service...");
                load();
            } catch (Error e) {
                log.error("[BUG] can not reade the service correctly", e);
                services = null;
                throw e;
            } catch (RuntimeException e) {
                log.error("[BUG] can not reade the service correctly", e);
                services = null;
                throw e;
            }
        }
        @SuppressWarnings("unchecked")
        T service = (T) services.get(name);
        return service;
    }
    /**
     * read the service of the path
     */
    private void load() {
        services = new HashMap<String, BaseService>();
        // get all the class
        try {
            for (Class<?> c : getClasses(TARGET_PATH)) {
                sun.com.struts.annotation.service.Service s = c
                        .getAnnotation(sun.com.struts.annotation.service.Service.class);
                if (s != null) {
                    BaseService service = createBaseService(c);
                    services.put(s.value(), service);
                    log.debug("    [annotation]：" + service);
                }
            }
        } catch (Exception e) {
            log.debug(e);
        }
        log.debug(services);
    }
    /**
     * get the service
     *
     * @param c class
     * @return BaseService service
     * @throws Exception error
     */
    private BaseService createBaseService(Class<?> c) throws Exception {
        try {
            BaseService service = (BaseService)c.newInstance();
            return service;
        } catch (Exception e) {
            e = new ClassCastException(c.getName());
            throw e;
        }
    }
    /**
     * <p>
     * read all the class belong to the path
     * </p>
     *
     * @param path class path (ex. sun/com/struts/service/)
     * @return class
     * @throws Exception error
     */
    public static Class<?>[] getClasses(String path) throws Exception {
        Enumeration<URL> e;
        try {
            ClassLoader loader = Thread.currentThread().getContextClassLoader();
            e = loader.getResources(path);
        } catch (IOException ex) {
            throw new RuntimeException(
                    "can not get the src(" + path + ")", ex);
        }
        if (log.isWarnEnabled()) {
            if (!e.hasMoreElements()) {
                log.warn("########## [getClasses] the source does not exist"
                        + "(" + path + ")");
            }
        }
        //buf of the path 
        StringBuilder buf = new StringBuilder();
        Set<Class<?>> classes = new LinkedHashSet<Class<?>>();
        while (e.hasMoreElements()) {
            URL url = e.nextElement();
            if (log.isDebugEnabled()) {
                log.debug("########## [getClasses] " + url);
            }
            // get the of the path
            File file = new File(url.getFile());
                URI uri = file.toURI();
                for (File f : listFiles(file)) {
                    buf.setLength(0);
                    classes.add(forClass(buf.append(path)
                                            .append(uri.relativize(f.toURI()).getPath())
                                            .toString()));
                
            }
        }
        return classes.toArray(new Class<?>[classes.size()]);
    }
    /**
     * get the next flow of the directory
     * return the directory
     *
     * @param file file
     * @return directory list
     */
    private static List<File> listFiles(File file) {
        List<File> files = new ArrayList<File>();
        // class file
        if (file.getName().endsWith(CLASS_EXTENSION)) {
            files.add(file);
        }
        // next flow is exit
        File[] fs = file.listFiles();
        if (fs != null) {
            for (File f : file.listFiles()) {
                files.addAll(listFiles(f));
            }
        }
        return files;
    }

/**
 * get the object of the path
 *
 *   Class<?> c = forClass("sun/com/struts/service/BaseService.class");
 *
 * equlesWith
 *
 *   Class<?> c = Class.forName("sun.com.struts.service.BaseService");
 *
 * @param path class
 * @return object
 * @throws Exception error
 */
private static Class<?> forClass(final String path) throws Exception {
    String name = toClassName(path);
    if (log.isDebugEnabled()) {
        log.debug("########## [forClass] " + path);
    }
    try {
        return Class.forName(name, false, Thread.currentThread().getContextClassLoader());
    } catch (ClassNotFoundException e) {
        if (log.isWarnEnabled()) {
            log.warn("########## [forClass] " + name + " does not exict。", e);
        }
        return null;
    } catch (ExceptionInInitializerError e) {
        log.error(name + " can not init。", e);
        throw new Exception(path, e);
    } catch (NoClassDefFoundError e) {
        log.error(name + " does not exict。", e);
        throw new Exception(path, e);
    }
}
/**
 * convert the path。
 *
 * @param path class path (ex. sun/com/struts/service/BaseService.class);
 * @return the class name (ex. sun.com.struts.service.BaseService)
 */
private static String toClassName(String path) {
    if (!path.endsWith(CLASS_EXTENSION)) {
        throw new IllegalArgumentException(
                    "[BUG]type is not the\"" + CLASS_EXTENSION +
                      " (" + path + ")");
    }
    return path.substring(0, path.length() - CLASS_EXTENSION.length()).replace("/", ".");
}
}
 

编写配置文件。struts-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC
          "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN"
          "http://jakarta.apache.org/struts/dtds/struts-config_1_2.dtd">
<struts-config>
  <!--
  ==================================================================================
            from Bean
  ==================================================================================
  -->
  <form-beans>
      <!-- user login from -->
    <form-bean name="LoginForm" type="sun.com.struts.pojo.LoginForm">
      <form-property name="name"               type="java.lang.String"/>
      <form-property name="passWord"       type="java.lang.String"/>
    </form-bean>
  </form-beans>
    <!--
  ==================================================================================
            action mapping
  ==================================================================================
  -->
  <action-mappings>
    <!-- user login from -->
    <action path="/loginAction" name="LoginForm" scope="request" validate="false"
            type="sun.com.struts.action.LoginAction" parameter="login">
      <forward name="success" path="/WEB-INF/jsp/success.jsp" />
      <forward name="input" path="/WEB-INF/jsp/error.jsp" />
    </action>
    </action-mappings>
</struts-config> 

修改web.xml添加struts1的支持。

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
 <display-name>
 myStruts1</display-name>
    <!--
    ================================================================================
    action servlet 
    ================================================================================
    -->
    <servlet>
        <servlet-name>action</servlet-name>
        <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
        <init-param>
            <param-name>config</param-name>
            <param-value>/WEB-INF/struts-config.xml</param-value>
        </init-param>
        <init-param>
            <param-name>debug</param-name>
            <param-value>2</param-value>
        </init-param>
        <init-param>
            <param-name>detail</param-name>
            <param-value>2</param-value>
        </init-param>
        <load-on-startup>2</load-on-startup>
    </servlet>
    <!--
    ================================================================================
    action servlet mapping 
    ================================================================================
    -->
    <servlet-mapping>
        <servlet-name>action</servlet-name>
        <url-pattern>/action/*</url-pattern>
    </servlet-mapping>
 <welcome-file-list>
  <welcome-file>login.jsp</welcome-file>
 </welcome-file-list>
</web-app>

login.jsp

<%@ page language="java" contentType="text/html; charset=windows-31j"
    pageEncoding="windows-31j"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-31j">
<title>Login Home</title>
</head>
<body>
<form action="action/loginAction" method="post">
<div align="center">
 <table><tr>
      <td>name</td>
      <td><input type = "text" name="name"/></td>
    </tr>
    <tr><td>passWord</td>
      <td><input type = "password" name="passWord"/></td>
    </tr>
    <tr><td>submit</td>
    <td> <input type = "submit" value="submit"/></td>
    </tr>
  </table>
  </div>
  </form>
</body>
</html>