一个简单的自定义web框架

只有一个servlet，这个servlet处理所有的*.do；

当有请求来时，根据请求的uri，选择对应的action进行处理；

action和uri使用注解来相互映射，中央控制的servlet在启动的时候就扫描classes目录下面的所有class文件，找出带有注解的类，并放入map中，key为uri的值，value为action对象；

需要自定义classloader来加载指定目录下的classes文件；

1.定义注解:

package com.oterman; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; @Retention(RetentionPolicy.RUNTIME) public @interface Control {      String value(); }

2.定义Action

package com.oterman; @Control("/book" ) public class BookAction {            /**       * 默认执行该方法       */      public void exec() {            System.out.println( "exec()....执行了哦" );            System.out.println( this.getClass().getClassLoader());//com.oterman.MyClassLoader@3d637d45                 }      public void add(){            System.out.println( "add()....执行了哦" );      }            public void delete(){            System.out.println( "delete()....执行了哦" );      } }

3.定义中央处理的ControllServlet,该servlet的映射为：

<servlet >     <servlet-name >ControllServlet </servlet-name>     <servlet-class> com.oterman.ControllServlet</servlet-class >   </servlet >   <servlet-mapping >     <servlet-name >ControllServlet </servlet-name>     <url-pattern >*.do </url-pattern>   </servlet-mapping >

ControllServlet.java

package com.oterman; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.HashMap; import java.util.Map; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ControllServlet extends HttpServlet {      private Map<String, Object> actionMap = null ;      @Override      public void init() throws ServletException {            super.init();            //中央处理servlet创建时，扫描classes目录下所有的class文件，找出action的class，并将 uri和对应的action放入到map中去；            actionMap = new HashMap<String, Object>();           String classpath = this.getServletContext().getRealPath("/WEB-INF/classes" );           File dir = new File(classpath);            try {               scanClass(dir);           } catch (Exception e) {               e.printStackTrace();           }                 }      //判断一个文件是目录还是文件，如果是文件，判断是否为class文件，如果为class文件，判断是有注解！      public void scanClass(File dir) throws Exception {            if (dir.isDirectory()) {//为目录               File[] files = dir.listFiles();                for (File file : files) {                    scanClass(file); //迭代操作               }           }            if (dir.isFile()) {//为文件                if (dir.getName().endsWith(".class" )) {                     //将硬盘上的class文件读取为byte[];                    FileInputStream fis = new FileInputStream(dir);                    ByteArrayOutputStream bos = new ByteArrayOutputStream();                     byte[] buffer = new byte[1024];                     int len = 0;                     while ((len = fis.read(buffer)) != -1) {                         bos.write(buffer, 0, len);                    }                    bos.close();                     byte[] bytes = bos.toByteArray();//class文件的字节码                                         //自定义classloader，将byte[]翻译成class对象                    MyClassLoader classloader = new MyClassLoader(this.getClass().getClassLoader());                     Class clazz =classloader.getClass(bytes);                                         //判断该类上是否有注解，如果有，则放入map中去；                     Control annotation = ( Control) clazz.getAnnotation(Control.class) ;                     if (annotation != null) {                         String uri = annotation.value();                          actionMap.put(uri, clazz.newInstance());                    }               }           }      }            public void doGet(HttpServletRequest request, HttpServletResponse response)                throws ServletException, IOException {                       //获取请求参数的 uri;           String uri = request.getRequestURI(); // /MySimpleWebFrame/book.do           String url = request.getRequestURL().toString();//http://localhost/MySimpleWebFrame/book.do                       //截取需要的uri；/book           uri=uri.substring(uri.lastIndexOf( "/"), uri.lastIndexOf("." ));           System. out.println(uri);            //根据uri，查找map，得到处理请求的action           Object action= actionMap.get(uri);            if(action==null ){                throw new RuntimeException("该请求没有对应的action！" );           }            //得到请求参数method,调用action相应的方法；           String methodname=request.getParameter("method" );            if(methodname==null){//如果请求参数没有改方法，则默认执行 exec方法！               methodname= "exec";           }           Method method= null;            try {                method= action.getClass().getMethod(methodname, null);           } catch (SecurityException e) {               e.printStackTrace();           } catch (NoSuchMethodException e) {               e.printStackTrace();                throw new RuntimeException("该action上没有"+methodname+ "方法！");           }                       //调用该方法            try {                method.invoke(action, null);           } catch (IllegalArgumentException e) {               e.printStackTrace();           } catch (IllegalAccessException e) {               e.printStackTrace();           } catch (InvocationTargetException e) {               e.printStackTrace();           }                 }      public void doPost(HttpServletRequest request, HttpServletResponse response)                throws ServletException, IOException {           doGet(request, response);      } } /**  * 自定义类加载器，将byte[]加载为class对象  * @author oterman  *  */ class MyClassLoader extends ClassLoader{      //自定父加载器，按照加载机制进行加载！加载一个类时，都先交给父类加载，父类加载不了，才一级一级往下传！      public MyClassLoader(ClassLoader parent) {            super(parent);      }      public Class getClass(byte[] bytes){           System. out.println("myclassloader2...." );            return defineClass(null, bytes, 0, bytes.length);      } }