模仿struts的servlet

package com.test.servlet; import java.io.IOException; import java.util.Enumeration; 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; import org.apache.commons.beanutils.BeanUtils; import org.apache.commons.beanutils.PropertyUtils; @SuppressWarnings("serial") public class CommonServlet extends HttpServlet { protected HttpServletRequest request; protected HttpServletResponse resposne; @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { process(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { process(req, resp); } protected void process(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { request = req; resposne = resp; try { initEntity(); } catch (Exception e){e.printStackTrace();} try { String method = (String)req.getAttribute("method"); if(method == null) throw new Exception("Could not find any method to invoke!"); this.getClass().getMethod(method).invoke(this); } catch (Exception e){e.printStackTrace();} } /** * 从request中获取参数来初始化servlet中定义的实体，servlet定义的实体必须提供标准的getter和setter * servlet里的对象实体应该先初始化，实体中的自定义实体也应该先初始化，例如： * Employee中有Date这个属性和Address这个自定义属性，那么再Employee初始化时，必须得初始化好Address， * Date可以不用初始化，因为他是Java里定义的。 * public class Employee { * private Date birthday; * private Address address; * public Employee() { * address = new Address(); * } * } * * 前台中的参数name定义应遵循以下规则： * example，假设MyServlet的属性都提供了getter和setter * public class MyServlet { * private int id; * private String name; * private Employee employee;//假设employee中有name属性 * } * 1.servlet里的基本类型可直接使用属性名作为参数名 <input type='text' name='id'> * 2.servlet里的对象实体的属性用 实体.属性 定义，如<input type='text' name='employee.name'> * 假如employee中还有另一个对象作为属性，可再用.来进入下层，如 employee.address.city * @throws Exception */ @SuppressWarnings("unchecked") protected void initEntity() throws Exception { Map<String, Object> entities = new HashMap<String, Object>();//实体 //各个实体所对应的键/值，实体作为键，属性/值的map作为值 Map<Object, Map<String, String>> propertiesOfEntity = new HashMap<Object, Map<String, String>>(); Enumeration<String> names = request.getParameterNames(); while(names.hasMoreElements()) { String name = names.nextElement(); String value = request.getParameter(name); /* * 如果参数名中没有带有"."的话，表示该参数名是servlet中定义的一个基础类型， * 则后面会将entity设置为servlet本身 */ boolean self = name.indexOf(".") == -1; Object entity = saveEntity(entities, name, self); //如果实体为servlet本身，则直接取name作为属性名，否则将第一个"."的右边作为属性名 //如employee.department.name，则取department.name作为属性名 String property = self ? name : name.substring(name.indexOf(".") + 1, name.length()); saveProperty(propertiesOfEntity, entity, property, value); } //将属性值注入到servlet里定义的各个实体中 for(String entityKey : entities.keySet()) { Object entity = entities.get(entityKey); Map<String, String> m = propertiesOfEntity.get(entity); BeanUtils.populate(entity, m); } } /** * 将实体保存到一个map中，首先会从entities中以name获取该实体，如果为空，则实例一个保存到entities中， * 如果self为true，表示该实体应该是servlet本身，否则从servlet中获取该实体 * @param entities 实体map * @param name 作为实体的键 * @param self 实体是否是servlet本身，如果为true表示是实体是servlet本身 * @return * @throws Exception */ private Object saveEntity(Map<String, Object> entities, String name, boolean self) throws Exception { if(!self) name = name.substring(0, name.indexOf(".")); Object entity = entities.get(name); if(entity == null) { entity = self ? this : PropertyUtils.getProperty(this, name); entities.put(name, entity); } return entity; } /** * 保存实体的属性值 * @param propertiesOfEntity 某个实体的属性值map * @param entity 作为属性值map的键，以实体作为键 * @param property 属性名 * @param value 属性值 */ private void saveProperty(Map<Object, Map<String, String>> propertiesOfEntity, Object entity, String property, String value) { Map<String, String> properties = propertiesOfEntity.get(entity); if(properties == null) { properties = new HashMap<String, String>(); } properties.put(property, value); propertiesOfEntity.put(entity, properties); } }