Spring的MVC模块
Spring提供了自己的MVC框架实现，相比Struts、WebWork等MVC模块，Spring的MVC模块显得小巧而灵活。Spring的MVC使用Controller处理用户请求，此处的Controller类似于Struts1.x中的Action。SpringMVC作为Spring框架的一部分，在进行框架整合时不需要像Struts1&2那样特意的去融合到Spring里面，其本身就在Spring里面。
先定义如下各层：
域模型层实体类Cat：
package com.spring.mvc;
import java.util.Date;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
@Table(name = "tb_cat")
public class Cat {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
private String name;
@Temporal(value = TemporalType.TIMESTAMP)
private Date createdDate;
public Date getCreatedDate() {
return createdDate;
}
public void setCreatedDate(Date createdDate) {
this.createdDate = createdDate;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
业务逻辑层接口ICatService：
package com.spring.mvc;
import java.util.List;
public interface ICatService {
public void createCat(Cat cat);
public List<Cat> listCats();
public int getCatsCount();
}
业务逻辑层接口的实现类CatServiceImpl：
package com.spring.mvc;
import java.util.List;
public class CatServiceImpl implements ICatService {
private ICatDao catDao;
public ICatDao getCatDao() {
return catDao;
}
public void setCatDao(ICatDao catDao) {
this.catDao = catDao;
}
public void createCat(Cat cat) {
if (catDao.findCatByName(cat.getName()) != null){
throw new RuntimeException("猫" + cat.getName() + "已经存在。" );
}
catDao.createCat(cat);
}
public int getCatsCount() {
return catDao.getCatsCount();
}
public List<Cat> listCats() {
return catDao.listCats();
}
}
数据库持久层接口ICatDao：
package com.spring.mvc;
import java.util.List;
public interface ICatDao {
public void createCat(Cat cat);
public Cat findCatByName(String name);
public List<Cat> listCats();
public int getCatsCount();
}
数据库持久层实现类CatDaoImpl：
package com.spring.mvc;
import java.util.List;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
public class CatDaoImpl extends HibernateDaoSupport implements ICatDao {
public void createCat(Cat cat) {
this.getHibernateTemplate().persist(cat);
}
public Cat findCatByName(String name) {
List<Cat> catList = this.getHibernateTemplate().find(" select c from Cat c where c.name = ? ", name);
if (catList.size() > 0)
return catList.get(0);
return null;
}
public int getCatsCount() {
return (Integer) this.getSession(true).createQuery(" select count(c) from Cat c ").uniqueResult();
}
public List<Cat> listCats() {
return this.getHibernateTemplate().find(" select c from Cat c ");
}
}
SpringMVC的控制层和视图层
SpringMVC的控制层是Controller。Controller是个接口，一般直接继承AbstractController抽象类，并实现handleRequestInternal方法，此方法类似于Struts1.x中的execute()方法。
SpringMVC的视图层使用的是ModelAndView对象。handleRequestInternal方法返回的即时此对象，ModelAndView相当于Struts1.x中的ActionForward。
ModelAndView可以方便的传递参数，例如
return new ModelAndView("cal/listCat","cat",cat);
等价于
request.setAttribute("cat",cat);
return new ModelAndView("cal/listCat");
当传递多个参数时，可以使用Map，例如：
Map map = new HashMap();
map.put("cat",cat);
map.put("catList",catList);
return new ModelAndView("cat/listCat",map);
package com.spring.mvc;
import java.util.Date;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;
public class CatController extends AbstractController {
private ICatService catService;
@Override
protected ModelAndView handleRequestInternal(HttpServletRequest request,HttpServletResponse response) throws Exception {
String action = request.getParameter("action");
if ("add".equals(action)) {
return this.add(request, response);
}
return this.list(request, response);
}
protected ModelAndView list(HttpServletRequest request,HttpServletResponse response) throws Exception {
List<Cat> catList = catService.listCats();
request.setAttribute("catList", catList);
return new ModelAndView("cat/listCat");
}
protected ModelAndView add(HttpServletRequest request,HttpServletResponse response) throws Exception {
Cat cat = new Cat();
cat.setName(request.getParameter("name"));
cat.setCreatedDate(new Date());
catService.createCat(cat);
return new ModelAndView("cat/listCat", "cat", cat);
}
public ICatService getCatService() {
return catService;
}
public void setCatService(ICatService catService) {
this.catService = catService;
}
}
多业务分发器
如果一个Controller需要处理多种业务逻辑，可以使用MultiActionController。MultiActionController就是一个分发器，相当于Struts1.x中的DispatchAction分发器，能根据某参数值将不同的请求分发到不同的方法上，比如可以设置分发器参数为method，则URL地址访问catMulti.mvc?method=add时将会执行add方法。CatMultiController不需要继承父类的任何方法，只需要定义形如public ModelAndView xxx(HttpServletRequest request,HttpServletResponse response)的方法，当地址栏参数method为xxx时，Spring会通过反射调用xxx()方法。
package com.spring.mvc;
import java.util.Date;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.multiaction.MultiActionController;
public class CatMultiController extends MultiActionController {
private ICatService catService;
public ICatService getCatService() {
return catService;
}
public void setCatService(ICatService catService) {
this.catService = catService;
}
@SuppressWarnings("unchecked")
public ModelAndView add(HttpServletRequest request,HttpServletResponse response) {
Cat cat = new Cat();
cat.setName(request.getParameter("name"));
cat.setCreatedDate(new Date());
catService.createCat(cat);
return this.list(request, response);
}
@SuppressWarnings("unchecked")
public ModelAndView list(HttpServletRequest request,HttpServletResponse response) {
List<Cat> catList = catService.listCats();
request.setAttribute("catList", catList);
return new ModelAndView("cat/listCat");
}
}