构建Spring web 应用程序 (二)

传递模型数据到视图中

(1)定义数据层

import java.util.List;

import entity.Spittle;

public interface Repository {

    List<Spittle> findSpittles(long max, int count);
    
    int save(Spittle spittle);
    
    Spittle findByUserName(String userName);
}

实现类  

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import org.springframework.stereotype.Component;

import entity.Spittle;

@Component("repository")//为该类命名为repository
public class RepositoryImpl implements Repository {

    @Override
    public List<Spittle> findSpittles(long max, int count) {
        Date date = new Date();
        Spittle spittle = new Spittle("1", date);
        Spittle spittle1 = new Spittle("2", date);
        Spittle spittle2 = new Spittle("3", date);
        Spittle spittle3 = new Spittle("4", date);
        
        List<Spittle> list = new ArrayList<>();
        list.add(spittle);
        list.add(spittle1);
        list.add(spittle2);
        list.add(spittle3);
        
        return list;
    }

    @Override
    public int save(Spittle spittle) {
        
        return 0;
    }

    @Override
    public Spittle findByUserName(String userName) {
        Date date = new Date();
        Spittle spittle = new Spittle("1", date);
        spittle.setUserName(userName);
        return spittle;
    }

}

实体类

import java.util.Date;

import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;

public class Spittle {

    private Long id;
    private String message;
    private Date time;
    private Double latitude;
    private Double longitude;
    private String userName;
    private String firstName;
    private String lastName;
    private String password;
    
    
    
    public Spittle() {
        super();
    }

    public Spittle(String message, Date time) {
        this(message, time, null, null);
    }
    
    public Spittle(String message, Date time, Double latitude, Double longitude) {
    
        this.message = message;
        this.time = time;
        this.latitude = latitude;
        this.longitude = longitude;
    }

    public Spittle(String userName, String firstName, String lastName, String password) {
        
        this.userName = userName;
        this.firstName = firstName;
        this.lastName = lastName;
        this.password = password;
    }

    public Double getLatitude() {
        return latitude;
    }
    public void setLatitude(Double latitude) {
        this.latitude = latitude;
    }
    public Double getLongitude() {
        return longitude;
    }
    public void setLongitude(Double longitude) {
        this.longitude = longitude;
    }
    public Long getId() {
        return id;
    }
    public String getMessage() {
        return message;
    }
    public Date getTime() {
        return time;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public boolean equals(Object that) {
        //EqualsBuilder 类需要引入  apache的commons-lang包
        return EqualsBuilder.reflectionEquals(this, that, "id", "time");
    }
    
    public int hashCode() {
        return HashCodeBuilder.reflectionHashCode(this, "id", "time");
    }
}

接受数据的控制器

import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

import data.Repository;
import entity.Spittle;

@Controller
@RequestMapping("/spittles")
public class SpittleController {
    //private static final String MAX_LONG_AS_STRING = Long.toString(Long.MAX_VALUE);

    private Repository repository;

    @Autowired
    public SpittleController(Repository repository) {//注入  Repository 
        this.repository = repository;
    }
    
//    @RequestMapping(method=RequestMethod.GET)
//    public String spittles(Model model) {
//        model.addAttribute("spittleList", repository.findSpittles(Long.MAX_VALUE, 20)); //将 spittle 添加到模型中 
//        return "spittles"; //返回视图名
//    }
    
//    @RequestMapping(method=RequestMethod.GET)
//    public String spittles(Map model) {//这里也可以用   Map 作为参数
//        model.put("spittleList", repository.findSpittles(Long.MAX_VALUE, 20)); //将 spittle 添加到模型中 
//        return "spittles"; //返回视图名
//    }
    
//    @RequestMapping(method=RequestMethod.GET)
//    public List<Spittle> spittles() {
//        return repository.findSpittles(Long.MAX_VALUE, 20);
//    }
    
    //接受请求的输入
    @RequestMapping(method=RequestMethod.GET)
    public List<Spittle> spittles(@RequestParam(value="max", defaultValue="30") long max, @RequestParam(value="count", defaultValue="20") int count) {
        System.out.println("pppppp");
        return repository.findSpittles(Long.MAX_VALUE, 20);
    }
    
    //通过路径参数接受输入   
    通过使用@RequestParam注解，让它接受ID作为查询参数  这个处理器方法会将如 /spittles/show?id=1234这样的请求
    @RequestMapping(value="show", method=RequestMethod.GET)
    public String showSpittle(@RequestParam("id") long id, Model model) {
        System.out.println("show");
        return "spittles";
    }
    
    //但是我们想要识别的资源通过URL路径进行标识，而不是通过查询参数 这种路径变量 SpringMVC允许我们在@RequestMapping路径中使用占位符
    //下面的可以处理对 /spittles/12345 的请求 ，12345会传递到 id 这个参数中 标为黄色的两属性名称要一致，如果参数名与占位符的名称相同，则可以将@PathVariable("spittleId") 简写为 @PathVariable
    //如果@PathVariable中没有 value 属性的话，它会假设占位符的名称与方法的参数名称相同
    @RequestMapping(value="/{spittleId}", method=RequestMethod.GET)
    public String spittle(@PathVariable("spittleId") long id, Model model) {
        System.out.println("" + id);
        return "spittles";
    }
}

返回的视图

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
hello c
  <c:forEach items="${spittleList}" var="spittle">
     <li id="spittle_<c:out value="spittle.id"/>">
        <div class="spittleMessage">
          <c:out value="${spittle.message}"></c:out>
        </div>
        <div>
          <span class="spittleTime"> <c:out value="${spittle.time}" /> </span>
          <span class="spittleLocation">
             (<c:out value="${spittle.latitude}"/>
             <c:out value="${spittle.longitude}"/>)
          </span>
        </div>
     </li>
  </c:forEach>
</body>
</html>