SpringMVC入门教程

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	id="WebApp_ID" version="2.5">
	<display-name>SpringMVC-01-HelloWorld</display-name>
	<welcome-file-list>
		<welcome-file>index.html</welcome-file>
		<welcome-file>index.htm</welcome-file>
		<welcome-file>index.jsp</welcome-file>
		<welcome-file>default.html</welcome-file>
		<welcome-file>default.htm</welcome-file>
		<welcome-file>default.jsp</welcome-file>
	</welcome-file-list>
	<!-- 中央控制器 (类比struts2的全局拦截器) -->
	<servlet>
		<servlet-name>springmvc</servlet-name>
		<!-- DispatcherServlet主要用于控制流程 -->
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>classpath:springmvc.xml</param-value>
		</init-param>
		<!-- 当值为0或者大于0时，表示容器在启动时就加载并初始化这个servlet -->
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>springmvc</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
</web-app>

DispatcherServlet是前置控制器，配置在web.xml文件中的。拦截匹配的请求，Servlet拦截匹配规则要本身定义，把拦截下来的请求，依据相应的规则分发到目标Controller来处理

根据上面的<servlet-name>springmvc</servlet-name>配置咱们还要在src下新建一个springmvc.xml配置以下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:aop="http://www.springframework.org/schema/aop" xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd
           http://www.springframework.org/schema/aop 
           http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
           http://www.springframework.org/schema/mvc
           http://www.springframework.org/schema/mvc/spring-mvc.xsd
           http://www.springframework.org/schema/tx 
           http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
        <!--指定扫描controller -->
	<context:component-scan base-package="cn.itcast_01_springmvc.controller"></context:component-scan>
	<!-- 视图解析器 -->
	<bean
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/jsp/"></property>
		<property name="suffix" value=".jsp"></property>
	</bean>
</beans>

其中"视图解析器"指明了要映射的jsp路径的结构目录，因此在WEB-INF下新建jsp文件夹放置jsp文件，在下面随便建一个jsp文件，命名为hello.jsp

新建cn.itcast_01_springmvc.controller以及Hello.java实例：

//通知spring须要扫描这个类，获得DispatchService解析
//注解至关于调用这个类,里面的参数至关于对应的构造方法
//访问路径名:http://localhost:8080/SpringMVC-01-HelloWorld/hello/world
//@Controller至关于<bean>注入，参考下面的struts2的<action>注入原理
@Controller
@RequestMapping("/hello")
public class Hello {
	//相似配置action,默认为method=RequestMethod.GET请求 
	@RequestMapping(value="/world")//,method=RequestMethod.POST
	public String hello() {
		System.out.println("hello");
		//返回要调用的jsp页面
		return "hello";
	}
}
//<package name="struct2" namespace="/" extends="struts-default">
//	<action name="hello" class="cn.itcast._01_hello.HelloAction" method="hello">
//		<result  type="dispatcher" name="good">hello.jsp</result>
//	</action>
//</package>

运行将会看到你的jsp页面

2. 页面跳转

2.1 实现代码

在Hello.java下添加以下的代码：

@RequestMapping(value="/loginForm")
public String loginFrom() {
	return "login";
}

在jsp下新建login页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="login" method="post">
帐号：<input name="user" />
密码：<input name="pass" />
<button>登录</button>
</form>
</body>
</html>

根据login页面咱们登录后要跳转到成功页面，因此提交到后台代码还要执行跳转页面：

@RequestMapping(value="/login",method=RequestMethod.POST)
public String login(String user,String pass) {
	System.out.println("login"+user);
	return "redirect:world";
}

登录提交后重定向到刚才的Hello.jsp则跳转成功

2.2 post编码统一

在后台打印的中文发生乱码，解决方法以下：
在web.xml中新增节点：

<!-- 统一编码 -->
<filter>
	<filter-name>setcharacter</filter-name>
	<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
	<init-param>
		<param-name>encoding</param-name>
		<param-value>UTF-8</param-value>
	</init-param>
</filter>
<filter-mapping>
	<filter-name>setcharacter</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>

3. 参数传递

新建UserController.java添加以下代码：

@Controller
public class UserController {
	@RequestMapping(value = "/list")
	public String list( Integer currentpage,Integer pagesize) {
		System.out.println("currentpage:" + currentpage);
		System.out.println("pagesize:" + pagesize);
		return "hello";
	}
}

你能够用以下方法测试并打印结果：

http://localhost:8080/SpringMVC-01-HelloWorld/list?currentpage=2&pagesize=100

固然要注意，若是不传值则会报null，用整形会报错，因此要用包装类Integer，还能够给参数设置默认值，方法改成：

@RequestMapping(value = "/list")
public String list(@RequestParam(value = "currentpage", defaultValue = "1") Integer currentpage,
		@RequestParam(value = "pagesize", defaultValue = "10") Integer pagesize) {
	System.out.println("currentpage:" + currentpage);
	System.out.println("pagesize:" + pagesize);
	return "hello";
}

你还能够用 @PathVariable(value="id")将链接字符拼接到url上

@RequestMapping("/get/{id}")
public String get(@PathVariable(value="id") Integer id){
	System.out.println("id:"+id);
	return "hello";
}

http://localhost:8080/SpringMVC-01-HelloWorld/get/1

4. 使用Maven构建项目

4.1 基本构建

须要安装Maven插件，eclipse自带可能版本太低，具体操做请见百度

新建项目二为SpringMVC-02-Mvn，利用pom.xml配置jar包(包含之后全部要用的jar包)：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>cn.itcast</groupId>
	<artifactId>SpringMVC-02-Mvn</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<spring.version>5.0.8.RELEASE</spring.version>
	</properties>
	<dependencies>
		<!-- <dependency> -->
		<!-- <groupId>javax.servlet</groupId> -->
		<!-- <artifactId>servlet-api</artifactId> -->
		<!-- <version>2.5</version> -->
		<!-- <scope>provided</scope> -->
		<!-- </dependency> -->
		<!-- spring核心包 -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-beans</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-expression</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-websocket</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-web</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-tx</artifactId>
			<version>${spring.version}</version>
		</dependency>

		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-jdbc</artifactId>
			<version>${spring.version}</version>
		</dependency>

		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<!-- AOP aspect -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aop</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aspects</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>commons-logging</groupId>
			<artifactId>commons-logging</artifactId>
			<version>1.2</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context-support</artifactId>
			<version>${spring.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-test</artifactId>
			<version>${spring.version}</version>
		</dependency>

		<!-- JSTL标签类 -->
		<dependency>
			<groupId>jstl</groupId>
			<artifactId>jstl</artifactId>
			<version>1.2</version>
		</dependency>
		<!-- json -->
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
			<version>2.9.5</version>
		</dependency>
		<!-- jsonp -->
		<dependency>
			<groupId>com.google.code.gson</groupId>
			<artifactId>gson</artifactId>
			<version>2.8.5</version>
		</dependency>
		<!-- 下载 -->
		<dependency>
			<groupId>commons-fileupload</groupId>
			<artifactId>commons-fileupload</artifactId>
			<version>1.3.3</version>
		</dependency>

	</dependencies>
</project>

web.xml的DispatcherServlet配置与post编码照搬过来

springmvc.xml放在src/main/resources，代码照搬，但新增下面的代码：

<!-- 匹配注解驱动,要使用spring mvc中的@Controller注解，就必需要配置<mvc:annotation-driven /> -->
<!-- conversion-service注明了类型转换器 -->
<mvc:annotation-driven/>

在WEB-INF创建jsp文件夹和home.jsp，内容随意

新建cn.itcast_01_springmvc.controller和类IndexController.java

4.2 一些注解的使用

IndexController后台代码：

//获取cookie的内置参数值
@RequestMapping("/testCookie")
public String testCookie(@CookieValue("JSESSIONID") String sessionID) {
    System.out.println(sessionID);
    return "home";
}
// 获取一类请求头参数
@RequestMapping("/testHeader")
public String testHeader(@RequestHeader(value = "User-Agent") String header) {
	System.out.println(header);
	return "home";
}

// 跳转条件设置，pass等于10，跳转失败
@RequestMapping(value = "/testparam", params = { "user", "pass!=10" })
public String testParam(String user, Integer pass) {
	System.out.println(user + " " + pass);
	return "home";
}

//test前接受任意字符访问
@RequestMapping(value = "/*test")
public String test() {
	return "home";
}

5. 数据回传

5.1 构建数据提交

新建cn.itcast_01_springmvc.pojo和实体类：

public class Address {
	private Integer id;
	private String province;
	private String city;
//...

public class User {
	private Integer id;
	private String usern;
	private String pass;
	private String email;
	private Integer age;
	private Address address;
//...

在jsp下新建文件夹user和form.jsp(关于${sessionScope.str1}见5.3)：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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=UTF-8">
<title>Insert title here</title>
</head>
<body>
${sessionScope.str1}<br />
${sessionScope.str2}
<form action="save1">
帐号：<input name="usern" value="${user.usern}"><br />
密码：<input name="pass" value="${user.pass}"/><br />
年龄：<input name="age" value="${user.age}"/><br />
邮箱：<input name="email" value="${user.email}"/><br />
省份：<input name="address.province" value="${user.address.province}"/><br />
城市：<input name="address.city" value="${user.address.city}"/><br />
<button>注册</button>
</form>
</body>
</html>

控制层代码：

//Controller 负责处理由DispatcherServlet 分发的请求，它把用户请求的
//数据通过业务处理层处理以后封装成一个Model ，而后再把该Model 返回给对应的View 
//进行展现。在SpringMVC 中提供了一个很是简便的定义Controller 的方法，而后
//使用@RequestMapping 和@RequestParam 等一些注解用以定义URL请求和Controller 方法之间的映射，这样的Controller 就能被外界访问到。
@Controller
public class UserController {
	@Autowired
	private UserDao userDao;

@RequestMapping(value = "/form")
public String test() {
	return "user/form";
}

@RequestMapping(value = "/save1")
 public String save1(User user) {
    System.out.println(user.toString());
	return "home";
}

5.2 数据回传方式

后台代码增长：

// 将数据传到前台ModelAndView
	 @RequestMapping(value = "/edit1")
	 public ModelAndView edit1() {
	 User user = new User();
	 user.setUser("Bob");
	 user.setPass("123");
	 user.setAge(12);
	 user.setEmail("123@qq.com");
	 Address address = new Address();
	 address.setCity("成都");
	 address.setProvince("四川");
	 user.setAddress(address);
	 ModelAndView mv = new ModelAndView();
	 mv.setViewName("user/form");
	 mv.addObject("user", user);
	 return mv;
}	
	 // 将数据传到前台Map
	 @RequestMapping(value = "/edit2")
	 public String edit2(Map<String, Object> map) {
	 User user = new User();
	 user.setUser("Lisa");
	 user.setPass("123");
	 user.setAge(12);
	 user.setEmail("123@qq.com");
	 Address address = new Address();
	 address.setCity("成都");
	 address.setProvince("四川");
	 user.setAddress(address);
	 map.put("user", user);
	 return "user/form";
}	
	 // 将数据传到前台Model
         //这里将user的信息存入session，只字符存入session，固然这个注解能够放在类上面
         @SessionAttributes(value = { "user" }, types = { String.class })
	 @RequestMapping(value = "/edit3")
	 public String edit3(Model model) {
	 User user = new User();
	 user.setUser("Lucy");
	 user.setPass("123");
	 user.setAge(12);
	 user.setEmail("123@qq.com");
	 Address address = new Address();
	 address.setCity("成都");
	 address.setProvince("四川");
	 user.setAddress(address);
	 model.addAttribute("user", user);
	
	 model.addAttribute("str1", "session1");
	 model.addAttribute("str2", "session2");
	 return "user/form";
}

上面实现了三种方式的数据回传到form.jsp，通常使用Model

5.3 session注解的使用

上面的后台代码中，最后使用了注解和model.addAttribute("str1", "session1");将值存入session，前面的前台代码利用EL表达式取出相应的值

6. 原生API

须要把tomcat的环境包build进来，包含

HttpServletRequest
HttpServletResponse
HttpSession
java.security.Principal
Locale
InputStream
OutputStream
Reader
Writer

这里不作详讲，写个HttpSession测试类：

@Controller
public class HttpController {
	//内置api的session
	@RequestMapping("/http")
	public String http(HttpSession session) {
		System.out.println(session.getId());
		return "home";
	}
}

7. rest风格案例

7.1 处理静态资源

在webapp下新建lib文件夹，在lib下面新建js文件夹，引入jq文件jquery-3.3.1.min.js

在springmvc.xml中添加以下代码：

<!--指定扫描dao -->
<context:component-scan base-package="cn.itcast_01_springmvc.dao"></context:component-scan>


<!-- 处理静态资源 -->
<!-- 若是遇到mapping路径，就去找到location -->
<mvc:resources location="/lib/" mapping="/lib/**" />

http://localhost:8080/SpringMVC-02-Mvn/lib/js/jquery-3.3.1.min.js

试着访问jq文件看可否成功

7.2 rest介绍

7.3 遍历数据

再web.xml中添加以下配置：

<!-- 用来过滤rest中的方法，在隐藏域中的put/delete方式,注意 因为执行顺序缘由  必定要放在编码过滤器下面，不然会出现编码问题 -->
    <filter>
        <filter-name>HiddenHttpMethodFilter</filter-name>
        <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
        <init-param>
            <param-name>methodParam</param-name>
            <param-value>_method</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>HiddenHttpMethodFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

新建cn.itcast_01_springmvc.dao以及UserDao.java以下：

@Repository("personDao")
public class UserDao {
	private static Map<Integer, User>users=null;
	
	static{
		users=new HashMap<Integer, User>();	
		users.put(1001, new User(1001,"Bob","123","123@qq.com",21,new Address(1,"黑龙江","哈尔滨")));
		users.put(1002, new User(1002,"Lucy","123","123@qq.com",21,new Address(1,"黑龙江","哈尔滨")));
		users.put(1003, new User(1003,"Lisa","123","123@qq.com",21,new Address(1,"黑龙江","哈尔滨")));
	}
	private Integer initId=1004;
	public void save(User user) {
		if (user.getId()==null) {
			user.setId(initId++);
		}
		users.put(user.getId(), user);
	}
	public Collection<User> getAll() {
		return users.values();
	}
	public User get(Integer id) {
		return users.get(id);
	}

	public void delete(Integer id) {
		users.remove(id);
	}
}

分别对应增长，遍历，查询，删除方法

在jsp下创建user文件夹，新建list.jsp(这里虽然有删除，修改等代码，但后文中会提示添加这些代码)：

<%@ 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=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h2>用户列表</h2>
	<table border="1" cellpadding="0" cellspacing="0">
		<tr>
			<td>id</td>
			<td>名字</td>
			<td>年龄</td>
			<td>操做</td>
		</tr>
		<c:forEach items="${userList}" var="s">
			<tr>
				<td>${s.id}</td>
				<td>${s.usern}</td>
				<td>${s.age}</td>
				<td><a href="javascript:void(0)" onclick="deleteById(${s.id})">删除</a>
					<a href="user/${s.id}">修改</a></td>
			</tr>
		</c:forEach>
	</table>

	<a href="user">增长</a>

	<form method="post" id="deleteForm">
		<input type="hidden" name="_method" value="DELETE" />
	</form>
</body>
<script
	src="${pageContext.request.contextPath}/lib/js/jquery-3.3.1.min.js"></script>
<script type="text/javascript">
	function deleteById(id) {
		var form=document.getElementById("deleteForm");
		form.action="user/"+id;
		document.getElementById("deleteForm").submit();
	}
	function showdata(data) {
		console.log(data);
	}
</script>
<script
	src="http://localhost:8080/SpringMVC-02-Mvn/users-jsonp?callback=showdata"></script>
</html>

UserController.java的后台代码：

@Autowired
private UserDao userDao;

@RequestMapping(value = "/users", method = RequestMethod.GET)
public String list(Model model) {
	Collection<User> userList = userDao.getAll();
	model.addAttribute("userList", userList);
	System.out.println("users");
	//int a=Integer.parseInt("as");
	//int b=2/0;
	// 显示列表页
	return "user/list";
}

7.4 新增操做

后台代码新增：

// 保持restful风格，获取资源
@RequestMapping(value = "/user", method = RequestMethod.GET)
public String add() {
	// 打开增长页
	return "user/add";
}

// 保持restful风格，新建资源
@RequestMapping(value = "/user", method = RequestMethod.POST)
public String save(User user) {
	userDao.save(user);
	// 执行插入
	System.out.println(user);
	return "redirect:/users";
}

前台list.jsp代码添加"增长的a标签"

再新建add.jsp页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!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=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<form name="form1" action="${pageContext.request.contextPath}/user"
		method="post">
		帐号：<input name="usern" /><br /> 密码：<input name="pass" /><br /> 年龄：<input
			name="age" /><br /> 邮箱：<input name="email" /><br /> 省份：<input
			name="address.province" /><br /> 城市：<input name="address.city" /><br />
		<button>注册</button>
	</form>
</body>
</html>

这个页面点击注册保存数据回到首页

7.5 删除操做

前台list.jsp已经添加删除的代码

后台代码：

@RequestMapping(value = "/user/{id}", method = RequestMethod.DELETE)
public String delete(@PathVariable(value = "id") Integer id) throws LackParamException {
	// 执行删除
	userDao.delete(id);
	return "redirect:/users";
}

7.6 修改数据

前台list.jsp已经添加修改的代码

须要添加edit.jsp以下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/user/${users.id }" method="post">
<input type="hidden" name="_method" value="PUT" />
<%-- <input type="hidden" name="id" value="${users.id }"/> --%>
帐号：<input name="usern" value="${users.usern}"><br />
密码：<input name="pass" value="${users.pass}"/><br />
年龄：<input name="age" value="${users.age}"/><br />
邮箱：<input name="email" value="${users.email}"/><br />
省份：<input name="address.province" value="${users.address.province}"/><br />
城市：<input name="address.city" value="${users.address.city}"/><br />
<button>保存</button>
</form>
</body>
</html>

后台代码新增：

@RequestMapping(value = "/user/{id}", method = RequestMethod.GET)
public String edit(@PathVariable(value = "id") Integer id, Model model){
	User users = userDao.get(id);
	model.addAttribute("users", users);
	// 打开回显页
	return "/user/edit";
}

@RequestMapping(value = "/user/{id}", method = RequestMethod.PUT)
public String update(@PathVariable(value = "id") Integer id, User users) {
	users.setId(id);
	userDao.save(users);
	// 执行更新
	return "redirect:/users";
}

8. SpringMVC执行原理

9. 自定义转换类型

自定义日期类型转换器

实体类User.java中添加以下属性：

private Date birthday;
//...

在add.jsp中添加：

生日：<input name="birthday" /><br />

springmvc.xml添加(第一行是在原来的基础上改动)：

<mvc:annotation-driven conversion-service="myConversion" />
<!-- 类型转换器 -->
<bean id="myConversion"
	class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
	<property name="converters">
		<set>
		    <bean class="cn.itcast_01_springmvc.converter.DateConverter"></bean>
		</set>
	</property>
</bean>

根据配置的<bean>的类会自动调用咱们自定义的类进行类型转换，因此咱们新建cn.itcast_01_springmvc.converter下新建DateConverter.java以下：

public class DateConverter implements Converter<String, Date> {
	@Override
	public Date convert(String source) {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		sdf.setLenient(false);
		try {
			return sdf.parse(source);
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return null;
	}
}

最后点击添加在add.jsp输入日期时可输入2018-9-3这种格式

10. json与jsonp

JSON是一种基于文本的数据交换方式（不支持跨域），而JSONP是一种非官方跨域数据交互协议。

关于这两个的特色又是一大堆知识，详情百度

10.1 获取数据

在原来的基础上新增后台代码：

// @responseBody注解的做用是将controller的方法返回
// 的对象经过适当的转换器转换为指定的格式以后，写入到response对象的body区
@ResponseBody
@RequestMapping(value = "/users-json", method = RequestMethod.GET)
public Collection<User> listJson() {
    return userDao.getAll();
}
@RequestMapping(value = "/users-jsonp", method = RequestMethod.GET)
public void listJsonp(String callback, HttpServletResponse response) throws IOException {
	Collection<User> list = userDao.getAll();
	Gson gson = new Gson();
	String json = gson.toJson(list);
	response.getWriter().println(callback + "(" + json + ")");
}

以上就是将List集合的数据转为json格式

10.2 提交数据

利用ajax提交

add.jsp新增以下代码：

<h2>json</h2>
	<form name="form3" action="" method="post">
		帐号：<input id="usern" name="usern" value="${users.usern}"><br />
		密码：<input id="pass" name="pass" value="${users.pass}" /><br /> 年龄：<input
		id="age" name="age" value="${users.age}" /><br />
	<button type="button" id="saveBtn">保存</button>
</form>
<script
	src="${pageContext.request.contextPath}/lib/js/jquery-3.3.1.min.js"></script>
<script type="text/javascript">
	$(function() {
		$("#saveBtn").click(function() {
			var str = {
				"usern" : $("#usern").val(),
				"pass" : $("#pass").val(),
				"age" : $("#age").val(),
			}
			$.ajax({
				url : "savejson",
				type : "post",
				contentType : "application/json;charset=utf-8",
				data : JSON.stringify(str)
			});
		});
	});
</script>

后台代码新增：

// 经过@requestBody能够将请求体中的JSON字符串绑定到相应的bean上
@RequestMapping(value = "/savejson", method = RequestMethod.POST)
public String saveJsonp(@RequestBody User users) throws IOException {
	System.out.println(users);
	userDao.save(users);
	return "redirect:/users";
}

运行查看你的json数据

11. 异常处理

11.1 通常异常

将原来的后台的遍历代码添加一个异常

@RequestMapping(value = "/users", method = RequestMethod.GET)
public String list(Model model) {
	Collection<User> userList = userDao.getAll();
	model.addAttribute("userList", userList);
	System.out.println("users");
	int b=2/0;
	return "user/list";
}

再添加异常处理：

@ExceptionHandler
public ModelAndView handleException(Exception e){
	System.out.println(e);
	ModelAndView mv=new ModelAndView();
	mv.setViewName("error");
	mv.addObject("exception",e);
	return mv;
}

在user文件夹下新建异常跳转页面error.jsp：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" isErrorPage="true"%>
<!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=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%=exception.getMessage() %>
${exception.message }
</body>
</html>

http://localhost:8080/SpringMVC-02-Mvn/users会跳转到异常并报错误信息

11.2 自定义异常处理

将刚才异常屏蔽，创建一个缺乏参数异常
新建包cn.itcast_01_springmvc.exception下新建异常处理代码：

public class LackParamException extends ServletException {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public LackParamException() {
		super("缺乏参数");
	}

	public LackParamException(String msg) {
		super(msg);
	}
}

后台代码新增：

//自定义异常测试
@RequestMapping(value = "/test_exception")
public String testException(String str) throws LackParamException {
		if (org.springframework.util.StringUtils.isEmpty(str)) {
		throw new LackParamException();
	}
	return "home";
}

http://localhost:8080/SpringMVC-02-Mvn/test_exception?str=w带参数则不会报错

11.3 全局异常

springmvc.xml添加：

<!--指定扫描exception -->
<context:component-scan base-package="cn.itcast_01_springmvc.exception"></context:component-scan>

在这个包下再新建一个异常处理类：

//表示出现异常查就插入通知
@ControllerAdvice
public class MyExceptionHandler {

	@ExceptionHandler(Exception.class)
	public ModelAndView handleException(Exception e) {
		System.out.println("全场异常"+e);
		ModelAndView mv = new ModelAndView();
		mv.setViewName("error");
		mv.addObject("exception", e);
		return mv;
	}
}

再将遍历代码异常打开观察结果

12. 简单拦截器

新建cn.itcast_01_springmvc.interceptor下新建拦截器代码：

public class Myinterceptor1 implements HandlerInterceptor {
	/**
	 * 在执行Handler以前执行，用于身份校验，权限认证,返回true表示通行 false表示拦截
	 */
	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		System.out.println("preHandle1");
		return true;
	}

	/**
	 * 在执行Handler时返回ModelAndView以前执行
	 * 若是想要向也买你提供一些公共数据或者一些公共的配置性信息，能够考虑使用这里的modelAndView
	 */
	@Override
	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
			ModelAndView modelAndView) throws Exception {
		System.out.println("postHandle1");
	}

	/**
	 * 在执行Handler以后执行
	 * 日志，系统性能分析
	 */
	@Override
	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
			throws Exception {
		System.out.println("afterCompletion1");
	}
}

你能够再复制一个同样的，取名为Myinterceptor2

接下来配置两次拦截，在springmvc.xml中注册：

<!-- 配置拦截器 -->
<mvc:interceptors>
	<!-- 配置多个拦截器 顺序执行 -->
	<mvc:interceptor>		
		<!-- /** 是拦截全部的文件夹及里面的子文件夹 -->
		<mvc:mapping path="/**" />
		<!-- 不拦截静态资源 -->
		<mvc:exclude-mapping path="/lib/**" />
		<bean class="cn.itcast_01_springmvc.interceptor.Myinterceptor1"></bean>
	</mvc:interceptor>
	<mvc:interceptor>
		<mvc:mapping path="/**" />
		<mvc:exclude-mapping path="/lib/**" />
		<bean class="cn.itcast_01_springmvc.interceptor.Myinterceptor2"></bean>
	</mvc:interceptor>
</mvc:interceptors>

运行遍历数据页面查看打印内容

13. 文件上传

我直接贴出springmvc.xml以上包括新增全部配置：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:aop="http://www.springframework.org/schema/aop" xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd
           http://www.springframework.org/schema/aop 
           http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
           http://www.springframework.org/schema/mvc
           http://www.springframework.org/schema/mvc/spring-mvc.xsd
           http://www.springframework.org/schema/tx 
           http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
	<!--指定扫描controller -->
	<context:component-scan base-package="cn.itcast_01_springmvc.controller"></context:component-scan>
	<!--指定扫描dao -->
	<context:component-scan base-package="cn.itcast_01_springmvc.dao"></context:component-scan>
	<!--指定扫描exception -->
	<context:component-scan base-package="cn.itcast_01_springmvc.exception"></context:component-scan>
	<!-- 视图解析器 -->
	<bean
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/jsp/"></property>
		<property name="suffix" value=".jsp"></property>
	</bean>

	<!-- 匹配注解驱动,要使用spring mvc中的@Controller注解，就必需要配置<mvc:annotation-driven /> -->
	<!-- conversion-service注明了类型转换器 -->
	<mvc:annotation-driven conversion-service="myConversion" />
	<!-- 处理静态资源 -->
	<!-- 若是遇到mapping路径，就去找到location -->
	<mvc:resources location="/lib/" mapping="/lib/**" />

	<!-- 类型转换器 -->
	<bean id="myConversion"
		class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
		<property name="converters">
			<set>
				<bean class="cn.itcast_01_springmvc.converter.DateConverter"></bean>
			</set>
		</property>
	</bean>

	<!-- 配置拦截器 -->
	<mvc:interceptors>
		<!-- 配置多个拦截器 顺序执行 -->
		<mvc:interceptor>
			<!-- /* 是拦截全部的文件夹，不包含子文件夹 -->		
			<!-- /** 是拦截全部的文件夹及里面的子文件夹 -->
			<mvc:mapping path="/**" />
			<!-- 不拦截静态资源 -->
			<mvc:exclude-mapping path="/lib/**" />
			<bean class="cn.itcast_01_springmvc.interceptor.Myinterceptor1"></bean>
		</mvc:interceptor>
		<mvc:interceptor>
			<mvc:mapping path="/**" />
			<mvc:exclude-mapping path="/lib/**" />
			<bean class="cn.itcast_01_springmvc.interceptor.Myinterceptor2"></bean>
		</mvc:interceptor>
	</mvc:interceptors>

	<!-- SpringMVC文件上传 -->
	<bean id="multipartResolver"
		class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
		<!--defaultEncoding：请求的编码格式必须和用户JSP的编码一致，以便正确读取表单中的内容。 -->
		<property name="defaultEncoding" value="UTF-8" />
		<!-- maxUploadSize:设置文件上传大小上限（单位为字节） -->
		<property name="maxUploadSize" value="102400000" />
		<!--uploadTempDir:文件上传过程当中的临时目录，上传完成后，临时文件会自动删除-->
		<!--uploadTempDir能够不作设置，有默认的路径，上传完毕会临时文件会自动被清理掉 -->
		<property name="uploadTempDir" value="/upload/"></property>
	</bean>
</beans>

UserController.java再新增：

@RequestMapping(value = "/fileupload")
public String fileupload(String desc,MultipartFile file,Model model) throws IllegalStateException, IOException {
	System.out.println(desc);
	System.out.println(file);
	System.out.println(file.getOriginalFilename());
	if(file!=null&&file.getOriginalFilename()!=null&&file.getOriginalFilename().length()>0){
		String filepath="D:/Project resources/springMVC/";
		String origName=file.getOriginalFilename();
		//扩展名
		String extendsName=origName.substring(origName.lastIndexOf("."));
		//文件名
		String newFileName=UUID.randomUUID().toString()+extendsName;
		//文件
		File uploadFile=new File(filepath+newFileName);
		file.transferTo(uploadFile);
		model.addAttribute("filepath","/file/"+newFileName);
	}
	return "success";		
}

jsp的success.jsp页面以下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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=UTF-8">
<title>Insert title here</title>
</head>
<body>
<img src="${filepath}"/>
</body>
</html>

万事俱备，只差上传表单：
add.jsp新增：

<h2>文件上传</h2>
<!-- 	能够经过配置Tomcat虚拟路径后能够经过 
http://localhost:8080/file/e861c7d3-473b-4cc3-8da1-41a7ef2f9d5d.jpg直接访问图片 -->
<form name="form3" action="fileupload" method="post"
		enctype="multipart/form-data">
	<input name="file" type="file"><br /> <input name="desc"
			type="text"><br />
	<button>上传</button>
</form>

http://localhost:8080/SpringMVC-02-Mvn/user上传图片并能再success页面预览