SSM学习笔记4 SpringMVC数据响应与请求（重中之重）

发布于：2023-01-13 ⋅ 阅读:(533) ⋅ 点赞:(0)

Spring MVCE的数据响应方式

页面跳转-直接返回字符串

    <!--配置内部资源视图解析器-->
<!--    只需要写名字就行了，会自动拼接后缀-->
    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--  /jsp/success.jsp  -->
        <property name="prefix" value="/jsp/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

页面跳转-返回ModelAndView对象（模型和视图对象）

    @RequestMapping(value="/quick2")
    public ModelAndView save2(){
        /*
            Model:模型 作用封装数据
            View：视图 作用展示数据
         */
        ModelAndView modelAndView = new ModelAndView();
        //设置模型数据
        modelAndView.addObject("username","itcast");
        //设置视图名称
        modelAndView.setViewName("success");

        return modelAndView;
    }
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>Success! ${username}</h1>
</body>
</html>

返回ModelAndView对象的其他形式

    @RequestMapping(value="/quick4")
    public String save4(Model model){
        //将model与view拆开，view通过return返回，即success.jsp,model定义在下方
        model.addAttribute("username","博学谷");//键值对形式
        return "success";
    }

    @RequestMapping(value="/quick3")
    public ModelAndView save3(ModelAndView modelAndView){
        //传入实参modelAndView，所以可以在下方直接定义你想要的返回值
        modelAndView.addObject("username","itheima");
        modelAndView.setViewName("success");
        return modelAndView;
    }

返回ModelAndView对象往Request域当中存数据

    @RequestMapping(value="/quick4")
    public String save4(Model model){
        //将model与view拆开，view通过return返回，即success.jsp,model定义在下方
        model.addAttribute("username","博学谷");//键值对形式
        return "success";

回写数据-直接返回字符串

    @RequestMapping(value="/quick6")
    public void save6(HttpServletResponse response) throws IOException {
        //response回写
        response.getWriter().print("hello itcast");
    }

  

    @RequestMapping(value="/quick7")
    @ResponseBody  //告知SpringMVC框架 不进行视图跳转 与ModelAndView形式区分开 直接进行数据响应
    public String save7() throws IOException {
        return "hello itheima";
    }

回写数据-直接返回json格式字符串

直接转换

    @RequestMapping(value="/quick8")
    @ResponseBody
    public String save8() throws IOException {
        return "{\"username\":\"zhangsan\",\"age\":18}";
    }

使用json转换工具-先导包

    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.9.0</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.9.0</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-annotations</artifactId>
      <version>2.9.0</version>
    </dependency>
    @RequestMapping(value="/quick9")
    @ResponseBody
    public String save9() throws IOException {
        User user = new User();
        user.setUsername("lisi");
        user.setAge(30);
        //使用json的转换工具将对象转换成json格式字符串在返回
        ObjectMapper objectMapper = new ObjectMapper();
        String json = objectMapper.writeValueAsString(user);

        return json;
    }

回写数据-返回对象或集合

主要是注入MappingJackson2HttpMessageConverter转换器    
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <property name="messageConverters">
            <list>
                <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
            </list>
        </property>
    </bean>
    @RequestMapping(value="/quick10")
    @ResponseBody
    //期望SpringMVC自动将User转换成json格式的字符串
    public User save10() throws IOException {
        User user = new User();
        user.setUsername("lisi2");
        user.setAge(32);

        return user;
    }

 先添加mvc的命名空间，以后这个是必写的

xmlns:mvc="http://www.springframework.org/schema/mvc"
 http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
    <!--mvc的注解驱动-->
    <mvc:annotation-driven conversion-service="conversionService"/>

SpringMVC获得请求数据

  基本简单参数

    @RequestMapping(value="/quick11")
    @ResponseBody
    public void save11(String username,int age) throws IOException {
        System.out.println(username);
        System.out.println(age);
    }

POJO类型参数

    @RequestMapping(value="/quick12")
    @ResponseBody
    public void save12(User user) throws IOException {
        //传入一个user类，springmvc会自动给你封装
        System.out.println(user);
    }

数组类型参数

    @RequestMapping(value="/quick13")
    @ResponseBody
    public void save13(String[] strs) throws IOException {
        System.out.println(Arrays.asList(strs));
    }

集合类型数据

    @RequestMapping(value="/quick14")
    @ResponseBody
    public void save14(VO vo) throws IOException {
        System.out.println(vo);
    }
package com.itheima.domain;

import java.util.List;

public class VO {

    private List<User> userList;

    public List<User> getUserList() {
        return userList;
    }

    public void setUserList(List<User> userList) {
        this.userList = userList;
    }

    @Override
    public String toString() {
        return "VO{" +
                "userList=" + userList +
                '}';
    }
}
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

    <form action="${pageContext.request.contextPath}/user/quick14" method="post">
        <%--表明是第几个User对象的username age--%>
        <input type="text" name="userList[0].username"><br/>
        <input type="text" name="userList[0].age"><br/>
        <input type="text" name="userList[1].username"><br/>
        <input type="text" name="userList[1].age"><br/>
        <input type="submit" value="提交">
    </form>
</body>
</html>

可以直接收集数据而无需POJO包装（重要）使用jquery

 D:\code\第三方扩展包\springmvc-ajax

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script src="${pageContext.request.contextPath}/js/jquery-3.3.1.js"></script>
    <script>
        var userList = new Array();
        userList.push({username:"zhangsan",age:18});
        userList.push({username:"lisi",age:28});

        $.ajax({
            type:"POST",
            url:"${pageContext.request.contextPath}/user/quick15",
            data:JSON.stringify(userList),
            contentType:"application/json;charset=utf-8"
        });

    </script>
</head>
<body>

</body>
</html>

<!--开放资源的访问-->
<!--<mvc:resources mapping="/js/**" location="/js/"/>
<mvc:resources mapping="/img/**" location="/img/"/>-->

或者

<mvc:default-servlet-handler/>
    @RequestMapping(value="/quick15")
    @ResponseBody
    public void save15(@RequestBody List<User> userList) throws IOException {
        System.out.println(userList);
    }

请求数据乱码问题（POST乱码问题）（重要）

    <!--配置全局过滤的filter-->
    <filter>
        <filter-name>CharacterEncodingFilter</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>CharacterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

参数绑定注解@requestParam

 数据转换 将浏览器传递的name 转换成username

    @RequestMapping(value="/quick16")
    @ResponseBody
    public void save16(@RequestParam(value="name",required = false,defaultValue = "itcast") String username) throws IOException {
        System.out.println(username);
    }

    @RequestMapping(value="/quick16")
    @ResponseBody
    public void save16(@RequestParam(value="name",required = false,defaultValue = "itcast") String username) throws IOException {
        System.out.println(username);
    }

获取Restful风格的参数

 

    // localhost:8080/user/quick17/zhangsan
    @RequestMapping(value="/quick17/{name}")
    @ResponseBody
    public void save17(@PathVariable(value="name") String username) throws IOException {
        System.out.println(username);
    }

自定义类型转换器

客户端请求的任何数据到服务端都会变成字符串

springmvc已经默认提供了一些类型转换器

 例如：在网页中发送2018-12-21格式的数据就无法正确响应

package com.itheima.converter;

import org.springframework.core.convert.converter.Converter;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateConverter implements Converter<String, Date> {
    public Date convert(String dateStr) {
        //将日期字符串转换成日期对象 返回
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Date date = null;
        try {
            date = format.parse(dateStr);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return date;
    }
}
    <!--声明转换器-->
    <bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
        <property name="converters">
            <list>
                <bean class="com.itheima.converter.DateConverter"></bean>
            </list>
        </property>
    </bean>
    <!--mvc的注解驱动-->
    <mvc:annotation-driven conversion-service="conversionService"/>
    @RequestMapping(value="/quick18")
    @ResponseBody
    public void save18(Date date) throws IOException {
        System.out.println(date);
    }

获得Servlet相关API

    @RequestMapping(value="/quick19")
    @ResponseBody
    public void save19(HttpServletRequest request, HttpServletResponse response, HttpSession session) throws IOException {
        System.out.println(request);
        System.out.println(response);
        System.out.println(session);
    }

SpringMVC获得请求数据-获得请求头

 例如：获取User-Agent

    @RequestMapping(value="/quick20")
    @ResponseBody
    public void save20(@RequestHeader(value = "User-Agent",required = false) String user_agent) throws IOException {
        System.out.println(user_agent);
    }

 

    @RequestMapping(value="/quick21")
    @ResponseBody
    public void save21(@CookieValue(value = "JSESSIONID") String jsessionId) throws IOException {
        System.out.println(jsessionId);
    }

 SpringMVC获得请求数据-文件上传（客户端）

    <form action="${pageContext.request.contextPath}/user/quick22" method="post" enctype="multipart/form-data">
        名称<input type="text" name="username"><br/>
        文件1<input type="file" name="uploadFile"><br/>
        文件2<input type="file" name="uploadFile2"><br/>
        <input type="submit" value="提交">
    </form>

 文件上传原理

 单文件上传步骤（服务端）

 

    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>1.3.1</version>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.3</version>
    </dependency>

    <!--配置文件上传解析器-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="UYF-8"/>
        <property name="maxUploadSize" value="500000"/>
    </bean>

    <form action="${pageContext.request.contextPath}/user/quick23" method="post" enctype="multipart/form-data">
        名称<input type="text" name="username"><br/>
        文件<input type="file" name="uploadFile"><br/>
        文件2<input type="file" name="uploadFile2"><br/>
        <input type="submit" value="提交">
    </form>
    @RequestMapping(value="/quick22")
    @ResponseBody
    public void save22(String username, MultipartFile uploadFile,MultipartFile uploadFile2) throws IOException {
        System.out.println(username);
        //获得上传文件的名称
        String originalFilename = uploadFile.getOriginalFilename();
        uploadFile.transferTo(new File("C:\\upload\\"+originalFilename));
        String originalFilename2 = uploadFile2.getOriginalFilename();
        uploadFile2.transferTo(new File("C:\\upload\\"+originalFilename2));
    }

多文件上传实现

 

    <form action="${pageContext.request.contextPath}/user/quick23" method="post" enctype="multipart/form-data">
        名称<input type="text" name="username"><br/>
        文件1<input type="file" name="uploadFile"><br/>
        文件2<input type="file" name="uploadFile"><br/>
        <input type="submit" value="提交">
    </form>
    @RequestMapping(value="/quick23")
    @ResponseBody
    public void save23(String username, MultipartFile[] uploadFile) throws IOException {
        System.out.println(username);
        for (MultipartFile multipartFile : uploadFile) {
            String originalFilename = multipartFile.getOriginalFilename();
            multipartFile.transferTo(new File("C:\\upload\\"+originalFilename));
        }
    }

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