SpringMVC

SpringMVC

SSM：Mybatis + Spring + SpringMVC

依赖：

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.1.9.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>5.1.9.RELEASE</version>
</dependency>

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>2.5</version>
</dependency>
<dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>jsp-api</artifactId>
    <version>2.2</version>
</dependency>
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
</dependency>
  • 新版的Spring框架需要用到Tomcat 10和jakarta.servlet才能跑

回顾

Model 1

JSP同样也做Servlet的事

MVC三层架构

  • Model：Dao、Service
    • 提供要展示的数据
  • View：JSP
    • 负责Model的展示
  • Controller：Servlet
    • 接收用户请求并交给Model处理
img

Servlet

依赖：

JDK 8 + Tomcat 9

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>2.5</version>
</dependency>
<dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>jsp-api</artifactId>
    <version>2.2</version>
</dependency>
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
</dependency>

HelloServlet.java

public class HelloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //取得参数
        String method = req.getParameter("method");
        if (method.equals("add")){
            req.getSession().setAttribute("msg","执行了add方法");
        }
        if (method.equals("delete")){
            req.getSession().setAttribute("msg","执行了delete方法");
        }
        //业务逻辑
        //视图跳转
        req.getRequestDispatcher("/WEB-INF/jsp/hello.jsp").forward(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

  <servlet>
    <servlet-name>hello</servlet-name>
    <servlet-class>com.lu.servlet.HelloServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>hello</servlet-name>
    <url-pattern>/hello</url-pattern>
  </servlet-mapping>
</web-app>

hello.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
    <body>
        ${msg}
    </body>
</html>

测试：

  • 访问http://localhost:8080/hello?method=add
  • 访问http://localhost:8080/hello?method=delete

疑问

  • 碰到一个问题，如果创建普通Maven项目然后添加框架支持的话，webapp下的JSP直接不会去编译，不是出错，而是直接不编译，找了好久没找到问题

HelloSpringMVC

通过配置文件实现

环境：JDK 8 + Tomcat 9

  1. web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <!--配置DispatchServlet：这个是SpringMVC的核心：请求分发器，前端控制器-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--DispatchServlet要绑定Spring的配置文件-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <!--启动级别-->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!--
        在SpringMVC中，   /   /*
        /:只匹配所有的请求，不会去匹配jsp
        /*：匹配所有请求，包括jsp页面
    -->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>
  1. springmvc-servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--处理器映射器-->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
    <!--处理器适配器-->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
    <!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>
    <!--BeanNameUrlHandlerMapping:匹配的id(Handler)-->
    <!--Handler-->
    <bean id="/hello" class="com.lu.controller.HelloController"/>
</beans>
  1. HelloController.java
public class HelloController implements Controller {
    @Override
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView mv = new ModelAndView();
        //业务代码
        String msg = "helloWorld";
        mv.addObject("msg",msg);
        //视图跳转
        mv.setViewName("text");//需要拼接的视图名称，参考视图解析器的代码实际地址就是（/WEB-INF/jsp/text.jsp）
        return mv;
    }
}

SpringMVC流程

img

通过注解实现

处理JDK版本问题

<properties>
    <maven.compiler.source>8</maven.compiler.source>
    <maven.compiler.target>8</maven.compiler.target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

处理Maven中资源过滤问题

<build>
   <resources>
       <resource>
           <directory>src/main/java</directory>
           <includes>
               <include>**/*.properties</include>
               <include>**/*.xml</include>
           </includes>
           <filtering>false</filtering>
       </resource>
       <resource>
           <directory>src/main/resources</directory>
           <includes>
               <include>**/*.properties</include>
               <include>**/*.xml</include>
           </includes>
           <filtering>false</filtering>
       </resource>
   </resources>
</build>
  1. web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>
  1. springmvc-servlet.xml
<?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:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       https://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc
       https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!-- 自动扫描包，让指定包下的注解生效,由IOC容器统一管理 -->
    <context:component-scan base-package="com.lu.controller"/>
    <!-- 让Spring MVC不处理静态资源 -->
    <mvc:default-servlet-handler />
    <!--
    支持mvc注解驱动
        在spring中一般采用@RequestMapping注解来完成映射关系
        要想使@RequestMapping注解生效
        必须向上下文中注册DefaultAnnotationHandlerMapping
        和一个AnnotationMethodHandlerAdapter实例
        这两个实例分别在类级别和方法级别处理。
        而annotation-driven配置帮助我们自动完成上述两个实例的注入。
     -->
    <mvc:annotation-driven />

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
          id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
    </bean>
</beans>
  1. HelloController.java
@Controller
@RequestMapping("/hello")
public class HelloController {

    @RequestMapping("/h1")
    public String hello(Model model) {
        model.addAttribute("msg", "helloWorld, Annotation");
        return "hello";
    }
}
  • 访问http://localhost:8080/hello/h1测试

Controller

实现方式

接口

  • 样例
  • 方法较老，且一个Controller类只能实现一个方法

注解

RequestMapping

配置访问的URL

@Controller
@RequestMapping("/test")
public class RequestMappingController {
    @RequestMapping("/t1")
    public String test(Model model) {
        String msg = "helloController";
        model.addAttribute("msg", msg);
        return "test";
    }
}
  • 访问https://localhost:808/test/t1测试

RestFul

用URL路径传变量

@Controller
public class RestFulController {
    // 原来: http://localhost:8080/add?a=1&b=1
    // RestFul: http://localhost:8080/add/1/2
    @RequestMapping(value = "/add/{a}/{b}", method = RequestMethod.GET)
    public String test(@PathVariable int a, @PathVariable int b, Model model) {
        int res = a + b;
        model.addAttribute("msg", "结果为: " + res);
        return "test";
    }
}
  • 可以显式定义提交方式method = RequestMethod.GET，也可直接使用GetMapping或PostMapping等
  • 因此可以通过同个路径，根据不同的method，调用不同的方法
@RequestMapping(value = "/add/{a}/{b}", method = RequestMethod.GET)
@GetMapping("/add/{a}/{b}")
@PostMapping("/add/{a}/{b}")

好处：

  • 路径更简洁、安全
  • 获得参数更方便，框架会自动进行类型转换
  • 通过路径可以约束访问参数
    • 假设正确访问形式为test/a/1，如果路径变为test/1/a则找不到对应方法

结果跳转方式

  • Web资源的路径是以webapp或web文件夹为开始

测试过程中，将视图解析器注释掉

@Controller
public class ResultController {
    @RequestMapping("/m/t1")
    public String test01(HttpServletRequest request, HttpServletResponse response, Model model) {
        HttpSession session = request.getSession();
        String msg = session.getId();
        model.addAttribute("msg", msg);
    // 	return "forward:/WEB-INF/jsp/test.jsp";
        return "/WEB-INF/jsp/test.jsp";  // 转发, 路径不会改变
    }

    @RequestMapping("/m/t2")
    public String test02(HttpServletRequest request, HttpServletResponse response, Model model) {
        HttpSession session = request.getSession();
        String msg = session.getId();
        model.addAttribute("msg", msg);
        return "redirect:/index.jsp"; // 重定向, 路径会改变
      	// 配置了视图解析器, 重定向也要写全路径
    }
}

前端数据处理

偷懒

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.24</version>
</dependency>

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private int id;
    private String name;
    private int age;
}

取前端数据

UserController.java

@Controller
public class UserController {
    // http://localhost:8080/u1?name=lct
    @RequestMapping("/u1")
    public String test01(String name) {
        System.out.println(name);
        return "test";
    }

    // http://localhost:8080/u2?username=lct
    @RequestMapping("/u2")
    public String test02(@RequestParam("username") String name) {
        System.out.println(name);
        return "test";
    }

    // http://localhost:8080/u3?name=lct&age=10&id=2
    // 对象属性名要相同, 但顺序可以不相同
    @RequestMapping("/u3")
    public String test02(User user) {
        System.out.println(user);
        return "test";
    }
}

乱码问题

  1. 设计一个表单
<html>
    <body>
        <form action="/mess" method="post">
            <label>
                <input type="text" name="name">
            </label>
            <input type="submit">
        </form>
    </body>
</html>
  1. 编写Controller
@Controller
public class MessController {
    @RequestMapping("/mess")
    public String test(Model model, String name) {
        model.addAttribute("msg", name);
        return "test";
    }
}
  1. 在web.xml中配置过滤器
<filter>
    <filter-name>encoding</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>encoding</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

如果这样乱码还未解决

方式一：查看并修改Tomcat下的config目录中的server.xml

<Connector URIEncoding="utf-8" port="8080" protocol="HTTP/1.1"
          connectionTimeout="20000"
          redirectPort="8443" />

方式二：终极乱码过滤器

/**
* 解决get和post请求 全部乱码的过滤器
*/
public class GenericEncodingFilter implements Filter {

   @Override
   public void destroy() {
  }

   @Override
   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
       //处理response的字符编码
       HttpServletResponse myResponse=(HttpServletResponse) response;
       myResponse.setContentType("text/html;charset=UTF-8");

       // 转型为与协议相关对象
       HttpServletRequest httpServletRequest = (HttpServletRequest) request;
       // 对request包装增强
       HttpServletRequest myrequest = new MyRequest(httpServletRequest);
       chain.doFilter(myrequest, response);
  }

   @Override
   public void init(FilterConfig filterConfig) throws ServletException {
  }

}

//自定义request对象，HttpServletRequest的包装类
class MyRequest extends HttpServletRequestWrapper {

   private HttpServletRequest request;
   //是否编码的标记
   private boolean hasEncode;
   //定义一个可以传入HttpServletRequest对象的构造函数，以便对其进行装饰
   public MyRequest(HttpServletRequest request) {
       super(request);// super必须写
       this.request = request;
  }

   // 对需要增强方法 进行覆盖
   @Override
   public Map getParameterMap() {
       // 先获得请求方式
       String method = request.getMethod();
       if (method.equalsIgnoreCase("post")) {
           // post请求
           try {
               // 处理post乱码
               request.setCharacterEncoding("utf-8");
               return request.getParameterMap();
          } catch (UnsupportedEncodingException e) {
               e.printStackTrace();
          }
      } else if (method.equalsIgnoreCase("get")) {
           // get请求
           Map<String, String[]> parameterMap = request.getParameterMap();
           if (!hasEncode) { // 确保get手动编码逻辑只运行一次
               for (String parameterName : parameterMap.keySet()) {
                   String[] values = parameterMap.get(parameterName);
                   if (values != null) {
                       for (int i = 0; i < values.length; i++) {
                           try {
                               // 处理get乱码
                               values[i] = new String(values[i]
                                      .getBytes("ISO-8859-1"), "utf-8");
                          } catch (UnsupportedEncodingException e) {
                               e.printStackTrace();
                          }
                      }
                  }
              }
               hasEncode = true;
          }
           return parameterMap;
      }
       return super.getParameterMap();
  }

   //取一个值
   @Override
   public String getParameter(String name) {
       Map<String, String[]> parameterMap = getParameterMap();
       String[] values = parameterMap.get(name);
       if (values == null) {
           return null;
      }
       return values[0]; // 取回参数的第一个值
  }

   //取所有值
   @Override
   public String[] getParameterValues(String name) {
       Map<String, String[]> parameterMap = getParameterMap();
       String[] values = parameterMap.get(name);
       return values;
  }
}

拦截器

过滤器与拦截器的区别：拦截器是AOP思想的具体应用，是横切进项目的

过滤器

  • servlet规范中的一部分，任何JavaWeb工程都可以使用
  • 在url-pattern中配置了/*之后，可以对所有要访问的资源进行过滤拦截

拦截器

  • 拦截器是SpringMVC框架自己的，只有使用了SpringMVC框架的工程才能使用
  • 拦截器只会拦截访问的控制器方法，即controller中的请求
  • 如果访问的是静态资源，如jsp，html，css，image，js是不会进行拦截的

配置

<!-- 拦截器配置 -->
<mvc:interceptors>
    <mvc:interceptor>
        <!--/** 包括路径及其子路径-->
        <!--/admin/* 拦截的是/admin/add等等这种 , /admin/add/user不会被拦截-->
        <!--/admin/** 拦截的是/admin/下的所有-->
        <mvc:mapping path="/**"/>
        <bean class="com.lu.interceptor.MyInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

样例

TestController.java

@RestController
public class TestController {
    @RequestMapping("/t1")
    public String test() {
        System.out.println("TestController => test()执行");
        return "OK";
    }
}

MyInterceptor.java

public class MyInterceptor implements HandlerInterceptor {
    /*
        在请求处理的方法之前执行
        return true执行下一个拦截器
        return false就不执行下一个拦截器
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("------------处理前------------");
        return true;
    }
}

登录判断验证

  • index页面上有两个a标签
    • 分别对应登录和首页
  • 如果未登录，点击首页会被拦截器转到登录页面
  • 拦截器放行条件
    1. 请求路径包含login
    2. session中的userInfo不为空
  • 满足任意一条放行条件则正常请求，否则转发到登录页面

LoginController.java

@Controller
@RequestMapping("/user")
public class LoginController {
    @RequestMapping("/main")
    public String toMainPage() {
        return "main";
    }

    @RequestMapping("/gologin")
    public String toLoginPage() {
        return "login";
    }

    @RequestMapping("/login")
    public String login(HttpSession session, String username, String password) {
        session.setAttribute("userInfo", username);
        return "main";
    }

    @RequestMapping("/logout")
    public String logout(HttpSession session) {
        session.removeAttribute("userInfo");
        return "login";
    }
}

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
    <a href="${pageContext.request.contextPath}/user/go">登录</a>
    <a href="${pageContext.request.contextPath}/user/main">首页</a>
</body>
</html>

login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>登录页面</h1>

    <form action="${pageContext.request.contextPath}/user/login" method="post">
        用户名：<input type="text" name="username">
        密码：<input type="text" name="password">
        <input type="submit" value="登录">
    </form>
</body>
</html>

main.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>首页</h1>

    ${userInfo}

    <a href="${pageContext.request.contextPath}/user/logout">注销</a>
</body>
</html>

LoginInterceptor.java

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (request.getRequestURI().contains("login")) {
            return true;
        }

        HttpSession session = request.getSession();
        if (session.getAttribute("userInfo") != null) {
            return true;
        }

        request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
        return false;
    }
}

拦截器配置

<!-- 拦截器配置 -->
<mvc:interceptors>
    <mvc:interceptor>
        <mvc:mapping path="/user/**"/>
        <bean class="com.lu.interceptor.LoginInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

文件上传下载

依赖

<!--文件上传-->
<dependency>
   <groupId>commons-fileupload</groupId>
   <artifactId>commons-fileupload</artifactId>
   <version>1.3.3</version>
</dependency>
<!--servlet-api导入高版本的-->
<dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>javax.servlet-api</artifactId>
   <version>4.0.1</version>
</dependency>

前端测试页面

  • 前端表单要求
    • 为了能上传文件，必须将表单的method设置为POST，并将enctype设置为multipart/form-data
    • 只有在这样的情况下，浏览器才会把用户选择的文件以二进制数据发送给服务器

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <form action="${pageContext.request.contextPath}/upload" enctype="multipart/form-data" method="post">
        <input type="file" name="file"/>
        <input type="submit">
    </form>

    <a href="${pageContext.request.contextPath}/download">点击下载</a>
</body>
</html>

MVC配置

  • Spring MVC为文件上传提供了直接的支持，这种支持是用即插即用的MultipartResolver实现的
  • 这个bena的id必须为：multipartResolver ，否则上传文件会报400的错误！
<!--文件上传配置-->
<bean id="multipartResolver"  class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
   <!-- 请求的编码格式，必须和jSP的pageEncoding属性一致，以便正确读取表单的内容，默认为ISO-8859-1 -->
   <property name="defaultEncoding" value="utf-8"/>
   <!-- 上传文件大小上限，单位为字节（10485760=10M） -->
   <property name="maxUploadSize" value="10485760"/>
   <property name="maxInMemorySize" value="40960"/>
</bean>

上传

FileController.java

@Controller
public class FileController {
    //@RequestParam("file") 将name=file控件得到的文件封装成CommonsMultipartFile 对象
    //批量上传CommonsMultipartFile则为数组即可
    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file , HttpServletRequest request) throws IOException {

        //获取文件名 : file.getOriginalFilename();
        String uploadFileName = file.getOriginalFilename();

        //如果文件名为空，直接回到首页！
        if ("".equals(uploadFileName)){
            return "redirect:/index.jsp";
        }
        System.out.println("上传文件名 : "+uploadFileName);

        //上传路径保存设置
        String path = request.getServletContext().getRealPath("/upload");
        //如果路径不存在，创建一个
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        System.out.println("上传文件保存地址："+realPath);

        InputStream is = file.getInputStream(); //文件输入流
        OutputStream os = Files.newOutputStream(new File(realPath, uploadFileName).toPath()); //文件输出流

        //读取写出
        int len;
        byte[] buffer = new byte[1024];
        while ((len = is.read(buffer)) != -1){
            os.write(buffer,0,len);
            os.flush();
        }
        os.close();
        is.close();
        return "redirect:/index.jsp";
    }
  
     /*
     * 采用file.Transto 来保存上传的文件
     */
    @RequestMapping("/upload2")
    public String  fileUpload2(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {

        //上传路径保存设置
        String path = request.getServletContext().getRealPath("/upload");
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        //上传文件地址
        System.out.println("上传文件保存地址："+realPath);

        //通过CommonsMultipartFile的方法直接写文件（注意这个时候）
        file.transferTo(new File(realPath + "/" + file.getOriginalFilename()));

        return "redirect:/index.jsp";
    }
}

下载

下载步骤：

  1. 设置 response 响应头
  2. 读取文件 -- InputStream
  3. 写出文件 -- OutputStream
  4. 执行操作
  5. 关闭流 （先开后关）
@RequestMapping(value="/download")
public String downloads(HttpServletResponse response , HttpServletRequest request) throws Exception{
    //要下载的图片地址
    String path = request.getServletContext().getRealPath("/upload");
    String fileName = "Linux目录.md";
    //1、设置response 响应头
    response.reset(); //设置页面不缓存,清空buffer
    response.setCharacterEncoding("UTF-8"); //字符编码
    response.setContentType("multipart/form-data"); //二进制传输数据
    //设置响应头
    response.setHeader("Content-Disposition",
            "attachment;fileName="+ URLEncoder.encode(fileName, "UTF-8"));
    File file = new File(path,fileName);
    //2、 读取文件--输入流
    InputStream input = Files.newInputStream(file.toPath());
    //3、 写出文件--输出流
    OutputStream out = response.getOutputStream();
    byte[] buff = new byte[1024];
    int index;
    //4、执行 写出操作
    while((index = input.read(buff)) != -1){
        out.write(buff, 0, index);
        out.flush();
    }
    out.close();
    input.close();
    return null;
}
posted @   James-Allen  阅读(5)  评论(0)  编辑  收藏  举报
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