SpringMVC基础-02

1.处理乱码问题

web.xml中配置CharacterEncodingFilter。

<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name>Archetype Created Web Application</display-name>

  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath*:springmvc-01.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!-- 解决乱码问题 -->
  <filter>
    <filter-name>encoding</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>encoding</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

解决json乱码问题。即使web.xml配置了CharacterEncodingFilter，但如果返回的是json数据依然会出现乱码问题。

解决方式一。请求中设置produces = "application/json;charset=utf-8"，定义输出格式。

@Controller
@RequestMapping("/hello")
public class HelloController {

    /**
     * 解决json乱码问题
     * @return
     */
    @ResponseBody
    @GetMapping(value = "/h1", produces = "application/json;charset=utf-8")
    public String h1() {
        User user = new User(2, "张三", 10);
        ObjectMapper objectMapper = new ObjectMapper();
        String s = null;
        try {
            s = objectMapper.writeValueAsString(user);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return s;
    }
}

解决方式二。springmvc.xml中配置全局解决乱码问题。

<?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
        https://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">

    <!-- 解决json的乱码问题 -->
    <mvc:annotation-driven>
        <mvc:message-converters register-defaults="true">
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <constructor-arg value="UTF-8"/>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                        <property name="failOnEmptyBeans" value="false"/>
                    </bean>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
</beans>

Tomcat乱码问题解决。

修改apache-tomcat-9.0.50\conf\server.xml中70行的配置。

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

2.json

导入依赖。有两种json工具类，任选其一即可。

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.12.3</version>
</dependency>

<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.76</version>
</dependency>

jackson的使用。先new ObjectMapper();，然后调用writeValueAsString()方法

@Controller
@RequestMapping("/hello")
public class HelloController {

    @ResponseBody
    @GetMapping("/h1")
    public String h1() {
        User user = new User(1, "张三", 10);
        ObjectMapper objectMapper = new ObjectMapper();
        String s = null;
        try {
            s = objectMapper.writeValueAsString(user);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return s;
    }
    
     /**
     * 直接将日期格式化为Json，会输出一个时间戳 1627822830320
     * @return
     * @throws JsonProcessingException
     */
    @ResponseBody
    @GetMapping("/h2")
    public String h2() throws JsonProcessingException {
        Date date = new Date();
        ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(date);
    }

    /**
     * 将日期格式化后输出。
     * @return
     * @throws JsonProcessingException
     */
    @ResponseBody
    @GetMapping(value = "/h3")
    public String h4() throws JsonProcessingException {
        Date date = new Date();

        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);

        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        mapper.setDateFormat(format);

        return mapper.writeValueAsString(date);
    }
}

3.fastjson的使用。JSON.toJSONString()，将对象解析为json字符串；JSON.parseObject()，json字符串解析为对象。

@Controller
@RequestMapping("/hello")
public class HelloController {

    @ResponseBody
    @GetMapping("/h1")
    public String h1() throws JsonProcessingException {
        User user = new User(2, "张三", 10);
        // User解析为Json字符串
        String s = JSON.toJSONString(user);

        // Json字符串解析为User对象
        User user1 = JSON.parseObject(s, User.class);
        return s + user1;
    }
}

3.SSM整合

导入依赖

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.26</version>
    </dependency>

    <!-- 数据库连接池 -->
    <dependency>
        <groupId>com.mchange</groupId>
        <artifactId>c3p0</artifactId>
        <version>0.9.5.5</version>
    </dependency>

    <!-- 低版本servlet-api -->
    <!--<dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.5</version>
    </dependency>-->

    <!-- 高版本的servlet-api -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>4.0.1</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>

    <!-- 文件上传 -->
    <dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.3.3</version>
    </dependency>

    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis-spring</artifactId>
        <version>2.0.6</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>5.3.8</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.3.8</version>
    </dependency>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.7</version>
    </dependency>
</dependencies>

dao配置文件。database.properties、spring-dao.xml、mybatis.xml、mapper.xml。

database.properties，MySQL8.0之后，需要设置时区配置。

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=UTF8&useSSL=false&serverTimezone=Asia/Shanghai
name=root
password=123456

spring-dao.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">

    <context:property-placeholder location="classpath:database.properties"/>

    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${driverClassName}"/>
        <property name="jdbcUrl" value="${url}"/>
        <property name="user" value="${name}"/>
        <property name="password" value="${password}"/>

        <property name="maxPoolSize" value="30"/>
        <property name="minPoolSize" value="10"/>
        <property name="autoCommitOnClose" value="false"/>
        <!-- 获取连接超时时间 -->
        <property name="checkoutTimeout" value="10000"/>
        <!-- 连接失败尝试次数 -->
        <property name="acquireRetryAttempts" value="2"/>
    </bean>

    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <!-- mybatis配置文件，web项目中value必须配置为classpath:，否则无法找到路径。 -->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <!-- mapper配置文件 -->
        <property name="mapperLocations" value="classpath*:com/my/dao/*.xml"/>
        <!-- 别名包的配置 -->
        <property name="typeAliasesPackage" value="com.my.pojo"/>
    </bean>

    <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!-- 将dao通过注解注入spring容器 -->
        <property name="basePackage" value="com.my.dao"/>
    </bean>
</beans>

mabatis.xml配置。别名也可以在spring-dao.xml中进行配置。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <typeAliases>
        <package name="com.my.dao.User"/>
    </typeAliases>
</configuration>

mapper.xml配置。需要和com.my.dao.UserDao的路径名称保持一致。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.my.dao.UserDao">
    <select id="getAll" resultType="com.my.pojo.User">
        select * from tb_user
    </select>
</mapper>

spring-server层配置。

<?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:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://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/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <context:component-scan base-package="com.my.service"/>

    <!-- 事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <tx:advice id="advice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="add" propagation="REQUIRED"/>
            <tx:method name="query" read-only="true"/>
        </tx:attributes>
    </tx:advice>
</beans>

spring-controller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:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://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">

    <!-- 扫描@Controller注解 -->
    <context:component-scan base-package="com.my.controller"/>
    <!-- 注解驱动。可以使用@RequestMapping、@GetMapping定义url。 -->
    <mvc:annotation-driven/>

    <!-- 静态资源过滤 -->
    <mvc:default-servlet-handler/>

    <!-- 视图解析 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

applicationContext.xml，将spring-dao.xml、spring-server.xml、spring-controller.xml到导入到applicationContext.xml中，在Tomcat启动时加载。

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <import resource="classpath:spring-controller.xml"/>
    <import resource="classpath:spring-dao.xml"/>
    <import resource="classpath:spring-service.xml"/>
</beans>

web.xml配置。

<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name>Archetype Created Web Application</display-name>

  <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <!-- 将Spring容器存在于Tomcat -->
      <param-value>classpath:applicationContext.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <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>

  <!-- session过期时间 -->
  <session-config>
    <session-timeout>15</session-timeout>
  </session-config>
</web-app>

4.拦截器。

拦截器的概念。
1. servlet中有过滤器(Filter)和监听器(EventListener，监听域对象中数据的变化)，其中过滤器在url-pattern配置了/*之后，可以对所有要访问的资源进行拦截。
2. 拦截器是SpringMVC框架自己的，只有使用了SpringMVC框架的工程才可以使用，同时拦截器类似于Servlet中的过滤器。
3. 拦截器只拦截访问控制器的方法，如果访问的是jsp/html/css/image/js是不会进行拦截的。

拦截器的实现。

定义一个拦截器。

public class MyInterceptor implements HandlerInterceptor {

    /**
     *
     * @param request
     * @param response
     * @param handler
     * @return 返回true，执行下一个拦截器；返回false，拦截。
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("方式执行前=====");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("方式执行后=====");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("=====方式执行后=====");
    }
}

配置拦截器。

<?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
        https://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">

    <!-- 配置拦截器 -->
    <mvc:interceptors>
        <mvc:interceptor>
            <!-- /** 拦截这个请求下的所有的请求 -->
            <mvc:mapping path="/**"/>
            <bean class="com.my.interceptor.MyInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>
</beans>

5.文件上传和下载

文件上传和下载的配置。

需要导入的依赖。

<!-- 文件上传 -->
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>

springmvc.xml中的配置。

<?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:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://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">
    
    <!-- 文件上传和下载 -->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- 请求的编码格式，必须和jsp的pageEncoding一致，以便正确读取表单内容，默认为ISO-8859-1 -->
        <property name="defaultEncoding" value="UTF-8"/>
        <!-- 上传文件大小限制，单位为字节，10485760=10M -->
        <property name="maxUploadSize" value="10485760"/>
        <property name="maxInMemorySize" value="40960"/>
    </bean>
</beans>

文件上传和下载的代码实现。

文件上传。

@Controller
public class FileUploadController {

    /**
     * 自定义文件传出。
     * 会将上传的名为file的文件封装为CommonsMultipartFile。
     * @param file
     * @param request
     * @return
     */
    @PostMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        String uploadFileName = file.getOriginalFilename();

        if ("".equals(uploadFileName)) {
            return "redirect:/index.jsp";
        }


        System.out.println("上传文件名: " + uploadFileName);
        String s = "E:\\Temp" + File.separator + "update";
        File path = new File(s);
        if (!path.exists()) {
            path.mkdir();
        }

        System.out.println("文件保存路径: " + path);

        InputStream inputStream = file.getInputStream();
        FileOutputStream fileOutputStream = new FileOutputStream(new File(path, uploadFileName));
        int len = 0;
        byte[] buffer = new byte[1024];
        while ((len = inputStream.read(buffer)) != -1) {
            fileOutputStream.write(buffer);
            fileOutputStream.flush();
        }

        inputStream.close();
        fileOutputStream.close();
        return "redirect:/index.jsp";
    }

    /**
     * 使用CommonsMultipartFile中的方法直接完成文件传输。
     * @param file
     * @param request
     * @return
     * @throws IOException
     */
    @PostMapping("/upload")
    public String upload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        String s = "E:\\Temp" + File.separator + "update2";
        File path = new File(s);
        if (!path.exists()) {
            path.mkdir();
        }

        System.out.println("文件保存路径: " + path);

        file.transferTo(new File(path + "/" + file.getOriginalFilename()));
        return "redirect:/index.jsp";
    }
}

文件下载。

@Controller
public class FileUploadController {

    @GetMapping("/download")
    public String download(HttpServletRequest request, HttpServletResponse response) throws IOException {
        String s = "E:\\Temp" + File.separator + "update";
        String fileName = "笔记.txt";

        // 设置响应头
        response.reset(); // 设置页面不缓存，情况buffer。
        response.setCharacterEncoding("UTF-8");
        response.setContentType("multipart/form-data"); //二进制传出数据

        response.setHeader("Content-Disposition",
                "attachment;fileName=" + URLEncoder.encode(fileName, "UTF-8"));

        File file = new File(s, fileName);
        InputStream inputStream = new FileInputStream(file);

        ServletOutputStream outputStream = response.getOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len = inputStream.read()) != -1) {
            outputStream.write(buffer, 0, len);
            outputStream.flush();
        }

        outputStream.close();
        inputStream.close();
        return null;
    }
}

posted @ 2021-08-07 15:36 行稳致远方阅读(33) 评论(0) 收藏举报

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行稳致远方

SpringMVC基础-02

SpringMVC基础-02

1.处理乱码问题

2.json

3.SSM整合

4.拦截器。

5.文件上传和下载

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