第88天学习打卡（SpringMVC springmvc数据处理 JSON 整合SSM的前一部分）

6 SpringMVC 数据处理

乱码问题

解决方法1：

package com.kuang.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class EncodingController {
    //过滤器解决乱码
    @GetMapping ("/e/t1")
    public String test1(String name, Model model )  {

        model.addAttribute("msg", name);
        return "test";
    }
}

form.jsp


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

<form action="/e/t1" method="get">
    <input type="text" name="name">
    <input type="submit">
</form>
</body>
</html>

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>

    <filter>
        <filter-name>encoding</filter-name>
        <filter-class>com.kuang.filter.EncodingFilter</filter-class>
    </filter>
<filter-mapping>
    <filter-name>encoding</filter-name>
    <url-pattern>/</url-pattern>
</filter-mapping>
</web-app>

解决办法2：

以前乱码问题通过过滤器解决，而SpringMVC给我们提供了一个过滤器，可以在web.xml中配置。

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>
    
    <!--配置SpringMVC的乱码过滤-->

    <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>

</web-app>

修改了xml文件需要重启服务器！

终极解决办法

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>

    <filter>
        <filter-name>encoding</filter-name>
        <filter-class>com.kuang.filter.GenericEncodingFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

form.jsp


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

<form action="/e/t1" method="post">
    <input type="text" name="name">
    <input type="submit">
</form>
</body>
</html>

GenericEncodingFilte.java

package com.kuang.filter;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;

/**
 * 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 {
        System.out.println("======================================");
        //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;
    }
}

7 JSON

前后端分离时代：

后端部署后端，提供接口，提供数据：

前端独立部署，负责渲染后端的数据：

7.1 什么是JSON

JSON(JavaScript Object Notation, JS对象标记)是一种轻量级的数据交换格式，目前使用特别广泛
采用完全独立于编程语言的文本格式来存储和表示数据
简洁和清晰的层次结构使得JSON成为理想的数据交换语言
易于人阅读和编写，同时也易于机器解析和生成，并有效地提升网络传输效率。

在JavaScript语言中，一切都是对象，因此，任何JavaScript支持的类型都可以通过JSON来表示，例如字符串、数字、对象、数组等。它的要求与语法格式：

对象表示键值对，数据由逗号分隔
花括号保存对象
方括号保存数组

JSON键值对是用来保存JavaScript对象的一种方式，和JavaScript对象的写法也大同小异，键值对组合中的键名写在前面并用双引号""包裹，使用冒号：分隔，然后紧接着值：

{"name": "QinJiang"}
{"age":"3"}
{"sex":"男"}

JSON是JavaScriipt对象的字符串表示法，它使用文本表示一个JS对象的信息，本质就是一个字符串。

var obj = {a:'Hello', b: 'World'};//这是一个对象，注意键名也是可以使用引号包裹的
var json ='{"a":"Hello", "b":"World"}';//这是一个JSON字符串，本质就是一个字符串

JSON和JavaScript对象互转

要实现从JSON字符串转换为JavaScript对象，使用JSON.parse()方法；

var obj = JSON.parse('{"a":"Hello","b":"World"}');
//结果是{a:'Hello',b:"World"}

要实现从JavaScript对象转换为JSON字符串，使用JSON.stringify()方法：

var json = JSON.stringify({a:'Hello', b:'World'});
//结果是'{"a":"Hello", "b":"World"}'

测试：

jsontest.html:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>


    <script type="text/javascript">
        //编写一个JavaScript对象
        var user = {
            name:"秦疆",
            age:3,
            sex:"男"
        };
        //将js对象转换为json对象
       var json = JSON.stringify(user);
       console.log(json);
       console.log("======================");

       //将JSON对象转换为javaScript对象
        var obj = JSON.parse(json);
        console.log(obj);
    </script>
</head>
<body>

</body>
</html>

7.2 Controller返回JSON数据

Jackson应该是目前比较好的json解析工具
工具不止一个，比如还有阿里巴巴fastjson等等
使用Jackson,使用它需要导入它的jar包；

官网地址：https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind/2.12.2

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.12.2</version>
</dependency>

配置SpringMVC需要的配置

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">

   <!--1.注册servlet-->
   <servlet>
       <servlet-name>SpringMVC</servlet-name>
       <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
       <!--通过初始化参数指定SpringMVC配置文件的位置，进行关联-->
       <init-param>
           <param-name>contextConfigLocation</param-name>
           <param-value>classpath:springmvc-servlet.xml</param-value>
       </init-param>
       <!-- 启动顺序，数字越小，启动越早 -->
       <load-on-startup>1</load-on-startup>
   </servlet>

   <!--所有请求都会被springmvc拦截 -->
   <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>

</web-app>

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">

   <!-- 自动扫描指定的包，下面所有注解类交给IOC容器管理 -->
   <context:component-scan base-package="com.kuang.controller"/>

   <!-- 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>
</beans>

发现出现了乱码问题，我们需要设置一下他的编码格式为utf-8,以及它的返回类型；
通过@RequestMapping 的produces属性来实现，修改代码

//produces:指定响应体返回类型和编码
@RequestMapping(value = "/j1", produces = "application/json;charset=utf-8")

注意：使用json记得处理乱码问题

解决乱码问题：

方法1：

package com.kuang.controller;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.kuang.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class UserController {

    // 使用了produces解决乱码问题  输出的结果 {"name":"秦疆1号","age":3,"sex":"男"}
    @RequestMapping(value = "/j1",produces = "application/json;charset=utf-8")
    @ResponseBody //它就不会走视图解析器， 会直接返回一个字符串    会返回你真实返回的东西，一般都是返回字符串，就实现了前后端分离
    public String json1() throws JsonProcessingException {

        //jackson  通过ObjectMapper就可以生成字符串
        ObjectMapper mapper = new ObjectMapper();


        //创建一个对象
        User user = new User("秦疆1号",3,"男");

        //{"name":"??1?","age":3,"sex":"?"}
        String str = mapper.writeValueAsString(user);

        return str;
    }
}

代码优化：乱码统一解决：

上面一种方法比较麻烦，如果项目中有许多请求则每一个都要添加，可以通过Spring配置统一指定，这样就不用每次都去处理了！
我们可以在springmvc的配置文件上添加一段消息StringHttpMessageConverter转换配置！

<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>

7.3 JSON使用

测试：

package com.kuang.controller;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.kuang.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

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

//@Controller会走视图解析
@RestController //标注了下面所有的方法只会返回字符串
public class UserController {

    //在xml中配置了乱码解决代码  输出的结果：{"name":"秦疆1号","age":3,"sex":"男"}
    @RequestMapping(value = "/j1")
    //@ResponseBody 配合Controller 使用

    public String json1() throws JsonProcessingException {

        //jackson  通过ObjectMapper就可以生成字符串
        ObjectMapper mapper = new ObjectMapper();


        //创建一个对象
        User user = new User("秦疆1号",3,"男");

        //{"name":"??1?","age":3,"sex":"?"}
        String str = mapper.writeValueAsString(user);

        return str;
    }

    @RequestMapping(value = "/j2")
    //@ResponseBody 配合Controller 使用

    public String json2() throws JsonProcessingException {


        ObjectMapper mapper = new ObjectMapper();
        List<User> userList = new ArrayList<User>();

        User user1 = new User("秦疆1号",3,"男");
        User user2 = new User("秦疆1号",3,"男");
        User user3 = new User("秦疆1号",3,"男");
        User user4 = new User("秦疆1号",3,"男");
        userList.add(user1);
        userList.add(user2);
        userList.add(user3);
        userList.add(user4);



        String str = mapper.writeValueAsString(userList);
// ObjectMapper mapper = new ObjectMapper();   String str = mapper.writeValueAsString(userList); 结合为一句话
        // return  new ObjectMapper().writeValueAsString(userList);
        return str;//结果[{"name":"秦疆1号","age":3,"sex":"男"},{"name":"秦疆1号","age":3,"sex":"男"},{"name":"秦疆1号","age":3,"sex":"男"},{"name":"秦疆1号","age":3,"sex":"男"}]
    }

    @RequestMapping(value = "/j3")
    //@ResponseBody 配合Controller 使用

    public String json3() throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        //不使用时间戳的方式
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
        //自定义日期格式
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        mapper.setDateFormat(sdf);
        Date date = new Date();


        //ObjectMapper,时间解析后的默认格式为：Timestamp, 时间戳
       // return mapper.writeValueAsString(date);//1617691453164
        return mapper.writeValueAsString(sdf.format(date));//"2021-04-06 14:49:09"
    }
}

优化代码：

JsonUtils: 实现方法重载

package com.kuang.util;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

import java.text.SimpleDateFormat;



public class JsonUtils {
    public static String getJson(Object object){
        return getJson(object,"yyyy-MM-dd HH:mm:ss");
    }
    public static String getJson(Object object,String dateFormat){
        ObjectMapper mapper = new ObjectMapper();

        //不使用时间戳的方式
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
        //自定义日期的格式
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
        mapper.setDateFormat(sdf);
        try {
            return mapper.writeValueAsString(object);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return null;
    }
}

UserController:

package com.kuang.controller;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.kuang.pojo.User;
import com.kuang.util.JsonUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

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

//@Controller会走视图解析
@RestController //标注了下面所有的方法只会返回字符串
public class UserController {

    //在xml中配置了乱码解决代码  输出的结果：{"name":"秦疆1号","age":3,"sex":"男"}
    @RequestMapping(value = "/j1")
    //@ResponseBody 配合Controller 使用

    public String json1() throws JsonProcessingException {

        //jackson  通过ObjectMapper就可以生成字符串
        ObjectMapper mapper = new ObjectMapper();


        //创建一个对象
        User user = new User("秦疆1号",3,"男");

        //{"name":"??1?","age":3,"sex":"?"}
        String str = mapper.writeValueAsString(user);

        return str;
    }

    @RequestMapping(value = "/j2")
    //@ResponseBody 配合Controller 使用

    public String json2() throws JsonProcessingException {



        List<User> userList = new ArrayList<User>();

        User user1 = new User("秦疆1号",3,"男");
        User user2 = new User("秦疆1号",3,"男");
        User user3 = new User("秦疆1号",3,"男");
        User user4 = new User("秦疆1号",3,"男");
        userList.add(user1);
        userList.add(user2);
        userList.add(user3);
        userList.add(user4);

        return JsonUtils.getJson(userList);//返回结果[{"name":"秦疆1号","age":3,"sex":"男"},{"name":"秦疆1号","age":3,"sex":"男"},{"name":"秦疆1号","age":3,"sex":"男"},{"name":"秦疆1号","age":3,"sex":"男"}]



    }

    @RequestMapping(value = "/j3")
    //@ResponseBody 配合Controller 使用

    public String json3() throws JsonProcessingException {

        Date date = new Date();

        return JsonUtils.getJson(date,"yyyy-MM-dd HH:mm:ss");//"2021-04-06 15:05:09"


    }
}

7.4FastJson使用

fastjson.jar是阿里开发的一款专门用于Java开发的包，可以方便的实现json对象与JavaBean对象的转换，实现JavaBean对象与json字符串的转换，实现json对象与json字符串的转换。实现json的转换方法很多，最后的实现结果都是一样的。

fastjson 的 pom依赖！

<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.75</version>
</dependency>

fastjson 三个主要的类：

JSONObject 代表 json 对象

JSONObject实现了Map接口, 猜想 JSONObject底层操作是由Map实现的。
JSONObject对应json对象，通过各种形式的get()方法可以获取json对象中的数据，也可利用诸如size()，isEmpty()等方法获取"键：值"对的个数和判断是否为空。其本质是通过实现Map接口并调用接口中的方法完成的。

JSONArray 代表 json 对象数组

内部是有List接口中的方法来完成操作的。

JSON代表 JSONObject和JSONArray的转化

JSON类源码分析与使用
仔细观察这些方法，主要是实现json对象，json对象数组，javabean对象，json字符串之间的相互转化。

测试：不要忘记把fastjson的包导入lib中不然会出错

  @RequestMapping(value = "/j4")
    //@ResponseBody 配合Controller 使用

    public String json4() throws JsonProcessingException {
        //不要忘记把fastjson的包导入lib中 不然会出错

        List<User> userList = new ArrayList<User>();

        User user1 = new User("秦疆1号",3,"男");
        User user2 = new User("秦疆1号",3,"男");
        User user3 = new User("秦疆1号",3,"男");
        User user4 = new User("秦疆1号",3,"男");
        userList.add(user1);
        userList.add(user2);
        userList.add(user3);
        userList.add(user4);
        String string = JSON.toJSONString(userList);
        return string;
        //输出的结果：[{"age":3,"name":"秦疆1号","sex":"男"},{"age":3,"name":"秦疆1号","sex":"男"},{"age":3,"name":"秦疆1号","sex":"男"},{"age":3,"name":"秦疆1号","sex":"男"}]



    }

8 整合SSM

环境要求

环境：

IDEA
MySQL
Tomcat
Maven

要求：

需要熟练掌握MySQL数据库，Spring，JavaWeb及MyBatis知识，简单的前端知识；

数据库环境

创建一个表：

CREATE DATABASE `ssmbuild`;

USE `ssmbuild`;

DROP TABLE IF EXISTS `books`;

CREATE TABLE `books` (
`bookID` INT(10) NOT NULL AUTO_INCREMENT COMMENT '书id',
`bookName` VARCHAR(100) NOT NULL COMMENT '书名',
`bookCounts` INT(11) NOT NULL COMMENT '数量',
`detail` VARCHAR(200) NOT NULL COMMENT '描述',
KEY `bookID` (`bookID`)
) ENGINE=INNODB DEFAULT CHARSET=utf8

INSERT  INTO `books`(`bookID`,`bookName`,`bookCounts`,`detail`)VALUES
(1,'Java',1,'从入门到放弃'),
(2,'MySQL',10,'从删库到跑路'),
(3,'Linux',5,'从进门到进牢');

基本环境搭建

1.新建一个Maven项目！ ssmbuild,添加web的支持

2.导入相关的pom依赖

<?xml version="1.0" encoding="UTF-8"?>
<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>com.kuang</groupId>
    <artifactId>ssmbuild</artifactId>
    <version>1.0-SNAPSHOT</version>
<!--    依赖：junit ,数据库驱动，连接池， servlet jsp mybatis mybatis-spring spring-->
    <dependencies>
<!--        junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>

        </dependency>
<!--        数据库依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.23</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.mchange/c3p0 -->
<!--        数据库连接池-->
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.5</version>
        </dependency>
<!--        Servlet -JSP -->
        <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>
<!--Mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.6</version>
        </dependency>
<!--Spring-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.5</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.3.5</version>
        </dependency>
  <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>
    </dependencies>
<!--    静态资源导出问题-->
    <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>

</project>

连接数据库：测试连接成功要注意写时区

jdbc:mysql://localhost:3306/?serverTimezone=GMT

dao

BookMapper:

package com.kuang.dao;

import com.kuang.pojo.Books;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface BookMapper {
    //增加一本书
    int addBook(Books books);

    //删除一本书
    int deleteBookById(@Param("bookId") int id);

    //更新一本书
    int updateBook(Books books);

    //查询一本书  查询的是具体的书
    Books queryBookById(@Param("bookId")int id);

    //查询全部的书
    List<Books> queryAllBook();

}

BookMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.kuang.dao.BookMapper">
    <insert id="addBook" parameterType="Books">
        insert into ssmbuild.books(bookName,bookCounts,detail)
        values(#{bookName},#{bookCounts},#{detail});
    </insert>
    <delete id="deleteBookById" parameterType="int">
        delete from ssmbuild.books
        where bookID = #{bookId}
    </delete>

    <update id="updateBook" parameterType="Books">
        update ssmbuild.books
        set bookName=#{bookName},bookCounts=#{bookCounts},detail=#{detail}
        where bookID = #{bookID};
    </update>

    <select id="queryBookId" resultType="Books">
        select * from ssmbuild.books
        where bookID = #{bookId}
    </select>

    <select id="queryAllBook" resultType="Books">
        select * from ssmbuild.books
    </select>

</mapper>

pojo

Books:

package com.kuang.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Books {
    private int bookID;
    private String bookName;
    private int bookCounts;
    private String detail;

}

service

BookService

package com.kuang.services;

import com.kuang.pojo.Books;


import java.util.List;

public interface BookService {
    //增加一本书
    int addBook(Books books);

    //删除一本书
    int deleteBookById(int id);

    //更新一本书
    int updateBook(Books books);

    //查询一本书  查询的是具体的书
    Books queryBookById(int id);

    //查询全部的书
    List<Books> queryAllBook();

}

BookServiceImpl

package com.kuang.services;

import com.kuang.dao.BookMapper;
import com.kuang.pojo.Books;

import java.util.List;

public class BookServiceImpl implements BookService{

    //services调dao层  业务层是调dao层  mapper=dao

    private BookMapper bookMapper;

    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }

    public int addBook(Books books) {
        return bookMapper.addBook(books);
    }

    public int deleteBookById(int id) {
        return bookMapper.deleteBookById(id);
    }

    public int updateBook(Books books) {
        return bookMapper.updateBook(books);
    }

    public Books queryBookById(int id) {
        return bookMapper.queryBookById(id);
    }

    public List<Books> queryAllBook() {
        return bookMapper.queryAllBook();
    }
}

database.properties:

jdbc.driver=com.mysql.jdbc.Driver
# 如果使用的是Mysql8.0+需要增加一个时区的配置 &serverTimezone=Asia/Shanghai   但是在连接数据库测试时就加了时区 所有我觉得这里可以不加
jdbc.url=jdbc:mysql://localhost:3306/ssmbuild?useSSL=true&useUnicode=true&characterEncoding=utf8
jdbc.username=root
jdbc.password=123456

mybatis-config.xml

<?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>
<!-- 配置数据库源，交给Spring去做   -->
    <typeAliases>
        <package name="com.kuang.pojo"/>

    </typeAliases>
    <!--        两个名字一样用class  不一样用resources-->
    <mappers>
        <mapper class="com.kuang.dao.BookMapper"/>
    </mappers>

</configuration>

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
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd">
<!--    1.关联数据库配置文件-->
<context:property-placeholder location="classpath:database.properties"/>

<!--    2.连接池
dbcp:半自动化操作，不能自动连接
c3p0:自动化操作（自动化的加载配置文件，并且可以自动设置到对象中！）
druid: hikari

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


        <!-- c3p0连接池的私有属性 -->
        <property name="maxPoolSize" value="30"/>
        <property name="minPoolSize" value="10"/>
        <!-- 关闭连接后不自动commit -->
        <property name="autoCommitOnClose" value="false"/>
        <!-- 获取连接超时时间 10秒-->
        <property name="checkoutTimeout" value="10000"/>
        <!-- 当获取连接失败重试次数 -->
        <property name="acquireRetryAttempts" value="2"/>
    </bean>

<!--    3.sqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
<!--        绑定mybatis的配置文件-->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
    </bean>
<!--   4. 配置dao接口扫描包，动态的实现了Dao接口可以注入到Spring容器中   sqlSessionFactoryBeanName是以继承的方式  sqlSessionTemplateBeanName"私有-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<!--        MapperScannerConfigurer会扫描这个包中的所有接口，把每个接口都执行一次getMapper()方法，得到每个接口的dao对象 service也可以整合在spring配置文件里
刚配置的扫描dao会自己创建好dao对象，所以直接在下面声明service就行-->
<!--        注入sqlSessionFactory-->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
<!--        要扫描的dao包    String类型用value-->
        <property name="basePackage" value="com.kuang.dao"/>
    </bean>

</beans>

一个mapper对应一个接口

两个名字一样用class 不一样用resources

bookMapper爆红的解决办法：

先去查看这个地方是不是都在applicationContext中：如果没有spring-service.xml就点击上面的加号就可以添加了就不会爆红了

<bean id="BookServiceImpl" class="com.kuang.services.BookServiceImpl">
    <property name="bookMapper" ref="bookMapper"/>
</bean>

法一：添加下面这个语句在spring-service.xml中
<import resource="classpath: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
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd">
<import resource="classpath:spring-dao.xml"/>
<!--1.扫描service下的包-->
    <context:component-scan base-package="com.kuang.services"/>

<!--    2.将我们的所有的业务类，注入到spring,可以通过配置，或者注解实现-->
    <bean id="BookServiceImpl" class="com.kuang.services.BookServiceImpl">
        <property name="bookMapper" ref="bookMapper"/>
    </bean>
</beans>

法二：在applicationContext.xml中添加下面的语句

法二:
<?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">

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

</beans>

spring-service.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
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd">
<import resource="classpath:spring-dao.xml"/>
<!--1.扫描service下的包-->
    <context:component-scan base-package="com.kuang.services"/>

<!--    2.将我们的所有的业务类，注入到spring,可以通过配置，或者注解实现-->
    <bean id="BookServiceImpl" class="com.kuang.services.BookServiceImpl">
        <property name="bookMapper" ref="bookMapper"/>
    </bean>
</beans>

posted @ 2021-04-06 22:05 豆豆tj 阅读(111) 评论(0) 收藏举报

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豆豆tj

第88天学习打卡（SpringMVC springmvc数据处理 JSON 整合SSM的前一部分）

6 SpringMVC 数据处理

乱码问题

7 JSON

7.1 什么是JSON

7.2 Controller返回JSON数据

7.3 JSON使用

7.4FastJson使用

8 整合SSM

dao

pojo

service

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