用来做springboot遇到的坑总结-后面会进行补充

错误一：

Invalid bound statement (not found)

在网上找了很多方法都没有解决：后面遇到的解决方法是：
mybatis会进行识别，比如mapper里面对应的resource下面文件名要一样（就是这个问题导致一直出错）
示例代码：

    @Resource
    private UserSystemMapper userSystemMapper;

采用这种方式进行service层进行mapper的引用 会出现文件名不一致而出现的导入错误，所以在使用的时候要注意文件命名问题；
具体其他解决方案：
参考：
参考地址一
参考地址二
记录时间：21-03-01

记录二：关于mybatis里面和数据库驼峰命名匹配问题

    <resultMap id="BaseResultMap" type="org.linlinjava.litemall.db.domain.TsendInfo">
        <!--
          WARNING - @mbg.generated
          This element is automatically generated by MyBatis Generator, do not modify.
        -->
        <id column="id" jdbcType="BIGINT" property="id" />
        <result column="admin_id" jdbcType="BIGINT" property="adminId" />
        <result column="send_name" jdbcType="VARCHAR" property="sendName" />
        <result column="send_phone" jdbcType="VARCHAR" property="sendPhone" />
        <result column="send_address" jdbcType="VARCHAR" property="sendAddress" />
        <result column="is_select" jdbcType="INTEGER" property="isSelect" />
        <result column="create_time" jdbcType="VARCHAR" javaType="Date" property="createTime" />
        <result column="update_time" jdbcType="VARCHAR" javaType="Date" property="updateTime" />
    </resultMap>
    <sql id="Example_Where_Clause">
        <!--
          WARNING - @mbg.generated
          This element is automatically generated by MyBatis Generator, do not modify.
        -->
        <where>
            <foreach collection="oredCriteria" item="criteria" separator="or">
                <if test="criteria.valid">
                    <trim prefix="(" prefixOverrides="and" suffix=")">
                        <foreach collection="criteria.criteria" item="criterion">
                            <choose>
                                <when test="criterion.noValue">
                                    and ${criterion.condition}
                                </when>
                                <when test="criterion.singleValue">
                                    and ${criterion.condition} #{criterion.value}
                                </when>
                                <when test="criterion.betweenValue">
                                    and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                                </when>
                                <when test="criterion.listValue">
                                    and ${criterion.condition}
                                    <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                                        #{listItem}
                                    </foreach>
                                </when>
                            </choose>
                        </foreach>
                        <foreach collection="criteria.galleryCriteria" item="criterion">
                            <choose>
                                <when test="criterion.noValue">
                                    and ${criterion.condition}
                                </when>
                                <when test="criterion.singleValue">
                                    and ${criterion.condition} #{criterion.value,typeHandler=org.linlinjava.litemall.db.mybatis.JsonStringArrayTypeHandler}
                                </when>
                                <when test="criterion.betweenValue">
                                    and ${criterion.condition} #{criterion.value,typeHandler=org.linlinjava.litemall.db.mybatis.JsonStringArrayTypeHandler} and #{criterion.secondValue,typeHandler=org.linlinjava.litemall.db.mybatis.JsonStringArrayTypeHandler}
                                </when>
                                <when test="criterion.listValue">
                                    and ${criterion.condition}
                                    <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                                        #{listItem,typeHandler=org.linlinjava.litemall.db.mybatis.JsonStringArrayTypeHandler}
                                    </foreach>
                                </when>
                            </choose>
                        </foreach>
                    </trim>
                </if>
            </foreach>
        </where>
    </sql>
    <sql id="Update_By_Example_Where_Clause">
        <!--
          WARNING - @mbg.generated
          This element is automatically generated by MyBatis Generator, do not modify.
        -->
        <where>
            <foreach collection="example.oredCriteria" item="criteria" separator="or">
                <if test="criteria.valid">
                    <trim prefix="(" prefixOverrides="and" suffix=")">
                        <foreach collection="criteria.criteria" item="criterion">
                            <choose>
                                <when test="criterion.noValue">
                                    and ${criterion.condition}
                                </when>
                                <when test="criterion.singleValue">
                                    and ${criterion.condition} #{criterion.value}
                                </when>
                                <when test="criterion.betweenValue">
                                    and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                                </when>
                                <when test="criterion.listValue">
                                    and ${criterion.condition}
                                    <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                                        #{listItem}
                                    </foreach>
                                </when>
                            </choose>
                        </foreach>
                        <foreach collection="criteria.galleryCriteria" item="criterion">
                            <choose>
                                <when test="criterion.noValue">
                                    and ${criterion.condition}
                                </when>
                                <when test="criterion.singleValue">
                                    and ${criterion.condition} #{criterion.value,typeHandler=org.linlinjava.litemall.db.mybatis.JsonStringArrayTypeHandler}
                                </when>
                                <when test="criterion.betweenValue">
                                    and ${criterion.condition} #{criterion.value,typeHandler=org.linlinjava.litemall.db.mybatis.JsonStringArrayTypeHandler} and #{criterion.secondValue,typeHandler=org.linlinjava.litemall.db.mybatis.JsonStringArrayTypeHandler}
                                </when>
                                <when test="criterion.listValue">
                                    and ${criterion.condition}
                                    <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                                        #{listItem,typeHandler=org.linlinjava.litemall.db.mybatis.JsonStringArrayTypeHandler}
                                    </foreach>
                                </when>
                            </choose>
                        </foreach>
                    </trim>
                </if>
            </foreach>
        </where>
    </sql>
    <sql id="Base_Column_List">
        <!--
          WARNING - @mbg.generated
          This element is automatically generated by MyBatis Generator, do not modify.
        -->
        id,admin_id,send_name,send_phone,send_address,is_select,create_time,update_time
    </sql>
    <sql id="Blob_Column_List">
        <!--
          WARNING - @mbg.generated
          This element is automatically generated by MyBatis Generator, do not modify.
        -->
        detail
    </sql>

只有配置完这些在mybatis里面才可以进行驼峰命名才可以使用

记录三：利用vue+element进行上传文件（这边是上传excel后端使用easyexcel进行处理）

//这边是上传excel
// 组件编写

<el-upload
        class="upload-demo"
        :action="uploadPath"
        :on-preview="handlePreview"
        :on-remove="handleRemove"
        :before-remove="beforeRemove"
        :limit="1"
        accept=".xls,.xlsx"
        :on-change="upload_excel"
        :on-exceed="handleExceed"
        :file-list="fileList"
      >
// 关键在于这一步的处理，把文件发送给后端，之前因为文件格式的错误导致一直报错
      upload_excel(fileList) {
      this.loading = false
      const formData = new FormData()
      formData.append('file', fileList.raw)
      upload_excel(formData).then(responese => {
        this.$message.success('上传成功！')
      }).catch(responese => {
        this.$message.error(responese.data.data.errmsg)
      })
    }
// 接口编写：
export function upload_excel(data) {
  return request({
    url: '/excelSystem/upload_excel',
    method: 'post',
    data
  })
}
// 这边接收的一定要是data的数据而且不加参数 如果加了：params:data这边会对数据进行解析就会导致错误,所以一定要避免

//后端的接受
@PostMapping("/upload_excel")
    public Object uploadExcel(@RequestParam("file") MultipartFile file){
        System.out.println(file);
        excelHandleService.handleExcel(file,excelHandleService);
        return ResponseUtil.ok();
    }
    // 最后使用easyexcel进行数据流的处理即可，图片上传也是 后面会加上oss直接上传到oos然后返回链接才是正确的操作

对了element中操作也不建议用on-success进行操作因为我们实际是操作数据流不做其他处理 所以会传一个undefine给后台会报错，使用on-change会上传两次 开始-结束，所以这边使用

        :http-request="upload_excel_btn"

使用这个方法然后,传文件上去即可

upload_excel_btn(file, fileList) {
      this.loading = false
      const formData = new FormData()
      formData.append('file', file.file)
      upload_excel(formData).then(responese => {
        this.$message.success('上传成功！')
      }).catch(responese => {
        this.$message.error(responese.data.data.errmsg)
      })
    }

记录问题三： discard long time none received connection. jdbcUrl : xxxx 使用阿里的druid出现

在大概的网上看了一下 有回答问题说回退版本。。。。。额，，这个治标不治本的回答。。

if (valid && isMySql) { // unexcepted branch
    long lastPacketReceivedTimeMs = MySqlUtils.getLastPacketReceivedTimeMs(conn);
    if (lastPacketReceivedTimeMs > 0) {
        long mysqlIdleMillis = currentTimeMillis - lastPacketReceivedTimeMs;
        if (lastPacketReceivedTimeMs > 0 //
                && mysqlIdleMillis >= timeBetweenEvictionRunsMillis) {
            discardConnection(holder);
            String errorMsg = "discard long time none received connection. "
                    + ", jdbcUrl : " + jdbcUrl
                    + ", version : " + VERSION.getVersionNumber()
                    + ", lastPacketReceivedIdleMillis : " + mysqlIdleMillis;
            LOG.warn(errorMsg);
            return false;
        }
    }
}

查看源码可以知道：这段代码大致意思就是如果一个连接空闲超过60s，就丢弃之（holder）并且打印一条warn日志。
所以我们就有了初步的解决方法，就是关掉ping方法 不让其过期
有具体做法：
1.运行时配置
即在运行参数中增加 ： 在运行参数中增加：
-Ddruid.mysql.usePingMethod=false
类文件配置
在项目的DruidConfig类中新增加：

/*
* 解决druid 日志报错：discard long time none received connection:xxx
* */
public class DruidConfig {
    @PostConstruct
    public void setProperties(){
        System.setProperty("druid.mysql.usePingMethod","false");
    }
}

关于出现配置问题：Spring Session without Spring Security leads to NoClassDefFoundError: org/springframework/security/web/authentication/RememberMeServices #16871

为了解决跨域问题导致的sessionId不一致的问题，引入了
spring-session-core会出现配置丢失的问题：
在百度怎么找都找不到解决方法，最后没办法上谷歌找到了解决方法
https://github.com/spring-projects/spring-boot/issues/16871

<dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.security</groupId>
                    <artifactId>spring-security-core</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

增加安全管理，排除安全验证 这样就可以了

关于redis中一些问题的解决：
关于redis的安装：
https://blog.youkuaiyun.com/w893932747/article/details/85549460
springboot注入不了redisTemplate<Long,Object>提示bean not foud
解决方法：@Autowrite 改为 @Resource

关于ssm项目的启动问题

1. Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cann
   这种问题一般要去看一下数据库配置问题：
   
   我出现的问题是后面的配置忘记加上导致配置出现错误；

还有一个问题搞了一晚上在开发前一定要对spring版本是否匹配jdk版本，这个问题导致出来的是配置一直出错