Happywzy

@Scheduled

实现cron表达式从application.yml文件中获取

dbc:
  cron: 0/5 * * * * ?

@Component
@EnableScheduling
public class CompareSchedule {

    @Scheduled(cron = "${dbc.cron}")
    public void schedule(){
        System.out.println(1);
    }

}

cron表达式含义

cron一共有7位，但是最后一位是年，可以留空，所以我们可以写6位：

• 第一位，表示秒，取值0-59
• 第二位，表示分，取值0-59 
• 第三位，表示小时，取值0-23 
• 第四位，日期天/日，取值1-31
• 第五位，日期月份，取值1-12 
• 第六位，星期，取值1-7，星期一，星期二…，注：不是第1周，第二周的意思 另外：1表示星期天，2表示星期一。
• 第七位，年份，可以留空，取值1970-2099

cron中，还有一些特殊的符号，含义如下：

• (*)星号：可以理解为每的意思，每秒，每分，每天，每月，每年… 
• (?)问号：问号只能出现在日期和星期这两个位置，表示这个位置的值不确定，每天3点执行，所以第六位星期的位置，我们是不需要关注的，就是不确定的值。同时：日期和星期是两个相互排斥的元素，通过问号来表明不指定值。比如，1月10日，比如是星期1，如果在星期的位置是另指定星期二，就前后冲突矛盾了。
• (-)减号：表达一个范围，如在小时字段中使用“10-12”，则表示从10到12点，即10,11,12 
• (,)逗号：表达一个列表值，如在星期字段中使用“1,2,4”，则表示星期一，星期二，星期四 
• (/)斜杠：如：x/y，x是开始值，y是步长，比如在第一位（秒） 0/15就是，从0秒开始，每15秒，最后就是0，15，30，45，60 另：*/y，等同于0/y

下面列举几个例子供大家来验证：

• 0 0 3 * * ? 每天3点执行 
• 0 5 3 * * ? 每天3点5分执行 
• 0 5 3 ? * * 每天3点5分执行，与上面作用相同
• 0 5/10 3 * * ? 每天3点的 5分，15分，25分，35分，45分，55分这几个时间点执行 
• 0 10 3 ? * 1 每周星期天，3点10分 执行，注：1表示星期天 
• 0 10 3 ? * 1 #3 每个月的第三个星期，星期天 执行，#号只能出现在星期的位置

方法1

这种方法能够查询到一些表信息，但是不够详细

PreparedStatement pst = connection.prepareStatement("select * from t_gateway_logs where 1=2");
ResultSet rs = pst.executeQuery();
ResultSetMetaData rsd = rs.getMetaData();
for(int i = 0; i < rsd.getColumnCount(); i++) {
    System.out.print("java类型："+rsd.getColumnClassName(i + 1));
    System.out.print("  数据库类型:"+rsd.getColumnTypeName(i + 1));
    System.out.print("  字段名称:"+rsd.getColumnName(i + 1));
    System.out.print("  字段长度:"+rsd.getColumnDisplaySize(i + 1));
    System.out.print("  是否为空:"+rsd.isNullable(i + 1));
    System.out.print("  是否自增:"+rsd.isAutoIncrement(i + 1));
    System.out.println();
}

方法二

查询出来的内容非常多。

查询出库中所有表

ResultSet tableRet = connection.getMetaData().getTables(null, "%","%",new String[]{"TABLE"});
while(tableRet.next()) {
    System.out.println(tableRet.getString("TABLE_NAME"));
}

查询某个表的主键信息

ResultSet pkInfo = connection.getMetaData().getPrimaryKeys(null, "%", "test_table");
while (pkInfo.next()) {
    System.out.println("TABLE_CAT:" + pkInfo.getString("TABLE_CAT") + " ");
    System.out.println("TABLE_NAME:" + pkInfo.getString("TABLE_NAME") + " ");
    System.out.println("COLUMN_NAME:" + pkInfo.getString("COLUMN_NAME") + " ");
    System.out.println("PK_NAME:" + pkInfo.getString("PK_NAME") + " ");
    System.out.println("TABLE_SCHEM:" + pkInfo.getString("TABLE_SCHEM") + " ");
    System.out.println("KEY_SEQ:" + pkInfo.getString("KEY_SEQ") + " ");
}

查询某个表的详细信息

ResultSet colRet = connection.getMetaData().getColumns(null, "%", "test_table", "%");
while (colRet.next()) {
    System.out.println(colRet.getString("TABLE_CAT"));
    System.out.println(colRet.getString("TABLE_SCHEM"));
    System.out.println(colRet.getString("TABLE_NAME"));
    System.out.println(colRet.getString("COLUMN_NAME"));
    System.out.println(colRet.getString("DATA_TYPE"));
    System.out.println(colRet.getString("TYPE_NAME"));
    System.out.println(colRet.getInt("COLUMN_SIZE"));
    System.out.println(colRet.getInt("BUFFER_LENGTH"));
    System.out.println(colRet.getInt("DECIMAL_DIGITS"));
    System.out.println(colRet.getInt("NUM_PREC_RADIX"));
    System.out.println(colRet.getInt("NULLABLE"));
    System.out.println(colRet.getString("REMARKS"));
    System.out.println(colRet.getString("COLUMN_DEF"));
    System.out.println(colRet.getInt("SQL_DATA_TYPE"));
    System.out.println(colRet.getInt("SQL_DATETIME_SUB"));
    System.out.println(colRet.getInt("CHAR_OCTET_LENGTH"));
    System.out.println(colRet.getInt("ORDINAL_POSITION"));
    System.out.println(colRet.getBoolean("IS_NULLABLE"));
    System.out.println(colRet.getInt("SCOPE_CATALOG"));
    System.out.println(colRet.getInt("SCOPE_SCHEMA"));
    System.out.println(colRet.getInt("SCOPE_TABLE"));
    System.out.println(colRet.getInt("SOURCE_DATA_TYPE"));
    System.out.println(colRet.getBoolean("IS_AUTOINCREMENT"));
    System.out.println(colRet.getBoolean("IS_GENERATEDCOLUMN"));
}

问题描述

Maven打包jar用的默认插件是maven-jar-plugin，默认Maven生成的JAR包只包含了编译生成的.class文件和项目资源文件。有两个问题：

• 运行时提示没有主清单属性;
• 依赖的jar包也没有打包进去.

解决办法

maven打包插件有很多种：

• maven-shade-plugin
• maven-assembly-plugin
• maven-jar-plugin

我们直接重新定义maven-jar-plugin,详细配置如下：

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>1.2.1</version>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                    <configuration>
                        <transformers>
                            <transformer
                                    implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                <!-- 这里指定main函数 -->
                                <mainClass>com.deri.App</mainClass>
                            </transformer>
                        </transformers>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

问题描述

使用logback打印日志，启动服务时logback会打印一些自身的调试信息如下，会打印它检查了哪些配置、看见了哪些配置：

18:00:22,729 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback-test.xml]
18:00:22,729 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback.groovy]
18:00:22,729 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Found resource [logback.xml] at [file:/D:/DeriGateway/DBCompare/target/classes/logback.xml]
18:00:22,770 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - debug attribute not set
18:00:22,775 |-INFO in ch.qos.logback.core.joran.action.TimestampAction - Using current interpretation time, i.e. now, as time reference.
18:00:22,788 |-INFO in ch.qos.logback.core.joran.action.TimestampAction - Adding property to the context with key="DATETIME" and value="2020-04-01 18:00:22" to the LOCAL scope
18:00:22,788 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.core.ConsoleAppender]
18:00:22,793 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [STDOUT]
18:00:22,796 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property
18:00:22,813 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.core.rolling.RollingFileAppender]
18:00:22,816 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [FILEOUT]
18:00:22,817 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property
18:00:22,828 |-INFO in c.q.l.core.rolling.TimeBasedRollingPolicy@984849465 - No compression will be used
18:00:22,829 |-INFO in c.q.l.core.rolling.TimeBasedRollingPolicy@984849465 - Will use the pattern ./logs//log.%d.%i.log for the active file
18:00:22,830 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@2eee9593 - The date pattern is 'yyyy-MM-dd' from file name pattern './logs//log.%d.%i.log'.
18:00:22,830 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@2eee9593 - Roll-over at midnight.
18:00:22,832 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@2eee9593 - Setting initial period to Wed Apr 01 18:00:22 CST 2020
18:00:22,833 |-WARN in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@2eee9593 - SizeAndTimeBasedFNATP is deprecated. Use SizeAndTimeBasedRollingPolicy instead
18:00:22,833 |-WARN in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@2eee9593 - For more information see http://logback.qos.ch/manual/appenders.html#SizeAndTimeBasedRollingPolicy
18:00:22,834 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILEOUT] - Active log file name: ./logs//log.2020-04-01.0.log
18:00:22,834 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILEOUT] - File property is set to [null]
18:00:22,835 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to INFO
18:00:22,835 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [STDOUT] to Logger[ROOT]
18:00:22,835 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILEOUT] to Logger[ROOT]
18:00:22,835 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - End of configuration.
18:00:22,836 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@7907ec20 - Registering current configuration as safe fallback point

关闭logback自身调试信息打印

只需增加一行以下配置即可。将状态信息监听器设置为无操作监听器。

<configuration>
    <statusListener class="ch.qos.logback.core.status.NopStatusListener" />
</configuration>

完整logback.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <statusListener class="ch.qos.logback.core.status.NopStatusListener" />
    <property name="ROOT" value="./logs/" />
    <property name="FILESIZE" value="100MB" />
    <property name="MAXHISTORY" value="30" />
    <timestamp key="DATETIME" datePattern="yyyy-MM-dd HH:mm:ss" />
    <!-- 控制台打印 -->
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>[%-5level] %d{${DATETIME}} [%thread] %logger{36} - %m%n</pattern>
        </encoder>
    </appender>
    <!-- 输入到文件，按日期和文件大小 -->
    <appender name="FILEOUT" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <encoder>
            <pattern>[%-5level] %d{${DATETIME}} [%thread] %logger{36} - %m%n</pattern>
        </encoder>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>${ROOT}/log.%d.%i.log</fileNamePattern>
            <maxHistory>${MAXHISTORY}</maxHistory>
            <timeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
                <maxFileSize>${FILESIZE}</maxFileSize>
            </timeBasedFileNamingAndTriggeringPolicy>
        </rollingPolicy>
    </appender>
    <!-- Logger 根目录 -->
    <root level="INFO">
        <appender-ref ref="STDOUT" />
        <appender-ref ref="FILEOUT" />
    </root>
</configuration>

静态方式

直接在bootstrap.yml或者application.yml中写死；

spring:
  #mysql数据配置
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: 123456
    url: jdbc:mysql://192.168.41.128:3306/gw?useUnicode=true&characterEncoding=utf8&useSSL=false

缺点是参数需要改变时，需要重新改写配置，再打包。特别docker部署时，环境变化了，配置改动麻烦。

解决办法

在yml文件中，通过${Envirment_variable}的方式可以获取系统环境变量中的值；如上面的配置改写成：

spring:
  #mysql数据配置
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: ${USER_NAME:root}
    password: ${PASSWORD:123456}
    url: jdbc:mysql://${IP:192.168.41.128:3306}/gw?useUnicode=true&characterEncoding=utf8&useSSL=false

以上配置，优先设置系统环境变量（USER_NAME、PASSWORD、IP）的值，如果没有，才会使用默认值。

docker部署传入环境变量

• 通过-e可以传入环境变量;
• docker-compose可以通过environment传入系统环境变量;