Java 개발에 일반적으로 사용되는 jar 패키지 구성 및 사용

<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 -->
<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.4</version>
</dependency>

<!-- https://mvnrepository.com/artifact/commons-io/commons-io --><dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.6</version></dependency>

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

public class Log4JTest {
    public static void main(String[] args) {   
        //获取Logger对象的实例（传入当前类）         
        Logger logger = Logger.getLogger(Log4JTest.class);
        //使用默认的配置信息，不需要写log4j.properties
        BasicConfigurator.configure();
        //设置日志输出级别为WARN，这将覆盖配置文件中设置的级别，只有日志级别低于WARN的日志才输出
        logger.setLevel(Level.WARN);
        logger.debug("这是debug");
        logger.info("这是info");
        logger.warn("这是warn");
        logger.error("这是error");
        logger.fatal("这是fatal");
    }
}

#控制台
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
#log jdbc
log4j.logger.java.sql.ResultSet=INFO
log4j.logger.org.apache=WARN
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG
#log mybatis设置
#log4j.logger.org.apache.ibatis=DEBUG
log4j.logger.org.apache.ibatis.jdbc=error
log4j.logger.org.apache.ibatis.io=info
log4j.logger.org.apache.ibatis.datasource=info
#springMVC日志
log4j.logger.org.springframework.web=WARN
# 文件输出配置
log4j.appender.A = org.apache.log4j.DailyRollingFileAppender
log4j.appender.A.File = D:/log.txt #指定日志的输出路径
log4j.appender.A.Append = true
log4j.appender.A.Threshold = DEBUG
log4j.appender.A.layout = org.apache.log4j.PatternLayout #使用自定义日志格式化器
log4j.appender.A.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n #指定日志的输出格式
log4j.appender.A.encoding=UTF-8 #指定日志的文件编码
#指定日志的输出级别与输出端
log4j.rootLogger=DEBUG,Console,A
#指定某个包名日志级别（不能超过上面定义的级别，否则日志不会输出）
log4j.logger.com.wan=DEBUG

//Logger的初始化（这个推荐定义为全局变量，方便使用）
Logger logger = Logger.getLogger(Log4JTest.class);
//输出Log
logger.info("这是info");

<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.8</version>
    <scope>provided</scope>
</dependency>

//这里我们只需要为类添加Data注解，就会自动生成对应属性的get/set方法，toString，equal等方法
@Data
public class User {
    private String username;
    private String password;
}

@Getter
@Setter
@NoArgsConstructor
public class User {
    private String username;
    private String password;
}

@Data
@Accessors(chain = true)
public class User {
    private String username;
    private String password;
}
//使用
User user = new User();
user.setUsername("helo").setPassword("123");

//如果调用此方法，就会抱一个空指针错误
public String print(@NotNull String str){
    ...
}

@ToString(callSuper=true, includeFieldNames=true)
public class User {
    private String username;
    private String password;
    //省略的get/set方法
}

@Data
@Builder
public class User {
    private String username;
    private String password;
}
//使用
User user1 = User.builder().username("user1").password("123").build();

@UtilityClass
public class MyUtils{
    //会将此方法自动转为静态方法
    public void print(String str){
        ...
    }
}
//使用
MyUtils.print("hello");

public static void main(String[] args) throws Exception {
    //使用Cleanup会自动调用close方法
    @Cleanup InputStream in = new FileInputStream(args[0]);
    @Cleanup OutputStream out = new FileOutputStream(args[1]);
    byte[] b = new byte[1024];
    while (true) {
        int r = in.read(b);
        if (r == -1) break;
        out.write(b, 0, r);
    }
}

@Log4j
@Log
public class User{
    //会自动添加此语句
    //Logger logger = Logger.getLogger(User.class);
    ...
}