模拟Log4j输出信息

一直以来都觉得system.out.print输出的信息不够详细，不能像log4j那样输出日期时间，输出的类，输出的类型等等；使用[log4j][1]虽然简单，但是在很多时候我们只需要log4j的简单的打印输出功能，所以在这里我模拟log4j，写了一个简单的工具类

public class Log {    protected Class<?> clazz = Log.class;//利用java反射得到class,继而可以得到类名    protected boolean date_type = false;//日期类型，true打印日期时间，false打印日期    protected int log_level = 1;//输出等级    //protected static int min_level = 1;//能输出的最小等级等级    //protected static int max_level = 1;//能输出的最大等级等级    public static final int LOG_LV_INFO = 3;    public static final int LOG_LV_DEBUG = 2;    public static final int LOG_LV_ERROR = 1;    public Log() {    }    public Log(Class<?> clazz) {        this.clazz = clazz;        this.date_type = false;        this.log_level = LOG_LV_INFO;    }    public Log(Class<?> clazz, boolean date_type) {        this.clazz = clazz;        this.date_type = date_type;        this.log_level = LOG_LV_INFO;    }    public Log(Class<?> clazz, boolean date_type, int LV) {        this.clazz = clazz;        this.date_type = date_type;        this.log_level = LV;    }    public void out(String msg, Exception e){        if(date_type == true) {            System.out.println("[" + Dates.currentDateTime() + "] - [Exception] - [" + clazz.getSimpleName() +"] " + msg + " : " + e.getMessage());        } else {            System.out.println("[" + Dates.currentDate() + "] - [Exception] - [" + clazz.getSimpleName() +"] " + msg + " : " + e.getMessage());        }        e.printStackTrace();    }    public /*synchronized*/ void out(String str) {        String outStr;        if(date_type == true) {            outStr = "[" + Dates.currentDateTime() + "]-";        } else {            outStr = "[" + Dates.currentDate() + "]-";        }        outStr += "[" + clazz.getSimpleName() + "]-";        switch (log_level) {        case 3:            outStr += "[info]-";break;        case 2:            outStr += "[debug]-";break;        case 1:            outStr += "[error]-";break;        default:            break;        }        outStr +=  "[" + Thread.currentThread().getName() + "] " + str;        System.out.println(outStr);    }    /**     * <p>模拟log4j对象映射输出</p>     * 通过匹配{}，映射传入的每个对象<br>     * 知识点：Object...obj 该用法是JDK1.7的新特性，可以传入多个不同类型的对象     * <pre>     * log.out("A={},B={}{}","a","b",e,1,111)      *      = ... A={a},B={b}{Exception} 1 111     * </pre     */    public /*synchronized*/ void out(String str, Object...obj) {        for (int i = 0; i < obj.length; i++) {            if(null != obj[i]){                if(str.contains("{}")){                    int begin_index = str.indexOf("{}");                    str = str.substring(0, begin_index + 1) + obj[i].toString() + str.substring(begin_index + 1, str.length());                } else {                    str += " " + obj[i].toString();                }            }        }        out(str);    }

其中的Dates是我自己写的时间工具类，下面是使用方法，和log4j很相似

public class Test {    private static final Log log = new Log(Test.class,false,Log.LOG_LV_DEBUG);    public static void main(String[] args) {        Log logger = new Log(Test.class);        logger.out("123");        log.out("A={},B={},C={}{}","a","b","c",1,2);    }

输出结果是：
[2015-08-21]-[Test]-[info]-[main] 123
[2015-08-21]-[Test]-[debug]-[main] A={a},B={b},C={c}{1} 2

当然也可以模拟log4j，通过properties配置文件获取date_type，log_level等属性，也可以利用IO输出成log文件