【java】弃用System.out.println()，迎接log

展示性能差异：

1.System.out.println()输出

package com.sxd.swapping.test;

import org.junit.Test;

public class LogTest {

    @Test
    public void system(){
        long start = System.currentTimeMillis() ;

        for (int i = 0; i < 1000000; i++) {
            System.out.println("System.out.println输出"+i);
        }

        long time = System.currentTimeMillis() - start;
        System.out.println(time);
    }
}

2. org.apache.log4j.Logger  输出

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

package com.sxd.swapping.test;

import org.apache.log4j.Logger;
import org.junit.Test;

public class LogTest {

    static Logger apache_log4j = Logger.getRootLogger();

    @Test
    public void system(){
        long start = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            apache_log4j.error("apache_log4j输出"+i);
        }
        long time = System.currentTimeMillis()-start;
        apache_log4j.info(time);
    }
}

3. java.util.logging.Logger 输出

package com.sxd.swapping.test;

import org.junit.Test;
import java.util.logging.Logger;

public class LogTest {

    static Logger util_logging = Logger.getLogger("");

    @Test
    public void system(){
        long start = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            util_logging.info("util_logging输出"+i);
        }
        long time = System.currentTimeMillis()-start;
        util_logging.info(String.valueOf(time));
    }
}