<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="INFO" monitorInterval="120">
    <properties>  
        <property name="MSG_LOG_HOME">/data/gpslog</property>
    </properties>
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d [%t] %-5p [%c] - %m%n" />
        </Console>
        <RollingRandomAccessFile name="msgAppender" immediateFlush="true"
            fileName="${MSG_LOG_HOME}/msg.log"
            filePattern="${MSG_LOG_HOME}/backup/msg.%d{yyyyMMddHH}.zip">
            <Filters>
                <ThresholdFilter level="INFO" onMatch="ACCEPT" onMismatch="DENY"/>
            </Filters>
            <PatternLayout pattern="%m%n" />
            <Policies>
                <TimeBasedTriggeringPolicy interval="1" modulate="true"/>
            </Policies>  
            <DefaultRolloverStrategy max="24">
                <Delete basePath="${MSG_LOG_HOME}" maxDepth="2">
                  <IfFileName glob="*/msg.*.zip" />
                  <IfLastModified age="24H" />
                </Delete>
            </DefaultRolloverStrategy>
        </RollingRandomAccessFile>
    </Appenders>
    <Loggers>
        <AsyncLogger name="com.roadway.DebugUtils" additivity="FALSE" level="INFO">
            <appender-ref ref="msgAppender" />
        </AsyncLogger>
    </Loggers>
</Configuration>

<DefaultRolloverStrategy max="24">
    <Delete basePath="${MSG_LOG_HOME}" maxDepth="2">
        <IfFileName glob="*/msg.*.zip" />
        <IfLastModified age="24H" />
    </Delete>
</DefaultRolloverStrategy>

<RollingRandomAccessFile name="msgAppender" 
   immediateFlush="false" 
   bufferSize="512"
   fileName="${MSG_LOG_HOME}/msg.log"
   filePattern="${MSG_LOG_HOME}/backup/msg.%d{yyyyMMddHH}.zip">
   ......

......
<AsyncLogger name="com.roadway.DebugUtils" additivity="FALSE" level="INFO">
    <appender-ref ref="msgAppender" />
</AsyncLogger>
......

public class DownLoadThread extends Thread {​
    private long start;
    private File src;
    private long total;
    private File desc;
​
    /**
     * 
     * @param start
     *            開始下載的位置
     * @param src
     *            要下載的文件
     * @param desc
     *            要下載的目的地
     * @param total
     *            要下載的總量
     */
    public DownLoadThread(long start, File src, File desc, long total) {
        this.start = start;
        this.src = src;
        this.desc = desc;
        this.total = total;
    }
​
    @Override
    public void run() {
        try {
            // 創(chuàng)建輸入流關(guān)聯(lián)源,因?yàn)橐付ㄎ恢米x和寫,所以我們需要用隨機(jī)訪問流
            RandomAccessFile src = new RandomAccessFile(this.src, "rw");
            RandomAccessFile desc = new RandomAccessFile(this.desc, "rw");
​
            // 源和目的都要從start開始
            src.seek(start);
            desc.seek(start);
            // 開始讀寫
            byte[] arr = new byte[1024];
            int len;
            long count = 0;
            while ((len = src.read(arr)) != -1) {
                //分三種情況
                if (len + count > total) {
                     //1.當(dāng)讀取的時(shí)候操作自己該線程的下載總量的時(shí)候,需要改變len
                    len = (int) (total - count);
                    desc.write(arr, 0, len);
                    //證明該線程下載任務(wù)已經(jīng)完畢,結(jié)束讀寫操作
                    break;
                } else if (len + count < total) {
                    //2.證明還沒有到下載總量,直接將內(nèi)容寫入
                    desc.write(arr, 0, len);
                    //并且使計(jì)數(shù)器任務(wù)累加
                    count += arr.length;
                } else {
                    //3.證明改好到下載總量
                    desc.write(arr, 0, len);
                    //結(jié)束讀寫
                    break;
                }
            }
            src.close();
            desc.close();
​
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

public class TestRandomAccess {​
    public static void main(String[] args) {
        //關(guān)聯(lián)源
        File src = new File("a.txt");
        //關(guān)聯(lián)目的
        File desc = new File("b.txt");
​
        //獲取源的總大小
        long length = src.length();
        // 開兩條線程,并分配下載任務(wù)
        new DownLoadThread(0, src, desc, length / 2).start();
        new DownLoadThread(length / 2 , src, desc, length - (length / 2)).start();
    }​
}