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线程代码提交
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‎city.xml‎

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<?xml version="1.0" encoding="UTF-8" standalone="no"?><china>
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<guangzhou play="gzchanglong">广州你好</guangzhou>
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<shenzhen>深圳</shenzhen>
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<shanghai>上海</shanghai>
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<guangxi>广西</guangxi>
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<hangzhou>杭州</hangzhou></china>

‎dom4j-1.6.1.jar‎

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‎dom4j.xml‎

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<?xml version="1.0" encoding="UTF-8" ?>
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<dom4j>
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<name littleName="属性值">dom4j模板</name>
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</dom4j>

‎src/city.xml‎

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<?xml version="1.0" encoding="UTF-8" ?>
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<china>
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<guangzhou>广州</guangzhou>
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<shenzhen>深圳</shenzhen>
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<shanghai>上海</shanghai>
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<beijing>北京</beijing>
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</china>

‎src/com/yale/test/run/Cleaner01.png‎

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‎src/com/yale/test/run/Cleaner02.png‎

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‎src/com/yale/test/run/CleanerTest.java‎

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package com.yale.test.run;
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import sun.misc.Cleaner;
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/**
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* 但是从JDK1.9开始,这一操作已经不建议使用了,而对于对象回收释放.从JDK1.9开始建议开发者使用AutoCloseable
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* 或者使用java.lang.ref.Cleaner类进行回收(Cleaner也支持有AutoCloseable处理).
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* Cleaner实际上是重新启用一个线程来做回收的
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* 在新一代的清除回收处理的过程之中,更过的情况下考虑的是多线程的使用,即:为了防止有可能造成的延迟,
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* 所以许多对象回收前的处理都是单独通过一个线程完成的。
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*/
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public class CleanerTest {
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public static void main(String[] args) {
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Cleaner cleaner = Cleaner.create();
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}
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}

‎src/com/yale/test/run/RunntimeTest.java‎

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package com.yale.test.run;
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/**
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* Runtime描述的是运行时的状态,也就是说在整个的JVM之中,Runtime类是唯一一个与JVM运行状态有关的类,
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* 并且都会默认提供有一个该类的实例化对象。
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* 由于在每一个JVM进程里面只允许提供一个Runtime类的对象,所以这个类的构造方法被默认私有化了,那么就证明该类
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* 使用的是单例设计模式
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* 阿里云 魔乐科技的JAVA教程视频
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* https://edu.aliyun.com/lesson_36_446?spm=5176.8764728.0.0.3ead521ct2pu1e#_446
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* https://edu.aliyun.com/course/explore/gentech?spm=5176.10731491.category.12.78904d8aB9zl2v&subCategory=java&filter%5Btype%5D=all&filter%5Bprice%5D=all&filter%5BcurrentLevelId%5D=all&orderBy=studentNum&title=
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* @author dell
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*/
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public class RunntimeTest {
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public static void main(String[] args) {
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public static void main(String[] args) throws InterruptedException {
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RunntimeTest sdf = new RunntimeTest();
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sdf = null;//等待垃圾回收
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Runtime run = Runtime.getRuntime();
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System.out.println("最大内存:" + run.maxMemory());
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System.out.println("可用内存:" + run.totalMemory());
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System.out.println("空余内存:" + run.freeMemory());
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System.out.println("获取最大可用内存空间:" + run.maxMemory() + "字节,默认的配置为本机系统内存的4分之1");
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System.out.println("获取可用内存空间:" + run.totalMemory() + "字节,默认的配置为本机系统内存的64分之1");
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System.out.println("获取空余内存空间:" + run.freeMemory() + "字节");
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System.out.println("availableProcessors方法可以获取本机的CPU内核数:" + run.availableProcessors());
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String str = "垃圾空间";
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for (int i=0;i <30000; i++) {
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str = str + i;
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}
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System.out.println("[2]获取最大可用内存空间:" + run.maxMemory() + "字节,默认的配置为本机系统内存的4分之1");
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System.out.println("[2]获取可用内存空间:" + run.totalMemory() + "字节,默认的配置为本机系统内存的64分之1");
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System.out.println("[2]获取空余内存空间:" + run.freeMemory() + "字节");
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System.out.println("availableProcessors方法可以获取本机的CPU内核数:" + run.availableProcessors());
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Thread.sleep(2000);
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run.gc();//手工调用垃圾回收
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System.gc();
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System.gc();//System.gc内部调用的就是run.gc()
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RunntimeTest sdf = new RunntimeTest();
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try {
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sdf.finalize();
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} catch (Throwable e) {
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e.printStackTrace();
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}
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System.out.println("[3]获取最大可用内存空间:" + run.maxMemory() + "字节,默认的配置为本机系统内存的4分之1");
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System.out.println("[3]获取可用内存空间:" + run.totalMemory() + "字节,默认的配置为本机系统内存的64分之1");
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System.out.println("[3]获取空余内存空间:" + run.freeMemory() + "字节");
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System.out.println("availableProcessors方法可以获取本机的CPU内核数:" + run.availableProcessors());
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// RunntimeTest sdf = new RunntimeTest();
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// try {
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// sdf.finalize();
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// } catch (Throwable e) {
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// e.printStackTrace();
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// }
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}
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@Override
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protected void finalize() throws Throwable {
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System.out.println("finalize方法会在JAVA进行垃圾回收前,被自动调用" );
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/**
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* 但是从JDK1.9开始,这一操作已经不建议使用了,而对于对象回收释放.从JDK
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* 或者使用java.lang.ref.Cleaner类进行回收(Cleaner也支持有AutoCloseable处理).
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*/
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System.out.println("finalize方法会在JAVA进行垃圾回收前,被自动调用,这个方法抛出的异常类型为Throwable,但是这个类即使抛出异常了,也不影响后面代码的执行" );
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throw new Exception("我不影响后面代码的继续运行,因为我这个类马上就死了");
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}
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}

‎src/com/yale/test/run/SystemTest.java‎

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package com.yale.test.run;
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public class SystemTest {
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public static void main(String[] args) {
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//System.arraycopy(src, srcPos, dest, destPos, length);数组复制
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System.out.println(System.currentTimeMillis());
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}
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}

‎src/com/yale/test/run/阿里云学习视频.png‎

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