xxx

mianshi/mianshi.iml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4" />

mianshi/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.example.mianshi</groupId>
+  <artifactId>mianshi</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+  <name>mianshi</name>
+  <!-- FIXME change it to the project's website -->
+  <url>http://www.example.com</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>1.7</maven.compiler.source>
+    <maven.compiler.target>1.7</maven.compiler.target>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.11</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
+      <plugins>
+        <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
+        <plugin>
+          <artifactId>maven-clean-plugin</artifactId>
+          <version>3.1.0</version>
+        </plugin>
+        <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
+        <plugin>
+          <artifactId>maven-resources-plugin</artifactId>
+          <version>3.0.2</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-compiler-plugin</artifactId>
+          <version>3.8.0</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-surefire-plugin</artifactId>
+          <version>2.22.1</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-jar-plugin</artifactId>
+          <version>3.0.2</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-install-plugin</artifactId>
+          <version>2.5.2</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-deploy-plugin</artifactId>
+          <version>2.8.2</version>
+        </plugin>
+        <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
+        <plugin>
+          <artifactId>maven-site-plugin</artifactId>
+          <version>3.7.1</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-project-info-reports-plugin</artifactId>
+          <version>3.0.0</version>
+        </plugin>
+      </plugins>
+    </pluginManagement>
+  </build>
+</project>

mianshi/src/main/java/org/example/mianshi/App.java

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+package org.example.mianshi;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * 不常使用的资源被释放掉
+ *
+ */
+public class App 
+{
+    public static void main( String[] args )
+    {
+
+        LinkedHashMap<String,String> linkedHashMap = new LinkedHashMap<String,String>(){
+
+            @Override
+            protected boolean removeEldestEntry(Map.Entry<String, String> eldest) {
+                return size()>3;
+            }
+        };
+
+        linkedHashMap.put("a","aaa");
+        linkedHashMap.put("b","bbb");
+        linkedHashMap.put("c","ccc");
+
+
+        linkedHashMap.forEach((k,v)->System.out.println(k+" = " + v));
+
+
+        System.out.println(linkedHashMap.get("a"));
+        System.out.println(linkedHashMap.get("b"));
+        System.out.println(linkedHashMap.get("c"));
+
+        linkedHashMap.forEach((k,v)->System.out.println(k+" = " + v));
+
+        linkedHashMap.put("d","ddd");
+
+        System.out.println("=========");
+
+        linkedHashMap.forEach((k,v)->System.out.println(k+" = " + v));
+
+
+    }
+}

mianshi/src/main/java/org/example/mianshi/filecopy/FilesFileCopyApp.java

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+package org.example.mianshi.filecopy;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.file.CopyOption;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
+
+/**
+ * 说明：Files的文件copy
+ * @author carter
+ * 创建时间： 2020年03月26日 9:32 上午
+ **/
+
+public class FilesFileCopyApp {
+
+    public static void main(String[] args) {
+
+        final File d = new File("/data/appenvs/fenv.properties");
+        final File s = new File("/data/appenvs/env.properties");
+
+        System.out.println("source file content :" + s.exists());
+        System.out.println("target file content :" + d.exists());
+
+        System.out.println("source content:");
+        try {
+            Files.lines(s.toPath()).forEach(System.out::println);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        System.out.println("do file copy !");
+
+        copy(s, d);
+
+        System.out.println("target file content :" + d.exists());
+        System.out.println("target content:");
+        try {
+            Files.lines(d.toPath()).forEach(System.out::println);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    private static void copy(File s, File d) {
+
+        try {
+            Files.copy(s.toPath(),d.toPath(), StandardCopyOption.COPY_ATTRIBUTES);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+}

mianshi/src/main/java/org/example/mianshi/filecopy/JioFileCopyApp.java

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+package org.example.mianshi.filecopy;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.file.Files;
+
+/**
+ * 说明：传统的文件copy
+ * @author carter
+ * 创建时间： 2020年03月26日 9:32 上午
+ **/
+
+public class JioFileCopyApp {
+
+    public static void main(String[] args) {
+
+        final File d = new File("/data/appenvs/denv.properties");
+        final File s = new File("/data/appenvs/env.properties");
+
+        System.out.println("source file content :" + s.exists());
+        System.out.println("target file content :" + d.exists());
+
+        System.out.println("source content:");
+        try {
+            Files.lines(s.toPath()).forEach(System.out::println);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        System.out.println("do file copy !");
+
+        copy(s, d);
+
+        System.out.println("target file content :" + d.exists());
+        System.out.println("target content:");
+        try {
+            Files.lines(d.toPath()).forEach(System.out::println);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    private static void copy(File s, File d) {
+
+        try (
+                final FileInputStream fileInputStream = new FileInputStream(s);
+
+                final FileOutputStream fileOutputStream = new FileOutputStream(d)
+        ) {
+
+            byte[] buffer = new byte[1024];
+            int length;
+            while ((length = fileInputStream.read(buffer)) > 0) {
+                fileOutputStream.write(buffer, 0, length);
+            }
+
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+}

mianshi/src/main/java/org/example/mianshi/filecopy/JnioFileCopyApp.java

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+package org.example.mianshi.filecopy;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+
+/**
+ * 说明：传统的文件copy
+ * @author carter
+ * 创建时间： 2020年03月26日 9:32 上午
+ **/
+
+public class JnioFileCopyApp {
+
+    public static void main(String[] args) {
+
+        final File d = new File("/data/appenvs/ndenv.properties");
+        final File s = new File("/data/appenvs/env.properties");
+
+        System.out.println(s.getAbsolutePath() + "source file content :" + s.exists());
+        System.out.println(d.getAbsolutePath() +"target file content :" + d.exists());
+
+        System.out.println("source content:");
+        try {
+            Files.lines(s.toPath()).forEach(System.out::println);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        System.out.println("do file copy !");
+
+        copy(s, d);
+
+        System.out.println(d.getAbsolutePath() +"target file content :" + d.exists());
+        System.out.println("target content:");
+        try {
+            Files.lines(d.toPath()).forEach(System.out::println);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    private static void copy(File s, File d) {
+
+        try (
+                final FileChannel sourceFileChannel = new FileInputStream(s).getChannel();
+
+                final FileChannel targetFileChannel = new FileOutputStream(d).getChannel()
+        ) {
+
+           for (long count= sourceFileChannel.size();count>0;){
+
+               final long transferTo = sourceFileChannel.transferTo(sourceFileChannel.position(), count, targetFileChannel);
+
+               count-=transferTo;
+
+           }
+
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+}