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BAEL-13505 Move articles out of core java - part 2

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This commit is contained in:
Sjmillington
2019-10-07 17:07:57 +01:00
parent c2b029fd85
commit d97f501cbd
25 changed files with 49 additions and 36 deletions
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32
core-java-modules/core-java/src/main/java/com/baeldung/classloader/CustomClassLoader.java
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@@ -1,32 +0,0 @@
package com.baeldung.classloader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
public class CustomClassLoader extends ClassLoader {
@Override
public Class findClass(String name) throws ClassNotFoundException {
byte[] b = loadClassFromFile(name);
return defineClass(name, b, 0, b.length);
}
private byte[] loadClassFromFile(String fileName) {
InputStream inputStream = getClass().getClassLoader().getResourceAsStream(
fileName.replace('.', File.separatorChar) + ".class");
byte[] buffer;
ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
int nextValue = 0;
try {
while ( (nextValue = inputStream.read()) != -1 ) {
byteStream.write(nextValue);
}
} catch (IOException e) {
e.printStackTrace();
}
buffer = byteStream.toByteArray();
return buffer;
}
}

22
core-java-modules/core-java/src/main/java/com/baeldung/classloader/PrintClassLoader.java
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@@ -1,22 +0,0 @@
package com.baeldung.classloader;
import com.sun.javafx.util.Logging;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
public class PrintClassLoader {
public void printClassLoaders() throws ClassNotFoundException {
System.out.println("Classloader of this class:" + PrintClassLoader.class.getClassLoader());
System.out.println("Classloader of Logging:" + Logging.class.getClassLoader());
System.out.println("Classloader of ArrayList:" + ArrayList.class.getClassLoader());
}
}

70
core-java-modules/core-java/src/main/java/com/baeldung/instrumentation/agent/AtmTransformer.java
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@@ -1,70 +0,0 @@
package com.baeldung.instrumentation.agent;
import javassist.CannotCompileException;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;
import javassist.NotFoundException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;
public class AtmTransformer implements ClassFileTransformer {
private static Logger LOGGER = LoggerFactory.getLogger(AtmTransformer.class);
private static final String WITHDRAW_MONEY_METHOD = "withdrawMoney";
/** The internal form class name of the class to transform */
private String targetClassName;
/** The class loader of the class we want to transform */
private ClassLoader targetClassLoader;
public AtmTransformer(String targetClassName, ClassLoader targetClassLoader) {
this.targetClassName = targetClassName;
this.targetClassLoader = targetClassLoader;
}
@Override
public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
byte[] byteCode = classfileBuffer;
String finalTargetClassName = this.targetClassName.replaceAll("\\.", "/"); //replace . with /
if (!className.equals(finalTargetClassName)) {
return byteCode;
}
if (className.equals(finalTargetClassName) && loader.equals(targetClassLoader)) {
LOGGER.info("[Agent] Transforming class MyAtm");
try {
ClassPool cp = ClassPool.getDefault();
CtClass cc = cp.get(targetClassName);
CtMethod m = cc.getDeclaredMethod(WITHDRAW_MONEY_METHOD);
m.addLocalVariable("startTime", CtClass.longType);
m.insertBefore("startTime = System.currentTimeMillis();");
StringBuilder endBlock = new StringBuilder();
m.addLocalVariable("endTime", CtClass.longType);
m.addLocalVariable("opTime", CtClass.longType);
endBlock.append("endTime = System.currentTimeMillis();");
endBlock.append("opTime = (endTime-startTime)/1000;");
endBlock.append("LOGGER.info(\"[Application] Withdrawal operation completed in:\" + opTime + \" seconds!\");");
m.insertAfter(endBlock.toString());
byteCode = cc.toBytecode();
cc.detach();
} catch (NotFoundException | CannotCompileException | IOException e) {
LOGGER.error("Exception", e);
}
}
return byteCode;
}
}

59
core-java-modules/core-java/src/main/java/com/baeldung/instrumentation/agent/MyInstrumentationAgent.java
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@@ -1,59 +0,0 @@
package com.baeldung.instrumentation.agent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.lang.instrument.Instrumentation;
public class MyInstrumentationAgent {
private static Logger LOGGER = LoggerFactory.getLogger(MyInstrumentationAgent.class);
public static void premain(String agentArgs, Instrumentation inst) {
LOGGER.info("[Agent] In premain method");
String className = "com.baeldung.instrumentation.application.MyAtm";
transformClass(className,inst);
}
public static void agentmain(String agentArgs, Instrumentation inst) {
LOGGER.info("[Agent] In agentmain method");
String className = "com.baeldung.instrumentation.application.MyAtm";
transformClass(className,inst);
}
private static void transformClass(String className, Instrumentation instrumentation) {
Class<?> targetCls = null;
ClassLoader targetClassLoader = null;
// see if we can get the class using forName
try {
targetCls = Class.forName(className);
targetClassLoader = targetCls.getClassLoader();
transform(targetCls, targetClassLoader, instrumentation);
return;
} catch (Exception ex) {
LOGGER.error("Class [{}] not found with Class.forName");
}
// otherwise iterate all loaded classes and find what we want
for(Class<?> clazz: instrumentation.getAllLoadedClasses()) {
if(clazz.getName().equals(className)) {
targetCls = clazz;
targetClassLoader = targetCls.getClassLoader();
transform(targetCls, targetClassLoader, instrumentation);
return;
}
}
throw new RuntimeException("Failed to find class [" + className + "]");
}
private static void transform(Class<?> clazz, ClassLoader classLoader, Instrumentation instrumentation) {
AtmTransformer dt = new AtmTransformer(clazz.getName(), classLoader);
instrumentation.addTransformer(dt, true);
try {
instrumentation.retransformClasses(clazz);
} catch (Exception ex) {
throw new RuntimeException("Transform failed for class: [" + clazz.getName() + "]", ex);
}
}
}

46
core-java-modules/core-java/src/main/java/com/baeldung/instrumentation/application/AgentLoader.java
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@@ -1,46 +0,0 @@
package com.baeldung.instrumentation.application;
import com.sun.tools.attach.VirtualMachine;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.util.Optional;
/**
* Created by adi on 6/10/18.
*/
public class AgentLoader {
private static Logger LOGGER = LoggerFactory.getLogger(AgentLoader.class);
public static void run(String[] args) {
String agentFilePath = "/home/adi/Desktop/agent-1.0.0-jar-with-dependencies.jar";
String applicationName = "MyAtmApplication";
//iterate all jvms and get the first one that matches our application name
Optional<String> jvmProcessOpt = Optional.ofNullable(VirtualMachine.list()
.stream()
.filter(jvm -> {
LOGGER.info("jvm:{}", jvm.displayName());
return jvm.displayName().contains(applicationName);
})
.findFirst().get().id());
if(!jvmProcessOpt.isPresent()) {
LOGGER.error("Target Application not found");
return;
}
File agentFile = new File(agentFilePath);
try {
String jvmPid = jvmProcessOpt.get();
LOGGER.info("Attaching to target JVM with PID: " + jvmPid);
VirtualMachine jvm = VirtualMachine.attach(jvmPid);
jvm.loadAgent(agentFile.getAbsolutePath());
jvm.detach();
LOGGER.info("Attached to target JVM and loaded Java agent successfully");
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}

14
core-java-modules/core-java/src/main/java/com/baeldung/instrumentation/application/Launcher.java
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@@ -1,14 +0,0 @@
package com.baeldung.instrumentation.application;
/**
* Created by adi on 6/14/18.
*/
public class Launcher {
public static void main(String[] args) throws Exception {
if(args[0].equals("StartMyAtmApplication")) {
new MyAtmApplication().run(args);
} else if(args[0].equals("LoadAgent")) {
new AgentLoader().run(args);
}
}
}

19
core-java-modules/core-java/src/main/java/com/baeldung/instrumentation/application/MyAtm.java
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@@ -1,19 +0,0 @@
package com.baeldung.instrumentation.application;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Created by adi on 6/11/18.
*/
public class MyAtm {
private static Logger LOGGER = LoggerFactory.getLogger(MyAtm.class);
private static final int account = 10;
public static void withdrawMoney(int amount) throws InterruptedException {
Thread.sleep(2000l); //processing going on here
LOGGER.info("[Application] Successful Withdrawal of [{}] units!", amount);
}
}

19
core-java-modules/core-java/src/main/java/com/baeldung/instrumentation/application/MyAtmApplication.java
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@@ -1,19 +0,0 @@
package com.baeldung.instrumentation.application;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class MyAtmApplication {
private static Logger LOGGER = LoggerFactory.getLogger(MyAtmApplication.class);
public static void run(String[] args) throws Exception {
LOGGER.info("[Application] Starting ATM application");
MyAtm.withdrawMoney(Integer.parseInt(args[2]));
Thread.sleep(Long.valueOf(args[1]));
MyAtm.withdrawMoney(Integer.parseInt(args[3]));
}
}

28
core-java-modules/core-java/src/main/java/com/baeldung/logforging/LogForgingDemo.java
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@@ -1,28 +0,0 @@
package com.baeldung.logforging;
import org.owasp.esapi.ESAPI;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class LogForgingDemo {
private final Logger logger = LoggerFactory.getLogger(LogForgingDemo.class);
public void addLog(String amount) {
logger.info("Amount credited = {}", amount);
}
public static void main(String[] args) {
LogForgingDemo demo = new LogForgingDemo();
demo.addLog("300");
demo.addLog("300 \n\nweb - 2017-04-12 17:47:08,957 [main] INFO Amount reversed successfully");
demo.addLog(encode("300 \n\nweb - 2017-04-12 17:47:08,957 [main] INFO Amount reversed successfully"));
}
public static String encode(String message) {
message = message.replace('\n', '_').replace('\r', '_').replace('\t', '_');
message = ESAPI.encoder().encodeForHTML(message);
return message;
}
}

2
core-java-modules/core-java/src/main/java/com/baeldung/printscreen/README.md
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@@ -1,2 +0,0 @@
### Relevant Articles:
- [How to Print Screen in Java](http://www.baeldung.com/print-screen-in-java)

23
core-java-modules/core-java/src/main/java/com/baeldung/printscreen/Screenshot.java
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@@ -1,23 +0,0 @@
package com.baeldung.printscreen;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
public class Screenshot {
private final String path;
public Screenshot(String path) {
this.path = path;
}
public void getScreenshot(int timeToWait) throws Exception {
Rectangle rectangle = new Rectangle(Toolkit.getDefaultToolkit()
.getScreenSize());
Robot robot = new Robot();
BufferedImage img = robot.createScreenCapture(rectangle);
ImageIO.write(img, "jpg", new File(path));
}
}

18
core-java-modules/core-java/src/main/java/com/baeldung/system/DetectOS.java
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@@ -1,18 +0,0 @@
package com.baeldung.system;
import org.apache.commons.lang3.SystemUtils;
public class DetectOS {
public String getOperatingSystem() {
String os = System.getProperty("os.name");
System.out.println("Using System Property: " + os);
return os;
}
public String getOperatingSystemSystemUtils() {
String os = SystemUtils.OS_NAME;
System.out.println("Using SystemUtils: " + os);
return os;
}
}