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Merge pull request #9428 from SmartyAnsh/BAEL-View_Bytecode_of_a_Class_File_in_Java 

BAEL-4049 View bytecode of a class file in java
This commit is contained in:
Eric Martin 2020-06-11 21:15:24 -05:00 committed by GitHub
parent 6d6e62edeb 5d9b41411d
commit 0d9e691fe4
2 changed files with 69 additions and 1 deletions
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19
core-java-modules/core-java-jvm/pom.xml
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@ -51,14 +51,31 @@
<scope>system</scope>
<systemPath>${java.home}/../lib/tools.jar</systemPath>
</dependency>
<dependency>
<groupId>org.ow2.asm</groupId>
<artifactId>asm</artifactId>
<version>${asm.version}</version>
</dependency>
<dependency>
<groupId>org.ow2.asm</groupId>
<artifactId>asm-util</artifactId>
<version>${asm.version}</version>
</dependency>
<dependency>
<groupId>org.apache.bcel</groupId>
<artifactId>bcel</artifactId>
<version>${bcel.version}</version>
</dependency>
</dependencies>
<properties>
<assertj.version>3.6.1</assertj.version>
<!-- instrumentation -->
<javaassist.version>3.21.0-GA</javaassist.version>
<javaassist.version>3.27.0-GA</javaassist.version>
<esapi.version>2.1.0.1</esapi.version>
<sun.tools.version>1.8.0</sun.tools.version>
<asm.version>8.0.1</asm.version>
<bcel.version>6.5.0</bcel.version>
</properties>
</project>

51
core-java-modules/core-java-jvm/src/test/java/com/baeldung/bytecode/ViewBytecodeUnitTest.java Normal file
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@ -0,0 +1,51 @@
package com.baeldung.bytecode;
import static org.junit.Assert.assertTrue;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.JavaClass;
import org.junit.Test;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.util.TraceClassVisitor;
import javassist.ClassPool;
import javassist.NotFoundException;
import javassist.bytecode.ClassFile;
public class ViewBytecodeUnitTest {
@Test
public void whenUsingASM_thenReadBytecode() throws IOException {
ClassReader reader = new ClassReader("java.lang.Object");
StringWriter sw = new StringWriter();
TraceClassVisitor tcv = new TraceClassVisitor(new PrintWriter(sw));
reader.accept(tcv, 0);
assertTrue(sw.toString().contains("public class java/lang/Object"));
}
@Test
public void whenUsingBCEL_thenReadBytecode() throws ClassNotFoundException {
JavaClass objectClazz = Repository.lookupClass("java.lang.Object");
assertEquals(objectClazz.getClassName(), "java.lang.Object");
assertEquals(objectClazz.getMethods().length, 14);
assertTrue(objectClazz.toString().contains("public class java.lang.Object"));
}
@Test
public void whenUsingJavassist_thenReadBytecode() throws NotFoundException {
ClassPool cp = ClassPool.getDefault();
ClassFile cf = cp.get("java.lang.Object").getClassFile();
assertEquals(cf.getName(), "java.lang.Object");
assertEquals(cf.getMethods().size(), 14);
}
}