jad command support -d/--directory option (#2646)

core/src/main/java/com/taobao/arthas/core/command/klass100/ClassDumpTransformer.java

@@ -52,18 +52,23 @@ class ClassDumpTransformer implements ClassFileTransformer {
         return dumpResult;
     }
 
-    private void dumpClassIfNecessary(Class<?> clazz, byte[] data) {
-        String className = clazz.getName();
-        ClassLoader classLoader = clazz.getClassLoader();
+    public File dumpDir() {
         String classDumpDir = "classdump";
-
-        // 创建类所在的包路径
-        File dumpDir = null;
+        final File dumpDir;
         if (directory != null) {
             dumpDir = directory;
         } else {
             dumpDir = new File(arthasLogHome, classDumpDir);
         }
+        return dumpDir;
+    }
+
+    private void dumpClassIfNecessary(Class<?> clazz, byte[] data) {
+        String className = clazz.getName();
+        ClassLoader classLoader = clazz.getClassLoader();
+
+        // 创建类所在的包路径
+        File dumpDir = dumpDir();
         if (!dumpDir.mkdirs() && !dumpDir.exists()) {
             logger.warn("create dump directory:{} failed.", dumpDir.getAbsolutePath());
             return;

core/src/main/java/com/taobao/arthas/core/command/klass100/JadCommand.java

@@ -47,6 +47,7 @@ import java.util.regex.Pattern;
 @Description(Constants.EXAMPLE +
         "  jad java.lang.String\n" +
         "  jad java.lang.String toString\n" +
+        "  jad java.lang.String -d /tmp/jad/dump\n" +
         "  jad --source-only java.lang.String\n" +
         "  jad -c 39eb305e org/apache/log4j/Logger\n" +
         "  jad -c 39eb305e -E org\\\\.apache\\\\.*\\\\.StringUtils\n" +
@@ -62,6 +63,7 @@ public class JadCommand extends AnnotatedCommand {
     private boolean isRegEx = false;
     private boolean hideUnicode = false;
     private boolean lineNumber;
+    private String directory;
 
     /**
      * jad output source code only
@@ -118,6 +120,12 @@ public class JadCommand extends AnnotatedCommand {
         this.lineNumber = lineNumber;
     }
 
+    @Option(shortName = "d", longName = "directory")
+    @Description("Sets the destination directory for dummped class files required by cfr decompiler")
+    public void setDirectory(String directory) {
+        this.directory = directory;
+    }
+
     @Override
     public void process(CommandProcess process) {
         RowAffect affect = new RowAffect();
@@ -173,10 +181,19 @@ public class JadCommand extends AnnotatedCommand {
         allClasses.add(c);
 
         try {
-            ClassDumpTransformer transformer = new ClassDumpTransformer(allClasses);
+            final ClassDumpTransformer transformer;
+            if (directory == null) {
+                transformer = new ClassDumpTransformer(allClasses);
+            } else {
+                transformer = new ClassDumpTransformer(allClasses, new File(directory));
+            }
             InstrumentationUtils.retransformClasses(inst, transformer, allClasses);
 
             Map<Class<?>, File> classFiles = transformer.getDumpResult();
+            if (classFiles == null || classFiles.isEmpty()) {
+                return ExitStatus.failure(-1, "jad: fail to dump class file for decompiler, make sure you have write permission of the directory \"" + transformer.dumpDir() +
+                "\" or try with \"-d/--directory\" to specify the directory of dump files");
+            }
             File classFile = classFiles.get(c);
 
             Pair<String,NavigableMap<Integer,Integer>> decompileResult = Decompiler.decompileWithMappings(classFile.getAbsolutePath(), methodName, hideUnicode, lineNumber);

site/docs/doc/jad.md

@@ -176,3 +176,11 @@ Affect(row-cnt:1) cost in 190 ms.
 对于只有唯一实例的 ClassLoader 还可以通过`--classLoaderClass`指定 class name，使用起来更加方便：
 
 `--classLoaderClass` 的值是 ClassLoader 的类名，只有匹配到唯一的 ClassLoader 实例时才能工作，目的是方便输入通用命令，而`-c <hashcode>`是动态变化的。
+
+### 反编译时指定dump class文件目录 
+
+`jad`反编译需要将class dump到文件，默认会dump到logback.xml中配置的log目录下，使用`-d/--directory`可以将文件dump到指定目录。
+
+```java
+$ jad demo.MathGame -d /tmp/jad/dump
+```

site/docs/en/doc/jad.md

@@ -176,3 +176,11 @@ Affect(row-cnt:1) cost in 190 ms.
 For classloader with only one instance, it can be specified by `--classLoaderClass` using class name, which is more convenient to use.
 
 The value of `--classloaderclass` is the class name of classloader. It can only work when it matches a unique classloader instance. The purpose is to facilitate the input of general commands. However, `-c <hashcode>` is dynamic.
+
+### Decompile with specified directory for dumpping class
+
+Decompile class with `jad` need to dump corresponding classes into files. The default directory for dumpping classes is the directory of log file specified in logback.xml, we can use `-d/--directory` to specify the directory for dummping class.
+
+```java
+$ jad demo.MathGame -d /tmp/jad/dump
+```