Class ClassBodyEvaluator

java.lang.Object
org.codehaus.commons.compiler.Cookable
org.codehaus.commons.compiler.jdk.ClassBodyEvaluator
All Implemented Interfaces:
IClassBodyEvaluator, ICookable
public class ClassBodyEvaluator extends Cookable implements IClassBodyEvaluator
To set up a ClassBodyEvaluator object, proceed as described for IClassBodyEvaluator. Alternatively, a number of "convenience constructors" exist that execute the described steps instantly.

Notice that this implementation of IClassBodyEvaluator is prone to "Java injection", i.e. an application could get more than one class body compiled by passing a bogus input document.

Also notice that the parsing of leading IMPORT declarations is heuristic and has certain limitations; see parseImportDeclarations(Reader).

See Also:

  • Constructor Details

    • ClassBodyEvaluator

      public ClassBodyEvaluator()

  • Method Details

    • setClassName

      public void setClassName(String className)
      Description copied from interface: IClassBodyEvaluator
      Sets the name of the generated class. Defaults to IClassBodyEvaluator.DEFAULT_CLASS_NAME. In most cases, there is no need to set this name, because the generated class is loaded into its own ClassLoader where its name cannot collide with classes generated by other evaluators.

      One reason to use this function is to have a class name in a non-default package, which can be relevant when types and members with DEFAULT accessibility are accessed.

      Specified by:
      setClassName in interface IClassBodyEvaluator

    • setDefaultImports

      public void setDefaultImports(String... defaultImports)
      Description copied from interface: IClassBodyEvaluator
      "Default imports" add to the system import "java.lang", i.e. the evaluator may refer to classes imported by default imports without having to explicitly declare IMPORT statements.

      Notice that JDK 5 "static imports" are also supported, as shown here: 

          sc.setDefaultImports(
        "java.util.Map",                          // Single type import
        "java.io.*",                              // Type-import-on-demand
        "static java.util.Collections.EMPTY_MAP", // Single static import
        "static java.util.Collections.*",         // Static-import-on-demand
    );
      Specified by:
      setDefaultImports in interface IClassBodyEvaluator

    • getDefaultImports

      public String[] getDefaultImports()
      Specified by:
      getDefaultImports in interface IClassBodyEvaluator
      Returns:
      The default imports that were previously configured with IClassBodyEvaluator.setDefaultImports(String...)

    • setExtendedClass

      public void setExtendedClass(@Nullable Class<?> extendedType)
      Description copied from interface: IClassBodyEvaluator
      Sets a particular superclass that the generated class will extend. If extendedClass is null, the generated class will extend Object.

      The usual reason to set a base class for an evaluator is that the generated class can directly access the superclass's (non-private) members.

      Specified by:
      setExtendedClass in interface IClassBodyEvaluator

    • setExtendedType

      @Deprecated public void setExtendedType(@Nullable Class<?> extendedClass)
      Deprecated.
      Use setExtendedClass(Class) instead
      Specified by:
      setExtendedType in interface IClassBodyEvaluator

    • setImplementedInterfaces

      public void setImplementedInterfaces(Class<?>[] implementedTypes)
      Description copied from interface: IClassBodyEvaluator
      Sets a particular set of interfaces that the generated class will implement.
      Specified by:
      setImplementedInterfaces in interface IClassBodyEvaluator

    • setImplementedTypes

      @Deprecated public void setImplementedTypes(Class<?>[] implementedInterfaces)
      Deprecated.
      Use setImplementedInterfaces(Class[]) instead
      Specified by:
      setImplementedTypes in interface IClassBodyEvaluator

    • setParentClassLoader

      public void setParentClassLoader(@Nullable ClassLoader parentClassLoader)
      Description copied from interface: IClassBodyEvaluator
      The "parent class loader" is used to load referenced classes. Useful values are:
      System.getSystemClassLoader() The running JVM's class path
      Thread.currentThread().getContextClassLoader() or null The class loader effective for the invoking thread
      ClassLoaders.BOOTCLASSPATH_CLASS_LOADER The running JVM's boot class path

      The parent class loader defaults to the current thread's context class loader.

      Specified by:
      setParentClassLoader in interface IClassBodyEvaluator

    • setSandboxPolicy

      public void setSandboxPolicy(@Nullable SandboxPolicy policy)
      Description copied from interface: ICookable
      Restricts the APIs that the cooked code may use. If set, then all generated classes are verified against the policy before they are loaded, and cooking fails with a CompileException that lists all violations if the code uses any field, method or constructor that the policy does not allow.

      Must be called before cooking. null (the default) means that the generated code is not restricted.

      If a policy is set, then the generated classes always contain debugging information about the source file and the line numbers, so that the violations can be reported with their locations in the cooked document (see SandboxViolation.getLocation()).

      Specified by:
      setSandboxPolicy in interface ICookable
      See Also:

    • setProtectionDomain

      public void setProtectionDomain(@Nullable ProtectionDomain protectionDomain)
      Description copied from interface: ICookable
      Sets the ProtectionDomain with which the generated classes are defined.

      Must be called before cooking. null (the default) means that the generated classes are defined with the protection domain of the compiler itself, i.e. that they have the same permissions as the compiler.

      Use this when the cooked code is executed in a Sandbox: Without it, the cooked code could call AccessController.doPrivileged() and would then run with the permissions of the compiler, not with the permissions of the sandbox. To prevent that, define the generated classes with the same permissions as the sandbox, through a protection domain with static permissions (i.e. one that is created with the two-argument constructor ProtectionDomain(java.security.CodeSource, java.security.PermissionCollection), which does not consult the global Policy): 

          Sandbox sandbox = new Sandbox(permissions);
    scriptEvaluator.setProtectionDomain(new ProtectionDomain(null, permissions));
    scriptEvaluator.cook(script);
    sandbox.confine(...);

      On JVMs without a security manager, protection domains have no effect.

      Specified by:
      setProtectionDomain in interface ICookable
      See Also:

    • setDebuggingInformation

      public void setDebuggingInformation(boolean debugSource, boolean debugLines, boolean debugVars)
      Description copied from interface: IClassBodyEvaluator
      Determines what kind of debugging information is included in the generates classes. The default is typically "-g:none".
      Specified by:
      setDebuggingInformation in interface IClassBodyEvaluator

    • setSourceVersion

      public void setSourceVersion(int version)
      Description copied from interface: ICookable
      Specifies the version of source code accepted, in analogy with JAVAC's -source command line option. May be ignored by an implementation (e.g. the janino implementation always accepts the language features as described on the home page). Allowed values, and the default value, depend on the implementation. -1 means to use a default version.
      Specified by:
      setSourceVersion in interface ICookable

    • setTargetVersion

      public void setTargetVersion(int version)
      Description copied from interface: ICookable
      Generates class files that target a specified release of the virtual machine, in analogy with JAVAC's -target command line option. Allowed values depend on the implementation. The default value also depends on the implementation. The only invariant is that the generated class files are suitable for the currently executing JVM. -1 means to use a default version.
      Specified by:
      setTargetVersion in interface ICookable

    • setCompileErrorHandler

      public void setCompileErrorHandler(@Nullable ErrorHandler compileErrorHandler)
      Description copied from interface: IClassBodyEvaluator
      Installs an ErrorHandler which is invoked during compilation on each error. (By default, the compilation throws a CompileException on the first error and terminates.)

      If the given ErrorHandler throws a CompileException, then the compilation terminates and the exception is propagated.

      If the given ErrorHandler does not throw a CompileException but completes normally, then the compilation may or may not continue, depending on the error. Iff the compilation completes normally but errors were reported, then it will throw a CompileException indicating the number of errors.

      In other words: The ErrorHandler may throw a CompileException or not, but the compilation will definitely throw a CompileException if one or more compile errors have occurred.

      Specified by:
      setCompileErrorHandler in interface IClassBodyEvaluator
      Parameters:
      compileErrorHandler - null to restore the default behavior (throwing a CompileException)

    • setWarningHandler

      public void setWarningHandler(@Nullable WarningHandler warningHandler)
      Description copied from interface: IClassBodyEvaluator
      By default, warnings are discarded, but an application my install a custom WarningHandler.
      Specified by:
      setWarningHandler in interface IClassBodyEvaluator
      Parameters:
      warningHandler - null to indicate that no warnings be issued

    • cook

      public void cook(@Nullable String fileName, Reader r) throws CompileException, IOException
      Description copied from interface: ICookable
      Reads, scans, parses and compiles Java tokens from the given Reader.
      Specified by:
      cook in interface ICookable
      Specified by:
      cook in class Cookable
      Parameters:
      fileName - Used when reporting errors and warnings
      Throws:
      CompileException
      IOException

    • cook

      protected void cook(@Nullable String fileName, String[] imports, Reader r) throws CompileException, IOException
      Parameters:
      imports - E.g. "java.io.*" or "static java.util.Arrays.asList"
      r - The class body to cook, without leading IMPORT declarations
      Throws:
      CompileException
      IOException

    • getClazz

      public Class<?> getClazz()
      Specified by:
      getClazz in interface IClassBodyEvaluator
      Returns:
      The Class created by the preceding call to Cookable.cook(Reader)

    • getBytecodes

      public Map<String,byte[]> getBytecodes()
      Specified by:
      getBytecodes in interface ICookable
      Returns:
      The generated Java bytecode; maps class name to bytes

    • newFileName

      protected Reader newFileName(@Nullable String fileName, Reader reader)
      Sets the given file name, and the current line number to 1, and the current column number to 1, when the first char is read from the reader.

    • parseImportDeclarations

      protected static String[] parseImportDeclarations(Reader r) throws IOException
      Heuristically parses IMPORT declarations at the beginning of the character stream produced by the given Reader. After this method returns, all characters up to and including that last IMPORT declaration have been read from the Reader.

      This method does not handle comments and string literals correctly, i.e. if a pattern that looks like an IMPORT declaration appears within a comment or a string literal, it will be taken as an IMPORT declaration.

      Parameters:
      r - A Reader that supports MARK, e.g. a BufferedReader
      Returns:
      The parsed imports, e.g. { "java.util.*", "static java.util.Map.Entry" }
      Throws:
      IOException

    • createInstance

      public Object createInstance(Reader reader) throws CompileException, IOException
      Description copied from interface: IClassBodyEvaluator
      Scans, parses and compiles a class body from the tokens delivered by the the given Reader, then creates and returns an instance of that class.
      Specified by:
      createInstance in interface IClassBodyEvaluator
      Parameters:
      reader - Source of class body tokens
      Returns:
      An object that extends the extendedType and implements the given implementedTypes
      Throws:
      CompileException
      IOException