Java tutorial
/** * BSD-style license; for more info see http://pmd.sourceforge.net/license.html */ package net.sourceforge.pmd.lang.java.rule.logging; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.HashSet; import java.util.List; import java.util.Set; import org.apache.commons.lang3.StringUtils; import net.sourceforge.pmd.lang.java.ast.ASTArgumentList; import net.sourceforge.pmd.lang.java.ast.ASTClassOrInterfaceBody; import net.sourceforge.pmd.lang.java.ast.ASTClassOrInterfaceType; import net.sourceforge.pmd.lang.java.ast.ASTExpression; import net.sourceforge.pmd.lang.java.ast.ASTFieldDeclaration; import net.sourceforge.pmd.lang.java.ast.ASTLiteral; import net.sourceforge.pmd.lang.java.ast.ASTMethodDeclaration; import net.sourceforge.pmd.lang.java.ast.ASTName; import net.sourceforge.pmd.lang.java.ast.ASTPrimaryExpression; import net.sourceforge.pmd.lang.java.ast.ASTPrimaryPrefix; import net.sourceforge.pmd.lang.java.ast.ASTPrimarySuffix; import net.sourceforge.pmd.lang.java.ast.ASTVariableDeclarator; import net.sourceforge.pmd.lang.java.ast.ASTVariableDeclaratorId; import net.sourceforge.pmd.lang.java.ast.AbstractJavaTypeNode; import net.sourceforge.pmd.lang.java.rule.AbstractJavaRule; import net.sourceforge.pmd.lang.java.symboltable.VariableNameDeclaration; import net.sourceforge.pmd.lang.symboltable.NameDeclaration; public class InvalidSlf4jMessageFormatRule extends AbstractJavaRule { private static final Set<String> LOGGER_LEVELS; private static final String LOGGER_CLASS = "org.slf4j.Logger"; static { LOGGER_LEVELS = Collections .unmodifiableSet(new HashSet<String>(Arrays.asList("trace", "debug", "info", "warn", "error"))); } @Override public Object visit(final ASTName node, final Object data) { final NameDeclaration nameDeclaration = node.getNameDeclaration(); // ignore imports or methods if (nameDeclaration == null || !(nameDeclaration instanceof VariableNameDeclaration)) { return super.visit(node, data); } // ignore non slf4j logger Class<?> type = ((VariableNameDeclaration) nameDeclaration).getType(); if (type == null || !type.getName().equals(LOGGER_CLASS)) { return super.visit(node, data); } // get the node that contains the logger final ASTPrimaryExpression parentNode = node.getFirstParentOfType(ASTPrimaryExpression.class); // get the log level final String method = parentNode.getFirstChildOfType(ASTPrimaryPrefix.class) .getFirstChildOfType(ASTName.class).getImage().replace(nameDeclaration.getImage() + ".", ""); // ignore if not a log level if (!LOGGER_LEVELS.contains(method)) { return super.visit(node, data); } // find the arguments final List<ASTExpression> argumentList = parentNode.getFirstChildOfType(ASTPrimarySuffix.class) .getFirstDescendantOfType(ASTArgumentList.class).findChildrenOfType(ASTExpression.class); final List<ASTPrimaryExpression> params = new ArrayList<ASTPrimaryExpression>(argumentList.size()); for (final ASTExpression astExpression : argumentList) { ASTPrimaryExpression primaryExpression = astExpression.getFirstChildOfType(ASTPrimaryExpression.class); if (primaryExpression != null) { params.add(primaryExpression); } } if (params.isEmpty()) { // no params we could analyze return super.visit(node, data); } final ASTPrimaryExpression messageParam = params.get(0); // remove the message parameter params.remove(0); final int expectedArguments = expectedArguments(messageParam); if (expectedArguments == 0) { // ignore if we are not expecting arguments to format the message // or if we couldn't analyze the message parameter return super.visit(node, data); } // Remove throwable param, since it is shown separately. // But only, if it is not used as a placeholder argument if (params.size() > expectedArguments) { removeThrowableParam(params); } if (params.size() < expectedArguments) { addViolationWithMessage(data, node, "Missing arguments," + getExpectedMessage(params, expectedArguments)); } else if (params.size() > expectedArguments) { addViolationWithMessage(data, node, "Too many arguments," + getExpectedMessage(params, expectedArguments)); } return super.visit(node, data); } private boolean isNewThrowable(ASTPrimaryExpression last) { // in case a new exception is created or the exception class is // mentioned. ASTClassOrInterfaceType classOrInterface = last.getFirstDescendantOfType(ASTClassOrInterfaceType.class); if (classOrInterface != null && classOrInterface.getType() != null && Throwable.class.isAssignableFrom(classOrInterface.getType())) { return true; } return false; } private boolean hasTypeThrowable(ASTPrimaryExpression last) { // if the type could be determined already if (last.getType() != null && Throwable.class.isAssignableFrom(last.getType())) { return true; } return false; } private boolean isReferencingThrowable(ASTPrimaryExpression last) { // check the variable type, if there is a reference by name ASTName variable = last.getFirstDescendantOfType(ASTName.class); if (variable != null && variable.getNameDeclaration() != null && variable.getNameDeclaration() instanceof VariableNameDeclaration) { VariableNameDeclaration declaration = (VariableNameDeclaration) variable.getNameDeclaration(); if (declaration.getType() != null && Throwable.class.isAssignableFrom(declaration.getType())) { return true; } // convention: Exception type names should end with Exception if (declaration.getTypeImage() != null && declaration.getTypeImage().endsWith("Exception")) { return true; } } return false; } private void removeThrowableParam(final List<ASTPrimaryExpression> params) { // Throwable parameters are the last one in the list, if any. if (params.isEmpty()) { return; } int lastIndex = params.size() - 1; ASTPrimaryExpression last = params.get(lastIndex); if (isNewThrowable(last) || hasTypeThrowable(last) || isReferencingThrowable(last)) { params.remove(lastIndex); return; } } private String getExpectedMessage(final List<ASTPrimaryExpression> params, final int expectedArguments) { return " expected " + expectedArguments + (expectedArguments > 1 ? " arguments " : " argument ") + "but have " + params.size(); } private int expectedArguments(final ASTPrimaryExpression node) { int count = 0; // look if the logger have a literal message if (node.getFirstDescendantOfType(ASTLiteral.class) != null) { count = countPlaceholders(node); } else if (node.getFirstDescendantOfType(ASTName.class) != null) { final String variableName = node.getFirstDescendantOfType(ASTName.class).getImage(); // look if the message is defined locally final List<ASTVariableDeclarator> localValiables = node.getFirstParentOfType(ASTMethodDeclaration.class) .findDescendantsOfType(ASTVariableDeclarator.class); count = getAmountOfExpectedArguments(variableName, localValiables); if (count == 0) { // look if the message is defined in a field final List<ASTFieldDeclaration> fieldlist = node.getFirstParentOfType(ASTClassOrInterfaceBody.class) .findDescendantsOfType(ASTFieldDeclaration.class); // only look for ASTVariableDeclarator that are Fields final List<ASTVariableDeclarator> fields = new ArrayList<ASTVariableDeclarator>(fieldlist.size()); for (final ASTFieldDeclaration astFieldDeclaration : fieldlist) { fields.add(astFieldDeclaration.getFirstChildOfType(ASTVariableDeclarator.class)); } count = getAmountOfExpectedArguments(variableName, fields); } } return count; } private int getAmountOfExpectedArguments(final String variableName, final List<ASTVariableDeclarator> variables) { for (final ASTVariableDeclarator astVariableDeclarator : variables) { if (astVariableDeclarator.getFirstChildOfType(ASTVariableDeclaratorId.class).getImage() .equals(variableName)) { return countPlaceholders(astVariableDeclarator); } } return 0; } private int countPlaceholders(final AbstractJavaTypeNode node) { int result = 0; // zero means, no placeholders, or we could not analyze the message parameter ASTLiteral stringLiteral = node.getFirstDescendantOfType(ASTLiteral.class); if (stringLiteral != null) { result = StringUtils.countMatches(stringLiteral.getImage(), "{}"); } return result; } }