Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.android.tools.lint.checks; import static com.android.SdkConstants.ANDROID_URI; import static com.android.SdkConstants.ATTR_CLASS; import static com.android.SdkConstants.ATTR_ID; import static com.android.SdkConstants.DOT_XML; import static com.android.SdkConstants.ID_PREFIX; import static com.android.SdkConstants.NEW_ID_PREFIX; import static com.android.SdkConstants.VIEW_TAG; import com.android.annotations.NonNull; import com.android.annotations.Nullable; import com.android.ide.common.res2.AbstractResourceRepository; import com.android.ide.common.res2.ResourceFile; import com.android.ide.common.res2.ResourceItem; import com.android.resources.ResourceFolderType; import com.android.resources.ResourceType; import com.android.tools.lint.client.api.LintClient; import com.android.tools.lint.detector.api.Category; import com.android.tools.lint.detector.api.Context; import com.android.tools.lint.detector.api.Detector; import com.android.tools.lint.detector.api.Implementation; import com.android.tools.lint.detector.api.Issue; import com.android.tools.lint.detector.api.JavaContext; import com.android.tools.lint.detector.api.LintUtils; import com.android.tools.lint.detector.api.ResourceXmlDetector; import com.android.tools.lint.detector.api.Scope; import com.android.tools.lint.detector.api.Severity; import com.android.tools.lint.detector.api.Speed; import com.android.tools.lint.detector.api.XmlContext; import com.android.utils.XmlUtils; import com.google.common.base.Joiner; import com.google.common.collect.ArrayListMultimap; import com.google.common.collect.Lists; import com.google.common.collect.Maps; import com.google.common.collect.Multimap; import com.google.common.collect.Sets; import org.w3c.dom.Attr; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import java.io.File; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.EnumSet; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; import lombok.ast.AstVisitor; import lombok.ast.Cast; import lombok.ast.Expression; import lombok.ast.MethodInvocation; import lombok.ast.Select; import lombok.ast.StrictListAccessor; /** Detector for finding inconsistent usage of views and casts * <p> * TODO: Check findFragmentById * <pre> * ((ItemListFragment) getSupportFragmentManager() * .findFragmentById(R.id.item_list)) * .setActivateOnItemClick(true); * </pre> * Here we should check the {@code <fragment>} tag pointed to by the id, and * check its name or class attributes to make sure the cast is compatible with * the named fragment class! */ public class ViewTypeDetector extends ResourceXmlDetector implements Detector.JavaScanner { /** Mismatched view types */ @SuppressWarnings("unchecked") public static final Issue ISSUE = Issue.create("WrongViewCast", //$NON-NLS-1$ "Mismatched view type", "Keeps track of the view types associated with ids and if it finds a usage of " + "the id in the Java code it ensures that it is treated as the same type.", Category.CORRECTNESS, 9, Severity.FATAL, new Implementation(ViewTypeDetector.class, EnumSet.of(Scope.ALL_RESOURCE_FILES, Scope.ALL_JAVA_FILES), Scope.JAVA_FILE_SCOPE)); /** Flag used to do no work if we're running in incremental mode in a .java file without * a client supporting project resources */ private Boolean mIgnore = null; private final Map<String, Object> mIdToViewTag = new HashMap<String, Object>(50); @NonNull @Override public Speed getSpeed() { return Speed.SLOW; } @Override public boolean appliesTo(@NonNull ResourceFolderType folderType) { return folderType == ResourceFolderType.LAYOUT; } @Override public Collection<String> getApplicableAttributes() { return Collections.singletonList(ATTR_ID); } @Override public void visitAttribute(@NonNull XmlContext context, @NonNull Attr attribute) { String view = attribute.getOwnerElement().getTagName(); String value = attribute.getValue(); String id = null; if (value.startsWith(ID_PREFIX)) { id = value.substring(ID_PREFIX.length()); } else if (value.startsWith(NEW_ID_PREFIX)) { id = value.substring(NEW_ID_PREFIX.length()); } // else: could be @android id if (id != null) { if (view.equals(VIEW_TAG)) { view = attribute.getOwnerElement().getAttribute(ATTR_CLASS); } Object existing = mIdToViewTag.get(id); if (existing == null) { mIdToViewTag.put(id, view); } else if (existing instanceof String) { String existingString = (String) existing; if (!existingString.equals(view)) { // Convert to list List<String> list = new ArrayList<String>(2); list.add((String) existing); list.add(view); mIdToViewTag.put(id, list); } } else if (existing instanceof List<?>) { @SuppressWarnings("unchecked") List<String> list = (List<String>) existing; if (!list.contains(view)) { list.add(view); } } } } // ---- Implements Detector.JavaScanner ---- @Override public List<String> getApplicableMethodNames() { return Collections.singletonList("findViewById"); //$NON-NLS-1$ } @Override public void visitMethod(@NonNull JavaContext context, @Nullable AstVisitor visitor, @NonNull MethodInvocation node) { LintClient client = context.getClient(); if (mIgnore == Boolean.TRUE) { return; } else if (mIgnore == null) { mIgnore = !context.getScope().contains(Scope.ALL_RESOURCE_FILES) && !client.supportsProjectResources(); if (mIgnore) { return; } } assert node.astName().astValue().equals("findViewById"); if (node.getParent() instanceof Cast) { Cast cast = (Cast) node.getParent(); String castType = cast.astTypeReference().getTypeName(); StrictListAccessor<Expression, MethodInvocation> args = node.astArguments(); if (args.size() == 1) { Expression first = args.first(); // TODO: Do flow analysis as in the StringFormatDetector in order // to handle variable references too if (first instanceof Select) { String resource = first.toString(); if (resource.startsWith("R.id.")) { //$NON-NLS-1$ String id = ((Select) first).astIdentifier().astValue(); if (client.supportsProjectResources()) { AbstractResourceRepository resources = client .getProjectResources(context.getMainProject(), true); if (resources == null) { return; } List<ResourceItem> items = resources.getResourceItem(ResourceType.ID, id); if (items != null && !items.isEmpty()) { Set<String> compatible = Sets.newHashSet(); for (ResourceItem item : items) { Collection<String> tags = getViewTags(context, item); if (tags != null) { compatible.addAll(tags); } } if (!compatible.isEmpty()) { ArrayList<String> layoutTypes = Lists.newArrayList(compatible); checkCompatible(context, castType, null, layoutTypes, cast); } } } else { Object types = mIdToViewTag.get(id); if (types instanceof String) { String layoutType = (String) types; checkCompatible(context, castType, layoutType, null, cast); } else if (types instanceof List<?>) { @SuppressWarnings("unchecked") List<String> layoutTypes = (List<String>) types; checkCompatible(context, castType, null, layoutTypes, cast); } } } } } } } @Nullable protected Collection<String> getViewTags(@NonNull Context context, @NonNull ResourceItem item) { // Check view tag in this file. Can I do it cheaply? Try with // an XML pull parser. Or DOM if we have multiple resources looked // up? ResourceFile source = item.getSource(); if (source != null) { File file = source.getFile(); Multimap<String, String> map = getIdToTagsIn(context, file); if (map != null) { return map.get(item.getName()); } } return null; } private Map<File, Multimap<String, String>> mFileIdMap; @Nullable private Multimap<String, String> getIdToTagsIn(@NonNull Context context, @NonNull File file) { if (!file.getPath().endsWith(DOT_XML)) { return null; } if (mFileIdMap == null) { mFileIdMap = Maps.newHashMap(); } Multimap<String, String> map = mFileIdMap.get(file); if (map == null) { map = ArrayListMultimap.create(); mFileIdMap.put(file, map); String xml = context.getClient().readFile(file); // TODO: Use pull parser instead for better performance! Document document = XmlUtils.parseDocumentSilently(xml, true); if (document != null && document.getDocumentElement() != null) { addViewTags(map, document.getDocumentElement()); } } return map; } private static void addViewTags(Multimap<String, String> map, Element element) { String id = element.getAttributeNS(ANDROID_URI, ATTR_ID); if (id != null && !id.isEmpty()) { id = LintUtils.stripIdPrefix(id); if (!map.containsEntry(id, element.getTagName())) { map.put(id, element.getTagName()); } } NodeList children = element.getChildNodes(); for (int i = 0, n = children.getLength(); i < n; i++) { Node child = children.item(i); if (child.getNodeType() == Node.ELEMENT_NODE) { addViewTags(map, (Element) child); } } } /** Check if the view and cast type are compatible */ private static void checkCompatible(JavaContext context, String castType, String layoutType, List<String> layoutTypes, Cast node) { assert layoutType == null || layoutTypes == null; // Should only specify one or the other boolean compatible = true; if (layoutType != null) { if (!layoutType.equals(castType) && !context.getSdkInfo().isSubViewOf(castType, layoutType)) { compatible = false; } } else { compatible = false; assert layoutTypes != null; for (String type : layoutTypes) { if (type.equals(castType) || context.getSdkInfo().isSubViewOf(castType, type)) { compatible = true; break; } } } if (!compatible) { if (layoutType == null) { layoutType = Joiner.on("|").join(layoutTypes); } String message = String.format("Unexpected cast to `%1$s`: layout tag was `%2$s`", castType, layoutType); context.report(ISSUE, node, context.getLocation(node), message); } } }