一、项目地址
项目地址：
二、ReaderTools解析
/** * Created by tangfuling on 2018/10/23. */public class ReaderTools { private static JsonSyntaxErrorListener mListener; public static void setListener(JsonSyntaxErrorListener listener) { mListener = listener; } /** * used for array、collection、map、object * skipValue when expected token error * * @param in input json reader * @param expectedToken expected token */ public static boolean checkJsonToken(JsonReader in, JsonToken expectedToken) { if (in == null || expectedToken == null) { return false; } JsonToken inToken = null; try { inToken = in.peek(); } catch (IOException e) { e.printStackTrace(); } if (inToken == expectedToken) { return true; } if (inToken != JsonToken.NULL) { String exception = "expected " + expectedToken + " but was " + inToken + " path " + in.getPath(); notifyJsonSyntaxError(exception); } skipValue(in); return false; } /** * used for basic data type, we only deal type Number and Boolean * skipValue when json parse error * * @param in input json reader * @param exception json parse exception */ public static void onJsonTokenParseException(JsonReader in, Exception exception) { if (in == null || exception == null) { return; } skipValue(in); notifyJsonSyntaxError(exception.getMessage()); } private static void skipValue(JsonReader in) { if (in == null) { return; } try { in.skipValue(); } catch (IOException e) { e.printStackTrace(); } } private static void notifyJsonSyntaxError(String exception) { if (mListener == null) { return; } String invokeStack = Log.getStackTraceString(new Exception("syntax error exception")); mListener.onJsonSyntaxError(exception, invokeStack); } public interface JsonSyntaxErrorListener { public void onJsonSyntaxError(String exception, String invokeStack); }} 1.对外暴露setListener()接口，用户可以监听到Json解析异常。
2.checkJsonToken()方法，用于判断输入字段的数据类型是否与预期的数据类型一致，如果数据类型不一致，则跳过解析，同时通知listener解析失败。该方法用于判断array、collection、map、object是否合法。3.onJsonTokenParseException()方法，会利用javassist对Gson抛出的Exception进行捕获，然后调用该方法，同时通知listener解析失败。该方法用于判断Integer、Boolean等基本数据类型。三、GsonPlugin插件编写
1.ReaderTools.java的setListener()方法需要暴露给用户使用，但Plugin仅仅是一个插件，无法将java语言的接口暴露出去给用户使用，所以需要建立2个工程。
2.gson-plugin-sdk：主要包含ReaderTools.java，与用户交互的类及方法需要在这个sdk中定义并实现。3.gson-plugin：主要是侵入编译流程，并修改Gson的字节码，同时在特定的地方调用ReaderTools.java中的方法，如checkJsonToken()方法，onJsonTokenParseException()方法等。4.这样用户接入需要引入两个库，gson-plugin-sdk和gson-plugin。5.为了方便用户接入，可以在gson-plugin中帮助用户引入gson-plugin-sdk，这样用户就只需要引入gson-plugin即可。6.在gson-plugin中帮助用户引入gson-plugin-sdkproject.dependencies.add("compile", "com.ke.gson.sdk:gson_sdk:1.3.0") 7.GsonPlugin为插件入口类，在此注册自定义的GsonJarTransform
/** * Created by tangfuling on 2018/10/25. */class GsonPlugin implements Plugin{ @Override void apply(Project project) { //add dependencies project.dependencies.add("compile", "com.ke.gson.sdk:gson_sdk:1.3.0") //add transform project.android.registerTransform(new GsonJarTransform(project)) }}
四、GsonJarTransform编译流程
@Override String getName() { return "GsonJarTransform" } @Override void transform(TransformInvocation transformInvocation) throws TransformException, InterruptedException, IOException { //初始化ClassPool MyClassPool.resetClassPool(mProject, transformInvocation) //处理jar和file TransformOutputProvider outputProvider = transformInvocation.getOutputProvider() for (TransformInput input : transformInvocation.getInputs()) { for (JarInput jarInput : input.getJarInputs()) { // name must be unique，or throw exception "multiple dex files define" def jarName = jarInput.name if (jarName.endsWith('.jar')) { jarName = jarName.substring(0, jarName.length() - 4) } def md5Name = DigestUtils.md5Hex(jarInput.file.getAbsolutePath()) //source file File file = InjectGsonJar.inject(jarInput.file, transformInvocation.context, mProject) if (file == null) { file = jarInput.file } //dest file File dest = outputProvider.getContentLocation(jarName + md5Name, jarInput.contentTypes, jarInput.scopes, Format.JAR) FileUtils.copyFile(file, dest) } for (DirectoryInput directoryInput : input.getDirectoryInputs()) { File dest = outputProvider.getContentLocation(directoryInput.name, directoryInput.contentTypes, directoryInput.scopes, Format.DIRECTORY) FileUtils.copyDirectory(directoryInput.file, dest) } } } 1.初始化ClassPool，javassist中用到的类都需要先加入ClassPath。
/** * Created by tangfuling on 2018/10/31. */public class MyClassPool { private static ClassPool sClassPool public static ClassPool getClassPool() { return sClassPool } public static void resetClassPool(Project project, TransformInvocation transformInvocation) { // ClassPool.getDefault() 有可能被其他使用 Javassist 的插件污染（如 nuwa）， // 导致ClassPool中出现重复的类，Javassist抛出异常，所以不能使用默认的 sClassPool = new ClassPool() sClassPool.appendSystemPath() // bootClasspath 包括 android.jar 和 useLibrary 指定的library 的路径（如 org.apache.http.legacy ) project.android.bootClasspath.each { sClassPool.appendClassPath(it.absolutePath) } // 其它class for (TransformInput input : transformInvocation.getInputs()) { for (JarInput jarInput : input.getJarInputs()) { sClassPool.appendClassPath(jarInput.file.getAbsolutePath()) } for (DirectoryInput directoryInput : input.getDirectoryInputs()) { sClassPool.appendClassPath(directoryInput.file.getAbsolutePath()) } } }} 2.transform处理过程
2.1.在编译过程中，transform会对项目中所有依赖的jar文件和项目本身的class文件进行处理，将处理结果交给下一个步骤，继续处理。2.2.如果不做任何处理，那么transform至少会做一件事情，将输入的jar文件和class文件，拷贝到build/intermediates/transforms/GsonJarTransform目录。2.3.gson-plugin需要对gson.jar做处理。File file = InjectGsonJar.inject(jarInput.file, transformInvocation.context, mProject)
五、处理gson.jar包
/** * Created by tangfuling on 2018/10/25. */class InjectGsonJar { public static File inject(File jarFile, Context context, Project project) throws NotFoundException { if (!jarFile.name.contains("gson")) { return null } println("GsonPlugin: inject gson jar start") //原始jar path String srcPath = jarFile.getAbsolutePath() //原始jar解压后的tmpDir String tmpDirName = jarFile.name.substring(0, jarFile.name.length() - 4) String tmpDirPath = context.temporaryDir.getAbsolutePath() + File.separator + tmpDirName //目标jar path String targetPath = context.temporaryDir.getAbsolutePath() + File.separator + jarFile.name //解压 Decompression.uncompress(srcPath, tmpDirPath) //修改 InjectReflectiveTypeAdapterFactory.inject(tmpDirPath) InjectMapTypeAdapterFactory.inject(tmpDirPath) InjectArrayTypeAdapter.inject(tmpDirPath) InjectCollectionTypeAdapterFactory.inject(tmpDirPath) InjectTypeAdapters.inject(tmpDirPath) //重新压缩 Compressor.compress(tmpDirPath, targetPath) //删除临时目录 StrongFileUtil.deleteDirPath(tmpDirPath) println("GsonPlugin: inject gson jar success") //返回目标jar File targetFile = new File(targetPath) if (targetFile.exists()) { return targetFile } return null }} 1.输入的gson.jar位置：.gradle/caches/modules-2/files-2.1/com.google.code.gson/gson
2.对输入的jar包解压到一个临时目录，并对解压后的class文件进行修改：build/tmp/transformClassesWithGsonJarTransformForDebug，会生成一个文件夹gson-2.8.53.将修改后的文件重新压缩到当前目录：build/tmp/transformClassesWithGsonJarTransformForDebug，会重新生成一个jar包gson-2.8.5.jar4.删除步骤2中生成的文件夹gson-2.8.55.将tmp目录下的gson-2.8.5.jar返回6.transform会将tmp目录下gson-2.8.5.jar拷贝到build/intermediates/transforms/GsonJarTransform目录供下一个步骤使用。六、修改内部类的方法
1.这个Adapter.class的read()方法是对Object类型的数据进行解析，我们判断输入的数据类型不是Object类型，就直接跳过解析，核心是在read()方法中插入ReaderTools.checkJsonToken()方法。
2.每一个类、每一个内部类、每一个匿名内部类，都会生成一个独立的.class文件，如ReflectiveTypeAdapterFactory.class,ReflectiveTypeAdapterFactory$Adapter.class,ReflectiveTypeAdapterFactory$BoundField.class,ReflectiveTypeAdapterFactory$1.class。3.遍历文件夹找到对应的class，通过javassist在read()方法前面插入判断代码。/** * Created by tangfuling on 2018/10/30. */public class InjectReflectiveTypeAdapterFactory { public static void inject(String dirPath) { ClassPool classPool = MyClassPool.getClassPool() File dir = new File(dirPath) if (dir.isDirectory()) { dir.eachFileRecurse { File file -> if ("ReflectiveTypeAdapterFactory.class".equals(file.name)) { CtClass ctClass = classPool.getCtClass("com.google.gson.internal.bind.ReflectiveTypeAdapterFactory\$Adapter") CtMethod ctMethod = ctClass.getDeclaredMethod("read") ctMethod.insertBefore(" if (!com.ke.gson.sdk.ReaderTools.checkJsonToken(\$1, com.google.gson.stream.JsonToken.BEGIN_OBJECT)) {\n" + " return null;\n" + " }") ctClass.writeFile(dirPath) ctClass.detach() println("GsonPlugin: inject ReflectiveTypeAdapterFactory success") } } } }} 七、字节码加 try-catch
1.TypeAdapters.class处理基本数据类型，每个基本数据类型都对应一个匿名内部类
public static final TypeAdapterBOOLEAN = new TypeAdapter () { public Boolean read(JsonReader in) throws IOException { if(in.peek() == JsonToken.NULL) { in.nextNull(); return null; } else { return in.peek() == JsonToken.STRING?Boolean.valueOf(Boolean.parseBoolean(in.nextString())):Boolean.valueOf(in.nextBoolean()); } } public void write(JsonWriter out, Boolean value) throws IOException { if(value == null) { out.nullValue(); } else { out.value(value.booleanValue()); } } };
2.找到TypeAdapters的所有内部类，获取内部类的read()方法的返回值，如果是Number或Boolean类型，添加try-catch代码块，并回调ReaderTools.onJsonTokenParseException()方法。
/** * Created by tangfuling on 2018/10/30. */public class InjectTypeAdapters { public static void inject(String dirPath) { ClassPool classPool = MyClassPool.getClassPool() File dir = new File(dirPath) if (dir.isDirectory()) { dir.eachFileRecurse { File file -> if (file.name.contains("TypeAdapters\$")) { String innerClassName = file.name.substring(13, file.name.length() - 6) CtClass ctClass = classPool.getCtClass("com.google.gson.internal.bind.TypeAdapters\$" + innerClassName) //only deal type Boolean and Number CtMethod[] methods = ctClass.declaredMethods boolean isModified = false for (CtMethod ctMethod : methods) { if ("read".equals(ctMethod.name)) { String returnTypeName = ctMethod.getReturnType().name if ("java.lang.Number".equals(returnTypeName) || "java.lang.Boolean".equals(returnTypeName)) { CtClass etype = classPool.get("java.lang.Exception") ctMethod.addCatch("{com.ke.gson.sdk.ReaderTools.onJsonTokenParseException(\$1, \$e); return null;}", etype) isModified = true } } } if (isModified) { ctClass.writeFile(dirPath) println("GsonPlugin: inject TypeAdapters success") } ctClass.detach() } } } }} 3.其中$1表示read()方法的第1个参数JsonReader，$e表示捕获的Exception