Gson源码的研读-2015/10/9

来源：互联网发布：des 算法函数原理图编辑：程序博客网时间：2024/06/02 03:59

当前发现最核心的代码如下：

public static final TypeAdapter<JsonElement> JSON_ELEMENT = new TypeAdapter<JsonElement>() {  @Override public JsonElement read(JsonReader in) throws IOException {    switch (in.peek()) {    case STRING:      return new JsonPrimitive(in.nextString());    case NUMBER:      String number = in.nextString();      return new JsonPrimitive(new LazilyParsedNumber(number));    case BOOLEAN:      return new JsonPrimitive(in.nextBoolean());    case NULL:      in.nextNull();      return JsonNull.INSTANCE;    case BEGIN_ARRAY:      JsonArray array = new JsonArray();      in.beginArray();      while (in.hasNext()) {        array.add(read(in));      }      in.endArray();      return array;    case BEGIN_OBJECT:      JsonObject object = new JsonObject();      in.beginObject();      while (in.hasNext()) {        object.add(in.nextName(), read(in));      }      in.endObject();      return object;    case END_DOCUMENT:    case NAME:    case END_OBJECT:    case END_ARRAY:    default:      throw new IllegalArgumentException();    }  }

以上代码返回各种具体类型的element

下面的代码用于对text继续遍历

/** * Returns the type of the next token without consuming it. */public JsonToken peek() throws IOException {  if (token != null) {    return token;  }  switch (stack[stackSize - 1]) {  case EMPTY_DOCUMENT:    if (lenient) {      consumeNonExecutePrefix();    }    stack[stackSize - 1] = JsonScope.NONEMPTY_DOCUMENT;    JsonToken firstToken = nextValue();    if (!lenient && token != JsonToken.BEGIN_ARRAY && token != JsonToken.BEGIN_OBJECT) {      throw new IOException("Expected JSON document to start with '[' or '{' but was " + token          + " at line " + getLineNumber() + " column " + getColumnNumber());    }    return firstToken;  case EMPTY_ARRAY:    return nextInArray(true);  case NONEMPTY_ARRAY:    return nextInArray(false);  case EMPTY_OBJECT:    return nextInObject(true);  case DANGLING_NAME:    return objectValue();  case NONEMPTY_OBJECT:    return nextInObject(false);  case NONEMPTY_DOCUMENT:    int c = nextNonWhitespace(false);    if (c == -1) {      return JsonToken.END_DOCUMENT;    }    pos--;    if (!lenient) {      throw syntaxError("Expected EOF");    }    return nextValue();  case CLOSED:    throw new IllegalStateException("JsonReader is closed");  default:    throw new AssertionError();  }}

如下的代码是一个出口，分析的结果会保存到members中

public void add(String property, JsonElement value) {  if (value == null) {    value = JsonNull.INSTANCE;  }  members.put($Gson$Preconditions.checkNotNull(property), value);}
 
当前的问题是peek和read是如何串起来的呢？
：在read的过程中，peek会一直调用，对内容的标志进一步分析，
待续！！

0 0