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/*
* Copyright (c) 2008-2025 The Aspectran 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.aspectran.utils.json;
import com.aspectran.utils.ArrayStack;
import com.aspectran.utils.Assert;
import com.aspectran.utils.BeanUtils;
import com.aspectran.utils.StringifyContext;
import com.aspectran.utils.annotation.jsr305.NonNull;
import com.aspectran.utils.annotation.jsr305.Nullable;
import com.aspectran.utils.apon.Parameter;
import com.aspectran.utils.apon.Parameters;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.StringReader;
import java.io.Writer;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.util.Collection;
import java.util.Date;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
/**
* Converts an object to a JSON formatted string.
* If pretty-printing is enabled, the JsonWriter will add newlines and
* indentation to the written data. Pretty-printing is disabled by default.
*
* Created: 2008. 06. 12 PM 8:20:54
*
* @author Juho Jeong
*/
public class JsonWriter {
private static final String DEFAULT_INDENT_STRING = " ";
private static final String NULL_STRING = "null";
private final ArrayStack writtenFlags = new ArrayStack<>();
private final Writer writer;
private StringifyContext stringifyContext;
private boolean prettyPrint = true;
private String indentString = DEFAULT_INDENT_STRING;
private boolean nullWritable = true;
private int indentDepth;
private String pendedName;
private Object upperObject;
/**
* Instantiates a new JsonWriter.
* Pretty printing is enabled by default, and the indent string is
* set to " " (two spaces).
* @param writer the character-output stream
*/
public JsonWriter(Writer writer) {
Assert.notNull(writer, "out must not be null");
this.writer = writer;
writtenFlags.push(false);
}
public void setStringifyContext(StringifyContext stringifyContext) {
this.stringifyContext = stringifyContext;
if (stringifyContext != null) {
if (stringifyContext.hasPretty()) {
prettyPrint(stringifyContext.isPretty());
}
if (stringifyContext.hasIndentSize()) {
indentString(stringifyContext.getIndentString());
}
if (stringifyContext.hasNullWritable()) {
nullWritable(stringifyContext.isNullWritable());
}
}
}
@SuppressWarnings("unchecked")
public T apply(StringifyContext stringifyContext) {
setStringifyContext(stringifyContext);
return (T)this;
}
@SuppressWarnings("unchecked")
public T prettyPrint(boolean prettyPrint) {
this.prettyPrint = prettyPrint;
if (prettyPrint) {
if (this.indentString == null) {
this.indentString = DEFAULT_INDENT_STRING;
}
} else {
this.indentString = null;
}
return (T)this;
}
@SuppressWarnings("unchecked")
public T indentString(@Nullable String indentString) {
this.indentString = indentString;
return (T)this;
}
@SuppressWarnings("unchecked")
public T nullWritable(boolean nullWritable) {
this.nullWritable = nullWritable;
return (T)this;
}
/**
* Begins encoding a new object.
* @throws IOException if an I/O error has occurred
*/
@SuppressWarnings("unchecked")
public T beginObject() throws IOException {
writePendedName();
writer.write("{");
nextLine();
indentDepth++;
writtenFlags.push(false);
return (T)this;
}
/**
* Ends encoding the current object.
* @throws IOException if an I/O error has occurred
*/
@SuppressWarnings("unchecked")
public T endObject() throws IOException {
indentDepth--;
if (writtenFlags.pop()) {
nextLine();
}
indent();
writer.write("}");
writtenFlags.update(true);
return (T)this;
}
/**
* Begins encoding a new array.
* @throws IOException if an I/O error has occurred
*/
@SuppressWarnings("unchecked")
public T beginArray() throws IOException {
writePendedName();
writer.write("[");
nextLine();
indentDepth++;
writtenFlags.push(false);
return (T)this;
}
/**
* Ends encoding the current array.
* @throws IOException if an I/O error has occurred
*/
@SuppressWarnings("unchecked")
public T endArray() throws IOException {
indentDepth--;
if (writtenFlags.pop()) {
nextLine();
}
indent();
writer.write("]");
writtenFlags.update(true);
return (T)this;
}
@SuppressWarnings("unchecked")
public T name(String name) throws IOException {
writeName(name);
return (T)this;
}
@SuppressWarnings("unchecked")
public T value(Object value) throws IOException {
writeValue(value);
return (T)this;
}
/**
* Writes a key name to the writer.
* @param name the string to write to the writer
*/
public void writeName(String name) {
pendedName = name;
}
private void writePendedName() throws IOException {
if (writtenFlags.peek()) {
writeComma();
}
if (pendedName != null) {
indent();
writer.write(escape(pendedName));
writer.write(":");
if (prettyPrint) {
writer.write(" ");
}
pendedName = null;
} else {
indent();
}
}
private void clearPendedName() {
pendedName = null;
}
/**
* Writes an object to the writer.
* @param object the object to write to the writer.
* @throws IOException if an I/O error has occurred.
*/
public void writeValue(Object object) throws IOException {
if (object == null) {
writeNull();
} else if (object instanceof String string) {
writeString(string);
} else if (object instanceof JsonString) {
writeJson(object.toString());
} else if (object instanceof Character) {
writeString(String.valueOf(object));
} else if (object instanceof Boolean bool) {
writeBool(bool);
} else if (object instanceof Number number) {
writeNumber(number);
} else if (object instanceof Parameters parameters) {
beginObject();
for (Parameter p : parameters.getParameterValues()) {
String name = p.getName();
Object value = p.getValue();
writeName(name);
writeValue(value, object);
}
endObject();
} else if (object instanceof Map map) {
beginObject();
for (Map.Entry entry : map.entrySet()) {
String name = entry.getKey().toString();
Object value = entry.getValue();
writeName(name);
writeValue(value, object);
}
endObject();
} else if (object instanceof Collection collection) {
beginArray();
for (Object value : collection) {
if (value != null) {
writeValue(value, object);
} else {
writeNull(true);
}
}
endArray();
} else if (object instanceof Iterator iterator) {
beginArray();
while (iterator.hasNext()) {
Object value = iterator.next();
if (value != null) {
writeValue(value, object);
} else {
writeNull(true);
}
}
endArray();
} else if (object instanceof Enumeration enumeration) {
beginArray();
while (enumeration.hasMoreElements()) {
Object value = enumeration.nextElement();
if (value != null) {
writeValue(value, object);
} else {
writeNull(true);
}
}
endArray();
} else if (object.getClass().isArray()) {
beginArray();
int len = Array.getLength(object);
for (int i = 0; i < len; i++) {
Object value = Array.get(object, i);
if (value != null) {
writeValue(value, object);
} else {
writeNull(true);
}
}
endArray();
} else if (object instanceof LocalDateTime localDateTime) {
if (stringifyContext != null) {
writeString(stringifyContext.toString(localDateTime));
} else {
writeString(localDateTime.toString());
}
} else if (object instanceof LocalDate localDate) {
if (stringifyContext != null) {
writeString(stringifyContext.toString(localDate));
} else {
writeString(localDate.toString());
}
} else if (object instanceof LocalTime localTime) {
if (stringifyContext != null) {
writeString(stringifyContext.toString(localTime));
} else {
writeString(localTime.toString());
}
} else if (object instanceof Date date) {
if (stringifyContext != null) {
writeString(stringifyContext.toString(date));
} else {
writeString(date.toString());
}
} else {
String[] readablePropertyNames = BeanUtils.getReadablePropertyNamesWithoutNonSerializable(object);
if (readablePropertyNames != null && readablePropertyNames.length > 0) {
beginObject();
for (String propertyName : readablePropertyNames) {
Object value;
try {
value = BeanUtils.getProperty(object, propertyName);
} catch (InvocationTargetException e) {
throw new IOException(e);
}
writeName(propertyName);
writeValue(value, object);
}
endObject();
} else {
writeString(object.toString());
}
}
}
private void writeValue(Object object, Object container) throws IOException {
checkCircularReference(container, object);
this.upperObject = container;
writeValue(object);
this.upperObject = null;
}
/**
* Writes a "null" string to the writer.
* @throws IOException if an I/O error has occurred
*/
public void writeNull() throws IOException {
writeNull(false);
}
/**
* Writes a "null" string to the writer.
* @param force true if forces should be written null value
* @throws IOException if an I/O error has occurred
*/
public void writeNull(boolean force) throws IOException {
if (nullWritable || force) {
writePendedName();
writer.write(NULL_STRING);
writtenFlags.update(true);
} else {
clearPendedName();
}
}
/**
* Writes a string directly to the writer stream without
* quoting or escaping.
* @param json the string to write to the writer
* @throws IOException if an I/O error has occurred
*/
public void writeJson(String json) throws IOException {
if (nullWritable || json != null) {
writePendedName();
if (json != null) {
BufferedReader reader = new BufferedReader(new StringReader(json));
boolean first = true;
String line;
while ((line = reader.readLine()) != null) {
if (!first) {
nextLine();
indent();
}
writer.write(line);
first = false;
}
} else {
writer.write(NULL_STRING);
}
writtenFlags.update(true);
} else {
clearPendedName();
}
}
/**
* Writes a string to the writer.
* If {@code value} is null, write a null string ("").
* @param value the string to write to the writer
* @throws IOException if an I/O error has occurred
*/
private void writeString(String value) throws IOException {
if (nullWritable || value != null) {
writePendedName();
writer.write(escape(value));
writtenFlags.update(true);
} else {
clearPendedName();
}
}
/**
* Writes a {@code Boolean} object to the writer.
* @param value a {@code Boolean} object to write to the writer
* @throws IOException if an I/O error has occurred
*/
private void writeBool(Boolean value) throws IOException {
if (nullWritable || value != null) {
writePendedName();
writer.write(value.toString());
writtenFlags.update(true);
} else {
clearPendedName();
}
}
/**
* Writes a {@code Number} object to the writer.
* @param value a {@code Number} object to write to the writer
* @throws IOException if an I/O error has occurred
*/
private void writeNumber(Number value) throws IOException {
if (nullWritable || value != null) {
writePendedName();
writer.write(value.toString());
writtenFlags.update(true);
} else {
clearPendedName();
}
}
/**
* Writes a comma character to the writer.
* @throws IOException if an I/O error has occurred
*/
private void writeComma() throws IOException {
writer.write(",");
nextLine();
}
/**
* Writes a tab character to the writer.
* @throws IOException if an I/O error has occurred
*/
private void indent() throws IOException {
if (prettyPrint && indentString != null && !indentString.isEmpty()) {
for (int i = 0; i < indentDepth; i++) {
writer.write(indentString);
}
}
}
/**
* Writes a new line character to the writer.
* @throws IOException if an I/O error has occurred
*/
private void nextLine() throws IOException {
if (prettyPrint) {
writer.write("\n");
}
}
/**
* Ensures all buffered data is written to the underlying
* {@link Writer} and flushes that writer.
* @throws IOException if an I/O error has occurred
*/
public void flush() throws IOException {
writer.flush();
}
public void close() throws IOException {
writer.close();
}
@Override
public String toString() {
return writer.toString();
}
private void checkCircularReference(Object object, Object member) throws IOException {
if (object == member || (upperObject != null && upperObject == member)) {
String what;
if (pendedName != null) {
what = "member '" + pendedName + "'";
} else {
what = "a member";
}
throw new IOException("JSON Serialization Failure: " +
"A circular reference was detected while converting " + what);
}
}
/**
* Produce a string in double quotes with backslash sequences in all the
* right places. A backslash will be inserted within </, allowing JSON
* text to be delivered in HTML. In JSON text, a string cannot contain a
* control character or an unescaped quote or backslash.
* @param string the input String, may be null
* @return a String correctly formatted for insertion in a JSON text
*/
@NonNull
private static String escape(String string) {
if (string == null || string.isEmpty()) {
return "\"\"";
}
int len = string.length();
char b;
char c = 0;
String t;
StringBuilder sb = new StringBuilder(len + 4);
sb.append('"');
for (int i = 0; i < len; i++) {
b = c;
c = string.charAt(i);
switch (c) {
case '\\':
case '"':
sb.append('\\');
sb.append(c);
break;
case '/':
if (b == '<') {
sb.append('\\');
}
sb.append(c);
break;
case '\b':
sb.append("\\b");
break;
case '\t':
sb.append("\\t");
break;
case '\n':
sb.append("\\n");
break;
case '\f':
sb.append("\\f");
break;
case '\r':
sb.append("\\r");
break;
default:
if (c < ' ' || (c >= '\u0080' && c < '\u00a0') || (c >= '\u2000' && c < '\u2100')) {
t = "000" + Integer.toHexString(c);
sb.append("\\u").append(t.substring(t.length() - 4));
} else {
sb.append(c);
}
}
}
sb.append('"');
return sb.toString();
}
}
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