org.xillium.base.beans.JSONBuilder Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of xillium-base Show documentation
There is a newer version: 1.2.2
package org.xillium.base.beans;

import java.lang.reflect.Array;


/**
 * A simple and fast JSON builder
 */
public class JSONBuilder {
    /**
     * Constructs a new JSONBuilder with a default buffer size.
     */
    public JSONBuilder() {
        _sb = new StringBuilder();
    }

    /**
     * Constructs a new JSONBuilder with the given buffer size.
     *
     * @param size - the preallocated buffer size
     */
    public JSONBuilder(int size) {
        _sb = new StringBuilder(size);
    }

    /**
     * Appends a liternal character to the JSON stream.
     *
     * @param c - a liternal character to append
     * @return the JSONBuilder itself
     */
    public JSONBuilder append(char c) {
        _sb.append(c);
        return this;
    }

    /**
     * Appends a liternal string to the JSON stream.
     *
     * @param s - a liternal string to append
     * @return the JSONBuilder itself
     */
    public JSONBuilder append(String s) {
        _sb.append(s);
        return this;
    }

    /**
     * Replaces the last character in the JSON stream.
     *
     * @param c - a new character to replace the last character with
     * @return the JSONBuilder itself
     */
    public JSONBuilder replaceLast(char c) {
        _sb.setCharAt(_sb.length()-1, c);
        return this;
    }

    /**
     * Quotes properly a string and appends it to the JSON stream.
     *
     * @param value - a liternal string to quote and then append
     * @return the JSONBuilder itself
     */
    public JSONBuilder quote(String value) {
        _sb.append('"');
        for (int i = 0; i < value.length(); ++i) {
            char c = value.charAt(i);
            switch (c) {
            case '"':
                _sb.append("\\\"");
                break;
            case '\\':
                _sb.append("\\\\");
                break;
            default:
                if (c < 0x20) {
                    _sb.append(CTRLCHARS[c]);
                } else {
                    _sb.append(c);
                }
                break;
            }
        }
        _sb.append('"');
        return this;
    }

    /**
     * Serializes an object and appends it to the stream.
     *
     * @param value - an object to serialize
     * @return the JSONBuilder itself
     */
    public JSONBuilder serialize(Object value) {
        if (value == null) {
            _sb.append("null");
        } else {
            Class t = value.getClass();
            if (t.isArray()) {
                _sb.append('[');
                boolean hasElements = false;
                for (int i = 0, ii = Array.getLength(value); i < ii; ++i) {
                    serialize(Array.get(value, i));
                    _sb.append(',');
                    hasElements = true;
                }
                if (hasElements) {
                    _sb.setCharAt(_sb.length()-1, ']');
                } else {
                    _sb.append(']');
                }
            } else if (Iterable.class.isAssignableFrom(t)) {
                _sb.append('[');
                boolean hasElements = false;
                for (Object object: (Iterable)value) {
                    serialize(object);
                    _sb.append(',');
                    hasElements = true;
                }
                if (hasElements) {
                    _sb.setCharAt(_sb.length()-1, ']');
                } else {
                    _sb.append(']');
                }
            } else if (Number.class.isAssignableFrom(t) || Boolean.class.isAssignableFrom(t)) {
                _sb.append(value.toString());
            } else if (String.class == t) {
                quote((String)value);
            } else {
                quote(value.toString());
            }
        }
        return this;
    }

    /**
     * Serializes a named object and appends it to the stream as name:serialized-value.
     *
     * @param name - a name for the object
     * @param value - an object to serialize
     * @return the JSONBuilder itself
     */
    public JSONBuilder serialize(String name, Object value) {
        return quote(name).append(':').serialize(value);
    }

    /**
     * Returns the current buffer length.
     *
     * @return the length of the buffer
     */
    public int length() {
        return _sb.length();
    }

    @Override
    public String toString() {
        return _sb.toString();
    }

    private static String[] CTRLCHARS = {
        /* 00 */"\\u0000",
        /* 01 */"\\u0001",
        /* 02 */"\\u0002",
        /* 03 */"\\u0003",
        /* 04 */"\\u0004",
        /* 05 */"\\u0005",
        /* 06 */"\\u0006",
        /* 07 */"\\u0007",
        /* 08 */"\\b",
        /* 09 */"\\t",
        /* 0A */"\\n",
        /* 0B */"\\u000b",
        /* 0C */"\\f",
        /* 0D */"\\r",
        /* 0E */"\\u000e",
        /* 0F */"\\u000f",
        /* 10 */"\\u0010",
        /* 11 */"\\u0011",
        /* 12 */"\\u0012",
        /* 13 */"\\u0013",
        /* 14 */"\\u0014",
        /* 15 */"\\u0015",
        /* 16 */"\\u0016",
        /* 17 */"\\u0017",
        /* 18 */"\\u0018",
        /* 19 */"\\u0019",
        /* 1A */"\\u001a",
        /* 1B */"\\u001b",
        /* 1C */"\\u001c",
        /* 1D */"\\u001d",
        /* 1E */"\\u001e",
        /* 1F */"\\u001f",
    };

    private final StringBuilder _sb;
}