Convert Object to Json String - Android File Input Output

Description

Convert Object to Json String
Demo Code


//package com.java2s;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Map;
import java.util.Set;

public class Main {

    @SuppressWarnings("unchecked")
    public static String toJson(final Object o) {
        if (o == null) {
            return "null";
        }//from   w  ww .  j  av  a 2 s . co  m
        if (o instanceof String) //String
        {
            return string2Json((String) o);
        }
        if (o instanceof Boolean) //Boolean
        {
            return boolean2Json((Boolean) o);
        }
        if (o instanceof Number) //Number
        {
            return number2Json((Number) o);
        }
        if (o instanceof Map) //Map
        {
            return map2Json((Map<String, Object>) o);
        }
        if (o instanceof Collection) //List  Set
        {
            return collection2Json((Collection) o);
        }
        if (o instanceof Object[]) //
        {
            return array2Json((Object[]) o);
        }

        if (o instanceof int[])//
        {
            return intArray2Json((int[]) o);
        }
        if (o instanceof boolean[])//
        {
            return booleanArray2Json((boolean[]) o);
        }
        if (o instanceof long[])//
        {
            return longArray2Json((long[]) o);
        }
        if (o instanceof float[])//
        {
            return floatArray2Json((float[]) o);
        }
        if (o instanceof double[])//
        {
            return doubleArray2Json((double[]) o);
        }
        if (o instanceof short[])//
        {
            return shortArray2Json((short[]) o);
        }
        if (o instanceof byte[])//
        {
            return byteArray2Json((byte[]) o);
        }
        if (o instanceof Object) //?
        {
            return object2Json(o);
        }

        throw new RuntimeException(": " + o.getClass().getName());
    }

    static String string2Json(final String s) {
        final StringBuilder sb = new StringBuilder(s.length() + 20);
        sb.append('\"');
        for (int i = 0; i < s.length(); i++) {
            final char c = s.charAt(i);
            switch (c) {
            case '\"':
                sb.append("\\\"");
                break;
            case '\\':
                sb.append("\\\\");
                break;
            case '/':
                sb.append("\\/");
                break;
            case '\b':
                sb.append("\\b");
                break;
            case '\f':
                sb.append("\\f");
                break;
            case '\n':
                sb.append("\\n");
                break;
            case '\r':
                sb.append("\\r");
                break;
            case '\t':
                sb.append("\\t");
                break;
            default:
                sb.append(c);
            }
        }
        sb.append('\"');
        return sb.toString();
    }

    static String boolean2Json(final Boolean bool) {
        return bool.toString();
    }

    static String number2Json(final Number number) {
        return number.toString();
    }

    static String map2Json(final Map<String, Object> map) {
        if (map.isEmpty()) {
            return "{}";
        }
        final StringBuilder sb = new StringBuilder(map.size() << 4); //4
        sb.append('{');
        final Set<String> keys = map.keySet();
        for (final String key : keys) {
            final Object value = map.get(key);
            sb.append('\"');
            sb.append(key); //?
            sb.append('\"');
            sb.append(':');
            sb.append(toJson(value)); //?
            sb.append(',');
        }
        //  ','  '}': 
        sb.setCharAt(sb.length() - 1, '}');
        return sb.toString();
    }

    static String collection2Json(final Collection<Object> c) {
        final Object[] arrObj = c.toArray();
        return toJson(arrObj);
    }

    static String array2Json(final Object[] array) {
        if (array.length == 0) {
            return "[]";
        }
        final StringBuilder sb = new StringBuilder(array.length << 4); //4
        sb.append('[');
        for (final Object o : array) {
            sb.append(toJson(o));
            sb.append(',');
        }
        //  ','  ']': 
        sb.setCharAt(sb.length() - 1, ']');
        return sb.toString();
    }

    static String intArray2Json(final int[] array) {
        if (array.length == 0) {
            return "[]";
        }
        final StringBuilder sb = new StringBuilder(array.length << 4);
        sb.append('[');
        for (final int o : array) {
            sb.append(Integer.toString(o));
            sb.append(',');
        }
        // set last ',' to ']':
        sb.setCharAt(sb.length() - 1, ']');
        return sb.toString();
    }

    static String booleanArray2Json(final boolean[] array) {
        if (array.length == 0) {
            return "[]";
        }
        final StringBuilder sb = new StringBuilder(array.length << 4);
        sb.append('[');
        for (final boolean o : array) {
            sb.append(Boolean.toString(o));
            sb.append(',');
        }
        // set last ',' to ']':
        sb.setCharAt(sb.length() - 1, ']');
        return sb.toString();
    }

    static String longArray2Json(final long[] array) {
        if (array.length == 0) {
            return "[]";
        }
        final StringBuilder sb = new StringBuilder(array.length << 4);
        sb.append('[');
        for (final long o : array) {
            sb.append(Long.toString(o));
            sb.append(',');
        }
        // set last ',' to ']':
        sb.setCharAt(sb.length() - 1, ']');
        return sb.toString();
    }

    static String floatArray2Json(final float[] array) {
        if (array.length == 0) {
            return "[]";
        }
        final StringBuilder sb = new StringBuilder(array.length << 4);
        sb.append('[');
        for (final float o : array) {
            sb.append(Float.toString(o));
            sb.append(',');
        }
        // set last ',' to ']':
        sb.setCharAt(sb.length() - 1, ']');
        return sb.toString();
    }

    static String doubleArray2Json(final double[] array) {
        if (array.length == 0) {
            return "[]";
        }
        final StringBuilder sb = new StringBuilder(array.length << 4);
        sb.append('[');
        for (final double o : array) {
            sb.append(Double.toString(o));
            sb.append(',');
        }
        // set last ',' to ']':
        sb.setCharAt(sb.length() - 1, ']');
        return sb.toString();
    }

    static String shortArray2Json(final short[] array) {
        if (array.length == 0) {
            return "[]";
        }
        final StringBuilder sb = new StringBuilder(array.length << 4);
        sb.append('[');
        for (final short o : array) {
            sb.append(Short.toString(o));
            sb.append(',');
        }
        // set last ',' to ']':
        sb.setCharAt(sb.length() - 1, ']');
        return sb.toString();
    }

    static String byteArray2Json(final byte[] array) {
        if (array.length == 0) {
            return "[]";
        }
        final StringBuilder sb = new StringBuilder(array.length << 4);
        sb.append('[');
        for (final byte o : array) {
            sb.append(Byte.toString(o));
            sb.append(',');
        }
        // set last ',' to ']':
        sb.setCharAt(sb.length() - 1, ']');
        return sb.toString();
    }

    public static String object2Json(final Object bean) {
        //
        if (bean == null) {
            return "{}";
        }
        final Method[] methods = bean.getClass().getMethods(); //
        final StringBuilder sb = new StringBuilder(methods.length << 4); //4
        sb.append('{');

        for (final Method method : methods) {
            try {
                final String name = method.getName();
                String key = "";
                if (name.startsWith("get")) {
                    key = name.substring(3);

                    //
                    final String[] arrs = { "Class" };
                    boolean bl = false;
                    for (final String s : arrs) {
                        if (s.equals(key)) {
                            bl = true;
                            continue;
                        }
                    }
                    if (bl) {
                        continue; //
                    }
                } else if (name.startsWith("is")) {
                    key = name.substring(2);
                }
                if (key.length() > 0
                        && Character.isUpperCase(key.charAt(0))
                        && method.getParameterTypes().length == 0) {
                    if (key.length() == 1) {
                        key = key.toLowerCase();
                    } else if (!Character.isUpperCase(key.charAt(1))) {
                        key = key.substring(0, 1).toLowerCase()
                                + key.substring(1);
                    }
                    final Object elementObj = method.invoke(bean);

                    //System.out.println("###" + key + ":" + elementObj.toString());

                    sb.append('\"');
                    sb.append(key); //?
                    sb.append('\"');
                    sb.append(':');
                    sb.append(toJson(elementObj)); //?
                    sb.append(',');
                }
            } catch (final Exception e) {
                //e.getMessage();
                throw new RuntimeException("bean?JSON?"
                        + e.getMessage(), e);
            }
        }
        if (sb.length() == 1) {
            return bean.toString();
        } else {
            sb.setCharAt(sb.length() - 1, '}');
            return sb.toString();
        }
    }
}
Convert Object to Json String - Android File Input Output

Description

Demo Code

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