Java tutorial
/******************************************************************************* * This file is part of RedReader. * * RedReader is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * RedReader is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with RedReader. If not, see <http://www.gnu.org/licenses/>. ******************************************************************************/ package org.quantumbadger.redreader.jsonwrap; import android.support.annotation.IntDef; import com.fasterxml.jackson.core.JsonFactory; import com.fasterxml.jackson.core.JsonParseException; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonToken; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.io.Reader; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.reflect.InvocationTargetException; import java.net.URL; /** * Contains a literal, object, or array value, and is responsible for parsing * the incoming JSON stream. * * <p> * <b>To parse a JSON stream, call the JsonValue constructor with a JsonParser * as the argument, then call the "build" method (with the same JsonParser as an * argument) in another thread.</b> * </p> */ public final class JsonValue { public static final int TYPE_OBJECT = 0; public static final int TYPE_ARRAY = 1; public static final int TYPE_NULL = 2; public static final int TYPE_BOOLEAN = 3; public static final int TYPE_STRING = 4; public static final int TYPE_FLOAT = 5; public static final int TYPE_INTEGER = 6; @IntDef({ TYPE_OBJECT, TYPE_ARRAY, TYPE_NULL, TYPE_BOOLEAN, TYPE_STRING, TYPE_FLOAT, TYPE_INTEGER }) @Retention(RetentionPolicy.SOURCE) public @interface Type { } private final @Type int type; private final Object value; private JsonParser jp = null; /** * Begins parsing a JSON stream into a tree structure. The JsonValue object * created contains the value at the root of the tree. * * This constructor will block until the first JSON token is received. To * continue building the tree, the "build" method (inherited from * JsonBuffered) must be called in another thread. * * @param jp * The incoming JSON stream * @throws java.io.IOException */ public JsonValue(final JsonParser jp) throws IOException { this(jp, jp.nextToken()); } /** * Begins parsing a JSON stream into a tree structure. The JsonValue object * created contains the value at the root of the tree. * * This constructor will block until the first JSON token is received. To * continue building the tree, the "build" method (inherited from * JsonBuffered) must be called in another thread. * * @param source * The source of incoming JSON data. * @throws java.io.IOException */ public JsonValue(final InputStream source) throws IOException { this(new JsonFactory().createParser(source)); } /** * Begins parsing a JSON stream into a tree structure. The JsonValue object * created contains the value at the root of the tree. * * This constructor will block until the first JSON token is received. To * continue building the tree, the "build" method (inherited from * JsonBuffered) must be called in another thread. * * @param source * The source of incoming JSON data. * @throws java.io.IOException */ public JsonValue(final URL source) throws IOException { this(new JsonFactory().createParser(source)); } /** * Begins parsing a JSON stream into a tree structure. The JsonValue object * created contains the value at the root of the tree. * * This constructor will block until the first JSON token is received. To * continue building the tree, the "build" method (inherited from * JsonBuffered) must be called in another thread. * * @param source * The source of incoming JSON data. * @throws java.io.IOException */ public JsonValue(final byte[] source) throws IOException { this(new JsonFactory().createParser(source)); } /** * Begins parsing a JSON stream into a tree structure. The JsonValue object * created contains the value at the root of the tree. * * This constructor will block until the first JSON token is received. To * continue building the tree, the "build" method (inherited from * JsonBuffered) must be called in another thread. * * @param source * The source of incoming JSON data. * @throws java.io.IOException */ public JsonValue(final String source) throws IOException { this(new JsonFactory().createParser(source)); } /** * Begins parsing a JSON stream into a tree structure. The JsonValue object * created contains the value at the root of the tree. * * This constructor will block until the first JSON token is received. To * continue building the tree, the "build" method (inherited from * JsonBuffered) must be called in another thread. * * @param source * The source of incoming JSON data. * @throws java.io.IOException */ public JsonValue(final File source) throws IOException { this(new JsonFactory().createParser(source)); } /** * Begins parsing a JSON stream into a tree structure. The JsonValue object * created contains the value at the root of the tree. * * This constructor will block until the first JSON token is received. To * continue building the tree, the "build" method (inherited from * JsonBuffered) must be called in another thread. * * @param source * The source of incoming JSON data. * @throws java.io.IOException */ public JsonValue(final Reader source) throws IOException { this(new JsonFactory().createParser(source)); } // The main constructor protected JsonValue(final JsonParser jp, final JsonToken firstToken) throws IOException { switch (firstToken) { case START_OBJECT: type = TYPE_OBJECT; value = new JsonBufferedObject(); this.jp = jp; break; case START_ARRAY: type = TYPE_ARRAY; value = new JsonBufferedArray(); this.jp = jp; break; case VALUE_FALSE: type = TYPE_BOOLEAN; value = false; break; case VALUE_TRUE: type = TYPE_BOOLEAN; value = true; break; case VALUE_NULL: type = TYPE_NULL; value = null; break; case VALUE_STRING: type = TYPE_STRING; value = jp.getValueAsString(); break; case VALUE_NUMBER_FLOAT: //noinspection FloatingPointEquality,UnnecessaryExplicitNumericCast if (jp.getValueAsDouble() == (double) jp.getValueAsLong()) { type = TYPE_INTEGER; value = jp.getValueAsLong(); } else { type = TYPE_FLOAT; value = jp.getValueAsDouble(); } break; case VALUE_NUMBER_INT: type = TYPE_INTEGER; value = jp.getValueAsLong(); break; default: throw new JsonParseException("Expecting an object, literal, or array", jp.getCurrentLocation()); } } /** * Continues the process of parsing the specified JSON stream. * * This method will block until the stream is fully parsed, but it is * possible to make use of this value and its descendants in other threads * while this is occurring. * * @throws java.io.IOException */ public void buildInThisThread() throws IOException { if (type == TYPE_OBJECT || type == TYPE_ARRAY) { ((JsonBuffered) value).build(jp); } this.jp = null; } /** * @return The type of value this JsonValue contains. */ public @Type int getType() { return type; } /** * @return True if the type of this value is NULL. */ public boolean isNull() { return type == TYPE_NULL; } /** * @return If this JsonValue contains a JSON object, then this method * returns that object. The type of value this JsonValue contains * can be checked with the getType() method. */ public JsonBufferedObject asObject() { switch (type) { case TYPE_NULL: return null; default: return (JsonBufferedObject) value; } } public <E> E asObject(final Class<E> clazz) throws InstantiationException, IllegalAccessException, InterruptedException, IOException, NoSuchMethodException, InvocationTargetException { switch (type) { case TYPE_NULL: return null; default: return asObject().asObject(clazz); } } /** * @return If this JsonValue contains a JSON array, then this method returns * that array. The type of value this JsonValue contains can be * checked with the getType() method. */ public JsonBufferedArray asArray() { switch (type) { case TYPE_NULL: return null; default: return (JsonBufferedArray) value; } } /** * @return If this JsonValue contains a boolean, then this method returns * that boolean. The type of value this JsonValue contains can be * checked with the getType() method. */ public Boolean asBoolean() { switch (type) { case TYPE_NULL: return null; default: return (Boolean) value; } } /** * @return If this JsonValue contains a string, then this method returns * that string. The type of value this JsonValue contains can be * checked with the getType() method. */ public String asString() { switch (type) { case TYPE_FLOAT: return String.valueOf(asDouble()); case TYPE_INTEGER: return String.valueOf(asLong()); case TYPE_BOOLEAN: return String.valueOf(asBoolean()); case TYPE_NULL: return null; default: return (String) value; } } /** * @return If this JsonValue contains a double, then this method returns * that double. The type of value this JsonValue contains can be * checked with the getType() method. */ public Double asDouble() { switch (type) { case TYPE_NULL: return null; case TYPE_INTEGER: return ((Long) value).doubleValue(); case TYPE_STRING: return Double.parseDouble(asString()); default: return (Double) value; } } /** * @return If this JsonValue contains an integer, then this method returns * that integer. The type of value this JsonValue contains can be * checked with the getType() method. */ public Long asLong() { switch (type) { case TYPE_NULL: return null; case TYPE_FLOAT: return ((Double) value).longValue(); case TYPE_STRING: return Long.parseLong(asString()); default: return (Long) value; } } @Override public String toString() { final StringBuilder sb = new StringBuilder(); try { prettyPrint(0, sb); } catch (InterruptedException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return sb.toString(); } protected void prettyPrint(final int indent, final StringBuilder sb) throws InterruptedException, IOException { switch (type) { case TYPE_BOOLEAN: sb.append(asBoolean()); break; case TYPE_FLOAT: sb.append(asDouble()); break; case TYPE_INTEGER: sb.append(asLong()); break; case TYPE_NULL: sb.append("null"); break; case TYPE_STRING: sb.append("\"").append(asString().replace("\\", "\\\\").replace("\"", "\\\"")).append("\""); break; case TYPE_ARRAY: case TYPE_OBJECT: ((JsonBuffered) value).prettyPrint(indent, sb); break; } } public void join() throws InterruptedException { if (getType() == TYPE_ARRAY || getType() == TYPE_OBJECT) { ((JsonBuffered) value).join(); } } }