maptile.java

基于J2ME的手机地图客户端源码

package org.sreid.j2me.gmapviewer;

import javax.microedition.lcdui.Image;
import java.io.*;

class MapTile {
	static final int WIDTH = 128;
	static final int HEIGHT = 128;

	static final byte WITH_BYTES = 101, WITH_RMSID = 102, WITH_MINIMUM = 0;
	private static final byte SERIALIZED_VERSION = 1;

	final XYZ xyz;
	Image image;
	byte[] bytes;
	int rmsID = -1; // ID in RMS-based cache, or -1 if invalid.
	int rmsBytesUsed; // only valid if rmsID != -1

	boolean downloading = false;
	boolean decoding = false;

	MapTile(XYZ xyz) {
		this.xyz = xyz;
	}

	/** Constructs from previously saved data. Only sets fields: xyz, and either bytes or rmsID */
	MapTile(DataInput in, byte withBytesOrRmsID) throws IOException {
		byte v = in.readByte();
		if (v != SERIALIZED_VERSION) throw new IOException("Bad version header in data");
		int x = in.readInt();
		int y = in.readInt();
		int z = in.readByte();
		xyz = new XYZ(x, y, z);
		switch (withBytesOrRmsID) {
			case WITH_BYTES:
				int nBytes = in.readInt();
				byte[] b = new byte[nBytes];
				in.readFully(b);
				bytes = b;
				rmsBytesUsed = b.length;
				break;
			case WITH_RMSID:
				rmsID = in.readInt();
				rmsBytesUsed = in.readInt();
				break;
			case WITH_MINIMUM:
				break;
			default:
				throw new IllegalArgumentException("Not a valid option: " + withBytesOrRmsID);
		}
	}

	void writeTo(DataOutput out, byte withBytesOrRmsID) throws IOException {
		out.writeByte(SERIALIZED_VERSION);
		out.writeInt(xyz.x);
		out.writeInt(xyz.y);
		out.writeByte((byte)xyz.z);
		switch (withBytesOrRmsID) {
			case WITH_BYTES:
				out.writeInt(bytes.length);
				out.write(bytes);
				break;
			case WITH_RMSID:
				out.writeInt(rmsID);
				out.writeInt(rmsBytesUsed);
				break;
			default:
				throw new IllegalArgumentException("Not a valid option: " + withBytesOrRmsID);
		}
	}

	public String toString() {
		return "MapTile["
		 + xyz
		 + "," + (bytes == null ? -1 : bytes.length)
		 + "," + rmsID
		 + "," + rmsBytesUsed 
		 + "," + (image == null ? "null" : "" + image.getWidth() + "x" + image.getHeight())
		 + "," + downloading
		 + "," + decoding
		 + "," + System.identityHashCode(this)
		 + "]";
	}

}