多流在线与离线数据读取之四（Android移动端开发读取四川地理信息中心切片底图）

本系列专题本来上次想一次性写完，无奈工作太忙，上月就中断了一个月，这个月补上两篇，在此对各位表示抱歉。

本实例主要是针对四川地理信息中心的切片，如果利用ArcGIS for Android API进行解析，并读入作用底图。

1）基础准备：下载Java版的Json解析库（http://code.google.com/p/json-simple/）、熟悉四川地理信息中心切片规则

2）关于四川地理信息中心的切片规则这就不做介绍了，在以前专题已介绍过，详见：http://www.scgis.net/

3）代码说明

AgsLOD.java:切片等级信息定义文件，在这定义了比例尽、等级、分辨率

package com.esri.arcgis.android.samples;import com.esri.core.internal.d.c;public class AgsLOD extends c {private static final long serialVersionUID = 4341699179151728883L;        private int level;    private double resolution;    private double scale;    public AgsLOD(int level, double scale, double resolution) {	super();	this.level = level;	this.scale = scale;	this.resolution = resolution;    }    public int a() {	return this.level;    }    public double b() {	return this.resolution;    }    public double c() {	return this.scale;    }}

package com.esri.arcgis.android.samples;import java.io.BufferedReader;import java.io.InputStreamReader;import java.net.HttpURLConnection;import java.net.URL;public class GetToken {	//get token	public String sendPost(String url) {  		StringBuilder result = new StringBuilder();          try {              URL httpurl = new URL(url);              HttpURLConnection httpConn = (HttpURLConnection) httpurl                      .openConnection();              httpConn.setDoInput(true);              BufferedReader in = new BufferedReader(new InputStreamReader(                      httpConn.getInputStream(),"UTF-8"));              String line;              while ((line = in.readLine()) != null) {                  result .append(line);              }              //System.out.println(result);            in.close();             //get token            return result.toString().split("\"")[15];        } catch (Exception e) {              e.printStackTrace();                   }		return null;	}}

SCGISModel.java：切片参数定义文件，包括切片的空间参考等基础信息

package com.esri.arcgis.android.samples;import java.io.BufferedInputStream;import java.io.ByteArrayOutputStream;import java.io.File;import java.net.HttpURLConnection;import java.net.URL;import com.esri.core.geometry.Envelope;import com.esri.core.geometry.SpatialReference;import com.esri.core.internal.d.k;import com.esri.core.map.TiledLayerModel;public class SCGISModel extends TiledLayerModel {    private static final long serialVersionUID = 7726567118839553087L;        private String location;    private String token;    public SCGISModel(String location, SpatialReference sr, Envelope full,	    k tileInfo) {	super(sr, full, tileInfo);	this.location = location;	this.token=new GetToken().sendPost("http://www.scgis.net.cn/imap/iMapServer/Token/getToken?username=test20110703&password=test20110703&IpAddress=&TimeSpan=100M&st=1302073818076");    }            @Override    public byte[] getTile(int level, int row, int col) throws Exception {	byte[] result = null;		try {			int levelCustom = level + 1;			String bundlesDir = location					+ levelCustom					+ File.separator					+ row					+ File.separator					+ col					+ "?token="+this.token;			;			ByteArrayOutputStream bos = new ByteArrayOutputStream();			URL sjwurl = new URL(bundlesDir);			HttpURLConnection httpUrl = null;			BufferedInputStream bis = null;			byte[] buf = new byte[1024];			httpUrl = (HttpURLConnection) sjwurl.openConnection();			httpUrl.connect();			bis = new BufferedInputStream(httpUrl.getInputStream());						while (true) {				int bytes_read = bis.read(buf);				if (bytes_read > 0) {					bos.write(buf, 0, bytes_read);				} else {					break;				}			}			;			bis.close();			httpUrl.disconnect();			result = bos.toByteArray();		} catch (Exception ex) {			ex.printStackTrace();		}	return result;    }}

SCGISMapServices.java：继承tiledLayer,自定义切片类。

package com.esri.arcgis.android.samples;import java.util.ArrayList;import android.content.Context;import android.util.AttributeSet;import com.esri.android.map.TiledLayer;import com.esri.core.geometry.Envelope;import com.esri.core.geometry.Point;import com.esri.core.geometry.SpatialReference;import com.esri.core.internal.d.c;import com.esri.core.internal.d.k;import com.esri.core.map.TiledLayerModel;public class SCGISMapServices extends TiledLayer {	private String location = "http://www.scgis.net.cn/iMap/iMapServer/NewRest/services/SCTileMap/tile/";	private SpatialReference spatialReference = SpatialReference.create(4326);	private Envelope fullExtent = new Envelope(95.918, 24.898, 110.14, 35.209);	private k tileInfo;	public SCGISMapServices(Context context, AttributeSet attrs) {		super(context, attrs);		try {			init();		} catch (Exception ex) {			ex.printStackTrace();		}	}	@Override	protected TiledLayerModel initModel() throws Exception {		return new SCGISModel(location, spatialReference, fullExtent, tileInfo);	}	private void init() {		try {			tileInfo = new k();						tileInfo.f = new Point(-180, 90);						tileInfo.a = 256;						tileInfo.b = 256;			tileInfo.h = new ArrayList<c>();						double resolution = 0.010998662747496;			double scale=4622333.68;			for (int j = 0, jcount = 11; j < jcount; j++) {								int level = j;				tileInfo.h.add(new AgsLOD(level, scale, resolution));								resolution/=2;				scale/=2;			}		} catch (Exception e) {			e.printStackTrace();		}	}}

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