MapXtreme for Java开发专题三：怎样进行空间特征值的搜索-MyGIS软件工作室/James MapInfo技术论坛

发表用户：LongRiver

收集整理：James.Liu

信息原始来源：不祥

文章标题：MapXtreme for Java开发专题三：怎样进行空间特征值的搜索

1.        Search介绍
有时可能做一些搜索，如搜索配送中心周围的零售店。MapXtreme提供了丰富的搜索功能。搜索的结果可以转换为被选中状态，从而显示在地图上。Search是Layer对象的方法，有：
• searchAll
• searchWithinRadius
• searchWithinRegion
• searchWithinRectangle
• searchAtPoint
• searchByAttribute
• searchByPrimaryKey
       使用这些查询都需要给出要返回的字段集合和执行的查询动作。返回的字段集合需要放在Vector对象中。下面的例子返回的是表中所有的字段：
//Assume myLayer is a Layer object.
TableInfo myTableInfo = myLayer.getTableInfo( );
Vector columnNames = new Vector( );
int columnCount = myTableInfo.getColumnCount( );
String col;
for (int j=0; j<columnCount; j++)
{
col = myTableInfo.getColumnName(j);
columnNames.addElement(col);
}
       在默认情况下，执行查询时后得到的FeatureSet包含Geometry，Rendition，LabelRendition，PrimaryKey，raster Data等，所以需要使用QueryParams 类来过滤这些信息，以提高程序的性能。
       进行查询时可以通过QueryParams指定查询类型SearchType。Mbr表示搜索最小外接矩形和搜索范围相交的图元；patial表示搜索和搜索范围相交的图元；entire表示搜索完全在搜索范围的的图元。
       下面代码示例如何使用QueryParams：
QueryParams qp = new QueryParams(bGeometry,bRendition,bPrimarykey,bLabelPoint,bRasterInfo,bLabelRendition, SearchType.entire);
       下面示例了如何过滤信息：
// find all Features entirely within a given search region, return a single Attribute column //and noRendition information.
Vector cols = new Vector();
cols.addElement(“County”);
Feature searchFeature  =mapj.getFeatureFactory().createRegion(points, rend,attribs,null);
QueryParams queryParams = new QueryParams(true, false,true,true, true, true, SearchType.entire);
FeatureSet fs = layer.searchWithinRegion(cols,searchFeature.getGeometry(),  queryParams);
2. Search方法
:        searchAll
示例：
//Assume fs is a FeatureSet object.Assume columnNames is a vector of the columns //to be returned.Assume qp is the QueryParams object.Assume myLayer is a Layer //object.
try
{
fs = myLayer.searchAll(columnNames,qp);
}
catch(exception e)
{
e.printStackTrace();
}

:==>searchWithinRadius
示例：
//Assume fs is a FeatureSet object. Assume columnNames is a vector of the desired //columns  to be returned. Assume qp is the QueryParams object.Assume myLayer //is a Layer object.
DoublePoint dblPt = new DoublePoint(-73.889444,42.765555);
double dRadius = 10.03;
try
{
fs = myLayer.searchWithinRadius(columnNames,dblPt,dRadius,LinearUnit.mile,qp);
}
catch(exception e)
{
e.printStackTrace();
}

==> searchWithinRegion
示例：
private boolean layerSearchWithinRegion()
{
//Assume fs is a FeatureSet object.Assume columnNames is a vector of the columns //to be  returned.Assume qp is the QueryParams object.Assume myLayer is a Layer //object.Assume vGeom is a VectorGeometry of TYPE_REGION
try
{
fs =myLayer.searchWithinRegion(columnNames,vGeom,qp);
}
catch(Exception e)
{
e.printStackTrace();
return false;
}
return true;
}

==> searchWithinRectangle
示例：
//Assume fs is a FeatureSet object.Assume columnNames is a vector of the columns //to be returned.Assume qp is the QueryParams object.Assume myLayer is a Layer //object.
DoubleRect dRect = new DoubleRect(-74.092662,42.765555,-73.668898,42.856420);
try
{
fs =myLayer.searchWithinRectangle(columnNames,dRect,qp);
}
catch(exception e)
{
e.printStackTrace();
}

==>searchAtPoint
示例：
//Assume fs is a FeatureSet object.Assume columnNames is a vector of the columns //to be returned.Assume qp is the QueryParams object.Assume myLayer is a Layer //object.
DoublePoint dp = new DoublePoint(12.3456,-67.890);
try
{
fs = myLayer.searchAtPoint(columnNames,dp,qp);
}
catch(exception e)
{
e.printStackTrace();
}

==> searchByAttribute
示例：
//Assume fs is a FeatureSet object.Assume columnNames is a vector of the columns to //be  returned.Assume qp is the QueryParams object.Assume myLayer is a Layer //object.Assume attr is the attribute to search against.Assume colName is the column to //search against.
try
{
fs =myLayer.searchByAttribute(columnNames,colName,attr,qp);
}
catch(Exception e)
{
e.printStackTrace();
return false;
}
==>searchByPrimaryKey
示例：
       可以使用searchByPrimaryKey返回特定的FeatureSet。
private boolean layerSearchByPrimaryKey()
{
// Assume fs is a FeatureSet object. Assume columnNames is a vector of the //columns to be returned. Assume qp is the QueryParams object. Assume myLayer //is a Layer object. Assume colName is the column to search against. Assume pk is a //PrimaryKey from a previous search.

PrimaryKey[] arraypk = new PrimaryKey[1];
arraypk[0] = pk;
try
{
fs = myLayer.searchByPrimaryKey(columnNames,arraypk,qp);
}
catch(Exception e)
{
e.printStackTrace();
return false;
}
return true;
}
}