java io

今天看maven项目的时候看了几个列子

1、主要是我一直对io方面的api也不是太熟悉，现在就写点一便下次记得

//main文件

import java.io.InputStream;
import org.apache.log4j.PropertyConfigurator;
public class Main {
public static void main(String[] args) throws Exception {
// Configure Log4J        取log4j的属性文件的时候，可以直接这么取
PropertyConfigurator.configure(Main.class.getClassLoader()
.getResource("log4j.properties"));
// Read the Zip Code from the Command-line (if none supplied, use 60202)
int zipcode = 60202;
try {
zipcode = Integer.parseInt(args[0]);
} catch( Exception e ) {}

........

}}

 

 

//2、通过url取的响应的输入流

import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import org.apache.log4j.Logger;
public class YahooRetriever {
private static Logger log = Logger.getLogger(YahooRetriever.class);
public InputStream retrieve(int zipcode) throws Exception {
log.info( "Retrieving Weather Data" );   //通过url取的响应的输入流
String url = "http://weather.yahooapis.com/forecastrss?p=" + zipcode;
URLConnection conn = new URL(url).openConnection();
return conn.getInputStream();
}

}

 

 

//将输入流转为java实例

import org.apache.log4j.Logger;
import org.dom4j.Document;
import org.dom4j.DocumentFactory;
import org.dom4j.io.SAXReader;
public class YahooParser {
private static Logger log = Logger.getLogger(YahooParser.class);
public Weather parse(InputStream inputStream) throws Exception {
Weather weather = new Weather();
log.info( "Creating XML Reader" );
SAXReader xmlReader = createXmlReader();         //通过xmlreader来读取输入
Document doc = xmlReader.read( inputStream );
log.info( "Parsing XML Response" );
weather.setCity( doc.valueOf("/rss/channel/y:location/@city") );
weather.setRegion( doc.valueOf("/rss/channel/y:location/@region") );
weather.setCountry( doc.valueOf("/rss/channel/y:location/@country") );
weather.setCondition( doc.valueOf("/rss/channel/item/y:condition/@text") );
weather.setTemp( doc.valueOf("/rss/channel/item/y:condition/@temp") );
weather.setChill( doc.valueOf("/rss/channel/y:wind/@chill") );
weather.setHumidity( doc.valueOf("/rss/channel/y:atmosphere/@humidity") );
return weather;
}
private SAXReader createXmlReader() {
Map<String,String> uris = new HashMap<String,String>();
uris.put( "y", "http://xml.weather.yahoo.com/ns/rss/1.0" );
DocumentFactory factory = new DocumentFactory();
factory.setXPathNamespaceURIs( uris );
SAXReader xmlReader = new SAXReader();
xmlReader.setDocumentFactory( factory );
return xmlReader;
}
}

 

 

//将读取的数据写入响应的文件中

import org.apache.log4j.Logger;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
public class WeatherFormatter {
private static Logger log = Logger.getLogger(WeatherFormatter.class);
public String format( Weather weather ) throws Exception {
log.info( "Formatting Weather Data" );
Reader reader =
new InputStreamReader( getClass().getClassLoader()
.getResourceAsStream("output.vm"));      //得到一个展示层
VelocityContext context = new VelocityContext();
context.put("weather", weather );
StringWriter writer = new StringWriter();
Velocity.evaluate(context, writer, "", reader);       //通过此模板将数据输入
return writer.toString();

 

 

 

最后maven中用。在项目的基
础目录下运行以下命令，以运行该程序的 Main 类。

$ mvn install
$ mvn exec:java -Dexec.mainClass=org.sonatype.mavenbook.weather.Main